Blood Perfusion Characteristics of Renal Cell Carcinoma in the Process of Tumor Growth: Monitored With Multiple Sonographic Modalities.

ABSTRACT: Tumor angiogenesis is an essential factor for tumor growth and antiangiogenic therapy. To simulate the blood perfusion characteristics of human renal cell carcinoma (RCC) longitudinally in the process of tumor growth, multimodal ultrasound examination was performed on 40 orthotopic xenograft RCC mouse models. According to tumor maximum diameter ( d ), tumor growth progress was divided into 3 steps: d ≤ 5 mm, 5 mm < d ≤ 10 mm, and d > 10 mm. Color Doppler flow imaging (CDFI), superb microvascular imaging (SMI), and contrast-enhanced ultrasound were administered to monitor tumor perfusion characteristics. The abundance of tumor vascularity on CDFI and SMI was divided into grades 0 to III in ascending order, and their distribution range was categorized into types I to IV. As a result, heterogeneous echogenicity and irregular shape were more common in tumors d > 10 mm than those d < 10 mm ( P < 0.001 for both). Tumor perfusion grade and type on both CDFI and SMI made statistic difference among different growth steps, with higher ratio of hypervascular characteristic in bigger ones (all P < 0.05). Tumor in the same growth step had a higher perfusion grade on SMI than that on CDFI ( P < 0.001). On contrast-enhanced ultrasound, heterogeneous enhancement was more common in those >10 mm ( P < 0.001). It can be concluded that the blood perfusion characteristics of RCC keep on changing during its growth process. In addition, SMI is more sensitive in evaluating tumor perfusion than CDFI.