Sum of the Curve Indices for Estimating the Vascular Tortuousness of the Internal Carotid Artery

Kim, Jae Kyun; Choi, Jin Woo; Choi, Byung Se; Kim, Tae Il; Whang, Sun Moon; Kim, Sang Joon; Suh, Dae Chul

Abstract

PURPOSE
Most technical difficulties in intracranial stenting are derived from the vascular resistance caused by the severe tortuousness of intracranial arteries. The purpose of this study was to develop a practical method for measuring vascular tortuousness so that it would be possible to predict technical difficulties requiring further technical support.
MATERIALS AND METHODS
We developed a best-fit circle metrics which made measurement of vascular tortuousness feasible, which was called "curve index (CI)". We compared the curve index in 56 consecutive patients who underwent M1 stenting for symptomatic severe stenosis. The difference in the CI between the successful and the aborted groups was statistically compared by using the Mann-Whitney U test. ROC curve analysis was performed to evaluate the diagnostic performance of the best-fit circle metrics.
RESULTS
There was no statistically significant difference between the successful and the aborted cases in the CIs of each curve segment. However, the sum of all CIs of the aborted group was significantly larger (3.49) than that of the successful group (2.53) (p=0.013). On ROC curve analysis, the area under the curve was 0.806. When we took the cut-off value to be 3, the sensitivity was 75% and the specificity 85%.
CONCLUSION
We developed a practical method for measuring the CI of vessel curves in order to estimate the tortuousness of the internal carotid artery. A CI less than 3, therefore, indicates a favorable vascular curvature for the intracranial stenting procedure. A vessel having a higher curve index was more likely to be aborted.