3D Reconstruction: Volume Rendering

OsiriX and Horos Course · 3D Reconstruction

In this video I give an introduction to three-dimensional reconstructions in OsiriX, focusing on 3D Volume Rendering. It is a big topic (we will go deeper later), but here I show the basics so you can start using 3D in your daily practice: Crop to speed things up, Presets, brightness/contrast adjustment and how to remove bones from the volume. 1) Types of 3D reconstruction in OsiriX In the gear icon menu, there are several three-dimensional reconstructions, such as: 3D MIP (Maximum Intensity Projection) 3D Volume Rendering (topic of this video) 3D Surface Rendering 3D Endoscopy In Volume Rendering, OsiriX uses voxels (three-dimensional points) with density to generate the image and apply colors/transparencies according to a scale. 2) Opening 3D Volume Rendering I open 3D Volume Rendering To make it faster, I choose Clip (in the video) 3) Crop: the first thing to do for better performance Often the whole exam is “too big” for what you need. I use Crop to create a “box” around the volume and reduce the area of interest: I shrink the cube (green dots) until only what matters is left Result: less memory, faster graphics-card performance and smoother navigation Then I remove the Crop and proceed with the final 3D image 4) Presets and brightness/contrast adjustment In 3D Preset, I try a few of the presets, but the practical suggestion for vascular is: Go into Soft Tissue On the second page, use the vascular-oriented presets My favorite here is Standard, very similar to what many labs deliver After that, I adjust brightness/contrast to highlight the structures I want to see (arteries, skin, etc.). 5) How to remove bones in 3D (two ways) A) “Skull” tool (automatic bone removal) I click the skull icon and select a bone (e.g., a vertebra) OsiriX tries to remove the bone automatically Advanced adjustment: Option + skull icon to configure the bone removal threshold/range Common problem shown in the video: Since bone density can be close to contrast density, it sometimes removes contrast-enhanced arteries as well If the result is poor, I use Edit → Undo and try other values (it is trial and error) B) Scissors (my preference) I use the scissors tool to manually cut out the structures I do not want I select the area and press Delete to erase it Practical tips: You have to “sculpt” from several angles (rotate the 3D and repeat) If you delete something by mistake: Tab restores what was removed in that region/selection In the end, you can make the image much “cleaner”, showing mainly the aorta and the vessels of interest.