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  1. UPDATED TUTORIAL: A Ridiculously Easily Way to Convert CT Scans to 3D Printable Bone STL Models for Free in Minutes Hello and welcome back. I hope you enjoyed my last tutorial on creating 3D printable medical models using free software on Macintosh computers. In this brief video tutorial I'll show you how to create a 3D printable skull STL file from a CT scan in FIVE minutes using only free and open source software. In the video I use a program called 3D Slicer, which is available from slicer.org. 3D Slicer works on Windows, Macintosh, and Linux operating systems. Also, I use Blender, which is available from blender.org, to perform some mesh cleanup. Finally, I check my model prior to 3D printing using Meshmixer from Autodesk. This is available at meshmixer.com. All software programs are free. If you like this, view my complete tutorial where I go through each step shown here in detail. I hope you enjoy the video.
  2. I was recently contacted by another doctor who asked if I could help him to create a 3D printed replicate of his spine to visualize pinched nerves in his low back and aid with planning a future back surgery. In order to work this doctor has to stand for long hours while performing surgical procedures. Excruciating low back pain had limited his ability to stand to only 30 minutes. As you can imagine, this means he couldn't work. Things only got worse after he had low back surgery. A CT scan of his lumbar spine (the low back portion of the spine) was performed. It showed that his fifth lumbar vertebra was partially sacralized. This means it looked more like a sacral vertebra than a lumbar vertebra. Was this causing his problem? On the image slices of the CT scan it was difficult to tell. How the Spine is Organized First, a word about the different vertebrae (bones) in the spine. There are four main sections of spinal bones. The seven cervical vertebrae are in the neck and support the head. They are generally small but flexible, and allow rotation of the head. The 12 thoracic vertebrae are in the chest. Their most distinctive characteristic is they all have associated ribs, which make up the rib cage. The five lumbar vertebrae are in the low back. These are large and strong, and designed for supporting lots of weight. They do not have associated ribs. The five sacral vertebrae are in the pelvis. In adults, they are fused together and effectively form a single bone, the sacrum. The coccyx, or tailbone, which is a tiny bone at the bottom end of the vertebral column, can be considered a fifth spinal section. This is the bone that is often injured when you fallen your behind. Figure 1 shows the different sections of the vertebral column. Figure 1. Sections of the vertebral column. Source:aimisspine.com Although the bones of the individual sections of the spine usually have their own unique features, it is not uncommon for vertebrae in one section to have features typically associated with an adjacent section. This is particularly true of the vertebrae that are immediately adjacent to a neighboring section. These hybrids are a mix between both sections, are called transitional vertebrae. Do you recall that only thoracic vertebrae have associated ribs? Occasionally the highest lumbar vertebra, L1, will have tiny ribs attached to it. This is a normal variant and is usually harmless. Radiologists who are interpreting medical scans need to be careful to not confuse an L1 vertebra which may have tiny ribs for the adjacent T12 vertebra which normally has ribs. Similarly, the lowest lumbar vertebra, L5, which is normally unfused, can exhibit fusion. As you recall, fusion is a characteristic of sacral vertebrae. A Congenital Spine Abnormality This was the situation with our physician. His lowest lumbar vertebra, L5, has partially fused with S1, the highest sacral vertebra. This condition is congenital. He has had it all his life. The fusion can have the side effect of creating a very narrow bony canal through which the L5 nerve roots can exit the spine. Normally, these nerve roots would have much more space as a large gap would exist between the normally unfused L5 and S1 vertebrae. Was this the problem? The CT scan showed the sacralization of L5, but it was difficult to get a sense for how tight the holes through which the nerves exit, the neural foramina, were. See Figures 2 and 3. Figure 2: Coronal CT image through the L5 and S1 vertebral bodies. Is this the cause of the problem? It is very difficult to get an intuitive sense of what is going on with these flat image slices. Figure 3: Image from Figure 2 with the neural foramina marked. Seeking help through Embodi3D The doctor contacted me through the Embodi3D website and asked if I could create a 3D model design and 3D print of his lumbar spine to help him and his team of spinal specialists understand his unique anatomy better. Of course, I was happy to help. The CT scan was of high quality and allowed me to extract the bones and metallic spinal fusion implants with little trouble. The individual nerves, however, were very difficult to see even on a high quality CT scan. I had to manually segment them one image at a time, which was a very tedious and time-consuming process. After fusing everything together, I had a very good digital model of the lumbar spine. I created some photorealistic 3D renders to illustrate the key findings. Figures 4 and 5 show the very tight L5-S1 bony neural foramina. The inter-vertebral disc sits within the gap between the two vertebral bodies, and you can see how a lateral bulge from this disc would significantly pinch these exiting nerve roots. Figure 4: Right L5 nerve root (yellow) exiting the tight neural foramen caused by the fused L5 and S1 lateral processes. Figure 5: Left L5 nerve root (yellow) exiting the tight neural foramen caused by the fused L5 and S1 lateral processes. Additionally, I showed that a bone screw that had been placed during the last surgery had partially exited the L4 vertebral body and was in very close proximity, and probably touching, the adjacent nerve root. Ouch! This can be seen in Figure 6. This may explain why the pain seem to get worse after the last surgery. Figure 6: Transpedicular orthopedic screw which has partially exited the L4 vertebral body and is in very close proximity or in contact with the right L3 nerve root. The Final 3D Printed Spine Model The doctor wanted his spine 3D printed in transparent material, so I used a stereolithographic printer with transparent resin. I printed the spine in two separate parts that could be separated and fit together. When separated, the nerves exiting through the neural foramina can be inspected from inside the spinal canal, which gives an added degree of understanding. Final pictures of the transparent 3D printed model are shown below. I just recently shipped the model to this doctor and don't yet know how his back problems will be resolved. With this 3D printed model in hand however, he will be able to have much more meaningful discussions with his spinal surgeons about the best way to definitively fix his low back problems. I hope that the 3D printed spine model will literally help to get this good doctor back on his feet again.
  3. Please note that any references to “Imag3D” in this tutorial should be replaced with “democratiz3D” In this tutorial we will discuss how to share, sell, organize, and reprocess 3D printable medical models you make using the free online democratiz3D service from embodi3D. democratiz3D is a powerful tool that automatically converts a medical CT scan into a 3D printable file in minutes with minimal user input. It is no longer necessary to master complicated desktop software and spend hours manually segmenting to create a 3D printable model. Learn how to make high quality medical 3D models with democratiz3D by following my introductory guide to creating medical 3D printing files and my more advanced 3D printing file processing tutorial. Once you create your medical masterpiece, you can share, sell, organize, or tweak your model to make it perfect. This tutorial will show you how. Resubmit your CT Scan for Reprocessing into Bone STL If you are trying to learn the basics of how to convert CT scans into 3D printable STL models, please see my earlier tutorials on basic creation of 3D printable models and more advanced multiprocessing. If you are not 100% satisfied with the quality of your STL model, you can resubmit the input scan file for repeat processing. To do this, go to the page for your input NRRD file. IMPORTANT: this is the NRRD file you originally uploaded to the website, NOT the STL file that was generated for you by the online service. Since both the original NRRD file and the processed STL file have similar titles, you can tell the difference by noting that the NRRD file you uploaded won't have any thumbnails, Figure 1. In most cases, the processed file will have the word "processed" appended to the file name. Figure 1: Choose the original NRRD file, not the generated STL file. You can find your files underneath your profile, as shown in Figure 2. That will show you your most recent activity, including recently uploaded files. Figure 2: Finding your files under your profile. If you uploaded the file long ago or contribute a lot of content to the site, your uploaded NRRD file may not be among the first content item shown. You can search specifically for your files by clicking on See My Activity under your Profile, and selecting Files from the left hand now bar, as shown in Figures 3 and 4. Figure 3: Showing all your activity. Figure 4: Showing the files you own. Once you have found your original NRRD file, open the file page and select File Actions on the lower left-hand corner, as shown in Figure 5. Choose Edit Details as shown in Figure 6. Figure 5: File Actions – start making changes to your file Figure 6: Edit Details Scroll down until you reach the democratiz3D Processing section. Make sure that the democratiz3D Processing slider is turned ON. Then, make whatever adjustments you want to the processing parameters Threshold and Quality, as shown in Figure 7. Threshold is the value in Hounsfield units to use when performing the initial segmentation. Quality is a measure of the number of polygons in the output mesh. Low quality is quick to process and generates a small output file. Low quality is suitable for small and geometrically simple structures, such as a patella or single bone. High quality takes longer to process and produces a very large output file, sometimes with millions of polygons. This is useful for very large structures or complex anatomy, such as a model of an entire spine where you wish to capture every crack and crevice of the spine. Medium quality is a good balance and suitable in most cases. Figure 7: Changing the processing parameters. When you're happy with your parameter choices, click Save. The file will now be submitted for reprocessing. In 5 to 15 minutes you should receive an email saying that your file is ready. From this NRRD file, an entirely new STL file will be created using your updated parameters and saved under your account. Sharing your 3D Printing File on embodi3D.com Sharing your file with the