Developing means of selecting patients most likely to benefit from revascularization is vital. New imaging techniques and use of biomarkers are two avenues under active investigation. Concurrently, technical advances such as drug eluting stents and embolic protection

devices (EPD) need to be assessed. MR imaging can provide a multipurpose assessment during investigation of ARVD. RG7204 Detailed assessment of not just renal morphology, but also function can be acquired from a single MR study.64–67 Although routinely measured, renal bipolar length is a poor predictor of renal parencymal volume, and yet the latter is the best predictor of single kidney GFR.68 Recent studies have encouragingly shown that kidney volume to GFR ratios in RAS kidneys might predict those that will benefit from revascularization, presumably by identifying kidneys with well-preserved renal parenchyma and/or relatively rapidly developing RAS lesions.69 This builds on the concept of ‘hibernating parenchyma’, a term used to describe renal tissue which has not yet undergone permanent damage and which may benefit from restoration of blood flow via revascularization.70 An

alternative term is ‘functionally significant stenosis’– a disproportionately low GFR despite preserved parenchymal volume reflecting potentially reversible reduced renal plasma flow. In light of concern regarding NSF, non-gadolinium enhanced MR functional imaging is an Doxorubicin avenue of expanding research. Methods which ‘label’ various components in the blood in an attempt to understand renal perfusion and function, for example, deoxyhaemoglobin (in blood oxygen level dependent imaging) and blood water flow (arterial spin labelling) are two such methods under investigation.71 Amoxicillin There is also increasing interest in the value of biomarker analysis in patients with ARVD. Vascular endothelial growth factor (VEGF) is an endothelial-specific growth factor and within the kidney it is expressed by tubular epithelial cells and glomerular podocytes. Its most vital function is to stimulate capillary endothelial cell growth and proliferation, primarily

in response to hypoxia, but release is also triggered by platelet aggregation at endothelial surfaces in response to vascular injury.72 Loss of VEGF is associated with development of glomerulosclerosis and tubulo-interstitial fibrosis.73 Although VEGF is a biomarker for renal ischaemia associated with RAS, it may also have potential utility as a treatment – for example, it can preserve the microvascular circulation in pig models of RAS. In these studies, pigs with RAS infused with VEGF developed significantly less glomerulosclerosis and tubulo-intersitital fibrosis than those untreated, and treated kidneys looked structurally similar to non-RAS kidneys.74 Brain natriuretic peptide (BNP) is a neurohormone released from cardiac myocytes.