ower (amplitude) CDS has significant potential to contribute to improved understanding of tumor vascularity and blood flow in vivo. 1 However, its inability to quantitate blood flow is a major current limitation. It was the purpose of this study to devise and test a 2D and 3D a-CDS system designed to quantitate tumor vascularity and flow as they correlate with histologic determinations of vascularity. In addition, changes in flow after intravenous infusion of CM-101 were studied as a means to evaluate possible effects (within 1 h) in tumor blood flow. This exotoxin has been reported to affect tumor vascularity in our previously reported study and was used as a means to produce changes in vascularity that might be detected by 3D a-CDS. This study was designed to evaluate the accuracy of a system to quantitate tumor vascularity with amplitude (power) color Doppler sonography twoand three-dimensionally. The vascularity of 20 transplanted murine tumors was determined with quantitated amplitude color Doppler sonography both two-and three-dimensionally and compared to tumor vascularity estimated by histologic examination. Serial examinations were performed 15, 30, 45, and 60 min after the injection of the exotoxin CM-101 and saline solution to assess changes in tumor vascularity. Three-dimensional amplitude color Doppler sonography best depicted the overall vascularity of tumor when compared to histologic estimation of vessel density. However, neither twonor three-dimensional amplitude color power angiography correlated well to the microvessel count, probably a reflection of the difference in the method for vessel quantification using sonographic versus histologic techniques. Three-dimensional amplitude Doppler sonography correlated better with counts of large vessels (> 100 µm) as opposed to small vessels (> 15 µm). Time-activity curves showed no difference in tumor flow at the times measured in the experimental group injected with CM-101 or when compared to saline solutions in either the peripheral or central portions of the tumor. This three-dimensional amplitude color Doppler sonographic system affords global quantification of tumor vascularity and flow that may, in turn, be useful in determining the probability of malignancy (by determination of branching patterns and vessel regularity) or tumor response or both to treatment. KEY WORDS: Color Doppler sonography; Tumor, vascularity; Vascularity, tumor.

Quantified power Doppler US is a noninvasive method for the evaluation of tumor vascularity and blood flow.