A Combined TCD and MRA Screening for Significant Siphon Portion of Internal Carotid Artery (S-ICA) Stenosis

Abstract

Background: We investigated whether combined transcranial Doppler (TCD) and magnetic resonance angiography (MRA) can diagnose significant stenosis (s-stenosis) of the siphon portion of the internal carotid artery (S-ICA) on digital subtraction angiography (DSA). Methods: TCD criteria cut-off peak systolic blood-flow velocity of 75 cm/s or mean blood-flow velocity of 50 cm/s, with both values more than 30% higher than in the contralateral S-ICA. MRA criterion was defined as a ≥50% signal reduction of the column width. Combined TCD and MRA criteria were fulfillment of both TCD and MRA criteria. Results: Among 295 vessels, seven (2%) had s-stenosis on DSA. Using TCD criteria, 16 vessels (5%) were identified to have s-stenosis, of which six (38%) had s-stenosis on DSA (sensitivity, specificity, positive predictive value [PPV], and negative predictive value [NPV] were .86, .97, .38, and .99). Using MRA criteria, 17 (6%) vessels were s-stenosis, of which seven (41%) had s-stenosis on DSA. Sensitivity, specificity, and NPV were 1.00, .97, and 1.00; however, PPV was low (.41). Combined TCD and MRA criteria identified six (2%) vessels as having s-stenosis, all were s-stenosis on DSA (PPV was 1.00). Conclusion: Combined TCD and MRA examinations have similar diagnostic power to DSA. © 2011 by the American Society of Neuroimaging.