Diagnostic Ultrasound - Abdomen and Pelvis

Hepatic Metastases
Diagnoses: Liver
○ Intraoperative ultrasound for small lesions
○ PET/CT is useful for whole-body screening
○ Gadoxetic acid-enhanced MR for detection of subtle
metastases
○ Abdominal ultrasound
– For metastasis screening or surveillance
– Readily accessible and radiation free, but low
sensitivity
DIFFERENTIAL DIAGNOSIS
Cysts (vs. Hypoechoic or Cystic Metastases)
• May have internal debris due to prior hemorrhage or
infection
• No peripheral rim or central vascularity/contrast
enhancement
• No mural nodule, thick wall, internal septa
• Posterior acoustic enhancement
Abscesses (vs. Hypoechoic Metastases)
• May be solid or cystic (internal debris/septa, thick irregular
wall)
• Typical systemic signs of infection
• "Cluster" sign on CT for pyogenic abscesses
Hemangiomas (vs. Hyperechoic Metastases)
• Classically uniformly hyperechoic on US
• Typical peripheral nodular discontinuous enhancement on
CECT or CEMR
• Markedly hyperintense on T2WI
Multifocal Hepatocellular Carcinomas or
Cholangiocarcinomas (vs. "Target" Lesion)
• Hepatocellular carcinoma (HCC): Cirrhotic liver, portal vein
invasion/thrombosis
○ In cirrhotic livers, metastases from non-hepatic primaries
are rare due todecreased portal blood flow
– Thus any mass in cirrhotic liver is highly suspicious for
HCC rather than metastasis
• Cholangiocarcinoma: Capsular retraction, delayed
enhancement
Steatosis (vs. Hypo- or Hyperechoic Metastasis)
• Focal fatty sparing: Hypoechoic area in hyperechoic liver
• Focal fatty infiltration: Hyperechoic area or areas
• Geometric borders, no architectural distortion, no mass
effect
• Fat density on NECT
• Focal signal dropout on opposed-phase T1 GRE MR
Hepatic Adenomatosis
• Mimic hypervascular metastasis
• Fat-containing and hemorrhagic; better seen on MR
• History of OCP or anabolic steroid use
– Neuroendocrine tumors, renal and thyroid cancers
– Some breast cancers, sarcomas, and melanoma
Staging, Grading, & Classification
• Liver metastases indicate stage IV tumor
CLINICAL ISSUES
Presentation
• Most common signs/symptoms
○ Asymptomatic, RUQ pain, tender hepatomegaly
○ Weight loss, jaundice or ascites
• Lab data: Elevated LFTs; normal in 25-50% of patients
Natural History & Prognosis
• Depends on primary tumor site
• 20-40% have good 5-year survival rate if resectable
• In patients with metastatic colon cancer
○ 3-year survival rate
– 21% in patients with solitary lesions
– 6% in patients with multiple lesions in 1 lobe
– 4% in patients with widespread disease
Treatment
• Resection or ablation for colorectal liver metastases
• Chemo- or radioembolization: Hypervascular
(neuroendocrine tumor) metastases
• Chemotherapy (oral or IV) for all others
DIAGNOSTIC CHECKLIST
Consider
• Rule out other causes of multiple liver lesions like hepatic
cysts, abscesses, hemangiomas
• Correlate with clinical history and look for evidence of
primary tumor
Image Interpretation Pearls
• In absence of other obvious metastasis
○ Hepatic lesions that are "too small to characterize" rarely
represent metastasis
○ Lesions higher than blood density on NECT rarely
represent metastasis
SELECTED REFERENCES
1. Westwood M et al: Contrast-enhanced ultrasound using SonoVue® (sulphur
hexafluoride microbubbles) compared with contrast-enhanced computed
tomography and contrast-enhanced magnetic resonance imaging for the
characterisation of focal liver lesions and detection of liver metastases: a
systematic review and cost-effectiveness analysis. Health Technol Assess.
17(16):1-243, 2013
2. Lefort T et al: Correlation and agreement between contrast-enhanced
ultrasonography and perfusion computed tomography for assessment of
liver metastases from endocrine tumors: normalization enhances
correlation. Ultrasound Med Biol. 38(6):953-61, 2012
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PATHOLOGY
General Features
• Etiology
○ Hypovascular liver metastases
– Lung, GI tract, pancreas, and most breast cancers
– Lymphoma, bladder and uterine malignancy
○ Hypervascular liver metastases
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