Liver Masses / Hepatoma

What are the common liver masses?

• Malignant liver tumors
  • Metastatic tumors
  • Hepatocellular carcinoma
  • Cholangiocarcinoma
• Benign focal liver lesions
  • Cysts
    • congenital
    • parasitic - echinococcal
  • Cavernous hemangiomas
  • Focal nodular hyperplasia
  • Hepatic adenomas
  • Abscesses

What are the useful imaging modalities to investigate liver masses?

• CT
• Ultrasound
• MRI

Utility of each procedure - Indicate when you would select each procedure.

• CT scan
  • Is the best imaging modality to evaluate liver masses. It can identify other intra-abdominal masses and vascular involvement, i.e., thrombosis, etc.
  • CT angiography shows early enhancement of tumor in arterial phase.
• Ultrasound
  • Is most useful intra-operatively, during which the transducer is placed directly upon the liver surface to recognize liver lesions.
  • Transabdominal ultrasonography is inferior in sensitivity for liver masses to CT or MRI.
  • Doppler is helpful to demonstrate vascularity of lesions.
• MRI
  • MRI is useful for delineating vascular involvement and identifying additional intra-abdominal lesions.

Pathology of hepatoma (hepatocellular carcinoma):

• Hepatoma can present as single or multiple masses or diffuse involvement.
• It has a tendency to invade portal and hepatic veins.

What are the imaging findings of hepatoma?

CT

• Single, multiple masses or diffuse involvement
  • Low attenuation lesion
  • Hemorrhage
  • Fat
  • Necrosis
  • Calcification
  • Hypodense capsule or rim
  • Enhancement seen with contrast
• Can invade portal and hepatic veins

Hepatoma with hemorrhage NML is the normal liver density. White arrows point to increased density of the liver from hemorrhage (blood appears white on CT). Black arrows point to the hepatoma. Note tiny calcification in the tumor. Black arrows in the angiogram show the hypervascular tumor.

Hepatoma Arrowheads point to the enhancing mass. Note the lobulated margins of the liver. Liver has lower density than spleen and ascites indicating underlying cirrhosis.

Hepatoma Arrows: Tumor Arrowheads: Tumor extends to portal vein Portal veins dilated with intraluminal tumor. Portal veins in Liver appears dark on CT because it does not enhance with contrast.

MR Imaging

• Single, multiple masses or diffuse involvement
  • T1 weighted images
    • Heterogeneous, iso intense to hyper intense
    • Hemorrhage
    • Fat
    • Necrosis
    • Calcification
  • T2 weighted images
    • Most hyperintense, may be iso intense
  • Vascular invasion
  • Enhancement reflects vascularity and necrosis

Hepatoma MR shows a mass that has low signal intensity on T1 and high signal on T2.

Ultrasound

• Carcinoma can be recognized as discrete nodules.
• These typically appear as slightly hyper echoic and hypo echoic nodules.

What are the imaging findings of liver cyst?

• Ultrasound features that are specific for a cyst include an echolucent mass with a well-defined thin wall and increased through-transmission.
• Lesions which show these features need no further evaluation.
• Small (< 1.0 cm) cysts may be difficult to characterize with confidence.

What are the imaging findings of liver metastases?

• Single lesion
• Multiple hypodense lesions
• Hypervascular lesions

Liver metastasis Multiple hypodense lesions seen in the liver with no significant contrast enhancement. Primary: Colon carcinoma

Discuss the utility of imaging procedures for detection of liver metastases.

• CT
  • CT scan is the imaging procedure of choice to evaluate liver for metastases.
  • Hypervascular metastases may be difficult to detect on CT scans performed with a single phase technique. Triphasic scans should be done.
  • CT arterial portography can improve sensitivity for metastatic lesions, albeit with lower specificity.
• Ultrasound
  • Is most useful intra-operatively, during which the transducer is placed directly upon the liver surface to recognize liver metastases.
  • Transabdominal ultrasonography is inferior in sensitivity for liver masses to CT or MRI.