embodi3D community is easy. You can quickly share the file by toggling the privacy setting on the file page underneath the File Information box on the lower right, as shown in Figure 8. If this setting says "Shared," then your file is visible and available for download by registered members of the community. If you wish to have more detailed control over how your file is shared, you can edit your file details by clicking on the File Actions button on the lower left-hand side of the file page, also shown in Figure 8. Click on the Edit Details menu item. This will bring you to the file editing page which will allow you to change the Privacy setting (shared versus private), License Type (several Creative Commons and a generic paid file license are available), and file Type (free versus paid). These are shown in detail in Figure 9. Click Save to save your settings. Figure 8: Quick sharing your file, and the File Actions button Figure 9: Setting the file type, privacy, and license type for your file. Sell your Biomedical 3D Printing File and Generate Income If you would like to sell your file and charge a fee for each download, you may do so by making your file a Paid File. If you have a specialized model that there is some demand for, you can generate income by selling your file in the marketplace. From the Edit Details page under File Actions, as shown in Figure 8, scroll down until you see Type. Choose Paid for the Type. Choose the price you wish to sell your file for in the Price field. This is in US dollars. Buyers will use PayPal to purchase the file where they can pay with Paypal funds or credit card. Make sure that the privacy setting is set to Shared. If you list your file for sale but keep it private and invisible to members, you won't sell anything. Finally, make sure you choose an appropriate license for users who will download your file. The General Paid File License is appropriate and most instances, but you have the option to include a customized license if you wish. This is shown in Figure 10. Figure 10: Configuring settings to sell your file The General Paid File License contains provisions appropriate for most sellers. It tells the purchaser of your file that they can download your file and create a single 3D print, but they can't resell your file or make more than one print without paying you additional license fees. All purchasers must agree to the license prior to download. If you wish to have your own customized license terms, you can select customized license and specify your terms in the description of the file. Organize your file by moving it to a new category If you share your file, you should move the file into an appropriate file category to allow people to find it easily. This is quite simple to do. From the file page, select File Actions and choose the Move item, as shown in Figure 11. You will be able to choose any of the file categories. Choose the one that best fits your particular file. Figure 11: Moving your file to a new category. That's it! Now you can share your amazing 3D printable medical models with the world.
  4. In this brief tutorial we will go over how to use Meshmixer to create a hollow shell from a medical 3D printable STL file. Hollowing out the shell, as shown in the pictures below, can allow you to 3D print the model using much less material that printing a solid piece. The print will take less time and cost less money. For this tutorial we will use a head that we created from a real medical CT scan in a prior tutorial, " Easily Create 3D Printable Muscle and Skin STL Files from Medical CT Scans" If you haven't seen the prior tutorial, please check it out. To follow along with the tutorial, please download the accompanying file. This will enable you to replicate the process exactly as it is shown in the tutorial. >> DOWNLOAD THE TUTORIAL FILE NOW <<
  5. Note: This tutorial accompanies a workshop I presented at the 2016 Radiological Society of North America (RSNA) meeting. The workflow and techniques presented in this tutorial and the conference workshop are identical. In this tutorial we will be using two different ways to create a 3-D printable medical model of a head and neck which will be derived from a real contrast-enhanced CT scan. The model will show detailed anatomy of the bones, as well as the veins and arteries. We will independently create this model using two separate methods. First, we will automatically generate the model using the free online service embodi3D.com. Next, we will create the same file using free desktop software programs 3D Slicer and Meshmixer. If you haven't already, please download the associated file pack which contains the files you'll need to follow along with this tutorial. Following along with the actual files used here will make learning these techniques much easier. The file pack is free. You need to be logged into your embodi3D account to download, but registration is also free and only takes a minute. Also, you'll need an embodi3D.com account in order to use the online service. Registration is worth it, so if you haven't already go ahead and register now. >> DOWNLOAD THE FILE PACK NOW << Online Service: embodi3D.com Step 1: Go to the embodi3D.com website and click on the democratiz3D menu item in the naw bar. Click on the "Launch democratizD" link, as shown in Figure 1. Figure 1: Opening the free online 3D model making service service democratiz3D. Step 2: Now you have to upload your imaging file. Drag and drop the file MANIX Angio CT.nrrd from the File Pack, as shown in Figure 2. This contains the CT scan of the head and neck in NRRD file format. If you are using a file other NRRD that provided by the file pack, please be aware the file must contain a CT scan (NOT MRI!) and the file must be in NRRD format. If you don't know how to create an NRRD file, here is a simple tutorial that explains how. Figure 2: Dragging and dropping the NRRD file to start uploading. Step 3: Type in basic information on the file being uploaded, including File name, file description, and whether you want to share the file or keep it private. Bear in mind that this information pertains to the uploaded file, not the file that will be generated by the service. Step 4: Type in basic parameters for file processing. Turn on the processing slider. Here you will enter in basic information about how you would like the file to be processed. Under Operation, select CT NRRD to Bone STL Detailed, as shown in Figure 3. This will convert a CT scan in NRRD format to a bone STL with high detail. You also have the option to create muscle and skin STL files. The standard operation, CT NRRD to Bone STL sacrifices some detail for a smoother output model. Leave the default threshold at 150. Figure 3: Selecting an operation for file conversion. Next, choose the quality of your output file. Low-quality files process quickly and are appropriate for structures with simple geometry. High quality files take longer to process and are appropriate for very complex geometry. The geometry of our model will be quite complex, so choose high quality. This may take a long time to process however, sometimes up to 40 minutes. If you don't wish to wait so long, you can choose medium quality, as shown in Figure 4, and have a pretty decent output file in about 12 minutes or so. Figure 4: Choosing a quality setting. Finally, specify whether you want your processed file to be shared with the community (encouraged) or private and accessible only to you. If you do decide to share you will need to fill out a few items, such as which CreativeCommons license to share under. If you're not sure, the defaults are appropriate for most people. If you do decide to share thanks very much! The 3D printing community thanks you! Click on the submit button and your file will be submitted for processing! Now all you have to do is wait. The service will do all the work for you! Step 5: Download your file. In 5 to 40 minutes you should receive an email indicating that your file is done and is ready for download. Follow the link in the email message or, if you are already on the embodi3D.com website, click on your profile to view your latest activity, including files belonging to you. Open the download page for your file and click on the "Download this file" button to download your newly created STL file! Figure 5: Downloading your newly completed STL file. Desktop software If you haven't already, download 3D Slicer and Meshmixer. Both of these programs are available on Macintosh and Windows platforms. Step 1: Create an STL file with 3D Slicer. Open 3D Slicer. Drag and drop the file MANIX Angio CT.nrrd from the file pack onto the 3D Slicer window. This should load the file into 3D Slicer, as shown in Figure 6. When Slicer asks you to confirm whether you want to add the file, click OK. Figure 6: Opening the NRRD file in 3D Slicer using drag-and-drop. Step 2: Convert the CT scan into an STL file. From within Slicer, open the Modules menu item and choose All Modules, Grayscale Model Maker, as shown in Figure 7. Figure 7: Opening the Grayscale Model Maker module. Next, enter the conversion parameters for Grayscale Model Maker in the parameters window on the left. Under Input Volume select MANIX Angio CT. Under Output Geometry choose "Create new model." Slicer will create a new model with the default name such as "Output Geometry. If you wish to rename this to something more descriptive, choose Rename current model under the same menu. For this tutorial I am calling the model "RSNA model." For Threshold, set the value to 150. Under Decimate, set the value to 0.75. Double check your settings to make sure everything is correct. When everything is filled in correctly click the Apply button, as shown in Figure 8. Slicer will process for about a minute. Figure 8: Filling in the Grayscale Model Maker parameters. Step 3: Save the new model to STL file format. Now it is time to create an STL file from our digital model. Click on the Save button on the upper left-hand corner of the Slicer window. The Save Scene pop-up window is now shown. Find the row that corresponds to the model name you have given the model. In my case it is called "RSNA model." Make sure that the checkbox next to this row is checked, and all other rows are unchecked. Next, under the File Format column make sure to specify STL. Finally, specify the directory that the new STL file is to be saved into. Double check everything. When you are ready, click Saved. This is all shown in Figure 9. Now that you've created an STL file, we need to postprocessing in Meshmixer. Figure 9: Saving your file to STL format. Step 4: Open Meshmixer, and drag-and-drop the newly created STL file onto the Meshmixer window to open it. Once the model opens, you will notice that there are many red dots scattered throughout the model. These represent errors in the mesh and need to be corrected, as shown in Figure 10. Figure 10: Errors in the mesh as shown in Meshmixer. Each red dot corresponds to an error. Step 5: Remove disconnected elements from the mesh. There are many disconnected elements in this model that we do not want in our final model. An example of unwanted mesh are the flat plates on either side of the head from the pillow that was used to secure