Objective: To determine whether the apparent diffusion coefficient (ADC) on 3T MR imaging including diffusion-weighted MR imaging (DWI) correlate with the standardized uptake value (SUV) on 18F-FDG PET/CT in musculoskeletal tumours. Methods: This retrospective cohort study included 57 patients (36 males, 21 females, mean age 54 years, range 12–90 years) with pathologically confirmed soft tissue (n = 32) and bone (n = 25) tumours who underwent 3T MR imaging including DWI and whole-body 18F-FDG PET/CT before treatment. 14 patients had follow-up MR imaging and 18F-FDG PET/CT after treatment. The minimum (ADCmin) and mean (ADCmean) ADCs of musculoskeletal tumour, ADC of normal skeletal muscle (ADCmus), SUVmax and SUVmean of musculoskeletal tumour were obtained. Correlation between ADCs and SUVs was assessed using Pearson correlation coefficients (r). ADCmin and SUVmax were compared between pretreatment and posttreatment by t-test. Results: There was inverse correlation between SUVmax and the ratio ADCmin/ADCmus (r = - 0.505 to - 0.495, p ≤ 0.001) and between SUVmean and the ratio ADCmean/ADCmus (r = - 0.501 to - 0.493, p = 0.001). After treatment ADC was significantly increased whereas SUV was significantly decreased (p = 0.001). There was significant correlation in percent change between the initial and follow-up values of ADCmin and SUVmax (r = 0.750 to 0.773, p ≤ 0.005). The ADCmin was increased by 163% and SUVmax was decreased by 61% in 11 patients with treatment response. Conclusion: ADC at 3T MR DWI and SUV at 18F-FDG PET/CT have an inverse correlation in musculoskeletal tumours. Advances in knowledge: Our study showed that ADC at 3T DWI and SUV at 18F-FDG PET/CT had an inverse correlation in musculoskeletal tumours.
Correlation of apparent diffusion coefficients measured by diffusion-weighted MR imaging and standardized uptake values from FDG PET/CT in metastatic neck lymph nodes of head and neck squamous cell carcinomas