2D and 3D parameter images for analysis of contrast medium enhancement based on dynamic CT and MR [2D- und 3D-parameterbilder zur analyse der kontrast-mittelverteilung bei dynamischen CT- und MR-untersuchungen]

Aim: For dynamic contrast medium (CM) studies, parameter images exploit specific features of the time/intensity curve (TIC) of each pixel and represent these values in a new image. Existing concepts of two-dimensional CM analysis are extended for three-dimensional applications using adequate computer graphic visualization. Methods: Imaging: intravenous CM injection; first-pass analysis using fast CT acquisition of a single slice; CM accumulation by 40 MR slices (6 sequences every 90 s=240 images). Software: TIC of arbitrary 2D/3D regions; parameter images: (1) temporal maximum intensity projection (TMIP) of all voxels over time, (2) temporal CM gradients (TG) based on TIC amplitude, (3) TIC slope,(4) time of TIC peak, (5) correlation coefficient to reference TIC. The calculated 3 D data of CM accumulation was visualized using multiplanar reformation, MIP, surface reconstruction, volume rendering, texture mapping and animation. Results: In first-pass analyses, TMIP and TG allowed the simultaneous or separated presentation of different temporal phases of the CM bolus. Correlation images emphasized regions with similarities to given TIC patterns. Three-dimensional computer graphic techniques enabled (1) anatomical/functional mapping of original image and CM accumulation and (2) fused display of both spatial CM enhancement and color-encoded time of TIC peak in one common image. Conclusions: The quantification of presence, magnitude, and time-of-peak of CM accumulation in local image regions supports the assessment of vascularization and of ischemic or necrotic areas.