CHICAGO – According to researchers from the Utrecht Netherlands University Medical Center, combining duplex ultrasound (DUS) and MR angiography (MRA) does not give additional value in diagnostic outcome for suspected carotid artery stenosis. However, agreement between these two tests in identifying severe stenosis gives better predictability than disagreement.
Researchers conducted a four-year, multicenter study of 375 consecutive patients suspected of having carotid artery stenosis. Patients with a peak systolic velocity (PSV) >150 cm/sec underwent digital subtraction angiography (DSA) and MRA. The authors applied their institute’s standardized cutoff criteria for the degree of stenosis, on the basis of PSVs, to validate DUS in the included population.
The diagnostic performance of MRA was analyzed to identify severe stenosis (70 to 99% blockage) in the internal carotid artery (ICA), using DSA criteria as defined in the North American Endarterectomy Trial (NASCET). A combination of the MRA and DUS results was evaluated referring to diagnostic outcome.
Standardized PSV criteria analyzed with DUS resulted in a sensitivity of 90% and a specificity of 83% in identifying severe ICA stenosis. Measurements carried out on 3D-time-of-flight (TOF) MR angiograms yielded a sensitivity of 90% and a specificity of 84%. Compared to DSA, MRA found a higher incidence of carotid artery stenosis.
The sensitivity in predicting severe stenosis decreased when DUS and MRA results were combined. Agreement between DUS and MRA in identifying severe stenosis gave better predictability than disagreement. According to Dr. Paul Nederkoorn, the study presenter, MRA predicted better then DUS in cases of disagreement between the modalities. This was attributed to the 12 projections taken with the MRA studies vs. the three projections taken with the DUS studies.
By Jonathan S. Batchelor
AuntMinnie.com staff writer
November 26, 2000
Copyright © 2000 AuntMinnie.com
Click here to view the rest of AuntMinnie’s coverage of the 2000 RSNA conference.
Click here to post your comments about this story.
