Correlation of the ADC values assessed by diffusion-weighted MRI and 18F­FDG PET/ CT SUV in patients with lung cancer

ABSTRACT

Background: Diffusion-weighted magnetic resonance imaging (DW-MRI) provides information on the cellularity and movement of water molecules in tissues and 18F­fluorodeoxyglucose (18F­FDG) positron emission tomography/computed tomography (18F­FDG PET/CT) assesses cellular glucose metabolism, however both variables are related to tumour aggressiveness. The aim of this study is to investigate the potential correlation of the apparent diffusion coefficient (ADC) assessed by diffusion-weighted MRI (DWI) and glucose metabolism determined by the standardized uptake value (SUV) calculated from 18F­FDG PET/CT data in non-small cell lung cancer (NSCLC) with the occurrence of metastasis to the lymph nodes. Methods: 18F­FDG PET/CT and DWI (TR/TE, 1800/93 ms; b-values, 0 and 600 s/mm2) were performed in 37 consecutive patients with histologically verified NSCLC. SUVmax was calculated based on the PET-CT data. The minimum ADC (ADCmin) was determined by placing a region-of-interest (ROI) covering the entire tumou. Results of 18F­FDG PET/CT and DWI were compared on a per-patient basis. Pearson's correlation coefficient was used for statistical analysis. Results: Correlation analysis of the ADCmin and SUVmax revealed that the inverse correlation was good for all the masses (p< 0.001) and the lymph nodes (p < 0.001) for each histological subtype, for both adenocarcinomas (p < 0.001) lymph nodes (p = 0.005) and squamous cell carcinomas (p < 0.001). No significant correlation was found in the comparison of the ADCmin and SUVmax of the lymph nodes for squamous cell carcinomas (p = 0.066). Conclusions: This study verified the relationship between the SUVmax and the ADCmin in NSCLC. The significant inverse correlation of these two quantitative imaging approaches highlights the association between metabolic activity and tumour cellularity. Therefore, DWI with ADC measurement might represent a new biomarker in NSCLC.