title: A semi-automated method for identifying and measuring myelinated nerve fibers in scanning electron microscope images.
abstract: Diagnosing illnesses, developing and comparing treatment methods, and conducting research on the organization of the peripheral nervous system often require the analysis of peripheral nerve images to quantify the number, myelination, and size of axons in a nerve. Current methods that require manually labeling each axon can be extremely time-consuming as a single nerve can contain thousands of axons. To improve efficiency, we developed a computer-assisted axon identification and analysis method that is capable of analyzing and measuring sub-images covering the nerve cross-section, acquired using a scanning electron microscope. This algorithm performs three main procedures - it first uses cross-correlation to combine the acquired sub-images into a large image showing the entire nerve cross-section, then identifies and individually labels axons using a series of image intensity and shape criteria, and finally identifies and labels the myelin sheath of each axon using a region growing algorithm with the geometric centers of axons as seeds. To ensure accurate analysis of the image, we incorporated manual supervision to remove mislabeled axons and add missed axons. The typical user-assisted processing time for a two-megapixel image containing over 2000 axons was less than 1h. This speed was almost eight times faster than the time required to manually process the same image. Our method has proven to be well suited for identifying axons and their characteristics, and represents a significant time savings over traditional manual methods.
authors.affiliation: Department of Biomedical Physiology & Kinesiology, Simon Fraser University, 8888 University Drive, Burnaby, BC V5A 1S6, Canada. hmore@sfu.ca
authors.forename: Heather L
authors.initials: HL
authors.lastname: More
authors.forename: Jingyun
authors.initials: J
authors.lastname: Chen
authors.forename: Eli
authors.initials: E
authors.lastname: Gibson
authors.forename: J Maxwell
authors.initials: JM
authors.lastname: Donelan
authors.forename: Mirza Faisal
authors.initials: MF
authors.lastname: Beg
mesh_terms: D000818:Animals; D001369:Axons / Q000648:ultrastructure*; D008855:Microscopy, Electron, Scanning / Q000379:methods*; D009413:Nerve Fibers, Myelinated / Q000648:ultrastructure*; D051381:Rats; D012584:Sciatic Nerve / Q000648:ultrastructure; D013997:Time Factors