VALIDATION OF TRANSCRANIAL DOPPLER ULTRASOUND WITH A STEREOTAXIC NEUROSURGICAL TECHNIQUE

Vessel identification during a transcranial Doppler (TCD) ultrasound e xamination is usually based on well-established inferential criteria w ithout confirmation by imaging. Part of a routine study involves takin g measurements from the M(1) segment of the middle cerebral artery (MC A) and the A(1) segment of the anterior cerebral artery (ACA) at the p oints of maximum mean linear blood now velocity (LBFV). The authors te sted the hypothesis that insonation is from the midpoints of the M(1) and A(1) segments during clinical TCD examinations. Conventional hand- held TCD examinations were performed oil five volunteers. The points o f maximum mean LBFV of the M(1) and A(1) segments of the MCA and ACA w ere located. Measurements were also taken from the midpoints of the M( 1) and A(1) segments using a magnetic resonance (MR) imaging-guided st ereotactic TCD technique. Values for depths of insonation and maximum mean LBFV obtained with the two techniques were compared. There was no significant difference between the two techniques for the measured va lues of depth of insonation of either the individual vessels (p > 0.11 ) or the aggregate (p = 0.46). There was a significant difference betw een the aggregate maximum mean LBFV measurements (p = 0.0022). The han d-held technique systematically produced higher maximum mean LBFV than the MR-guided stereotactic technique. The authors conclude that when using traditional criteria for TCD examination of the ACA and MCA, the points of insonation approximate the middle of the A(1) and M(1) segm ents.