the head during the CT scan. Let's get rid of this unwanted mesh. First use the select tool and place the cursor over the four head of the model and left click. The area under the cursor should turn orange, indicating that those polygons have been selected, as shown in Figure 11. Figure 11: Selecting a small zone on the forehead. Next, we are going to expand the selection to encompass all geometry that is attached to the area that we currently have selected. Go to the Modify menu item and select Expand to Connected. Alternatively, you can use the keyboard shortcut and select the E key. This operation is shown in Figure 12. Figure 12: Expanding the selection to all connected parts. You will notice that the right clavicle and right scapula have not been selected. This is because these parts are not directly connected to the rest of the skeleton, as shown in Figure 13. We wish to include these in our model, so using the select tool left click on each of these parts to highlight a small area. Then expand the selection to connected again by hitting the E key. Figure 13: The right clavicle and right scapula are not included in the selection because they are not connected to the rest of the skeleton. Individually select these parts and expand the selection again to include them. At this point you should have all the geometry we want included in the model selected in orange, as shown in Figure 14. Figure 14: All the desired geometry is selected in orange Next we are going to delete all the unwanted geometry that is currently unselected. To start this we will first invert the selection. Under the modify menu, select Invert. Alternatively, you can use the keyboard shortcut I, as shown in Figure 15. Figure 15: Inverting the selection. At this point only the undesired geometry should be highlighted in orange, as shown in Figure 16. This unwanted geometry cannot be deleted by going to the Edit menu and selecting Discard. Alternatively you can use the keyboard shortcut X. Figure 16: Only the unwanted geometry is highlighted in orange. This is ready to delete. Step 6: Correcting mesh errors using the Inspector tool. Meshmixer has a nice tool that will automatically fix many mesh errors. Click on the Analysis button and choose Inspector. Meshmixer will now identify all of the errors currently in the mesh. These are indicated by red, blue, and pink balls with lines pointing to the location of the error. As you can see from Figure 17, there are hundreds of errors still within our mesh. We can attempt to auto repair them by clicking on the Auto Repair All button. At the end of the operation most of the errors have been fixed, but if you remain. This can be seen in Figure 18. Figure 17: Errors in the mesh. Most of these can be corrected using the Inspector tool. Figure 18: Only a few errors remain after auto correction with the Inspector tool. Step 7: Correcting the remaining errors using the Remesh tool. Click on the select button to turn on the select tool. Expand the selection to connected parts by choosing Modify, Expand to Connected. The entire model should now be highlighted and origin color. Next under the edit menu choose Remesh, or use the R keyboard shortcut, as shown in Figure 19. This operation will take some time, six or eight minutes depending on the speed of your computer. What remesh does is it recalculates the surface topography of the model and replaces each of the surface triangles with new triangles that are more regular and uniform in appearance. Since our model has a considerable amount of surface area and polygons, the remesh operation takes some time. Remesh also has the ability to eliminate some geometric problems that can prevent all errors from being automatically fixed in Inspector. Figure 19: Using the Remesh tool. Step 8: Fixing the remaining errors using the Inspector tool. Once the remesh operation is completed we will go back and repeat Step 6 and run the Inspector tool again. Click on Analysis and choose Inspector. Inspector will highlight the errors. Currently there are only two, as shown in Figure 20. These two remaining errors can be easily auto repair using the Auto Repair All button. Go ahead and click on this. Figure 20: running the Inspector tool again. At this point the model is now completed and ready for 3D printing as shown in Figure 21. The mesh is error-free and ready to go! Congratulations! Figure 21: The final, error-free model ready for 3D printing. Conclusion Complex bone and vascular models, such as the head and neck model we created in this tutorial, can be created using either the free online service at embodi3D.com or using free desktop software. Each approach has its benefits. The online service is easier to use, faster, and produces high quality models with minimal user input. Additionally, multiple models can be processed simultaneously so it is possible to batch process multiple files at once. The desktop approach using 3D Slicer and Meshmixer requires more user input and thus more time, however the user has greater control over individual design decisions about the model. Both methods are viable for creating high quality 3D printable medical models. Thank you very much for reading this tutorial. Please share your medical 3D printing designs on the embodi3D.com website. Happy 3D printing!
  6. If you are planning on using the democratiz3D service to automatically convert a medical scan to a 3D printable STL model, or you just happen to be working with medical scans for another reason, it is important to know if you are working with a CT (Computed Tomography or CAT) or MRI (Magnetic Resonance Imaging) scan. In this tutorial I'll show you how to quickly and easily tell the difference between a CT and MRI. I am a board-certified radiologist, and spent years mastering the subtleties of radiology physics for my board examinations and clinical practice. My goal here is not to bore you with unnecessary detail, although I am capable of that, but rather to give you a quick, easy, and practical way to understand the difference between CT and MRI if you are a non-medical person. Interested in Medical 3D Printing? Here are some resources: Free downloads of hundreds of 3D printable medical models. Automatically generate your own 3D printable medical models from CT scans. Have a question? Post a question or comment in the medical imaging forum. A Brief Overview of How CT and MRI Works For both CT (left) and MRI (right) scans you will lie on a moving table and be put into a circular machine that looks like a big doughnut. The table will move your body into the doughnut hole. The scan will then be performed. You may or may not get IV contrast through an IV. The machines look very similar but the scan pictures are totally different! CT and CAT Scans are the Same A CT scan, from Computed Tomography, and a CAT scan from Computed Axial Tomography are the same thing. CT scans are based on x-rays. A CT scanner is basically a rotating x-ray machine that takes sequential x-ray pictures of your body as it spins around. A computer then takes the data from the individual images, combines that with the known angle and position of the image at the time of exposure, and re-creates a three-dimensional representation of the body. Because CT scans are based on x-rays, bones are white and air is black on a CT scan just as it is on an x-ray as shown in Figure 1 below. Modern CT scanners are very fast, and usually the scan is performed in less than five minutes. Figure 1: A standard chest x-ray. Note that bones are white and air is black. Miscle and fat are shades of gray. CT scans are based on x-ray so body structures have the same color as they don on an x-ray. How does MRI Work? MRI uses a totally different mechanism to generate an image. MRI images are made using hydrogen atoms in your body and magnets. Yes, super strong magnets. Hydrogen is present in water, fat, protein, and most of the "soft tissue" structures of the body. The doughnut of an MRI does not house a rotating x-ray machine as it does in a CT scanner. Rather, it houses a superconducting electromagnet, basically a super strong magnet. The hydrogen atoms in your body line up with the magnetic field. Don't worry, this is perfectly safe and you won't feel anything. A radio transmitter, yes just like an FM radio station transmitter, will send some radio waves into your body, which will knock some of the hydrogen atoms out of alignment. As the hydrogen nuclei return back to their baseline position they emit a signal that can be measured and used to generate an image. MRI Pulse Sequences Differ Among Manufacturers The frequency, intensity, and timing of the radio waves used to excite the hydrogen atoms, called a "pulse sequence," can be modified so that only certain hydrogen atoms are excited and emit a signal. For example, when using a Short Tau Inversion Recovery (STIR) pulse sequence hydrogen atoms attached to fat molecules are turned off. When using a Fluid Attenuation Inversion Recovery (FLAIR) pulse sequence, hydrogen atoms attached to water molecules are turned off. Because there are so many variables that can be tweaked there are literally hundreds if not thousands of ways that pulse sequences can be constructed, each generating a slightly different type of image. To further complicate the matter, medical scanner manufacturers develop their own custom flavors of pulse sequences and give them specific brand names. So a balanced gradient echo pulse sequence is called True FISP on a Siemens scanner, FIESTA on a GE scanner, Balanced FFE on Philips, BASG on Hitachi, and True SSFP on Toshiba machines. Here is a list of pulse sequence names from various MRI manufacturers. This Radiographics article gives more detail about MRI physics if you want to get into the nitty-gritty. Figure 2: Examples of MRI images from the same patient. From left to right, T1, T2, FLAIR, and T1 post-contrast images of the brain in a patient with a right frontal lobe brain tumor. Note that tissue types (fat, water, blood vessels) can appear differently depending on the pulse sequence and presence of IV contrast. How to Tell the Difference Between a CT Scan and an MRI Scan? A Step by Step Guide Step 1: Read the Radiologist's Report The easiest way to tell what kind of a scan you had is to read the radiologist's report. All reports began with a formal title that will say what kind of scan you had, what body part was imaged, and whether IV contrast was used, for example "MRI brain with and without IV contrast," or "CT abdomen and pelvis without contrast." Step 2: Remember Your Experience in the MRI or CT (CAT) Scanner Were you on the scanner table for less than 10 minutes? If so you probably had a CT scan as MRIs take much longer. Did you have to wear earmuffs to protect your hearing from loud banging during the scan? If so, that was an MRI as the shifting magnetic fields cause the internal components of the machine to make noise. Did you have to drink lots of nasty flavored liquid a few hours before the scan? If so, this is oral contrast and is almost always for a CT. How to tell the difference between CT and MRI by looking at the pictures If you don't have access to the radiology report and don't remember the experience in the scanner because