ASSESSMENT OF MYOMETRIAL INVASION BY ENDOMETRIAL - CARCINOMA - TRANSVAGINAL SONOGRAPHY VS CONTRAST-ENHANCED MR-IMAGING

OBJECTIVE. A prospective study was designed to compare transvaginal so nography with contrast-enhanced MR imaging to determine preoperatively the depth of myometrial invasion in patients with early-stage endomet rial carcinoma. SUBJECTS AND METHODS. In 40 patients, findings on tran svaginal sonograms, unenhanced T2-weighted MR images, and contrast-enh anced T1-weighted MR images were compared with histologic findings. Th e depth of myometrial invasion was classified as stage E (tumor limite d to endometrium, n = 12), stage S (superficial invasion: tumor invade s up to 50% of the myometrium, n = 15), or stage D (deep invasion: tum or invades more than 50% of the myometrium, n = 13). RESULTS. Findings on transvaginal sonograms were accurate in 27 of 40 patients (accurac y, 68%); the depth of invasion was overestimated in five patients and underestimated in eight patients. The results of unenhanced T2-weighte d MR images were accurate in 27 patients (accuracy, 68%), with four ov erestimations and nine underestimations. The results of contrast-enhan ced T1 -weighted MR images were accurate in 34 patients (accuracy, 85% ), with five underestimations and one overestimation. In the assessmen t of each stage of myometrial invasion, the sensitivity and specificit y of contrast-enhanced T1-weighted imaging were higher than those of T 2-weighted MR imaging and transvaginal sonography. The false-positive diagnoses based on transvaginal sonograms and T2-weighted images, resp ectively, involved polypoid tumors (n = 4 and 2), distension of the en dometrial cavity by pyometra (n = 2 and 1), the presence of myoma (n = 2 and 1), atrophy of the myometrium (n = 1 and 0), and poor tumor/myo metrium contrast (n = 0 and 2). On contrast-enhanced MR images, accura cy was influenced only in a case of polypoid tumor, because tumor, end ometrial cavity, and myometrium were clearly distinguished and residua l myometrium was clearly visualized. With all imaging techniques, fals e-negative diagnoses were caused mainly by tumors with superficially s preading growth or microscopic invasion. With transvaginal sonography, infiltrative tumor also tended to be understaged (n = 3). CONCLUSION. Contrast-enhanced MR imaging is significantly superior to transvagina l sonography and unenhanced T2-weighted MR imaging for detecting myome trial invasion.