Evaluating early response of cervical cancer under concurrent chemo-radiotherapy by intravoxel incoherent motion MR imaging

Background: Intravoxel incoherent motion (IVIM) MR imaging has been applied in researches of various diseases, however its potential in cervical cancer patients has not been fully explored. The purpose of this study was to investigate the feasibility of IVIM MR imaging to monitor early treatment response in patients receiving concurrent chemo-radiotherapy (CCRT) for advanced cervical cancers. Methods: Twenty-one patients receiving CCRT for advanced cervical cancer were prospectively enrolled. MR examinations including IVIM imaging (with 14 b values, 0 similar to 1000 s/mm(2)) were performed at 4 time points: 1-week prior to, 2-week and 4-week during, as well as immediately post CCRT (within 1 week). The apparent diffusion coefficient (ADC) maps were derived from the mono-exponential model, while the diffusion coefficient (D), perfusion fraction (f) and pseudo-diffusion coefficient (D*) maps were calculated from the bi-exponential model. Dynamic changes of ADC, D, f and D* in cervical cancers were investigated as early surrogate markers for treatment response. Results: ADC and D values increased throughout the CCRT course. Both f and D* increased in the first 2 to 3 weeks of CCRT and started to decrease around 4 weeks of CCRT. Significant increase of f value was observed from prior to CCRT (f(1) = 0.12 +/- 0.52) to two-week during CCRT (f(2) = 0.20 +/- 0.90, p = 0.002). Conclusions: IVIM MR imaging has the potential in monitoring early tumor response induced by CCRT in patients with cervical cancers.