Diagnostic yield of a 1-MHz transducer in evaluation of the basal cerebralarteries

The authors examined the efficacy of a 1-MHz transducer in routine ultrasou nd monitoring. Fifty outpatients (34 women, 16 men; mean age, 65 +/- 2) wit h inadequate temporal bone window for examination with 2-MHz transducers we re re-examined with a 1-MHz transducer. Additionally, 50 controls (34 men, 16 women; mean age 49 +/- 2) with adequate temporal bone window were examin ed with both the 1- and 2-MHz transducers. Signal duality was classified as good (GQ), adequate (AQ), or poor (PQ). Finally, 30 normal controls were e xamined with both transducers under standardized conditions, to evaluate po tential differences in velocity measurements. A total of 90 temporal window s were lacking in the 50 patients. Use of the 1-MHz transducer resulted in identification of the middle cerebral artery in 68 cases (76%; PQ, n=13; AQ , n=29; GQ, n=26), the anterior cerebral artery in 51 cases (57%; PQ, n=23; AQ, n=17; GQ, n=11) and the posterior cerebral artery in 46 cases (51%; PQ , n=12; AQ, n=21 GQ, n=13). Examination was feasible with both transducers in the 50 controls, with minimal differences in signal quality between the two transducers. Correlation between velocity values acquired with the 1- a nd 2-MHz transducers was significant for all vessels examined. Best values were measured for the middle cerebral artery, followed by the anterior cere bral artery and posterior cerebral artery. The authors conclude that the us e of the 1-MHz transducer increases the yield of transcranial Doppler sonog raphy.