We performed an ultrasound study using duplex ultrasonography and B-mode to examine the graft using Toshiba Aplio 500 machines at our hospital. Two senior neuroradiologists reviewed and recorded the ultrasonography images independently; neither of them were involved in the surgery and they were blinded to the clinical information. The patient was placed in a supine position to maintain the incident angle of 60° or less between the STA and the Doppler beam. Probing the artery trunk of the STA in front of the tragus, we gradually traced along the trunk to the distal end until the STA entered the skull. Branch vessels were confirmed to be operated upon, and the junction of the intracranial-extracranial segment was selected as the check point. If a double barrel was involved, the check point was changed to a location 3–5 mm proximal to the bifurcation of the frontal and parietal branches of the STA.
The blood flow (ml/min), diameter (mm), pulsatility index (PI), and resistance index (RI) values were calculated automatically by the software and recorded when the measurement was usable. The recorded diameter is the maximum internal diameter of a blood vessel during cardiac contraction. The recorded flow is the average blood flow over a complete cardiac cycle. The RI value reflects the elasticity of the vascular wall and the resistance at the distal end of the blood flow. It equals to (Vs-Vd)/Vs, (Vs: peak systolic flow velocity, Vd: end diastolic flow velocity). Pi value reflects the activity, hardness and the resistance of blood vessel during the whole cardiac cycle. It equals to (Vs-Vd)/Vm (Vm: Space Peak time average velocity, the average value of flow velocity at each point during the whole cardiac cycle).
Ultrasound examination was conducted for patients pre-operatively, and follow-ups were scheduled at 1 day, 7 days, 3 months, and 6 months after surgery. Ultrasonographic data were recorded only according to the examination results, and data acquisition was blinded to the angiographic results.
The blood flow (ml/min), diameter (mm), pulsatility index (PI), and resistance index (RI) values were calculated automatically by the software and recorded when the measurement was usable. The recorded diameter is the maximum internal diameter of a blood vessel during cardiac contraction. The recorded flow is the average blood flow over a complete cardiac cycle. The RI value reflects the elasticity of the vascular wall and the resistance at the distal end of the blood flow. It equals to (Vs-Vd)/Vs, (Vs: peak systolic flow velocity, Vd: end diastolic flow velocity). Pi value reflects the activity, hardness and the resistance of blood vessel during the whole cardiac cycle. It equals to (Vs-Vd)/Vm (Vm: Space Peak time average velocity, the average value of flow velocity at each point during the whole cardiac cycle).
Ultrasound examination was conducted for patients pre-operatively, and follow-ups were scheduled at 1 day, 7 days, 3 months, and 6 months after surgery. Ultrasonographic data were recorded only according to the examination results, and data acquisition was blinded to the angiographic results.
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