Initial Staging of Locally Advanced Rectal Cancer and Regional Lymph Nodes: Comparison of Diffusion-Weighted MRI With 18F-FDG-PET/CT. (April 2016)

• Record Type: Journal Article
• Authors: Cerny, Milena; Dunet, Vincent; Prior, John Olivier; Hahnloser, Dieter; Wagner, Anna Dorothea; Meuli, Reto Antoine; Schmidt, Sabine
• Is Part Of: Clinical nuclear medicine. Volume 41:Number 4(2016)
• Publication Date: 2016-04
• Subjects: 18F-FDG SUV -- ADC -- locally advanced rectal cancer -- lymph nodes -- MRI -- PET/CT; Nuclear medicine -- Periodicals; Radioisotope scanning -- Periodicals; Nuclear Medicine -- Periodicals; 616.07575
• DOI: 10.1097/RLU.0000000000001172
• Languages: English
• ISSNs: 0363-9762

Abstract

Abstract : Purpose: The aim of the study was to compare diffusion-weighted MRI (DW-MRI) parameters with 18 F-FDG PET/CT in primary locally advanced rectal cancer (LARC). Methods: From October 2012 to September 2014, 24 patients with histologically confirmed and untreated LARC (T3–T4) prospectively underwent a pelvic 1.5-T DW-MRI ( b = 0 s/mm 2, b = 600 s/mm 2 ) and a whole-body 18 F-FDG PET/CT, before neoadjuvant therapy. The 2 examinations were performed on the same day. Two readers measured 18 F-FDG SUVmax and SUVmean of the rectal tumor and of the pathological regional lymph nodes on PET/CT and compared these with minimum and mean values of the ADC (ADCmin and ADCmean) on maps generated from DW-MRI. The diagnostic performance of ADC values in identifying pathological lymph nodes was also assessed. Results: Regarding tumors (n = 24), we found a significant negative correlation between SUVmean and corresponding ADCmean values (ρ = −0.61, P = 0.0017) and between ADCmin and SUVmax (ρ = −0.66, P = 0.0005). Regarding the lymph nodes (n = 63), there was a significant negative correlation between ADCmean and SUVmean values (ρ = −0.38, P = 0.0021), but not between ADCmin and SUVmax values (ρ = −0.11, P = 0.41). Neither ADCmean nor ADCmin values helped distinguish pathological from benign lymph nodes (AUC of 0.24 [confidence interval, 0.10–0.38] and 0.41 [confidence interval, 0.22–0.60], respectively). Conclusions: The correlations between ADCmean and SUVmean suggest an association between tumor cellularity and metabolic activity in untreated LARC and in regional lymph nodes. However, compared with 18 F-FDG PET/CT, ADC values are not reliable for identifying pathological lymph nodes.