Validation of transcranial Doppler ultrasound with a stereotactic neurosurgical technique

Abstract

Vessel identification during a transcranial Doppler (TCD) ultrasound examination is usually based on well-established inferential criteria without confirmation by imaging. Part of a routine study involves taking measurements from the M1 segment of the middle cerebral artery (MCA) and the A1 segment of the anterior cerebral artery (ACA) at the points of maximum mean linear blood flow velocity (LBFV). The authors tested the hypothesis that insonation is from the midpoints of the M1 and A1 segments during clinical TCD examinations. Conventional hand-held TCD examinations were performed on five volunteers. The points of maximum mean LBFV of the M1 and A1 segments of the MCA and ACA were located. Measurements were also taken from the midpoints of the M1 and A1 segments using a magnetic resonance (MR) imaging-guided stereotactic 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 values of depth of insonation of either the individual vessels (p > 0.11) or the aggregate (p = 0.46). There was a significant difference between the aggregate maximum mean LBFV measurements (p = 0.0022). The hand-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 A1 and M1 segments.

Intraoperative ultrasound for guidance and tissue shift correction in image‐guided neurosurgery

“…41,42 Since then, others have developed techniques to either compare 2D ultrasound images to other modalities, [43][44][45] or to accumulate a series of ultrasound images to create volumetric data sets. [46][47][48][49] Each of these techniques requires that the coordinate transformation from the US image space to the pre-operative image space be established. This is accomplished using a 3D tracking device or articulated arm attached to a stereotactic frame.…”

Derivation of Power M‐Mode Transcranial Doppler Criteria for Angiographic Proven MCA Occlusion

“…MFV, pulsatility index (PI), and M‐mode resistance signature (absent, high, or low) were recorded for each vessel (Fig 1). PMD signatures were rated as absent, high resistant, and low resistant at depths of 55‐65 mm corresponding to the MCA stem origin 10 . Low‐resistance flow signature is defined as M‐mode signal continuously present throughout the cardiac cycle.…”

Intracranial Cerebrovascular Ultrasound Examination Techniques

“…Step 1: Set the depth at 50 mm (most TCD units start with this depth since the mid-point of the M1 MCA segment was established at an average of 50 mm depth in cadaver skulls [7]). Place the probe above the zygomatic arch and aim it slightly upwards and anterior to the contralateral ear/window.…”

“…Previous studies have established normal values and variations for depth of insonation [1,2,4-6] and a multicenter study was performed to validate TCD findings [7]. Some variation between the depths of insonation can be expected due to the differences in patient skull diameters and sample volumes used for insonation.…”