GI Radiology > Liver > Masses > Metastases

Hepatic Masses

Metastases
  1. Pathogenesis:
  • the most common malignant mass in the liver.
     
  • the three most common sources of metastasis to the liver:
      1. Primary tumors of the GI tract (e.g. tumors of the colon, pancreas, or stomach)
      2. Breast tumors
      3. Lung tumors
         
  • Hepatic artery is the main blood supply to most metastases.
     
  • Hypervascular liver tumors: 3 primary tumors + 5 metastases (MRI CT).
      1. HCC
      2. FNH
      3. Adenoma
      4. Melanoma
      5. Renal Cell Carcinoma
      6. Islet cell tumor of the pancreas
      7. Carcinoid tumor
      8. Thyroid cancer
  1. Radiographic findings:
  • Sensitivity of various modalities in the detection of a metastatic lesion is as followed (Kinkel MetaAnalysis Radiology 2002):
    • US: 55%
    • CT: 72%
    • MRI: 76%
    • PET: 90% (statistically significant)
       
  • Contrast CT:
      1. Most metastastic tumors are hypodense during the portal venous phase of bolus or dynamic CT. Some may have rim enhancement.
      2. Hypervascular masses are enhanced during the arterial phases. (Many are also well visualized during the portal venous phase.)
      3. Metastases have calcification.
         
  • T1-weighted MRI: mostly hypo-isointense, can also be hyperintense. Doughnut sign: low signal rim around even lower signal center.
     
  • T2-weighted MRI: Iso-hyperintense. Target sign: hyperintense center surrounded by less intense rim.
     
  • NOTE:
    • Hypervascular lesions: Early uniform enhancement with washout on portal venous or delayed images. Ring enhancement.
    • Hypovascular lesions: Ring enhancement early which washes out. Greatest lesion contrast in portal phase.