the scan was A) not done on you, or you were to drunk/high/sedated to remember, then you may have to figure out what kind of scan you had by looking at the pictures. This can be complicated, but don't fear I'll show you how to figure it out in this section. First, you need to get a copy of your scan. You can usually get this from the radiology or imaging department at the hospital or clinic where you had the scan performed. Typically these come on a CD or DVD. The disc may already have a program that will allow you to view the scan. If it doesn't, you'll have to download a program capable of reading DICOM files, such as 3D Slicer. Open your scan according to the instructions of your specific program. You may notice that your scan is composed of several sets of images, called series. Each series contains a stack of images. For CT scans these are usually images in different planes (axial, coronal, and sagittal) or before and after administration of IV contrast. For MRI each series is usually a different pulse sequence, which may also be before or after IV contrast. Step 3: Does the medical imaging software program tell you what kind of scan you have? Most imaging software programs will tell you what kind of scan you have under a field called "modality." The picture below shows a screen capture from 3D Slicer. Looking at the Modality column makes it pretty obvious that this is a CT scan. Figure 3: A screen capture from the 3D Slicer program shows the kind of scan under the modality column. Step 4: Can you see the CAT scan or MRI table the patient is laying on? If you can see the table that the patient is laying on or a brace that their head or other body part is secured in, you probably have a CT scan. MRI tables and braces are designed of materials that don't give off a signal in the MRI machine, so they are invisible. CT scan tables absorb some of the x-ray photons used to make the picture, so they are visible on the scan. Figure 4: A CT scan (left) and MRI (right) that show the patient table visible on the CT but not the MRI. Step 5: Is fat or water white? MRI usually shows fat and water as white. In MRI scans the fat underneath the skin or reservoirs of water in the body can be either white or dark in appearance, depending on the pulse sequence. For CT however, fat and water are almost never white. Look for fat just underneath the skin in almost any part of the body. Structures that contained mostly water include the cerebrospinal fluid around the spinal cord in the spinal canal and around the brain, the vitreous humor inside the eyeballs, bile within the gallbladder and biliary tree of the liver, urine within the bladder and collecting systems of the kidneys, and in some abnormal states such as pleural fluid in the thorax and ascites in the abdomen. It should be noted that water-containing structures can be made to look white on CT scans by intentional mixing of contrast in the structures in highly specialized scans, such as in a CT urogram or CT myelogram. But in general if either fat or fluid in the body looks white, you are dealing with an MRI. Step 6: Is the bone black? CT never shows bones as black. If you can see bony structures on your scan and they are black or dark gray in coloration, you are dealing with an MRI. On CT scans the bone is always white because the calcium blocks (attenuates) the x-ray photons. The calcium does not emit a signal in MRI scans, and thus appears dark. Bone marrow can be made to also appear dark on certain MRI pulse sequences, such as STIR sequences. If your scan shows dark bones and bone marrow, you are dealing with an MRI. A question I am often asked is "If bones are white on CT scans, if I see white bones can I assume it is a CT?" Unfortunately not. The calcium in bones does not emit signal on MRI and thus appears black. However, many bones also contain bone marrow which has a great deal of fat. Certain MRI sequences like T1 and T2 depict fat as bright white, and thus bone marrow-containing bone will look white on the scans. An expert can look carefully at the bone and discriminate between the calcium containing cortical bone and fat containing medullary bone, but this is beyond what a layperson will notice without specialized training. Self Test: Examples of CT and MRI Scans Here are some examples for you to test your newfound knowledge. Example 1 Figure 5A: A mystery scan of the brain Look at the scan above. Can you see the table that the patient is laying on? No, so this is probably an MRI. Let's not be hasty in our judgment and find further evidence to confirm our suspicion. Is the cerebrospinal fluid surrounding the brain and in the ventricles of the brain white? No, on this scan the CSF appears black. Both CT scans and MRIs can have dark appearing CSF, so this doesn't help us. Is the skin and thin layer of subcutaneous fat on the scalp white? Yes it is. That means this is an MRI. Well, if this is an MRI than the bones of the skull, the calvarium, should be dark, right? Yes, and indeed the calvarium is as shown in Figure 5B. You can see the black egg shaped oval around the brain, which is the calcium containing skull. The only portion of the skull that is white is in the frontal area where fat containing bone marrow is present between two thin layers of calcium containing bony cortex. This is an MRI. Figure 5B: The mystery scan is a T1 spoiled gradient echo MRI image of the brain. Incidentally this person has a brain tumor involving the left frontal lobe. Example 2 Figure 6A: Another mystery scan of the brain Look at the scan above. Let's go through our process to determine if this is a CT or MRI. First of all, can you see the table the patient is lying on or brace? Yes you can, there is a U-shaped brace keeping the head in position for the scan. We can conclude that this is a CT scan. Let's investigate further to confirm our conclusion. Is fat or water white? If either is white, then this is an MRI. In this scan we can see both fat underneath the skin of the cheeks which appears dark gray to black. Additionally, the material in the eyeball is a dark gray, immediately behind the relatively white appearing lenses of the eye. Finally, the cerebrospinal fluid surrounding the brainstem appears gray. This is not clearly an MRI, which further confirms our suspicion that it is a CT. If indeed this is a CT, then the bones of the skull should be white, and indeed they are. You can see the bright white shaped skull surrounding the brain. You can even see part of the cheekbones, the zygomatic arch, extending forward just outside the eyes. This is a CT scan. Figure 6B: The mystery scan is a CT brain without IV contrast. Example 3 Figure 7A: A mystery scan of the abdomen In this example we see an image through the upper abdomen depicting multiple intra-abdominal organs. Let's use our methodology to try and figure out what kind of scan this is. First of all, can you see the table that the patient is laying on? Yes you can. That means we are dealing with the CT. Let's go ahead and look for some additional evidence to confirm our suspicion. Do the bones appear white? Yes they do. You can see the white colored thoracic vertebrae in the center of the image, and multiple ribs are present, also white. If this is indeed a CT scan than any water-containing structures should not be white, and indeed they are not. In this image there are three water-containing structures. The spinal canal contains cerebrospinal fluid (CSF). The pickle shaped gallbladder can be seen just underneath the liver. Also, this patient has a large (and benign) left kidney cyst. All of these structures appear a dark gray. Also, the fat underneath the skin is a dark gray color. This is not in MRI. It is a CT. Figure 7B: The mystery scan is a CT of the abdomen with IV contrast Example 4 Figure 8A: A mystery scan of the left thigh Identifying this scan is challenging. Let's first look for the presence of the table. We don't see one but the image may have been trimmed to exclude it, or the image area may just not be big enough to see the table. We can't be sure a table is in present but just outside the image. Is the fat under the skin or any fluid-filled structures white? If so, this would indicate it is an MRI. The large white colored structure in the middle of the picture is a tumor. The fat underneath the skin is not white, it is dark gray in color. Also, the picture is through the mid thigh and there are no normal water containing structures in this area, so we can't use this to help us. Well, if this is a CT scan than the bone should be white. Is it? The answer is no. We can see a dark donut-shaped structure just to the right of the large white tumor. This is the femur bone, the major bone of the thigh and it is black. This cannot be a CT. It must be an MRI. This example is tricky because a fat suppression pulse sequence was used to turn the normally white colored fat a dark gray. Additionally no normal water containing structures are present on this image. The large tumor in the mid thigh is lighting up like a lightbulb and can be confusing and distracting. But, the presence of black colored bone is a dead giveaway. Figure 8B: The mystery scan is a contrast-enhanced T2 fat-suppressed MRI Conclusion: Now You Can Determine is a Scan is CT or MRI This tutorial outlines a simple process that anybody can use to identify whether a scan is a CT or MRI. The democratiz3D service on this website can be used to convert any CT scan into a 3D printable bone model. Soon, a feature will be added that will allow you to convert a brain MRI into a 3D printable model. Additional features will be forthcoming. The service is free and easy to use, but you do need to tell it what kind of scan your uploading. Hopefully this tutorial will help you identify your scan. If you'd like to learn more about the democratiz3D service click here. Thank you very much and I hope you found this tutorial to be helpful. Nothing in this article should be considered medical advice. If you have a medical question, ask your doctor.
