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Figure 1 CPS Signal Intensity–Time Curve in the Semimembranosus Muscle After a Bolus Injection of SonoVue Contrast Agent Via the Rabbit Ear Vein 6 Days After AdVEGF and AdLacZ Gene Transfer

The gamma variate function was used to model the first-pass kinetics of the contrast agent and to calculate blood flow ratios (i.e., perfusion ratios if tissue volume is equal) between transduced and contralateral intact limbs. The area under the curve represents blood volume in the region of interest. Blood flow is blood volume divided by the mean transit time (MTT) of the contrast agent. Alternatively, we found that a very good estimate of blood flow (perfusion) can be achieved with the ratio of peak signal intensities between the hind limbs (see Fig. 4). Times to arrival as well as MTT give important information on the structure of the vasculature (see Fig. 4). Ad = adenovirus; AdLacZ = adenoviral beta-galactosidase; CPS = contrast pulse sequence; VEGF = vascular endothelial growth factor.