Evaluation of the three dimendional microvascular structure and physiological function of renal glomerulus using superphoton derived X-ray micro focus CT

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We aimed at visualizing thee dimensional (3D) glomerular micro- structures using a superphoton derived X- ray micro focus CT (Mct) to accurately measure glomerular volumes throughout a cortex and quantitatively evakuate global heterogeneity of the volume- distribution in a rat with spontaneous diabetes mellitus (DM). Using the Otsuka Long Evans Tokushima Fatty (OLETF) rats as rats of early stage DM (28 weeks, n=5) and control rats (Long Evans Tokushima Fatty; LETO, n=5) of the same age, the vessels of the left kidney was filled up with contrast media (BaSO_4 + India ink + 8%gelatin). A sampled renal column (3-4 mm) was observed using two Mct system; 8GeV- superphoton Mct for the highest image quality (3-6 mm in resolution) and commercially available Mct (10 mm in resolution) for data accumulation. The glomerular volumes more than 400 per sample were computed by coefficient variation (CV). By stereomicroscopic observation, we confirmed complete- filling of the vessels with the contrast media. The glomeruli in OLETF were characterized by irregular stereostractures, whereas those in LETO were characterized by regular glomerular structure. The CV of glomerular volume was significantly larger in OLETF than LETO (p<0.01). In addition, absolute glomerular volume was larger in OLETF than LETO (p<0.005). The normalized glomerular volume was, however, comparable (NS), indicating glomerular enlargement in early DM may associate with increase in body mass. Both Mct provided similar results. Highly heterogeneous glomerular volume- distribution in DM rat was quantitatively demonstrated using our developed 3D glomerular micro- structural visualizing method. This technique provides a new aspect for the evaluation of global heterogeneity in glomerular remodeling under the chronic renal dysfunction, which may provide more sensitive insight into early complications of diabetic nephropathy