Measurement of carotid stenosis on computed tomographic angiography: reliability depends on postprocessing technique

CT Angiography Manual Multiplanar Vessel Diameter Measurement vs. Semiautomated Perpendicular Area Minimal Caliber Computation of Internal Carotid Artery Stenosis

Objective: To determine the diagnostic agreement of CT angiography (CTA) manual multiplanar reformatting (MPR) stenosis diameter measurement and semiautomated perpendicular stenosis area minimal caliber computation of extracranial internal carotid artery (ICA) stenosis.

Methods: We analyzed acute cerebral ischemia CTA at our tertiary stroke center in a 12-month period. Prospective NASCET-type stenosis grading for each ICA was independently performed using (1) MPR to manually determine diameters and (2) perpendicular stenosis area with minimal caliber semiautomated computation to grade luminal constriction. Corresponding to clinically relevant NASCET strata, results were grouped into severity ranges: normal, 1–49%, 50–69%, and 70–99%, and occlusion.

Results: We included 647 ICA pairs from 330 patients (median age of 74 [66–80, IQR]; 38–92 years; 58% men; median NIHSS 4 [1–9, IQR]). MPR diameter and semiautomated caliber measurements resulted in stenosis grades of 0–49% in 143 vs. 93, 50–69% in 29 vs. 27, 70–99% in 6 vs. 14, and occlusion in 34 vs. 34 ICAs (p = 0.003), respectively. We found excellent reliability between repeated manual CTA assessments of one expert reader (ICC = 0.997; 95% CI, 0.993–0.999) and assessments of two expert readers (ICC = 0.972; 95% CI, 0.936–0.988). For the semiautomated vessel analysis software, both intrarater reliability and interrater reliability were similarly strong (ICC = 0.981; 95% CI, 0.952–0.992 and ICC = 0.745; 95% CI, 0.486–0.883, respectively). However, Bland–Altman analysis revealed a mean difference of 1.6% between the methods within disease range with wide 95% limits of agreement (−16.7–19.8%). This interval even increased with exclusively considered vessel pairs of stenosis ≥1% (mean 5.3%; −24.1–34.7%) or symptomatic stenosis ≥50% (mean 0.1%; −25.7–26.0%).

Conclusion: Our findings suggest that MPR-based diameter measurement and the semiautomated perpendicular area minimal caliber computation methods cannot be used interchangeably for the quantification of ICA steno-occlusive disease.

The TXA2R rs1131882, P2Y1 rs1371097 and GPIIIa rs2317676 three-loci interactions may increase the risk of carotid stenosis in patients with ischemic stroke

Background

The genetic risk factors for carotid stenosis are not fully understood. The aim of this study is to investigate the relationship between variants in platelet activation-relevant genes and carotid stenosis in patients with ischemic stroke (IS).

Methods

Eleven variants of platelet activation-relevant genes, aggregates of platelet-leukocyte, and platelet aggregation were examined in 236 IS patients with carotid stenosis and 378 patients without carotid stenosis. High-resolution B-mode ultrasound was used to assess carotid stenosis. Generalized multifactor dimensionality reduction (GMDR) methods were applied in analyzing gene-gene interactions to determine whether there was any interactive role of assessed variants in affecting risk of carotid stenosis.

Results

Platelet aggregation and aggregates of platelet-leukocyte showed higher value in patients with carotid stenosis, compared with patients without carotid stenosis. Excluding potential disturbance variables, these 11 variants were not associated with carotid stenosis. However, according to the GMDR analysis, gene-gene interactions among TXA2R rs1131882, P2Y1 rs1371097 and GPIIIa rs2317676 had a synergistic influence on carotid stenosis. The high-risk interactions between the three variants showed a relationship with higher platelet activation, and have independent associations with risk of carotid stenosis (OR = 2.72, 95% CI: 1.28–7.82, P = 0.001).

Conclusion

The interactions among rs1131882, rs1371097 and rs2317676 perhaps increase the risk of symptomatic carotid stenosis, and maybe a potential marker for carotid stenosis. In this study, the combinatorial analysis made good use in elucidating complex risk factors in the heredity of carotid stenosis.

Systematic review of preoperative carotid duplex ultrasound compared with computed tomography carotid angiography for carotid endarterectomy

INTRODUCTION

We reviewed the literature for preoperative computed tomography carotid angiography and/or carotid duplex to determine their respective sensitivity and specificity in assessing the degree of carotid stenosis. We aimed to identify whether one imaging modality can accurately identify critical stenosis in patients presenting with transient ischaemic attack or symptoms of a cerebrovascular accident requiring carotid endarterectomy.

