What are the implications of a hypervascular lesion on the liver?

From the Guidelines

A hypervascular lesion on the liver requires prompt evaluation by a hepatologist or liver specialist, starting with multiphasic contrast-enhanced imaging such as a 4-phase CT scan or MRI with liver protocol, as recommended by the most recent guidelines 1. The recommended approach is to first characterize the lesion with these imaging studies, which help distinguish between benign lesions (like hemangiomas, focal nodular hyperplasia, or adenomas) and malignant ones (like hepatocellular carcinoma or metastases).

• The imaging studies should include dynamic (multiple phase) MRI or CT studies for diagnosis and evaluation of tumor extent (number and size of nodules, vascular invasion, extra-hepatic spread) 1.
• If imaging is inconclusive, a liver biopsy may be necessary for definitive diagnosis, but this decision should be made by a multidisciplinary team, including a hepatobiliary and transplant surgeon, and taking into account the patient's overall condition and potential treatment options 1. Management depends entirely on the specific diagnosis - benign lesions often require only monitoring with follow-up imaging every 6-12 months, while malignant lesions may require surgical resection, ablation therapy, or systemic treatment.
• The hypervascular nature of these lesions refers to their increased blood supply compared to normal liver tissue, which causes them to enhance more intensely during the arterial phase of contrast imaging, a characteristic particularly important in diagnosing hepatocellular carcinoma, which typically shows arterial enhancement followed by "washout" in later phases 1.
• Patients should avoid alcohol and hepatotoxic medications while awaiting diagnosis to prevent further liver damage. It's also important to consider the size of the lesion, as nodules smaller than 1 cm have a low likelihood of being HCC, and those between 1-2 cm require further investigation with two dynamic studies, either CT scan, contrast ultrasound or MRI with contrast 1.

From the Research

Hypervascular Lesion on Liver

• A hypervascular lesion on the liver can be either benign or malignant, and its diagnosis is crucial for appropriate treatment 2.
• Benign hypervascular lesions include focal nodular hyperplasia, adenoma, and some regenerative nodules in cirrhosis, as well as vascular lesions like hemangiomas and arteriovenous malformations 2.
• Malignant hypervascular primary liver lesions include hepatocellular carcinoma, fibrolamellar carcinoma, and peripheral cholangiocarcinoma, while certain metastatic cancers like neuroendocrine tumors can also appear hypervascular 2.

Diagnosis and Characterization

• The diagnosis of hypervascular liver lesions can be challenging, especially in cirrhotic patients, and requires a multistep approach combining clinical data, pathological findings, and imaging features 3.
• Magnetic Resonance Imaging (MRI) can assess the same lesion features as Computed Tomography (CT) and better characterize the enhancement patterns of nodules, with the added benefit of lacking irradiation 3.
• New liver-specific contrast agents and imaging techniques like diffusion-weighted sequences are available to aid in the diagnosis and characterization of hypervascular liver lesions 3.

Treatment and Outcomes

• The treatment outcomes of subcentimeter hypervascular nodules at high risk for developing into hepatocellular carcinomas (SHNHR) were compared between early treatment and watchful waiting, with no significant difference in recurrence-free survival found between the two strategies 4.
• Treatment modality was a significant factor for local recurrence-free survival, with transarterial chemoembolization being associated with a higher risk of local recurrence 4.
• The presence of arterial hypervascularity in hepatic masses found in cirrhotic patients is highly predictive of malignancy, with a positive predictive value of 100% for hepatocellular carcinoma 5.

Classification and Blood Supply

• A simplified model of tumor blood supply can be applied to standard triphasic CT scans to distinguish benign and malignant liver lesions, based on hepatic artery and portal vein blood supply coefficients 6.
• Hepatocellular carcinoma and hypervascular metastases had increased hepatic artery coefficients compared to the background liver, while benign lesions had either a greater hepatic artery coefficient or a greater portal vein coefficient 6.
• The sensitivity and specificity of hypervascularity with washout as a diagnostic criterion for hepatocellular carcinoma can be improved by examining hepatic artery and portal vein blood supply coefficients 6.