Additional ultrasound capabilities for local haemodynamically significant carotid deformity: a one-stage observational study

Background. Despite a wide range of studies, no consensus has been reached on the relative weight of ultrasound parameters for assessing local haemodynamically significant carotid deformations.
Objectives. To estimate a diagnostic value for an additional multiparametric ultrasound parameter for local haemodynamically significant carotid deformations.
Methods. In the first phase, 388 patients underwent an outpatient multiparametric ultrasound examination of the carotid arteries. The study involved patients of the age of 18 and older with a primary referral for carotid ultrasound by a resident physician, neurologist or cardiologist in order to rule out a carotid pathology. As a supplement to the main haemodynamic significance assessment parameters, we introduced an additional metric — the deformity coefficient – in order to diagnose carotid abnormalities. Based on the first phase results, two cohorts were selected. Cohort 1 (control) consisted of patients with no abnormalities in multiparametric carotid ultrasound. Cohort 2 consisted of patients with isolated unilateral internal carotid artery deformities at no haemodynamically significant stenosis of common and internal carotid arteries in multiparametric carotid ultrasound. In the second phase, the patients underwent transcranial duplex sonography of the middle cerebral arteries, in order to detect regional haemodynamically significant internal carotid artery deformities.
Results. Mathematical modelling of abnormal arteries produced the empirical upper deformity coefficient thresholds to distinguish acute angulation. This value is >1.41 for C-shaped and >1.34 — for S-shaped curves.
Subsequent statistical analysis revealed a clear positive correlation between angulation and the deformity coefficient at a p < 0.01 significance level. More acute angulation corresponds to higher coefficient values.
The Spearman correlation between the deformity coefficient and blood flow asymmetry values for middle cerebral artery was 0.89. This defines a significant positive correlation (higher deformity coefficient corresponds to higher blood flow asymmetry) at a p < 0.01 significance level.
Conclusion. The deformity coefficient is an additional ultrasound parameter for assessing local haemodynamically significant carotid abnormalities.