Differences on DWI may help to differentiate PC, mass-forming FP, and normal pancreas from each other.

Purpose: To review magnetic resonance imaging (MRI) and secretin stimulated magnetic resonance cholangiopancreatography (S-MRCP) findings of patients with suspected chronic pancreatitis and compare them with endoscopic pancreatic function testing (ePFT). Materials and Methods:MRI and S-MRCP findings of 36 patients with clinically suspected chronic pancreatitis were reviewed. Baseline ductal changes, duodenal filling grades, and pancreatic duct caliber change (PDC) on S-MRCP, mean values of pancreatic anteroposterior (AP) diameter, signal intensity ratio (SIR) between pancreas and the spleen on T1-weighted fat saturated images, and arterial to venous (A/V) enhancement ratios were compared between groups of normal and abnormal pancreatic exocrine function determined by ePFT.Results: All patients (n ¼ 24) with normal ePFT (HCO 3 >80 mEq/L) had grade 3 normal duodenal filling. Patients with abnormal ePFT (HCO 3 <80 mEq/L) (n ¼ 12) had grade 1 (n ¼ 1) and grade 2 (n ¼ 11) diminished duodenal filling (P < 0.0001). PDC was 1.51 in the normal ePFT group versus 1.27 in the abnormal ePFT group (P ¼ 0.01). No significant differences were found in terms of mean pancreatic AP diameter (21.8 vs. 19.8 cm), SIR (1.59 vs. 1.44), and A/V (1.08 vs. 1.01) between groups of normal/abnormal pancreatic exocrine function. Conclusion:Despite discrepancies between pancreatic exocrine function and the findings on standard MRI/ MRCP, the S-MRCP findings are comparable to ePFT in the evaluation of chronic pancreatitis. CURRENTLY, the most sensitive diagnostic tool to detect chronic pancreatitis at its earliest stage is hormonal pancreatic function testing. Secretin stimulated endoscopic pancreatic function testing (ePFT) is considered one of the most sensitive clinical pancreatic exocrine function testing methods (1-3). Secretin stimulated magnetic resonance cholangiopancreatography (S-MRCP) can estimate pancreatic exocrine function, and at the same time an increased number of side branch ectasia and or decreased pancreatic duct compliance after secretin stimulation can be demonstrated as early imaging findings of chronic pancreatitis (4-7). In addition, there have been studies that compared pancreatic exocrine function and pancreatic parenchymal and ductal findings on magnetic resonance imaging (MRI), MRCP, ERCP, and endoscopic ultrasound (EUS). Discrepancies have been reported over the years between each imaging modality and exocrine function test (4,7-11).The purpose of this study was 2-fold; first, we compared ePFT with S-MRCP for the assessment of pancreatic exocrine function. Second, we reviewed if pancreatic exocrine function correlates with the parenchymal imaging findings on MRI and ductal changes on MRCP before and after secretin stimulation.

Diffusion-weighted imaging (DWI) assesses the random motion of the water protons. The technique is more frequently used in body imaging, and recent investigations showed its use in pancreatic imaging. Diffusion-weighted imaging can be helpful as a complementary imaging method in the differentiation between mass-forming focal pancreatitis and pancreatic adenocarcinoma. The apparent diffusion coefficient (ADC) values derived from DWI can distinguish between simple pancreatic cyst, inflammatory cysts, and cystic neoplasms of the pancreas. Presence of parenchymal fibrosis in chronic pancreatitis causes diffusion restriction and results in lower ADC values on baseline DWI. The ADC values reveal either delayed peak after secretin stimulation or lower peak values in patients with early chronic pancreatitis, which may be helpful to depict chronic pancreatitis in its earliest stage. In this paper, we reviewed the technical aspects of DWI and its use in pancreatic imaging.

Pancreatitis can occur in acute and chronic forms. Magnetic resonance imaging (MRI) plays an important role in the early diagnosis of both conditions and complications that may arise from acute or chronic inflammation of the gland. Standard MRI techniques including T1-weighted and T2-weighted fat-suppressed imaging sequences together with contrast-enhanced imaging can both aid in the diagnosis of acute pancreatitis and demonstrate complications as pseudocysts, hemorrhage, and necrosis. Combined use of MRI and MR cholangiopancreatography can show both parenchymal findings that are associated with chronic pancreatitis including pancreatic size and signal and arterial enhancements, all of which are diminished in chronic pancreatitis. The degree of main pancreatic duct dilatation and/or the number of side branch ectasia determines the diagnosis of chronic pancreatitis and its severity. In this paper, we report the spectrum of imaging findings of acute and chronic pancreatitis on MRI and MR cholangiopancreatography.

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