  7. In this tutorial we will learn how to easily create a 3D printable dental, orthodontic, or maxillofacial bone model quickly and easily using the free democratiz3D® file conversion service on the embodi3D.com website. Creating the 3D printable dental model takes about 10 minutes and requires no prior experience or specialized knowledge. Dental 3D printing is one of the many uses for democratiz3D. You can 3D print teeth, braces, dental implants and so much more. Step 1: Download the CT scan file for dental 3D printing. Go to the navigation bar on the embodi3D.com website and click on the Download menu. This is shown in Figure 1. Figure 1: The Download menu This will take you to the download section of the website, which has a very large and extensive library of 3D printable anatomy files and source medical scan files. Look for the category along the right side of the page that says Medical Scan Files. Click on the section within that that says Dental, Orthodontic, Maxillofacial, as shown in Figure 2. Figure 2: Viewing the medical scan library on the embodi3D website This section contains anonymized CT scans of the teeth and face. Many of the scans in this section are perfect for 3D printing dental models. For this tutorial we will use the file openbiteupdated by member gcross, although you can use any source CT scan. This particular scan is a good one to choose because the patient does not have metallic fillings which can create streak artifact which can lower the quality of the model. Click on the link below to go to the file download page. Step 2: Preview the Dental CT scan file. Once you've downloaded the file you can inspect the CT scan using 3D Slicer. If you don't know about 3D Slicer, it is a free open source medical image viewing software package that can be downloaded from slicer.org. Once you have installed and opened Slicer, you can drag-and-drop the downloaded NRRD file onto the slicer window and it will open for you to view. You can see as shown in Figure 3 that the file appears to be quite good, without any dental fillings that cause streak artifact. Figure 3: Viewing the dental CT scan in Slicer. Step 3: Upload your dental CT scan NRRD file to the democratiz3D online service. Now that we are happy with our NRRD source file, we can upload it to the democratiz3D service for conversion into a 3D printable STL file. On the embodi3D website click on the democratiz3D navigation menu and Launch App, as shown in Figure 4. Figure 4: Launching the democratiz3D service. Once the online application opens, you will be asked to drag-and-drop your file onto the webpage. Go ahead and do this. Make sure that the file you are adding is an NRRD file and corresponds to a dental CT scan. An MRI will not work. This is shown in Figure 5. Figure 5: Dragging and dropping the CT scan NRRD file onto the democratiz3D application page. Step 4: Fill in basic information about your uploaded scan and generated model file While the file is uploading you can begin to fill out some of the required form fields. There are two main sections to the form. The section labeled 3 pertains to the file currently being uploaded, the NRRD file. Section 4 pertains to the generated STL file that democratiz3D will create. In Section 3 fill out a filename and a short description of your uploaded NRRD file. Specify whether you want the file to be private or shared, and whether this is a free file or a paid file that you wish to sell. You must choose a license type, although this is only really applicable if your file is shared as if it is private nobody will be able to download it. This portion of the form is shown in Figure 6. Figure 6: Filling out the submission form, part 1. Enter in information related to the uploaded NRRD file. Next proceed to section 4, the portion of the form related to the file you wish to generate. Make sure that democratiz3D processing is turned on and the slider shows green. Choose the appropriate operation. For creation of dental files, the best operation is "CT NRRD to Bone STL Detailed." This takes a CT scan in NRRD file format and converts it to a bone STL file using maximum detail. Leave the threshold at the default value of 150. Set quality to high. Make sure that you specify whether you want the file to be private or shared, and free versus paid. Make sure you specify file license. The steps are shown in Figure 7. Figure 7: Filling out the submission form, part 2. Enter in information related to the generated STL file. Make sure you check the checkbox that states you agree to the terms of use, and click the submit button. Your file will now start processing. In approximately 10 minutes or so you should receive an email stating that the file has been processed and your newly created 3D printable STL model is ready for download. The email should contain a link that will take you to your file download page, which should look something like the page in Figure 8. There should be several thumbnails which show you what the model looks like. To download the file click on the Download button. Figure 8: The file download page for your newly created dental model. Step 5: Check your dental STL file for errors and send it to your dental 3D printer! Once you have downloaded the STL file open it in Meshmixer. Meshmixer is a free 3D software program available from meshmixer.com that has many handy 3D printing related features. The democratized service is a good job of creating error-free files, but occasionally a few errors will sneak through, which can be easily fixed and Meshmixer. Click on the analysis button and then select Inspector as shown in Figure 9. Click on the Auto Repair All button and any minor defects that are remaining will be automatically fixed. Make sure to save your repaired and finalized 3D printable model by clicking on the menu File -> Export. You can now send your STL file to the 3D printer of your choice. Here is an example of the model when printed on a Form 1+ using white resin. You can see that the level of detail is very good. Formlabs has several examples of 3d printing teeth and other dental applications on their website. Thank you very much. I hope this tutorial was helpful. If you are not already a member, please consider joining the embodi3D community of medical 3D printing enthusiasts. If you have any questions or comments, please feel free to post them below.
  8. Hello everybody it's Dr. Mike here again with another medical 3D printing tutorial. In this tutorial we are going to be going over freeware and open-source software options for medical 3D printing. This tutorial is based on a workshop I am giving at the 2017 Radiological Society of North America (RSNA) Annual Meeting in Chicago Illinois, November 2017. In this tutorial we will be going over desktop software that can be used to create 3D printable anatomic models from medical scans, as well as a free online automated conversion service. At the end of this tutorial you should be able to make high-quality 3D printable models from a medical imaging scan using free software or services. Do I need to use FDA-approved software for Medical 3D Printing? Before I dive into the tutorial I'd like to take a minute to talk to learners from the United States about the US Food and Drug Administration (FDA) and how this federal agency impacts medical 3D printing. Many healthcare professionals are confused and concerned about the ability to use non-FDA-approved software for medical 3D printing. Software vendors sell software that has been FDA-approved, but the software is usually quite expensive, to the tune of many thousands of dollars per year in license fees. There has been a lot of confusion about whether non-FDA-approved free software can be used for medical applications. In August 2017 a meeting was held at the main FDA campus between FDA staff and representatives from RSNA. During this meeting the FDA clarified its stance on the issue (Figure 1). Basically the FDA indicated that if a doctor needs a 3D printed model for patient care, the doctor does NOT need to use FDA-approved software, as this is a medical decision and the FDA does not regulate the practice of medicine. FDA-approved software is not required even if the doctor is using the model for diagnostic use (Figure 2). If a company or other organization is marketing or designing software for diagnostic use, then that company or organization is required to seek FDA approval for that product. Basically if you are a physician or working on behalf of the physician and require a model, FDA-approved software is not required as long as you are not running a commercial service or company. Despite this leeway granted by the FDA's interpretation, I encourage anyone considering using freeware to create models for diagnostic use to use common sense and double check your findings before making any critical decision that could impact patient care. I also encourage you to look at the slides from the FDA presentation directly at the link below. Of course, none of this applies if you are not creating models for medical use. https://www.fda.gov/downloads/MedicalDevices/NewsEvents/WorkshopsConferences/UCM575723.pdf Figure 1: Title slide from the FDA presentation Figure 2: The relevant slide from the FDA presentation. Doctors creating 3D printable models for clinical and diagnostic use do not need to use FDA-approved software as this is considered practice of medicine, which the FDA does not regulate. Medical 3D Printing Overview In this tutorial we're going to go over two different ways to use free and open-source software to convert a medical imaging scan to a 3D printable model. This can be done using free desktop software or a free online service. The desktop software requires more steps and more of a learning curve, but also allows more control for customized models. The online service is fast, easy, and automated. However, if you want to design customized elements into your model, you'll not be able to. The overall workflow of the session is shown in Figure 3. Figure 3: Workflow overview Part 1: Free online service – embodi3D.com Step 1: Download the scan Please download the scan for this tutorial from the embodi3D.com website at the link below. You have to have a free embodi3D.com account in order to download. If you don't have an account go ahead and register by clicking on the "Sign Up" button on the upper right-hand portion of the page. Registration is easy and only takes about one minute. You will have to confirm your email address before your account is active, so make sure you have access to your email. Step 2: Inspect the scan If you don't already have it, download and install the desktop software program 3D Slicer from slicer.org (http://www.slicer.org/). Slicer is a free medical image viewing and research software application. We are going to use Slicer to view our scan. Once Slicer is installed, open the application. Drag-and-drop the file "CTA Head.nrrd" onto the Slicer window. Slicer will ask if you want to add the file, click OK. The scan should now show in Figure 4. If your window doesn't look this then select the Four Up layout from the Layouts drop-down menu. Figure 4: The 4 panel view and Slicer You can navigate and manipulate the images with Slicer using the various mouse buttons. Your left mouse button to adjust the window/level settings as shown in Figure 5. Figure 5: Use the left mouse button to adjust window/level. The right mouse button allows you to zoom into a specific panel, as shown in Figure 6. Figure 6: The right mouse button controls zoom. The scroll wheel allows you to move through the various slices of the scan, as shown in Figure 7. Figure 7: The mouse wheel controls scrolling Step 3: Upload the scan to embodi3D.com Now that we have an idea about what's in the scan, you can upload it to embodi3D.com for automatic processing into a 3D printable model. Go to https://www.embodi3d.com/. If you don't yet have a free embodi3D.com user account, you will need one now. Go ahead and register. The process only takes a minute. Under the democratiz3D menu, click Launch App, as shown in Figure 8. Figure 8: Launching the democratiz3D medical scan to 3D printable model automated conversion service. Drag and drop the file "CTA Head.nrrd" onto the upload panel, as shown in Figure 9. The NRRD file format is an anonymized file format so this transfer is HIPAA compliant. If you want to know more about how to create an NRRD file from a DICOM data set, please see