Evaluation of Cross-Sectional Luminal Morphology in Carotid Atherosclerotic Disease by Use of Spiral CT Angiography

Abstract

Background and Purpose-This study sought to determine the frequency of noncircular lumens in patients with significant carotid atherosclerotic disease and to evaluate the effect of noncircular lumens on stenosis measurement derived from angiographic projections. Methods-One hundred consecutive patients presenting with an internal carotid artery stenosis of at least 50% were imaged with spiral CT angiography. The transverse morphology of the diseased lumen was assessed on axial images, and the frequency of noncircular lumens was determined. In these cases, maximum intensity projection angiograms were reconstructed in standardized angiographic planes and in a plane selected according to the luminal obliquity, which was chosen to optimize the angiographic representation of the maximal stenosis. North American Symptomatic Carotid Endarterectomy Trial (NASCET) measurements were calculated from the maximum intensity projection images, and differences between values obtained from standard and optimized projections were recorded. Results-Noncircular lumens were observed in 18 of 100 patients and consisted of elliptical and linear transverse profiles.The transverse orientation of the lumen in these cases ranged from ϩ90°to Ϫ87°relative to the anteroposterior plane. An increase in the calculated NASCET stenosis was demonstrated when measurements were obtained from angiographic reconstructions obtained in the exact plane of the luminal obliquity compared with standard angiographic projections. As a result, the stenosis severity was upgraded from moderate to severe in 2 patients. Conclusions-Noncircular

Carotid Stenosis Index Revisited With Direct CT Angiography Measurement of Carotid Arteries to Quantify Carotid Stenosis

“…CTA is the only current angiographic method that allows such high-resolution images of contrast-filled vessels, plaque, and surrounding soft tissues. 21 Measurement of noncontrast-enhanced soft tissues is not without its challenge. Not only does the vessel wall need to be identified, but it needs to be separated from adjacent calcifications and plaque.…”

“…As imaging technologies advanced, alternatives to catheter DSA such as magnetic resonance angiography, Doppler ultrasound, and early CTA were intensively studied. [12][13][14][15][16][17][18][19][20][21][22] Nonetheless, these modalities all refer to catheter DSA and NASCET and ECST trials as standards to base their quantification methods as percentage stenosis, most often to NASCET.…”

Evaluation of carotid stenosis with axial high-resolution black-blood MR imaging

“…There is evidence in the literature that the limited number of projections with DSA can lead to an underestimation of the actual stenosis owing to non-circular lumens [5]. On retrospective analysis, five out of these eight cases had non-circular lumens and may actually represent underestimation of stenosis by DSA.…”

“…Conventional digital subtraction X-ray angiography (DSA), ultrasound, CT angiography (CTA) and MR angiography (MRA) are the current methods of choice in clinical practice for evaluating the severity of carotid stenosis [3][4][5][6][7][8]. DSA, CTA and MRA primarily depict the arterial lumen, but generally provide little information concerning the diseased vessel wall.…”

Correlation between Doppler Velocities and Duplex Ultrasound Carotid Cross-sectional Percent Stenosis

“…Furthermore, longitudinal measurements may lead to a suboptimal evaluation of the hemodynamic meaning of the stenosis, at least in those (not unusual) cases where sectional morphology of arteries with plaques is irregular (7). Therefore, cross-sectional area would be a more accurate parameter than longitudinal measurements to infer the real residual blood flow velocities through a stenosed artery (8,9), especially in evaluating those stenoses with a noncircular lumen (10). When properly validated, crosssectional imaging might indeed replace the conventional gold standard to better characterize carotid plaque.…”