Tumor volume and subvolume concordance between FDG-PET/CT and diffusion-weighted MRI for squamous cell carcinoma of the cervix

Purpose: To compare [18F]fluorodeoxyglucose (FDG) / positron emission tomography (PET) / computed tomography (CT) and magnetic resonance imaging (MRI) for evaluating patients with cervical cancer. We compared tumor characteristics on FDG‐PET and apparent diffusion coefficient (ADC) maps on diffusion‐weighted MRI (DWI) to evaluate concordance of two functional imaging techniques. Materials and Methods: Twenty women with cervical cancer underwent pretreatment FDG‐PET/CT and pelvic MRI. Images were rigidly fused by pelvic anatomy using coregistration software. Tumor contours on PET images were generated by autosegmentation of the region containing at least 40% of the maximum standardized uptake value (SUV). DWI contours were generated by manual segmentation. Tumor volume similarity was evaluated using the [PET]/[ADC] volume proportion, Dice's coefficient, and the mean SUV isothreshold at the surface of each ADC contour. Tumor subvolume similarity was evaluated with analysis of variance (ANOVA). Results: The [PET]/[ADC] volume proportion was 0.88 ± 0.14. Dice's coefficient between PET and ADC tumor contours was 0.76 ± 0.06. The mean SUV isothreshold at the ADC‐delineated tumor surface was 34 ± 4%. Subvolumes with increased metabolic activity on FDG‐PET also had more restricted diffusion on DWI (P < 0.0001, ANOVA). Conclusion: Concordance of functional imaging was observed between FDG‐PET and DWI for cervical cancer. Tumor subvolumes with increased metabolic activity on FDG‐PET also have greater cell density by DWI. J. Magn. Reson. Imaging 2013;37:431–434. © 2012 Wiley Periodicals, Inc.