my tutorial on the topic here. Figure 9: Drag-and-drop the scan file "CTA Head.nrrd" onto the highlighted upload panel A submission form will open up. The first part of the form will ask you questions about the source file you're uploading. The second part will ask about the new model being generated. Start with the first part of the form, as shown in Figure 10, and fill in information about your uploaded scan file, including a filename, short description, any tags you wish to use to help people identify your file, whether you wish to share the file with the community or keep it private, and whether you want to make the file free for download or for sale. Obviously if you keep the file private this last setting doesn't matter as nobody will be able to see the file except you. Figure 10: The first part of the form relates to information about your uploaded scan file. Make sure you fill in at least the required elements. In the second part of the form fill in information about your model file that will be generated, as shown in Figure 11. First of all, make sure democratized processing is turned on. The slider should be green in color, as shown in Figure 11. This is very important because if processing is turned off, you will not generate an output model file! Specify what operation you would like to perform on the scan, and whether you would like to generate a bone, muscle, or skin model. Also, specify the desired quality of the output model (low, medium, high, etc.) and whether you want the output model to be shared with the community (recommended) or private. If your file is going to be shared, choose a Creative Commons license that people can use it under. When you're satisfied with your parameters, click the Submit button. Figure 11: The second part of the form relates to information about your 3D printable model to be generated. Choose an operation, quality level, as well as privacy settings. Step 4: Download your finished 3D printable model. After anywhere between 5 to 20 minutes you should receive an email saying that your model processing is complete. The exact time depends on a variety of factors including the complexity of your model, the quality that you've chosen, as well as server load. Once you receive the email follow the link to the model download page. Alternatively you can find the model by clicking on your username at the upper right-hand corner of any embodi3D.com webpage and selecting My Files. Once you find your model page you can inspect the thumbnails to make sure the model meets your criteria, as shown in Figure 12. When you are ready click the download button, agree to the terms, and your model STL file will download to your computer. Figure 12: Download your file after processing is complete. That's it! Your 3D printable model is ready to send to a printer. The process takes about 2 to 3 minutes to enter the data, plus 5 to 15 minutes to wait for the processing to be done. The embodi3D.com service is batchable, so it is possible for you to upload multiple files simultaneously. The service will crank out models as fast as you can upload them. Part 2: Free desktop software – 3D Slicer and Meshmixer You can use the free software program 3D slicer and Meshmixer to generate 3D printable models. The benefit of using desktop software is that you have more control over the appearance of the model and which structures you want included and excluded. The downside of using desktop software is that software is complicated and somewhat time-consuming to learn. If you haven't already download 3D Slicer and Meshmixer from the links below. Be sure to choose the appropriate operating system for your computer. http://www.slicer.org/ http://meshmixer.com/ Step 1: Download the tutorial scan file and load into Slicer as described above in Part 1 Steps 1 and 2. Step 2: Create a surface model from the scan data. From within Slicer, open the Grayscale Model Maker module. In the Modules menu at the top now bar, select All Modules and choose the Grayscale Model Maker item, as shown in Figure 13. Figure 13: Selecting the Grayscale Model Maker module. You will now be taken to the Grayscale Model Maker module, which will convert the volumetric data in the CT scan to a surface model that can be used to create a STL file for 3D printing. In the parameters panel on the left side of the screen, make sure that the parameter set value is set to "Grayscale Model Maker", and the Input Volume is set to "CTA Head." Under Output Geometry, choose Create a New Model, since we wish to create a new output model. These parameters are shown in Figure 14. Figure 14: Input parameters for the Grayscale Model Maker module Set the Threshold value to 150 Hounsfield units. Also, set the Decimate value to 0.8 and make sure the Split Normals checkbox is unchecked. These are shown in Figure 15. When you're happy with your parameters, check Apply, and the grayscale model maker will work for a minute or so to create your surface model. Figure 15: Additional input parameters for the Grayscale Model Maker module Step 3: Save the surface model to an STL file. Now that you have generated a surface model, you are ready to export it to an STL file. Click on the Save button on the upper left-hand corner of the 3D Slicer window. A Save dialog box will pop up, as shown in Figure 16. Find the row that contains the item "Output Geometry.vtk." Make sure that the checkbox next to this item is checked. All other rows should be unchecked. In the File Format column, make sure that the file shows as STL. Finally, make sure that the directory specified in the third column is the one you wish to save the file to. When everything is correct go ahead and click Save. Your surface model will now be exported and STL file saved in the directory specified. Figure 16: The Save dialog box Step 4: Repair the model in Meshmixer The model is in STL format, but it has multiple errors in it which need to be corrected prior to 3D printing. We will do this in the freeware software program Meshmixer. Open Meshmixer, and drag-and-drop the just-created STL file "Output Geometry.stl" onto the Meshmixer window. The model will now open in Meshmixer. You will notice that the model is quite large, having about 300,000 polygons, as shown in Figure 17. Figure 17: Open the model in Meshmixer Navigating in Meshmixer is quite intuitive. The left mouse button uses tools and selects structures. The right mouse button is used to rotate the model. The scroll wheel is used to zoom in and out, as shown in Figure 18. Figure 18: Navigating in Meshmixer Run an initial repair on the model using the Inspector tool We will be able to get rid of most (but not all) errors using the automated Inspector tool. Click on the Analysis button on the left navigation pane and choose the Inspector tool. Inspector will run and highlight all of the problems with the model, as shown in Figure 19. As you can see there are many hundreds of errors. Click on the Auto Repair All button to automatically attempt to fix these. At least one error will remain after the end of the process, but don't worry we will fix that later. Click on the Done button. Figure 19: The Inspector tool shows errors in the mesh Remesh the model The Remesh operation recalculates all the polygons in the model, adjusting their size, and giving the model in more natural and less faceted look. Remesh and can also help to fix lingering mesh errors. First, select all the polygons in the model by hitting control-A. The entire model should turn orange, as shown in Figure 20. Figure 20: Selecting all the polygons in the model. Next, run the Remesh operation. Hit the R key, or choose Select-> Edit-> Remesh. The Remesh operation will now run, and will take approximately 1.5 to 2 minutes, depending on the power of your computer. This is shown in Figure 21. Figure 21: The Remesh operation. At the end of the Remesh operation, your model should have a much smoother and more natural appearance. You can adjust some of the Remesh parameters in the visualized pane, and the operation will recalculate. When you're happy with the result, click on the Accept button. This is shown in Figure 22. Figure 22: The model after the Remesh operation. Repeat the Inspector tool operation Now that we have re-mashed the model, we can rerun the Inspector tool to clean up any residual errors. Click on Analysis and then the Inspector menu item. Click Auto Repair All, and inspector should repair any problems that still remain. When you're finished, click the Done button, as shown in Figure 23. Figure 23: Running the Inspector tool a second time Expose the cerebral vessels. We are now going to take an extra step and make a cut through the crowd of the skull to expose the cerebral vessels. This can be easily achieved in about one minute. First, make sure to select all the vertices in the model by hitting control-A or using the menus Select-> Modify-> Select all, as shown in Figure 24. The entire model should turn orange to indicate that it is selected. Figure 24: Selecting all the polygons in the model prior to performing a cut. Next, start a plane cut by choosing Select-> Edit-> Plane cut. The plane cut will show on the screen. The portion of the model that is transparent will be cut off. The portion of the model that is opaque will be left behind. Move the plane by using the purple and green arrow handles. Rotate the plane by using the red arc handle, as shown in Figure 25. Figure 25: Move and rotate the plane cut using the arrow and arc handles. In this case we wish to move the plane cut to the four head, and rotated 180° so that the transparent portion of the cut is at the top of the head, and the opaque portion encompasses the face, jaw, and lower part of the skull. After you have finished positioning the plane, your model should look similar to Figure 26. When you're happy with position, click Accept. Figure 26: The best position of the plane cut tool The crown of the skull will now be cut off, exposing the cerebral vessels within the brain. This includes the anterior, posterior, and middle cerebral arteries as well as the venous structures such as the straight sinus and sigmoid sinuses, as shown in Figure 27. As you can see, this is a highly detailed model and excellent for educational purposes and teaching neurovascular anatomy. Figure 27: The final model Conclusion In this tutorial we learn how to create a 3D printable skull and vascular model utilizing the free online service from embodi3D.com, as well as free desktop software 3D Slicer and Meshmixer. Both methods have their advantages and disadvantages. Embodi3D.com has a very fast and easy to use service. The desktop software is more difficult to use and learn, but gives more flexibility in terms of customization. Alternatively, you can use a combination of the two techniques, for example generating your model on the embodi3D.com website and then performing custom modifications, such as the plane cut we did in this tutorial, utilizing Meshmixer. I hope you found this tutorial helpful and entertaining. Please give the tutorial a like. If you are engaged in medical 3D printing, please consider sharing your work on the embodi3D.com website. Thank you very much and happy 3D printing!
  9. 166 downloads

