Extent of ovarian cancers. Evaluation on CT and MR imaging

Fourty patients with ovarian cancer were retrospectively studied to assess the extention of disease with computed tomography (CT) and magnetic resonance imaging (MRI). The following assessments were made: invasive disease to adjacent pelvic structures, intra-abdominal extent of disease, lymphadenopathy and ascites. Twenty-five abdominal CT scans and 33 pelvic scans, 19 abdominal MR imaging and 36 pelvic MR imaging were obtained. All patients were examined prior to initial operation. Contralateral ovarian metastases were seen in 25 patients, and 20 patients (66.7%) had visible or palpable mesenterial and peritoneal carcinomatosis at surgery. Ascites was the most common finding, direct invasion to rectum, sigmoid colon and parametrium, omental metastases and mesenterial metastases were followed. Involved lesions were depicted in 58.0% sites with CT and 57.0% with MRI. In uterus and ovarian involvement, the diagnostic ability of MR imaging was superior to that of CT. In lymph node metastases and mesenterium lesions, CT had superior diagnostic ability over MR imaging. Fat on MRI tended to mask high signal intensity lesions. Furthermore, motion artifacts due to bowel peristalsis and pulsation of vessels will lead to misinterpret the margin of normal organs. Small metastases under 0.5 cm in diameter were missed both on MRI and CT. The results of this study suggest that MR imaging is equivalent to CT in the detection of disseminated and metastatic lesions of ovarian cancer. (author)