In this study, we investigated the use of high-resolution magnetic resonance imaging (MRI) methods for in vivo detection and quantitative characterization of colorectal tumors in the transgenic APCδ468 mouse model. High-resolution T1-weighted (T1W) images, T2-weighted (T2W) images, and dynamic contrast-enhanced (DCE) measurements were performed using a 7.0 T small-animal imaging system (N 5 10). Individual tumors were identified on both T1Wand T 2Wimages. Twenty-eight tumors (2.8 ± 0.9 mm, mean ± SD) were detected with high-resolution MRI across a distance of roughly 3 cm from the rectum to the splenic flexure, whereas 29 tumors were found within corresponding colon tissue samples examined at gross necropsy in the same area. T2 values were significantly different between tumor, skeletal muscle, and normal intestinal wall tissues (p <.05). For analysis of the vascular characteristics of colon tumor tissues using DCE measurements, the initial area under the curve (IAUC) for Gd contrast concentration curve (time) (CGd [t]) was calculated with integration times of 60 and 120 seconds post-contrast infusion; two integration times were selected to capture both tracer wash-in and wash-out characteristics. IAUC measurements were significantly larger in tumor tissues compared to both normal intestinal wall and skeletal muscle tissues (p <.001). In vivo anatomic and quantitative MRI measurements were readily feasible in the transgenic APCδ468 mouse model. These noninvasive methods should improve experimental efficiencies during longitudinal survival studies that otherwise would require single-end-point necropsy measurements.
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