The Application of Iodine Quantitative Information Obtained by Dual-Source Dual-Energy Computed Tomography on Chemoradiotherapy Effect Monitoring for Cervical Cancer: A Preliminary Study.

OBJECTIVE: The aim of the study is to investigate the potential contribution of the iodine quantitative parameters of dual-phase dual-energy computed tomography (DECT) scanning for chemoradiotherapy (CRT) response monitoring for cervical cancer.

METHODS: Patients who were pathologically certified having cervical cancer and intended for concurrent radiotherapy and chemotherapy were prospectively included in our study. Contrast-enhanced DECT scanning was performed before CRT, which was repeated after 1 month of therapy, using a dual-source CT scanner onset. Changes in tumor size were assessed according to RECIST 1.0. Quantification of volume-normalized iodine uptake (mg/mL) was measured in dual phases and was standardized using the iodine uptake in the iliac artery. The decreased ratio of the standard iodine uptake was calculated and compared with the tumor size for the evaluation of the CRT effect. Data were analyzed using the statistics software SPSS version 19.0. Twenty women who performed normal pelvic contrast-enhanced CT scanning were randomly chosen as the control group for the radiation dose comparison with the dual-energy group.

RESULTS: A total of 21 patients who completed therapeutic courses and performed the contrast-enhanced CT scanning were subsequently evaluated. According to RECIST 1.0, 15 cases were classified into the regression (R, including 5 completed regression cases and 10 partial regression cases) group. The remaining 6 cases were classified into the nonregression (NR, including 6 stable disease cases) group. The iodine value decreased ratio in the arterial phase (standardized iodine in arterial phase [SAI]) of the partial regression group was significantly higher than that of the stable disease group (P < 0.01), and there was no significant difference in the venous phase (P > 0.05). In a general quantitative comparison between the R group and the NR group before CRT, we controlled for the maximum diameter, age, iodine uptake in the arterial phase before CRT (pre-SAI), iodine uptake in the venous phase before CRT, and cell differentiated level, and we ultimately found no significant statistical differences except for the pre-SAI. In other words, the iodine value in the arterial phase of the R group before CRT was significantly higher than that of the NR group (P < 0.01). When the pre-SAI was 0.345, the area under the curve was 0.875 for therapeutic effect prediction. The mean effective dose was 5.63 ± 1.68 mSv for the DECT group and 5.37 ± 1.82 mSv for the control group (t = -1.137, P = 0.262), which showed no statistical difference in the radiation dose between the 2 scanning methods.

CONCLUSIONS: The iodine mapping can be used to help evaluate the radiochemotherapy response effectively on the basis of tumor size change and can also be helpful in predicting the radiochemotherapy outcome for cervical cancer. The dual-phase DECT scanning did not increase the radiation dose and provided more valuable information, and thus, it was suitable for promotion in clinical application.