Accuracy of Diffusion-Weighted Echo-Planar MR Imaging and ADC Mapping in the evaluation of residual Cervical Carcinoma after radiation therapy

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} mm²/s and the SD was 1.94 ± 1.11 × 10^{- 4}. The mean ADC was 1.62 ± 0.21 × 10^{- 3} mm²/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} mm²/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} mm²/s and none of them had an ADC of < 1.7 × 10^{- 3} mm²/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.