Can MRI predict local control rate of uterine cervical cancer immediately after radiation therapy?

Purpose: To evaluate the utility of measuring the volumes of areas of high signal intensity on T-2-weighted magnetic resonance (MR) images immediately after irradiation for predicting the local control rate of uterine cervical cancer. Materials and Methods: From our departmental database, we identified 109 patients with cervical cancer who underwent MR imaging before irradiation and just before or just after completion of radiation therapy from 1994 to 2007. We included 46 of the 109 patients in this study, 5 patients with local recurrence and 41 patients who were free of disease for more than 2 years. Fifteen received radiation therapy alone, and 28 patients received concurrent chemoradiation therapy. We measured the volumes of areas of high signal intensity involving the uterine cervix on T-2-weighted MR images before radiation therapy and just before or just after its completion. We measured the 3 orthogonal diameters to calculate the volume as an ellipsoid and evaluated proportional tumor volume and the rate of reduction. We analyzed statistics with Student's t-test. Results: In patients with local recurrence, the mean volume of the areas of high signal intensity on T-2-weighted MR images just before completion of irradiation therapy or just after was 19.70 cm(3), which was significantly larger than that in patients without recurrence (1.77 cm(3), P<0.05). The proportional tumor volume was also significantly larger (P<0.05). Conclusions: Although areas of high signal intensity on T-2-weighted MR images include acute radiation change, their volume and the proportional tumor volume after irradiation can be useful clues in predicting the local control rate of uterine cervical cancer.