[Quantification of extracranial ICA stenoses with vessel ultrasound by CCDS and B-flow in comparison to 64-slice multidector CTA, contrast-enhanced MRA and DSA]

Abstract

Purpose: To evaluate the value of vascular ultrasound determining the pre-interventional degree of distal stenosis in the extracranial internal carotid artery (ICA) by means of color-coded duplex sonography (CCDS) and B-flow. Comparison with contrast-enhanced 64-line CT angiography (CTA), contrast-enhanced MRA (ceMRA) and digital subtraction angiography (DSA).

Materials and methods: Complementary diagnostics and evaluation of the stenosis by means of CCDS, B-flow, CTA, ceMRA and DSA were performed prior to percutaneous stent-assisted PTA in 21 symptomatic ICA stenosis. Ultrasound diagnostics were carried out with high-resolution linear transducers (5-10 MHz and 9-14 MHz). A bolus-triggered contrast-enhanced multislice CTA (collimation 64x0.5 mm) and a ceMRA (1.5 Tesla) as well as selective DSA were performed in every patient. The degree of distal stenosis was established in accordance to NASCET criteria by averaging 5 single measurements per modality and patient. The source images as well as MPR and MIP reconstructions were evaluated in the CTA and ceMRA. Hemodynamic flow parameters were determined with CCDS and B-flow. The images were assessed by two experienced readers in consensus.

Results: The extent of stenosis ranged from 45 to 95%, averaging 73% (+/-13%). There was a high degree of agreement between the B-flow results (r=0.938), the CCDS (r=0.852), the measurements from the source data of the ceMRA (r=0.9117) and reconstructions of the CTA (r=0.8598) compared to quantitative DSA as a reference technique.

Conclusion: Compared to selective DSA, vascular ultrasound in combination with CTA and ceMRA increase the reliability of the diagnostic quantification of ICA stenosis.