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Here comes the “MIP” September 22, 2007

Posted by tomography in Uncategorized.
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Maximum Intensity Projection of a 18F-FDG wholebody PET acquisition

source: Wikipedia (Jens Langner)

A maximum intensity projection (MIP) is a computer visualization method for 3D data that projects in the visualization plane the voxels with maximum intensity that fall in the way of parallel rays traced from the viewpoint to the plane of projection. This implies that two MIP renderings from opposite viewpoints are symmetrical images.

MIP-mouseThis technique is computationally fast, but the 2D results do not provide a good sense of depth of the original data. To improve the sense of 3D, animations are usually rendered of several MIP frames in which the viewpoint is slightly changed from one to the other, thus creating the illusion of rotation. This helps the viewer’s perception to find the relative 3D positions of the object components. However, since the projection is orthographic the viewer cannot distinguish between left or right, front or back and even if the object is rotating clockwise or anti-clockwise.

(E.g. MIP is used for the detection of lung nodules in lung cancer screening programs which utilise computerized tomography scans. MIP enhances the 3D nature of these nodules, making them stand out from pulmonary bronchi and vasculature.)

Use of depth weighting during production of rotating cines of MIP images can avoid the problem of difficulty of distinguishing right from left, and clockwise vs anti-clockwise rotation. MIP imaging is used routinely by physicians in interpreting PET (Positron Emission Tomography) imaging studies.

CT visualized by a MIP of a mouse

source: Wiki

Az MIP egy számítógépes megjelenítési módszer 3D-s adat halmazokra, amely a nézőpontból a vetítés síkjáig követett párhuzamos sugarak útjába eső voxeleket maximum intenzitással vetíti a megjelenítés síkjába. Eszerint két ellentétes nézetből készült MIP “fordítás” szimmetrikus képeket ad.

A technika számításilag gyors, de a 2D-s eredmény nem nyújt megfelelő mélység érzékenységet. A 3D-s hatás elérésére, ezen animációkat általában a nézőpont folyamatos apró változtatásával számos MIP mező felhasználásával készítik, így megteremtve a forgatás illuzióját. Ez segít a szemlélőnek elhelyezni a vizsgált anyag részeit 3D-ban. Azonban, mivel a vetítés merőleges, a néző nem tud különbséget tenni jobb és bal, elöl és hátul vagy akár a tárgy órajárással megegyező vagy ellentétes irányban való forgásában.

Forgó MIP képek készítésekor, mélység súlyozással elkerülhető az oldaliság és a forgásirány eldöntésének problémája. A MIP leképezés rutin szerűen alkalmazott PET képek értelmezésekor.Maximum Intensity Projection of a 18F-FDG wholebody PET acquisition

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Comments»

1. Isabelle - September 24, 2007

I am quite interested in this technique, but I find the explanation puzzling. For example- what are voxels? It would be great to have a diagram of what “parallel rays traced from the viewpoint to the plane of projection” are, too. And I used to be a 3D aerospace designer!

Love the mouse MIP, though.

2. tomography - September 25, 2007

Hi!
First of all, Thank you for commenting!
Your first quistion: voxel. Well, I chose the easy way and linked wiki… here: http://en.wikipedia.org/wiki/Voxel. I couldn’t explain you better and shorter:-)
And the rest: as you are interested in this technique, I’ll have new post(s) then or edit the former one. – SOON!

3. tomography - September 28, 2007

Dear Isabelle!

I was really into this “diagram” thing you asked for, but honestly I couldn’t find or make any (as i don’t really understand how could i explain this by diagrams). I can suggest you some pages, I think they’ll work.
Don’t forget, this technique is mainly used in the medical sector. Like angiography!
http://delivery.acm.org/10.1145/1100000/1095886/p1392-mora.pdf?key1=1095886&key2=3792101911&coll=&dl=acm&CFID=15151515&CFTOKEN=6184618
http://www.vrvis.at/via/resources/diss-LM/node16.html
http://www.iit.bme.hu/~cseb/Publications/WSCG99/paper.pdf
Of course I do not give up finding out some other posts about MIP. 🙂


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