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Figure 2 Comparison of MRI and High-Resolution Ultrasound for Imaging of Therapeutic Angiogenesis in Rabbit Hind Limbs

(A and B) Relative blood volume–magnetic resonance imaging (BV-MRI) performed with transversal plane contrast-enhanced T₂*-weighted MRI with intravenous superparamagnetic iron oxide particles (Resovist) 6 days after AdLacZ or AdVEGF gene transfer. Shown are R₂* maps that demonstrate highly increased blood volume in the AdVEGF-injected semimembranosus muscle (brackets). (C and D) Contrast-enhanced power Doppler ultrasound (CEU) can detect blood flow only in large vessels, whereas in panels E and F, CPS ultrasound imaging at 8.0 MHz shows blood flow with a very high spatial resolution and effective tissue subtraction. Arrowheads indicate the profound femoral artery, and asterisks denote free fluid between muscles owing to AdVEGF-induced vascular permeability. See Online Videos 1 and 2. Abbreviations as in Figure 1.