Analysis of the glomerular basement membrane in images of renal biopsies using the split-and-merge method: a pilot study.

Abnormal thinning, thickening, or variation in the thickness of the glomerular basement membrane (GBM) are caused by familial hematuria, diabetes mellitus, and Alport syndrome, respectively. We propose a semi-automated procedure for the segmentation and analysis of the thickness of the GBM in images of renal biopsy samples obtained by using a transmission electron microscope (TEM). The procedure includes the split-and-merge algorithm, morphological image processing, skeletonization, and statistical analysis of the width of the GBM. The procedure was tested with 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 368 +/- 177 nm, those for a patient with thin GBM associated with familial hematuria were 216 +/- 95 nm, and those for a patient with thick GBM due to diabetic nephropathy were 1,094 +/- 361 nm. Comparative analysis of the results of image processing with manual measurements by an experienced renal pathologist indicated low error in the range of 12 +/- 9 nm.