Effects of Antiangiogenic Agents on CT Perfusion Parameters in Liver Metastases From Renal Cell Carcinoma and Normal Liver

To investigate the effects of targeted antiangiogenic agents on CT perfusion parameter values in liver metastases from renal cell carcinoma (mRCC) and on normal liver, before and after initiation of therapy.

CT perfusion parameter values of liver metastases from RCC and adjacent normal liver were evaluated before and after 8 weeks of bevacizumab and pazopanib. Perfusion parameters blood flow (BF), blood volume (BV), mean transit time (MTT), permeability surface area product (PS), portal venous perfusion (PVP), hepatic arterial perfusion (HAP), and hepatic arterial fraction (HAF) were derived from General Electric CT Perfusion (4D) software. Differences between tissues at baseline and percent changes (Δ) in perfusion values after therapy were evaluated by the Wilcoxon signed-rank test.

There were 9 patients in the study (6 bevacizumab, 3 pazopanib). BF, HAP, and HAF were significantly higher, and MTT significantly lower, in untreated metastases than normal liver (all P<0.02); and PS was borderline significantly higher (P=0.058). For the liver metastases 8 weeks after therapy, there were significant reductions in ΔBF, ΔBV, ΔHAP and ΔHAF compared with baseline: -27.4% (P=0.05), -54.9% (P=0.008), -80.6% (P=0.004), and -46.6% (P=0.019), respectively. No significant changes after 8 weeks of therapy were observed in normal liver for any of the 7 perfusion parameters.

This small preliminary data set suggests that targeted antiangiogenic agents might have significant effects on tumor perfusion, which can be detected by CT perfusion just 8 weeks after initiation of therapy. The agents have differential effects on tumor and normal liver. CT perfusion may assist in monitoring therapies and offer insights into pathophysiological aspects of tumors.