Segmentation and analysis of the glomerular basement membrane using active contour models

Some renal diseases are associated with significant alterations in the structure of the glomerular basement membranes (GBM). Increased thickness is commonly seen in diabetic nephropathy, where it may be an early sign of renal involvement. Abnormally thin GBMs are associated with the passing of blood in the urine, or hematuria. Measurement of the GBM thickness is carried out on images obtained from transmission electron microscopy (TEM). We propose image processing methods for the detection and measurement of the GBM. The methods include edge detection, morphological image processing, active contour modeling, skeletonization, and statistical analysis of the width of the GBM. The proposed methods were applied to 34 TEM images of six patients. The mean and standard deviation of the GBM width for a patient with normal GBM were estimated to be 348 plusmn 135 nm; those for a patient with thin GBMs associated with familial hematuria were 227 plusmn 94 nm; and those for a patient with diabetic nephropathy were 1152 plusmn 411 nm. Comparative analysis of the results of image processing with manual measurements by an experienced renal pathologist indicated low error in the range of 36 plusmn 11 nm.