Correlation of apparent diffusion coefficients measured by 3T diffusion-weighted MRI and SUV from FDG PET/CT in primary cervical cancer

Purpose  Diffusion-weighted magnetic resonance imaging (DWI) and fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) are oncological feasible techniques. Currently, apparent diffusion coefficient (ADC) measured by DWI and standard uptake value (SUV) from FDG PET/CT have similar applications in clinical oncology. The aim of this study was to assess the correlation between ADC and SUV in primary cervical cancer. Materials and methods  Patients with documented primary cervical cancer were recruited. All participants underwent abdominopelvic DWI at 3T and FDG PET/CT within 2 weeks. For the primary tumor, ADC was measured as minimum ADC (ADC_min) and mean ADC (ADC_mean) within the whole tumor by DWI. Maximum SUV (SUV_max) and mean SUV (SUV_mean) were measured by FDG PET/CT. Results  A total of 33 patients were included. There was no significant correlation either between ADC_min and SUV_max or between ADC_mean and SUV_mean. The relative ADC_min (rADC_min) defined as ADC_min/ADC_mean ratio was significantly inversely correlated with the relative SUV_max (rSUV_max) defined as SUV_max/SUV_mean ratio (r = –0.526, P = 0.0017) in all study patients. A significantly inverse correlation between rADC_min and rSUV_max was observed in patients with adenocarcinoma/adenosquamous carcinoma (r = –0.685, P = 0.0012) and those with well-to-moderate differentiated tumor (r = –0.631, P = 0.0050). No significant correlation was demonstrated in patients with squamous cell carcinoma or poorly differentiated tumor. Conclusions  The significantly inverse correlation between rADC_min and rSUV_max in primary cervical tumor suggests that DWI and FDG PET/CT might play a complementary role for the clinical assessment of this cancer type.