    Transposition of the great arteries is a serious but rare heart defect present at birth, in which the two main arteries leaving the heart are reversed (transposed). Transposition of the great arteries is usually detected either prenatally or within the first hours to weeks of life. Transposition of the great arteries changes the way blood circulates through the body, leaving a shortage of oxygen in blood flowing from the heart to the rest of the body. Without an adequate supply of oxygen-rich blood, the body can't function properly and a child faces serious complications or death without treatment. Corrective surgery soon after birth is the usual treatment for transposition of the great arteries. There are three STL files available for download segmented as seen in the video and images. These files have been zipped to save space and data transfer. The model is provided for distribution on Embodi3D with the permission of the author, pediatric cardiologist Dr. Matthew Bramlet, MD, and is part of the Heart Library. We thank Dr. Bramlet and all others who are working to help children with congenital heart problems lead normal and happy lives. It is distributed by Dr. Bramlet under the Creative Commons license Attribution-NonCommercial-NoDerivs. Please respect the terms of the licensing agreement. A US quarter is shown for scale in the images below.

    Free

  10. From the album: embodi3D 3D Printed Models

    This skull with left MCA aneurysm was printed by embodi3D for a customer who wants to use the model for simulating neurosurgical aneurysm clipping.
  11. We recently 3D printed a multimaterial skull with MCA aneurysm from a CTA head for customer who needed the skull in rigid plastic and the vessels and aneurysm in flexible material. The model will be used by neurosurgeons to practice intracranial aneurysm clipping surgery. To properly simulate the surgery, the skull needs to be hard and the vessels elastic. Combining two materials (and two printers!) provides the best solution. The model was created on democratiz3D. You can learn more about embodi3D's printing service here.
  12. 358 downloads

    Normally there are two main blood vessels leaving the heart: the aorta, carrying blood to the body, and the pulmonary artery that branches immediately to carry blood to each lung. Instead of having a separate pulmonary artery and aorta, each with its own three-leafed valves, a baby with truncus arteriosus has only one great blood vessel or trunk leaving the heart, which then branches into blood vessels that go to the lungs and the body. This great vessel usually has one large valve which may have between two and five leaflets. Usually this great vessel sits over both the left and right ventricle. The upper portion of the wall between these two chambers is missing, resulting in what is known as a ventricular septal defect (VSD). There are 3 separate files as well as a fourth STL file for 3D printing the whole model. The three part model has holes for magnets, which can be used to connect and separate the pieces. All the STL files have been zipped to conserve space. The model is provided for distribution on Embodi3D with the permission of the author, pediatric cardiologist Dr. Matthew Bramlet, MD, and is part of the Congenital Heart Defects library. We thank Dr. Bramlet and all others who are working to help children with congenital heart problems lead normal and happy lives. It is distributed by Dr. Bramlet under the Creative Commons license Attribution-NonCommercial-NoDerivs. Please respect the terms of the licensing agreement. A US quarter is shown for scale in the images below.

