Retinal Blood Vessel Segmentation by Means of Multiscale Analysis and Region Growing

M. Elena Martínez-Pérez $^{a*}$, Alun D. Hughes $^b$, Simon A. Thom $^b$,
Neil Chapman $^b$, Anil A. Bharath $^a$ and Kim H. Parker $^a$

Abstract:

Retinal blood vessel morphology can be an important indicator for many diseases such as diabetes, hypertension and arteriosclerosis, and the measurement of geometrical changes in veins and arteries can be applied to a variety of clinical studies. Two of the major problems in the segmentation of retinal blood vessels are the presence of a wide variety of vessel widths and the inhomogeneous background of the retina. We present a method based upon the multiscale analysis of the first and second spatial derivatives of the intensity image which gives information about vessel topology, overcomes the problem of variations in contrast inherent in these images and ensures the robust detection of blood vessels of different widths, lengths and orientations. The local maxima over scales of the magnitude of the gradient and the maximum principal curvature of the Hessian tensor are then used in a two stage region growing procedure. In the first stage, the growth is constrained to regions of low gradient magnitude. In the final stage this constraint is relaxed to allow borders between regions to be defined. The algorithm is tested in both red-free and fluorescein retinal images. Segmented vessel diameters and branching angles are validated against manual measurements and between imaging techniques.

Keywords: Blood vessel segmentation, multiscale analysis, region growing, retinal imaging.

$^a$ Department of Biological and Medical Systems. Imperial College of Science, Technology and Medicine. Prince Consort Road, London, SW7 2BY, UK. Martínez-Pérez was supported by the Mexican National Council for Science and Technology (CONACYT). Asterisk indicates corresponding author.

$^b$ Department of Clinical Pharmacology. Imperial College of Science, Technology and Medicine. School of Medicine at St. Mary's Hospital. Paddington, London, W2 1NY, UK.