Accuracy of diffusion-weighted echo-planar MR imaging and ADC mapping in the evaluation of residual cervical carcinoma after radiation therapy.

ABSTRACT

OBJECTIVES: The impact of diffusion-weighted imaging (DWI) and apparent diffusion coefficients (ADCs) of MR imaging on the evaluation of residual Uterine Cervical Carcinoma after Radiation Therapy, in addition to conventional MR images. METHODS: Fourty-nine women presenting with a uterine cervical cancer were examined with 1.5 T MRI and DWI, 8 (4-20) weeks after treatment. Treatment response was determined based on the histopathological results after therapy and was classified as a complete response (CR) or residual disease (RD). Post-treatment DWI and ADC results were compared. RESULTS: Five (11%) and 44 (89%) patients were considered as having histologically-proven RD or a CR respectively. The mean ADC of cervical tissue for all patients was 1.74±0.324×10(-3) mm(2)/s and the SD was 1.94±1.11×10(-4). The mean ADC was 1.62±0.21×10(-3) mm(2)/s (SD=1.45×10(-4)) for the 5 patients with RD versus 1.76±0.33×10(-3) mm(2)/s (SD=1.99×10(-4)) for the 44 patients with a CR (p=0.09). Using 1.7×10(-3) mm(2)/s as a radiological cut-off value for the ADC, all patients classified as having histologically-proven RD had a mean ADC of ≤1.7×10(-3). In 12 (25%) cases, RD was suspected on T2-weighted MRI images alone. Eight of these cases were considered as false positives compared to the histological results. Their mean ADC was 1.98×10(-3) mm(2)/s and none of them had an ADC of <1.7×10(-3) mm(2)/s. CONCLUSION: Although our results were not statistically significant, ADC values could potentially be used to predict and monitor the response of uterine cervical cancer.