<prompt> Which of the following is the most specific and sensitive screening test for Renovascular hypeension.HRCTCT angiographyCaptopril enhanced radionucleatide scanMRI  <response>: Ref Harrison 19 th ed pg 1627 The renal resistive index has predictive value regarding the bility of the kidney. It remains operator- and institution-dependent, however. Captopril-enhanced renography has a strong negative predictive value when entirely nor- mal. Magnetic resonance angiography MRA is now less often used, as gadolinium contrast has been associated with nephrogenic systemic fibrosis. Contrast-enhanced computed tomography CT with vascu- lar reconstruction provides excellent vascular images and functional assessment, but carries a small risk of contrast toxicity. 