Imaging features in anatomical variations of the dorsal pancreas and main pancreatic duct

Abstract

Objective To summarize the imaging features in anatomical variations of the dorsal pancreas and main pancreatic duct, and investigate the essentials of diagnosis and differential diagnosis. Methods The retrospective descriptive study was adopted. The clinical data of 1 patient with the anatomical variations of the dorsal pancreas and main pancreatic duct who was admitted to the Affiliated Hospital of Ningbo University at November 2013 were collected. The patient received plain and enhanced scans of computed tomography (CT) and magnetic resonance image (MRI), and magnetic resonance cholangiopancreatography (MRCP) examination. Observation indexes included: (1) manifestations of CT and MRI examinations. (2) Pancreas associated dimensions: ①the main pancreatic duct: the maximum width and the expansion length. ②The pancreatic parenchyma: the width of the dorsal pancreas and the ventral pancreas. ③Other dimensions: the distance from the ventral pancreas to the midline, the distance from the dorsal pancreas to the midline, the distance from the dorsal pancreas to the splenic hilum. (3)Follow-up situation: results of laboratory and imaging reexaminations. The follow-up of outpatient examination and telephone interview was performed on the patient up to January 2016. Results (1) Manifes-tations of CT and MRI examinations: CT examination demostrated a normal pancreatic length with parenchyma of the pancreatic body and tail atrophy and a slightly enlarged pancreatic head. The pancreatic parenchyma showed homogeneous density and main pancreatic duct of the pancreatic body and tail showed dilatation. On MRI, T1 weight imaging (T1WI) and T2 weight imaging (T2WI) demonstrated a slightly enlarged pancreatic head with homogeneous signal. The in-phase and out-phase imagings showed no signal loss on and diffusion weighted imaging (DWI) showed no restricted diffusion. Enhanced scanning demonstrated a marked homogenous enhancement of pancreatic head. Pancreatic body and tail showed thin and parenchyma atrophy on T1WI and T2WI without restricted diffusion on DWI and abnormal enhancement on enhanced scan. Of pancreatic duct and bile duct, MRI examination showed main pancreatic duct dilatation of the pancreatic body and tail with smooth inner wall and narrowed main pancreatic duct of pancreatic neck and no dilatation of the pancreatic head. Enhanced scanning demonstrated no abnormal enhancement of the enlarged duct. The branch pancreatic duct showed no dilatation. MRCP examination demonstrated no dilatation of intra- and extra bile duct and gallbladder and no abnormal signal of intracavity. Pancreatic margin showed smooth, regular and clear surrounding fat space. Other findings included a circular nodule under the spleen with a similar signal with the spleen on plain and enhanced scan. (2) Pancreas associated dimensions: ① the main pancreatic duct: the maximum width and the expansion length were 12.6 mm and 91.6 mm, respectively. ② the pancreatic parenchyma: the width of the dorsal pancreas and the ventral pancreas were 19.6 mm and 26.7 mm, respectively. ③ other dimensions: the distance from the ventral pancreas to the midline, the distance from the dorsal pancreas to the midline and the distance from the dorsal pancreas to the splenic hilum were 54.6 mm, 77.3 mm and 18.5 mm, respectively. (3) Follow-up status: results of laboratory reexaminations showed normal indexes at November 2014, and ultrasonography examination demonstrated slightly enlarged pancreatic head with homogenous internal echo, thin of the pancreatic body and tail, and an enlarged main pancreatic duct with the maximum width of 12.3 mm. The patient was followed up at November 2015, and laboratory reexaminations and ultrasonography examination demonstrated similar findings. Conclusion Imaging features of anatomical variations of the dorsal pancreas and main pancreatic duct include normal length of the pancreas, atrophy of the pancreatic body and tail, main pancreatic duct dilatation with smooth inner wall, slightly enlarged pancreatic head without any abnormal signal on dynamic enhancement imaging. Key words: Dorsal pancreas; Pancreatic duct; Anatomic variantion; Magnetic resonance Imaging