[MRI in evaluation of myometrial invasion and staging of endometrial carcinoma]

Recently, nuclear magnetic resonance (NMR)-CT has become available for clinical use. A number of reports have stressed its diagnostic usefulness for gynecologic diseases. In the present report, we studied the clinical usefulness of magnetic resonance imaging (MRI) in diagnosing endometrial carcinoma. 1. Determination of the extent of myometrial invasion. We applied following five parameters: 1) transverse area ratio of occupying tumor in the uterine body (TAR), 2) sagittal area ratio of occupying tumor in the uterine body (SAR), 3) volume ratio of occupying tumor in the uterine body (VR), 4) minimal thickness of normal myometrium (MT) and 5) ratio of the maximal thickness to the minimal thickness of normal myometrium (Min./Max.ratio). We compared the NMR-CT findings with those for the surgically removed uterus. The Min./Max.ratio showed a statistically significant difference (p less than 0.05) between cases with myometrial invasion less than 1/3 of the whole thickness and those with invasion from 1/3 to 2/3. VR showed a significant difference (p less than 0.01) between cases with invasion from 1/3 to 2/3 and those with invasion more than 2/3. Thus, we suggest that the Max./Min.-ratio may be useful in detecting invasion less than 1/3, and that VR might be useful in detecting invasion more than 2/3. 2. Determining the clinical stages (FIGO) Correct staging rates by MRI were 100% for stage Ia, 83.3% for stage Ib, 50% for stage II and 100% for stage III. We could completely differentiate stage III cases from those of the lower stages. These results indicate that MRI is quite useful in diagnosing endometrial carcinoma.