MR and pathologic correlation of rabbit VX-2 carconoma

This paper evaluates the reliability of MR imaging in tissue characterization and depiction of tumor boundaries. The authors performed MR-pathologic correlation using parosteally implanted VX-2 carcinoma in 17 rabbit thighs. T1-weighted, T2-weighted, and Gd-DTPA-enhanced T1-weighted axial images were obtained 10-20 days after tumor implantation. After the animals were killed, freezing, sectioning along the MR imaging planes, and histopathologic examination were done. For accurate MR-pathologic correlation, rabbits were fixed on the cardboard plate to minimize position change during the procedures. Tumor boundaries depicted on MR images were larger than those depicted on the specimen. Small tumors were surrounded by capsule-like, hypervascular (mainly lymphatics), loose connective tissue. Loose connective tissue became compact with tumor growth. This connective tissue showed high signal intensity on both T2-weighted and Gd-DTPA-enhanced T1-weighted images. Muscle atrophy with development of lymphatics around the tumor also contributed high signal intensity on MR images. Peritumoral edema and inflammatory reaction were not remarkable. Peritumoral lymphatics, rich connective tissue, and muscle atrophy exaggerated the size of experimentally induced malignant musculoskeletal tumors on MR images