Comparative accuracy of intravenous contrast-enhanced CT versus noncontrast CT plus intravenous contrast-enhanced CT in the detection and characterization of patients with hypervascular liver metastases: a critically appraised topic.

Rational And Objectives: To evaluate whether addition of nonenhanced computed tomography (NECT) to intravenous contrast-enhanced (CE) abdominal CT improves detection or characterization of hypervascular liver masses. Patients were referred for initial staging or follow-up with known breast, melanoma, neuroendocrine, or thyroid cancer.

Material And Methods: The literature was searched using the patient, intervention, comparison, and outcome (PICO) method. Retrieved articles were critically appraised and assigned a level of evidence based on the Oxford University Centre for Evidence-based Medicine hierarchy of validity for diagnostic studies.

Results: One thousand one hundred studies were reviewed; only 11 studies matched the PICO of our study and were appraised. Most of the appraised articles were published in the 1990s using older technology and contrast delivery. The retrieved diagnostic performance for characterization of liver metastases showed sensitivity/specificity of 97%/76% for NECT, 97%/75% for arterial CT, and 98%/76% for portal venous phase CT in patients with breast cancer; sensitivity of 96% (arterial and portal CT) versus 100% (NECT, arterial and portal CT) in patients with melanoma; and sensitivity of 43% (portal CT) versus 17% (NECT) in patients with neuroendocrine tumor. No primary study was found for performance of different CT protocols in patients with thyroid cancer. Available evidence showed radiologists reported more conspicuous liver masses on CECT compared to NECT in patients with breast or neuroendocrine cancer.

Conclusions: Based on existing evidence, NECT only adds a small incremental value to CECT for detection/characterization of hypervascular liver metastases. Addition of NECT increases patient's exposure to radiation and the number of images available for interpretation.