Biliary Normal Variants and Artifacts
Left hepatic duct formed by segmental branches from segments II-IV Right hepatic duct has 2 branches, including a horizontally oriented anterior branch draining segments V and VIII and a vertically…
Ischemic Bile Duct Injury
Solitary or multifocal strictures of variable length • Cholangiography: Gold standard for diagnosis Appearance may be identical to PSC with “beading” of biliary tree (alternating stenosis, normal ducts, and mild dilatation)…
Ischemic Colitis
Emboli to SMA from cardiac sources most commonly Affects right colon ± small bowel CT findings often subtle (ileus, lack of mucosal enhancement, no wall thickening acutely) • Mesenteric venous thrombosis Thrombosis…
Fibrolamellar Carcinoma
Uncommon malignant hepatocellular tumor • Also known as fibrolamellar hepatocellular carcinoma (HCC) Distinct clinical, histopathologic, and imaging features differentiate it from conventional HCC IMAGING • Heterogeneously enhancing, large, lobulated mass with hypointense…
Appendicitis
Sonographic McBurney sign with focal pain over appendix Shadowing, echogenic appendicolith Increased flow within wall of appendix, indicating inflammation Increased echogenicity of inflamed periappendiceal fat • CT: Abnormal mural enhancement of…
Small Bowel Obstruction
Air-fluid levels on upright or decubitus radiograph • Transition zone between dilated and collapsed bowel is critical to define presence, site, and cause of obstruction All better determined on CT than…
Hepatic TB and Fungal Infections
MR: FLASH sequences Gadolinium enhancement required to detect very small lesions TOP DIFFERENTIAL DIAGNOSES • Metastases • Lymphomatous/leukemic foci in liver • Biliary hamartomas • Caroli disease PATHOLOGY • Originates from intestinal seeding of portal…
Atypical and Rare Pancreatic Tumors
Extremely aggressive and almost always unresectable Large, heterogeneous, moderately enhancing, exophytic mass with necrosis and cystic change • Small cell carcinoma Highly aggressive, with hematologic and lymphatic metastases at time of…
Transient Hepatic Attenuation or Intensity Difference (THADs and THIDs)
Become isodense (isointense) on venous and delayed phases • Pseudolesions on nuclear medicine studies e.g., “hot” accumulation of Tc-sulfur colloid in left lobe of liver in patients with SVC obstruction “Hot”…