METHODS

Systematic search of MEDLINE, Embase, Cochrane database of systematic reviews, all Evidence-Based Medicine Reviews (Cochrane Database of Systematic Reviews, ACP Journal club, Database of Abstracts of Reviews of Effects, Cochrane Clinical Answers, Cochrane Controlled Trials Register, Cochrane Methodology Register, Health Technology Assessment and NHS Economic Evaluation Database) for primary studies relating to computed tomography carotid angiography (CTA) and/or carotid duplex ultrasound (CDU). Studies included were published between 1990 and 2018 and focused on practice in the UK, Europe and North America.

RESULTS

The sensitivity and specificity of CTA and CDU are comparable. CDU is safe and readily available in the clinical environment hence its use in the initial preoperative assessment of carotid stenosis. CDU is an adequate imaging modality for determining stenosis greater than 70%; sensitivity and specificity are improved when the criteria for determining greater than 70% stenosis are adjusted. Vascular laboratories opting to use duplex as their sole imaging modality should assess the sensitivity and specificity of their own duplex procedure before altering practice to preoperative single imaging for patients.

CONCLUSIONS

The sensitivity and specificity of CTA (90.6% and 93%, respectively) and CDU (92.3% and 89%, respectively) are comparable. Both are dependent on criteria used in vascular laboratories. CDU sensitivity and specificity was improved to 98.7% and 94.1%, respectively, where peak systolic velocity and end diastolic velocity were assessed. Either modality can be used to determine greater than 70% stenosis, although a secondary imaging modality may be required for cases of greater than 50% stenosis.

Diagnostic Accuracy of 4 Commercially Available Semiautomatic Packages for Carotid Artery Stenosis Measurement on CTA

BACKGROUND AND PURPOSE

Semiautomatic measurement of ICA stenosis potentially increases observer reproducibility. In this study, we assessed the diagnostic accuracy and interobserver reproducibility of a commercially available semiautomatic ICA stenosis measurement on CTA and estimated the agreement among different software packages.

MATERIALS AND METHODS

We analyzed 141 arteries from 90 patients with TIA or ischemic stroke. Manual stenosis measurements were performed by 2 neuroradiologists. Semiautomatic measurements by using 4 methods (3mensio and comparable software from Philips, TeraRecon, and Siemens) were performed by 2 observers. Diagnostic accuracy was estimated by comparing semiautomatic with manual measurements. Interobserver reproducibility and agreement between different packages was assessed by calculation of the intraclass correlation coefficient and Bland-Altman 95% limits of agreement. False-negative classifications were retrospectively inspected by a neuroradiologist.

RESULTS

There was no significant difference in the diagnostic performance of the 4 semiautomatic methods. The sensitivity for detecting ≥50% and ≥70% degree of stenosis was between 76% and 82% and 46% and 62%, respectively. Specificity and overall diagnostic accuracy were between 92% and 97% and 85% and 90%, respectively. The interobserver intraclass correlation coefficient was between 0.83 and 0.96 for semiautomatic measurements and 0.81 for manual measurement. The limits of agreement between each pair of semiautomatic packages ranged from -18%-24% to -33%-31%. False-negative classifications were caused by ulcerative plaques and observer variation in stenosis and reference measurements.

CONCLUSIONS

Semiautomatic methods have a low-to-good sensitivity and a good specificity and overall diagnostic accuracy. The high interobserver reproducibility makes semiautomatic stenosis measurement valuable for clinical practice, but semiautomatic measurements should be checked by an experienced radiologist.

Performance of semiautomatic assessment of carotid artery stenosis on CT angiography: clarification of differences with manual assessment

BACKGROUND AND PURPOSE

Semiautomated methods for ICA stenosis measurements have the potential to reduce interobserver variability and to speed up its analysis. In this study, we estimate the precision and accuracy of a semiautomated measurement for carotid artery stenosis degree and identify and explain differences compared with the manual method.

MATERIALS AND METHODS

In this retrospective study involving 90 patients, 2 observers determined the stenosis degree twice, with both the semiautomated and the manual method. Intra- and interobserver correlations were calculated for both methods. The accuracy was estimated by comparing average semiautomated with manual measurements. The semiautomated stenosis calculations were performed using either the minimal or maximal intersection at the reference site. Individual cases with large differences in measurement were retrospectively inspected by 3 observers.

RESULTS

Intra- (R = 0.93, 0.96) and interobserver (R = 0.98) correlations for the semiautomated method were excellent and exceeded the manual performance correlations (R = 0.87, 0.86). The semiautomated measurements correlated well with the manual measurements (R = 0.87), with high specificity of 96% and lower sensitivity of 63%. Large differences were caused by misinterpretations of the semiautomated method associated with calcified plaques, resulting in overestimations of the minimal diameter, underestimation of stenosis degree, and incorrect centerlines. The effect of using the minimal diameter at the reference position resulted in a small, but significant, underestimation of the stenosis degree by the semiautomated method.

CONCLUSIONS

The semiautomated method showed an excellent reproducibility and good correlation with manual measurements with a high specificity and lower sensitivity for detecting a significant stenosis. Erroneous semiautomatic stenosis measurements were associated with the presence of calcium.