Atherosclerotic renal artery stenosis in the post-CORAL era part 1: the renal penumbra concept and next-generation functional diagnostic imaging

• Discordant renovascular hypertension clinical outcomes may relate to natural history.
• Penumbra denotes salvageable ischemic parenchyma and may unify renovascular research.
• Functional renal imaging may noninvasively detect and stage renal penumbra.

After three neutral trials in which renal artery stenting failed to improve renal function or reduce cardiovascular and renal events, the controversy surrounding diagnosis and treatment of atherosclerotic renal artery stenosis and renovascular hypertension has led to paradigm shifts in the diagnostic algorithm. Noninvasive determination of earlier events (cortex hypoxia and renal artery hemodynamic changes) will supersede late sequelae (calcific stenosis, renal cortical thinning). Therefore, this review proposes the concept of renal penumbra in defining at-risk ischemic renal parenchyma. The complex field of functional renal magnetic resonance imaging will be reviewed succinctly in a clinician-directed fashion.