Clinical Utility Assessment
RENAL
Renal ultrasound provides qualitative evidence of distribution of renal blood flow as evidenced by changes in the color doppler signal as it progresses from the large hilar vessels toward smaller arcades deeper into the kidney. Thus, if renal perfusion improves in response to therapy, the color doppler signal should be evident from the hilum into the interlobar circulation and finally the arcuate arterial arcade located at the cortico-medullary junction. Another measurement of renal vascular flow is the renal resistance index (0-1.0) which reflects the total cross-sectional area of the renal artery network. These measurements were carried out at the level of the hilar artery.All 36 individual kidneys were assessed by a single radiologist using a Toshiba Canon Aplio 300 CV ultrasound machine for changes in distribution of blood flow. The radiologist was not blinded as all subjects were treated and results were needed in real time as part of safety evaluations. Renal resistive index (RRI) calculated from serial measurements of the arterial wave form, noting the difference in the systolic and diastolic velocity peaks. As reported in the literature, an RRI value of >0.70 is considered abnormal. A change in RRI value (Δ) ≥ 0.02 between measurements is clinically significant.