INTEGRAL AND SHELL-MIP DISPLAY ALGORITHMS IN MR AND CT 3-DIMENSIONAL MODELS OF THE BRAIN SURFACE

BACKGROUND AND PURPOSE: Our purpose was to demonstrate the use of inte gral and shell maximum intensity projection (shell-MIP) display algori thms in the 3-D CT and MR depiction of cerebral gyral and surface veno us anatomy and disorders. These new algorithms are compared against MI P and shaded-surface-display (SSD) algorithms. METHODS: Integral and s hell-MIP displays were generated from a specified number of proximal s urface voxel layers in a 3-D model. Algorithmic models were compared o n nine contrast-enhanced spoiled gradient-recalled acquisition in a st eady state (SPGR) MR venograms for brain surface anatomic identificati on and detail. Seven CT venograms were compared for conspicuity of fil ling defects. Twelve contrast-enhanced preoperative planning 3-D MR mo dels were rated for neurosurgical utility. RESULTS: A shell-MIP score of 7.00 and an integral score of 6.78 represented the highest mean sub jective MR gyral quality (1-10 scale) followed by an SSD score of 3.89 and an MIP score of 1.06. Mean confidence scores for MR central sulcu s identification (1-10 scale) were shell-MIP, 7.67; integral, 7.00; SS D, 3.22; and MIP, 1.00. Mean superficial venous quality MR ratings (1- 10 scale) were shell-MIP, 8.22; MIP, 7.39; integral, 7.00; and SSD, 3. 72. The mean number of cortical veins draining into each side of the s uperior sagittal sinus on MR was as follows: MIP, 6.19; integral, 6.06 ; shell-MIP, 5.94; and SSD, 3.81. Mean confidence scores for filling d efect identification on CT venograms (1-5 scale) revealed a shell-MIP score of 4.36 and an integral score of 4.29 to be superior to a MIP sc ore of 3.00. In selected cases, 3-D presurgical planning, prior to tum or resection, was clinically useful. CONCLUSION: Integral and shell-MI P are useful 3-D display algorithms for simultaneous display of superf icial cerebral veins and gyri on MR images and of thrombosis on CT ven ograms.