Inscientific visualization, amaximum intensity projection (MIP) is a method for3D data thatprojects in the visualization plane thevoxels 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 if they are rendered usingorthographic projection.
MIP is used for the detection of lungnodules inlung cancer screening programs which usecomputed tomography scans. MIP enhances the 3D nature of these nodules, making them stand out from pulmonary bronchi and vasculature. MIP imaging is also used routinely by physicians in interpretingPositron Emission Tomography (PET) orMagnetic Resonance Angiography studies.
 | This articlemay need to be rewritten to comply with Wikipedia'squality standards. Relevant discussion may be found on thetalk page.You can help. The talk page may contain suggestions.(February 2023) |
This 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 ofrotation. This helps the viewer'sperception to find the relative 3D positions of the object components. However, since the projection isorthographic the viewer cannot distinguish between left or right, front or back and even if the object is rotating clockwise or anti-clockwise. 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.
An alternate version of MIP isLocal maximum intensity projection. In this technique we don't take theglobal maximum value, but the first maximum value that is above a certain threshold. Because - in general - we can terminate the ray earlier this technique is faster and also can give better results in some settings as it approximates occlusion.[1] Choice of Local MIP vs Full MIP depends on the display goals and how the MIP is to be used.
MIP Display was invented for use in Nuclear Medicine by Gerrold Wallis, MD, in 1988 atWashington University in St. Louis, and subsequently published in IEEE Transactions on Medical Imaging.[2] In the setting of Nuclear Medicine, it was originally called MAP (Maximum Activity Projection).[3][4]
