Evaluation of the therapeutic effect of radiotherapy on cervical cancer using magnetic resonance imaging

Purpose: This study was performed to evaluate magnetic resonance imaging (M RI) in determining the therapeutic effect of radiotherapy (RT) on cervical cancer. Methods and Materials: Serial MRI studies were performed in 42 patients wit h predominantly advanced cervical cancer before, during, and after radiothe rapy. Patients underwent external irradiation combined with high-dose-rate intracavitary (HDR) brachytherapy. T-2 weighted spin-echo pulse sequences w ith long repetition and echo times were used at a field strength of 1.5 T. Multiple punch biopsies of the cervix were obtained from the high-signal in tensity area in all patients at the same time as the MRI. Result: In biopsies performed immediately after RT, no residual tumors were found in 36 patients (86%); in 6 patients, residual tumors were observed. The simultaneous MRI study demonstrated no high-signal intensity on T2-weig hted images in 28 patients. A high-signal area was observed in 14 patients, and this disappeared 3 months after RT in 8 patients with a negative histo logical study. The sensitivity, specificity, and accuracy of MRI studies at 3 months after RT were 100%. When the relationship between reduction of tu mor volume at 30 Gy and local tumor control was analyzed, every patient wit h a reduction under 30% gained local control. Also, patients with no residu al tumors 3 months after RT gained local control. Conclusion: MRI studies performed at 30 Gy of external irradiation and 3 mo nths after RT were predictive factor of local control. (C) 1999 Elsevier Sc ience Inc.