    Free

  13. Version 1.0.0

    431 downloads

    There are four STL files for 3D printing demonstrating a moderate secundum atrial septal defect (ASD) and a mild coarctation. An atrial septal defect is a birth defect of the heart in which there is a hole in the wall (septum) that divides the upper chambers of the heart (atria). A hole can vary in size and may close on its own or may require surgery. If one of these openings does not close, a hole is left, and it is called an atrial septal defect. The hole increases the amount of blood that flows through the lungs and over time, it may cause damage to the blood vessels in the lungs. Damage to the blood vessels in the lungs may cause problems in adulthood, such as high blood pressure in the lungs and heart failure. Other problems may include abnormal heartbeat, and increased risk of stroke. MRI obtained for evaluation of distal arch and pulmonary veins due to findings of pulmonary overcirculation out of proportion to typical ASD pathophysiology. The MRI provided a complete anatomic overview and quantified the right sided enlargement from the 2:1 shunt through the ASD. Due to saturation band nulling of blood returning through the right sided pulmonary veins, there was excellent definition of the ASD due to the "dark" blood mixing with the "bright" blood and outlining the borders of the ASD which transfers to the model very well. Please keep in mind, that the model represents a heart in end-systole rather than diastole. Disclaimer: The available model has been validated to demonstrate the case’s pathologic features on a Z450 3D printer, (3DSystems, Circle Rock Hill, South Carolina)(or other printer as appropriate). While the mask applied to the original DICOM images accurately represents the anatomic features, some anatomic detail may be lost due to thin walled structures or inadequate supporting architecture; while other anatomic detail may be added due to similar limitations resulting in bleeding of modeling materials into small negative spaces. However, intracardiac structures, relationships, and pathologic features represent anatomic findings to scale and in high detail. Credit: The model is provided for distribution on Embodi3D with the permission of the author, pediatric cardiologist Dr. Matthew Bramlet, MD, and is part of the Congenital Heart Defects library. We thank Dr. Bramlet and all others who are working to help children with congenital heart problems lead normal and happy lives. It is distributed by Dr. Bramlet under the Creative Commons license Attribution-NonCommercial-NoDerivs. Please respect the terms of the licensing agreement.

    Free

  14. Currently, Ebola is the most dreaded epidemic in the world which accounts to more than 5,000 lives lost mainly in Africa. As of this writing, the Ebola disease does not have any vaccines available. Those who are inflicted with this virus are treated based on their symptoms. To make matters worse, the scientists all over the world is running a race against a global Ebola pandemic threat that is about to become a reality. However, the spread of the Ebola virus has also given the opportunity for DIY enthusiasts to find a cure for the virus using DIY biotech experimentation. In fact, fighting Ebola using digital fabrication maybe one of the solutions to the alarming problem. So how will DIY biotech come into the fore when it comes to treating Ebola virus? One of the experimental treatments show that transfusion of blood from survivors is the best medical practice that can cure victims afflicted with this disease. Since there is a 24-day incubation, the DIY bio movement can help a lot by creating digitally fabricated centrifuges to help with plasma separation. Toolkits should be built around the centrifuge using digital open source software so that it will be easier for people to sterilize, draw blood and do blood typing. These kits should be able to run on locally available energy sources like solar power and car or motorcycle batteries. With the use of available local energy sources, this technology will be accessible to areas hard hit by Ebola. The more these DIY-fabricated component are available to third world countries in Africa, the more lives will be saved, the higher the chances of containing the virus and prevention of a global Ebola pandemic.
  15. I receive a lot of inquiries to my account. I'm going to try to share them with the community in the hope that any information that is shared can help many others. A member recently contacted me and asked the following: "Do you have any experience in dicom images by TUI mode in Voluson E10, for print 3d fetus models" Unfortunately, I don't personally have experience with 3D printing ultrasound images. I'm not sure how the slice-by-slice registration will work as ultrasound images are not in fixed orthographic planes. However, I know it must be possible since there is a company that is 3D printing fetuses. http://www.3ders.org/articles/20160118-3d-printed-fetuses-the-hottest-parenting-trend-of-2016.html Anyone in the community have experience with converting ultrasound to STL?
  16. Version 1.0.0

    68 downloads

    This 3D printable STL file contains a model of the torso, neck, and arms was derived from a real medical CT scan and shows anatomic structures in great detail. This model was created using the democratiz3D free online 3D model creation service. QIN-HN-01-0003

    Free

  17. Version 1.0.0

    20 downloads

    This 3D printable STL file contains a model of the right shoulder was derived from a real medical CT scan. It shows the pectoralis, deltoid, biceps, and triceps muscles, as well as musculature of the chest wall. This model was created using the democratiz3D free online 3D model creation service. QIN-HN-01-0003

    Free

  18. Version 1.0.0

    8 downloads

    This 3D printable STL file contains a model of the muscles of the chest and back was derived from a real medical CT scan. The pectoralis, latissimus dorso, scalene and other muscles are shown in great detail. This model was created using the democratiz3D free online 3D model creation service. QIN-HN-01-0003

    Free

  19. Version 1.0.0

    18 downloads

    This 3D printable STL file contains a model of the left shoulder was derived from a real medical CT scan. It shows the deltoid, pectoralis, triceps, and biceps muscles in great detail. Also, the muscles of the chest wall and ribs are also shown. This model was created using the democratiz3D free online 3D model creation service. QIN-HN-01-0003

    Free

  20. Version 1.0.0

    35 downloads

    This 3D printable STL file contains a model of the torso, including the spine, shoulders and arms, pelvis, and proximal legs. It was derived from a real medical CT scan. This model was created using the democratiz3D free online 3D model creation service. QIN-HN-01-0003

    Free

  21. Version 1.0.0

    31 downloads

    This 3D printable STL file contains a model was derived from a real medical CT scan. It includes all of the bony anatomy from the skull base to the hips, including the spine, pelvis, rib cage and arms This model was created using the democratiz3D free online 3D model creation service. QIN-HN-01-0003

    Free

  22. Version 1.0.0

    12 downloads

    This 3D printable STL file contains a model of the cervical spine was derived from a real medical CT scan. This model was created using the democratiz3D free online 3D model creation service. QIN-HN-01-0003

    Free

  23. Version 1.0.0

    21 downloads

    This 3D printable STL file contains a model of the right shoulder was derived from a real medical CT scan. This model was created using the democratiz3D free online 3D model creation service. QIN-HN-01-0003

    Free

  24. Version 1.0.0

    59 downloads

    This 3D printable STL file contains a model of the rib cage was derived from a real medical CT scan. This model was created using the democratiz3D free online 3D model creation service. QIN-HN-01-0003

    Free

  25. Version 1.0.0

    22 downloads

    This 3D printable STL file contains a model of the thoracic spine was derived from a real medical CT scan. This model was created using the democratiz3D free online 3D model creation service. QIN-HN-01-0003

    Free

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