Liver Protocol for CT Imaging

Essential Components of Liver CT Protocol

• The American College of Radiology recommends a multiphasic approach with arterial, portal venous, and delayed phases to optimize detection and characterization of liver lesions 1, 2
• The American College of Radiology suggests using intravenous contrast with an injection rate of 4-5 mL/sec for optimal arterial phase imaging 2
• The American College of Radiology recommends including a non-contrast phase for patients with prior liver-directed therapy or when hemorrhage/calcification is suspected 2, 3

Imaging Phases

• The American College of Radiology states that the arterial phase is critical for detection of hypervascular lesions and lesion characterization 1, 2
• The American College of Radiology recommends that the portal venous phase is essential for detection of hypovascular metastases 1, 2
• The American College of Radiology suggests that the portal venous phase should be acquired 60-70 seconds after contrast injection 2
• The American College of Radiology states that the delayed phase (3-5 minutes) improves lesion characterization 1

Technical Parameters

• The American College of Radiology recommends a slice thickness of 2.5-5 mm (thinner slices improve lesion detection) 1
• The American College of Radiology suggests using a kVp of 120-150 1
• The American College of Radiology recommends using an mA of 80-300 1

Protocol Variations Based on Clinical Context

For Suspected Hepatocellular Carcinoma (HCC)

• The National Comprehensive Cancer Network recommends multiphasic imaging as HCC typically shows arterial hypervascularity and "washout" on portal venous phases 4
• The American College of Radiology suggests including all phases (non-contrast, arterial, portal venous, delayed) for patients who have received liver-directed therapy 5

For Suspected Metastases

• The American College of Radiology states that for hypovascular metastases, the portal venous phase is most sensitive (85-91.5% sensitivity) 2
• The American College of Radiology recommends that for hypervascular metastases, the arterial phase is critical as these lesions may be missed if only portal venous phase is performed 2, 3

For Post-Treatment Surveillance

• The American College of Radiology recommends including a non-contrast phase for patients who have received liver-directed therapy 5
• The American College of Radiology suggests first follow-up imaging at 1 month post-treatment, followed by imaging every 3 months 5

Special Considerations

• The American College of Radiology recommends considering alternative imaging modalities such as MRI for patients with renal insufficiency 6, 7