Liver mass CT

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Maria Fernanda Villarreal, M.D. [2]

Overview

Computed tomography may be useful for the evaluation and diagnosis of liver masses. The evaluation of liver mass should be performed with a triphasic CT, this modality includes 3 phases: non-contrast, arterial phase, and portal venous phase. On CT, characteristic findings of liver mass, may include: solitary or multiple lesion, solid or cystic consistency, and normally a rounded lesion. The evaluation of liver mass will depend on several characteristics, such as: vascular pattern, size, location, size, distribution, margins, attenuation, and contrast enhancement.

CT

Computed tomography may be useful for the evaluation and diagnosis of liver masses.

• The evaluation of liver mass should be performed with a triphasic CT, this modality includes 3 phases:
  • Non-contrast
  • Arterial phase
  • Portal venous phase

• On CT, characteristic findings of liver mass, include:
  • Solitary or multiple lesion
  • Solid or cystic
  • Rounded lesion

		CT scan Findings
Hepatocellular carcinoma Early arterial phase enhancement and then rapid wash out Rim enhancement of capsule may persist	Massive (focal)	Large mass May have necrosis, fat and /or calcification
	Nodular (multifocal)	Multiple masses of variable attenuation May also have central necrosis
	Infiltrative (diffuse)
Hemangioma		Discontinuous, nodular, peripheral enhancement starting in arterial phase Gradual central filling Enhancement must match blood pool in each phase, or not a hemangioma (i.e. similar to aorta in arterial, portal vein in portal phase, etc) Small hemangiomas (< ~1.5 cm) may demonstrate "flash filling" - complete homogenous enhancement in arterial phase (no gradual filling in)
Focal nodular hyperplasia		Bright arterial phase enhancement except central scar Isodense/isointense to liver on portal venous phase Central scar enhancement on delayed phase
Hepatic adenoma		Large, well circumscribed encapsulated tumors The distribution of hepatic adenoma 80% solitary 20% multiple Arterial phase: transient homogenous enhancement Returns to near isodensity on portal venous and delayed phase image
Liver metastases		Hypodense and enhance less than the surrounding liver Metastases from certain primaries demonstrate an increase in the number of vessels Rim enhancement is a feature of malignant lesions, especially metastases.

Hepatocellular carcinoma

• Most common hypervascular primary liver malignancy
• Early arterial phase enhancement and then rapid wash out
• Rim enhancement of capsule may persist
• Malignant liver mass, particularly hepatocellular carcinoma, can have a variety of appearances, such as:

• Massive (focal)

• Large mass
• May have necrosis, fat and /or calcification

• Nodular (multifocal)

• Multiple masses of variable attenuation
• May also have central necrosis

• Infiltrative (diffuse)

• May be difficult to distinguish from associated cirrhosis

Hemangioma

• Benign; most common liver tumor overall
• Discontinuous, nodular, peripheral enhancement starting in arterial phase
• Gradual central filling in
• Enhancement must match blood pool in each phase, or not a hemangioma (i.e. similar to aorta in arterial, portal vein in portal phase, etc)
• Small hemangiomas (< ~1.5 cm) may demonstrate "flash filling" - complete homogenous enhancement in arterial phase (no gradual filling in)

Focal nodular hyperplasia

• Bright arterial phase enhancement except central scar
• Isodense/isointense to liver on portal venous phase
• Central scar enhancement on delayed phase

Hepatic adenoma

• Large, well circumscribed encapsulated tumors
• The distribution of hepatic adenoma

• 80% solitary
• 20% multiple

• Arterial phase: transient homogenous enhancement
• Returns to near isodensity on portal venous and delayed phase image

Liver metastases

• Hypodense and enhance less than the surrounding liver
• Metastases from certain primaries demonstrate an increase in the number of vessels
• Rim enhancement is a feature of malignant lesions, especially metastases.

On CT, radiological signs of liver mass, include:

• Bright dot sign: Presence of a bright dot within a lesion which remains hyper-attenuating on arterial and portal venous phase CT, corresponding to early nodular enhancement seen on liver hemangioma.

Gallery

• 
  Liver hemangioma: discontinuous, nodular, peripheral enhancement starting in arterial phase
• 
  Bright dot sign: Bright dot within a lesion which remains hyper-attenuating on arterial and portal venous phase CT, corresponding to early nodular enhancement seen on liver hemangioma
• 
  Focal nodular hyperplasia: bright arterial contrast enhancement except for the central scar which remains hypoattenuating
• 
  Hepatic abscess: peripheral enhancement, centrally hypoattenuating lesions. Occasionally they appear solid, or contain gas. Segmental perfusion abnormalities, with early enhancement, may be seen.