Perfusion CT monitors drug response in hepatocellular carcinoma

CONTEXT: Dr. Dushyant Sahani, director of CT at Massachusetts General Hospital in Boston, evaluated the effects of the anti-angiogenic drug bevacizumab (Avastin, Genentech) on patients with advanced hepatocellular carcinoma (HCC). Perfusion CT was used compare changes in tumor perfusion with tumor size and biomarkers such as alpha-fetoprotein (AFP) and circulating endothelial cells (CEC).

RESULTS: Perfusion CT was performed on 17 patients with HCC before receiving Avastin and again 12 days following treatment. Sahani performed a dynamic first-pass perfusion exam using 16-slice CT after administering 70 mL of iodinated contrast agent. Within two weeks of therapy, blood flow, blood volume, and permeability of surface area products all decreased, while mean transit time increased markedly. Magnitude of change was greater in responders, although almost all the tumors showed some alterations in perfusion CT. No correlation was found between the change in tumor perfusion and AFP, CEC, and tumor size. Treatment effects captured on perfusion CT are probably at the molecular level and therefore too early to manifest with any alterations in tumor size, a criterion currently used for estimating tumor response, according to Sahani.

IMAGE: Elevated blood flow (A) and blood volume (B) depicted with CT perfusion correlate with an HCC liver lesion that appears in a contrast-enhanced CT (C).

IMPLICATIONS: The research demonstrates perfusion CT is an effective method for evaluating early therapeutic results of Avastin on HCC. The study also shows that tumor response may not be determined at this early stage by more traditional diagnostic factors such as tumor size, AFP, and CEC.

"We would next like to test this method with other novel anticancer drugs that have anti-angiogenic effects," Sahani said.