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Uncinate process of pancreas

The uncinate process of the pancreas is a small hook-like projection extending from the lower part of the pancreatic head. It curves posteriorly and medially, wrapping around the superior mesenteric vessels. This deep-seated portion of the gland is an important surgical and radiological landmark due to its intimate relation to the superior mesenteric artery (SMA) and vein (SMV).

Pathology involving the uncinate process, particularly pancreatic carcinoma, has high clinical significance because it can invade adjacent vascular structures, impacting resectability and prognosis.

Synonyms

  • Pancreatic uncinate process

  • Inferior projection of pancreatic head

  • Hook process of pancreas

Location and Relations

  • Anteriorly: Superior mesenteric vessels (SMV, SMA) and pancreatic head

  • Posteriorly: Inferior vena cava (IVC), aorta

  • Superiorly: Neck of pancreas and portal vein confluence

  • Inferiorly: Duodenum (third portion)

  • Medially: Duodenojejunal flexure

  • Laterally: Pancreatic head

Function

  • Acts as part of the exocrine pancreas, contributing to enzyme secretion via ducts joining the main pancreatic duct (duct of Wirsung)

  • Provides minor contribution to endocrine functions (islets of Langerhans scattered throughout)

  • Serves as an anatomical anchor around SMA and SMV, maintaining relation between pancreas and mesenteric vessels

Clinical Significance

  • Carcinoma: Tumors in the uncinate process may encase SMA/SMV, often presenting late and limiting surgical resection

  • Pancreatitis: Inflammation may extend into this region, causing localized edema or vascular compression

  • Vascular involvement: Its close relation to SMA/SMV makes it crucial in surgical planning for pancreaticoduodenectomy (Whipple procedure)

  • Imaging importance: Careful evaluation required in pancreatic cancer staging (vascular invasion assessment)

MRI Appearance

T1-weighted images:

  • Normal uncinate parenchyma: intermediate signal intensity (slightly higher than liver)

  • Tumors: appear as low-signal intensity focal lesions

  • Fat planes: bright, outlining the process against vessels

T2-weighted images:

  • Normal pancreas: low-to-intermediate signal

  • Pancreatic duct: high signal if visualized within or near uncinate process

  • Tumors/cysts: appear brighter than normal parenchyma

STIR (Short Tau Inversion Recovery):

  • Normal parenchyma: low-to-intermediate signal

  • Inflammatory changes: bright hyperintensity

  • Fat suppressed for better lesion detection

T1 GRE Fat-Sat Pre-Contrast:

  • Normal parenchyma: homogeneous intermediate signal

  • Tumors: hypointense compared to surrounding gland

T1 GRE Fat-Sat Post-Gadolinium:

  • Normal uncinate process: intense, homogeneous early enhancement due to rich vascular supply

  • Adenocarcinoma: hypoenhancing focal mass relative to background pancreas

  • Pancreatitis: heterogeneous patchy enhancement, with non-enhancing necrotic areas if severe

  • Cysts: non-enhancing lumen; walls may enhance if inflamed

CT Appearance

Non-Contrast CT:

  • Normal uncinate: soft tissue density similar to pancreas

  • Fat planes around SMA/SMV help identify boundaries

  • Tumors: hypoattenuating compared to normal pancreas

Post-Contrast CT:

  • Normal uncinate process: bright homogeneous enhancement in arterial phase

  • Carcinoma: hypoattenuating, ill-defined lesion; assessment focuses on vascular invasion of SMA/SMV

  • Pancreatitis: glandular enlargement, heterogeneous enhancement, peripancreatic fat stranding

  • Cysts or abscesses: low-attenuation lesions, rim enhancement if infected

MRI image

Uncinate process of pancreas MRI axial anatomy image-img-00000-00000

MRI image

Uncinate process of pancreas MRI coronal anatomy image-img-00000-00000

CT image

Uncinate process of pancreas CT axial anatomy image-img-00000-00000

CT image

Uncinate process of pancreas CT coronal anatomy image-img-00000-00000