Utility of MRI in detection of PET-CT proven local recurrence of pancreatic adenocarcinoma after surgery.

The aim of this prospective study was to investigate the accuracy and inter-observer reliability of MRI in detection of local recurrence (LR) of pancreatic adenocarcinoma (PAC) after surgery, which was proved by PET-CT and access correlation between functional MRI and PET parameters. Forty-five patients who underwent PET-CT and MRI for follow-up purposes after radical operation of PAC were included. Twenty-three were PET positive (study group) and 22 negative for LR (control group). MR examination was performed within one month after PET-CT and three readers who were blind for PET-CT findings searched LR in T2W, 3D-dynamic post-contrast T1W-FS and DWI sequences, respectively. Sensitivity and specificity were calculated while inter-reader agreement was estimated by Cronbach's Alpha reliability coefficient (CARC). Apparent diffusion coefficient (ADC) of LR was correlated with the size (maximal diameter) and functional PET-CT parameters: mean and maximum standardized uptake values (SUVmean, SUVmax), metabolic tumor volume (MTV) and total lesion glycolysis (TLG), using Spearman's correlation coefficient (r S ). Sensitivity and specificity among three readers in detecting the LR were 70% and 77-84% in T2W (CARC 0.806), 91-100% and 100% in 3D post-contrast T1W-FS (CARC 0.980), and both 100% in DWI sequences (CARC 1.000). Moderate inverse correlation was found between the ADC and SUVmean (r S  = - 0.484), MTV (r S  = - 0.494), TLG (r S  = - 0.519) and lesion size (r S  = - 0.567). MRI with DWI shows high diagnostic accuracy in detecting the LR of PAC in comparison to PET-CT as reference standard. ADC significantly inversely correlates with standard and advanced PET parameters and size of LR.