Anatomical Variations and Morphometry of Carotid Sinus: A Computed Tomography Study

Abstract

Background: The radiological evaluation of the carotid sinus (CS) anatomy and its morphometry is essentially important for various surgical procedures involving the carotid bifurcation and the CS itself. Despite its tremendous clinical significance, studies dealing with the CS anatomy are seldom reported. Hence, the present study aimed to evaluate the frequencies of the CS positional variants and their morphometry and correlate them with age and body mass index (BMI).

Methods: In this retrospective cross-sectional study, a total of 754 disease-free carotid arteries were examined using computed tomography angiography scans to determine the CS positional variations (such as types I to III) and its morphometry, including the CS diameter and length. Additionally, the association between these parameters and factors such as sex, age, and body mass index were explored using appropriate statistical tests. The inter-rater agreement of the collected dataset was evaluated using Cohen's Kappa.

Results: The CS type I was observed in 87.67% of the cases, and type II and type III were observed at lower frequencies with 9.02% and 3.32%, respectively. There were statistically significant (p < 0.001) differences observed in the mean diameter and length of the sinus between the sex and the type I CS variations. However, there was no significant and strong correlation between the age and BMI factors with sinus length and sinus diameter. The kappa values for inter-rater agreement ranged from 0.77 to 0.99 for all parameters.

Conclusions: In type I, the CS length and carotid vessel's diameter is significantly different between the sexes. However, age and BMI do not affect the CS anatomy in radiologically disease-free carotid arteries. Knowledge of the CS variant anatomy is clinically significant as it influences the patients' surgical and physiological outcomes.

Keywords: atherosclerosis; carotid artery; carotid sinus; morphometry; variations.

Figure 1

Types of carotid sinus using CT maximum intensity projection images and CT 3D reconstructions: (A,B) type I with dilatation of the CS extending from the distal CCA to the ICA; (C,D) type II with a dilated CCA extending to both the ICA and ECA; (E,F) type III CS with the dilatation in the distal CCA without extension to the ICA or ECA. (Arrowhead = CCA, solid arrow = ECA, dashed arrow = ICA, yellow circle = extension of the CS).