A quantitative index for the measurement of the tortuosity of blood vessels

We propose a novel index for quantitating arterial tortuosity, based on sec ond differences of the coordinates of the Vessel midline. The index is inde pendent of the magnification of the image and of sampling frequency. We hav e demonstrated its validity as an indicator of changes in morphology using simulated shapes. It is superior to two other putative indices based on ves sel elongation and the variance of differences in the vessel midline coordi nates, presented previously in the literature. The proposed index is easily generalised to three dimensions, allowing a true three-dimensional tortuos ity index to be calculated from biplane angiograms or serial tomographic sl ices. It has a number of clinical applications. Preliminary data, using 82 aortograms from radiographic archives, showed a significant correlation bet ween the tortuosity of the abdominal aorta and subject age (r=0.684, P<0.00 1). For this group, increased tortuosity was especially evident for subject s above 40 yr of age. (C) 2001 IPEM. Published by Elsevier Science Ltd. All rights reserved.