Changes in middle cerebral artery blood flow velocity during sonolysis using a diagnostic transcranial probe with a 2-MHz Doppler frequency in healthy volunteers.

Objectives: Ultrasound has various biological effects in the human body. The effects of continuous monitoring with ultrasound (sonolysis) on vasodilatation of the radial artery were described recently. We wanted to ascertain whether similar changes in the blood flow velocity during sonolysis could also be detected in the middle cerebral artery.
Methods: Fifteen healthy volunteers (6 male and 9 female; age range, 23-68 years; mean ± SD, 47.1 ± 15.1 years) were subjected to 1 hour of middle cerebral artery sonolysis using a diagnostic transcranial probe with a 2-MHz Doppler frequency and measurement of the blood flow velocity at 2-minute intervals. During a second session, a flow curve was recorded for 10 seconds at 2-minute intervals. The peak systolic velocity, end-diastolic velocity, mean flow velocity, pulsatility index, and resistive index were recorded during both measurements.
Results: Irregular changes in the measured blood flow parameters were recorded during both sessions. Changes in particular hemodynamic parameters during both measurements were similar. The changes in the peak systolic velocity, end-diastolic velocity, mean flow velocity, pulsatility index, and resistive index were not significantly different between the two measurements (P < .05 in all cases).
Conclusions: As opposed to sonolysis of the radial artery, sonolysis of the middle cerebral artery using a diagnostic 2-MHz frequency in healthy volunteers did not lead to changes in the flow curve or peripheral vasodilatation.