Gadolinium mesoporphyrin as an MR imaging contrast agent in the evaluationof tumors: An experimental model of VX2 carcinoma in rabbits

OBJECTIVE. We determined the enhancement features of experimentally induced malignant rumors on MR imaging with the use of gadolinium mesoporphyrin, a recently developed MR contrast agent that may be necrosis-specific. MATERIALS AND METHODS, VX2 carcinoma was inoculated into 24 rabbit thighs. T1-weighted contrast-enhanced MR imaging with IV gadopentetate dimeglumine (2-min delay) and gadolinium mesoporphyrin (20-hr delay) was performed 3-4 days (n = 6), 6-7 days (n = 6), 10-11 days (n = 5), and 13-14 days (n = 7) after the implantation of VX2 carcinoma. All tumors were sectioned along th e same plane of MR images, and a detailed MR imaging-histopathologic correl ation was performed. RESULTS, Pathologically, areas enhanced with gadolinium mesoporphyrin inclu ded necrotic tissue, viable tumor, inflammatory granulation tissue, hemorrh age, and fibrosis. On gadopentetate dimeglumine-enhanced MR images, unenhan ced areas of the tumor corresponded with intratumoral necrosis and hemorrha ge, CONCLUSION. Gadolinium mesoporphyrin enhances tumor necrosis on delayed pha se MR imaging; however, it is impossible to specifically depict necrosis wi th gadolinium mesoporphyrin because it also enhances other parts of lesions , including viable tumor.