Ultrasonography and contrast-enhanced MRA in ICA-stenosis: is conventionalangiography obsolete?

Background The standard techniques for the screening and staging of interna l carotid artery (ICA) stenosis are Doppler (continuous wave) and Duplex so nography. For the imaging of ICA occlusive disease, magnetic resonance angi ography (MRA) is replacing digital subtraction angiography (DSA). The purpo se of this observational study was to assess whether contrast enhanced MRA (CE-MRA) combined with ultrasound provided sufficient information for the p lanning of surgical treatment. Methods CE-MRA was performed in 195 patients (mean age 67.5 years) with sonographic evidence of severe ICA stenosis. Th e MRA examination protocol contained a heavily T1-weighted contrast bolus e nhanced 3D-gradient echo sequence. The degree of stenosis was estimated ret rospectively by two experienced neuroradiologists who were blinded to the s onographic findings. Results The consistency of MRA and ultrasound was suff icient to plan thrombendarterectomy in 182/195 patients. The estimations of the degree of stenosis were congruent between MRA and ultrasound in 91% of 197 vessels with high-degree carotid artery stenosis. CE-MRA evaluation ha d a high interobserver agreement. In 3 cases ultrasound examination diagnos ed a filiform ICA stenosis which was not visible with MRA. In all these cas es, DSA and the intraoperative findings revealed very short (1-2 mm), high- grade, excentric stenosis. CE-MRA correctly detected patency in 5 patients with high-grade and low-flow carotid artery stenosis, which had been regard ed as occluded by ultrasound. Conversely with, in CE-MRA two occluded vesse ls were falsely considered as open. Conclusions The combination of sonograp hy and CE-MRA is a powerful tool for the non-invasive presurgical evaluatio n of the carotid arteries. DSA should be reserved for selected cases.