Cervical cancer: serial MR imaging before and after primary radiation therapy--a 2-year follow-up study.

Serial magnetic resonance imaging studies were performed in 28 patients undergoing primary radiation therapy for invasive cervical cancer. T2-weighted spin-echo pulse sequences with long repetition times (2,500 msec) and echo times (30-100 msec) were used at a field strength of 1.5 T. Eighteen tumors responded promptly to radiation therapy with a volume reduction and significant decrease of signal intensity in the early posttreatment phase (1-3 months) and with total tumor regression at 1-6 months (immediate responders). At 6 months seven tumors were visible as residual tumors with declining signal intensity; all seven of these tumors had resolved at 9 months (delayed responders). Thus, a delayed response with residual tumor at 6 months was still compatible with subsequent clinical cure. The tumors showed progression and no marked change in signal intensity (nonresponders). Primary tumors with a volume of more than 50 cm3 were more likely to have no or delayed response. An early (2-3 months) and significant decrease in the signal intensity and volume of a tumor indicates a favorable response. Large primary tumors may show a delayed response.