P ersonalized medicine is a popular topic in radiology today. Scientists are flooding academic journals, conference proceedings, and book chapters with arguments about radiation reduction strategies with a personalized approach. However, contrast media (CM) dose reduction has been overlooked, which is of great concern. As such, 3% of all patients admitted for renal dialysis are a direct result of excessive CM volume delivered during radiologic imaging in the course of their hospital stay (1).Studies suggest that CM volumes employed during renal computed tomography (CT) angiography (CTA) range from 30-120 mL (2-4). This wide array of CM dose has different effects on scanner parameters. For example, employing 30 mL CM volume with a tube current selection of 80 kVp renders acceptable image quality. However, image quality can either be quantitative or qualitative in nature, which increase the subjectivity of good versus acceptable image quality with desired CM doses. Therefore, judging optimal image quality is determined by the amount of noise and vascular opacification of the renal arteries.Vascular opacification that is too low may compromise the visualization of small renal vasculature and underestimate plaque formation and stenosis (5). Previous studies on contrast-injection protocols for renal CTA suggested that the adequate attenuation value for the arteries is greater than 211 Hounsfield units (HU) (6). However, attenuation values of the renal arteries have reached as high as 435±48 HU, while those of the renal veins have reached 277±29 HU (7).The sensitivity and specificity for diagnosing greater than 50% renal artery stenosis during renal CTA range from 67%-100% and 77%-98%, respectively (8). Renal magnetic resonance angiography (MRA) has sensitivity and specificity of 88%-100% and 70%-100% with low interobserver variability, especially for severe stenosis greater than 70% (9).Renal CTA provides accurate, noninvasive, and time-efficient diagnostic evaluation for medical management of renal arterial disease as well as creating a roadmap prior to surgical intervention. Such clinical questions arise when a hypertensive individual has renal CTA to exclude renal artery stenosis, fibromuscular dysplasia, or dissection. Pathology-specific renal CTA examinations include determining if vasculitis involves the renal arteries or the extent of renal aneurysmal changes. Preoperative renal CTA planning can be useful for nephron-sparing surgery prior to resection of renal masses or as post-procedural follow-up of renal stenting or surgical revascularization. Finally, renal CTA is also employed in the evaluation of the kidney donor and recipient prior to transplantation.
ABSTRACTOver the last decade, exponential advances in computed tomography (CT) technology have resulted in improved spatial and temporal resolution. Faster image acquisition enabled renal CT angiography to become a viable and effective noninvasive alternative in diagnosing renal vascular pathologies. However, with these advances, new challenges in contras...