Image guidance for transcranial Doppler ultrasonography

Transcranial Doppler (TCD) ultrasonography is an important tool for noninvasive detection and monitoring of vasospasm and other pathological conditions of the intracranial vessels.

To demonstrate that image-guided TCD allows rapid identification and blood-flow analysis of specific sections of the vascular anatomy and provides excellent orientation, also allowing diagnostic procedures on pathological vascular structures.

Three patients who underwent computed tomographic angiography scanning for reasons not related to this study were examined by neuronavigated image-guided TCD. The Doppler probe was fitted with reflective markers and tracked by a commercially available Kolibri image guidance system.

Image-guided TCD allowed identification of all major intracranial vessels. Unilateral acquisition of reliable Doppler signals for the internal carotid artery, carotid T, middle cerebral artery, middle cerebral artery bifurcation, and anterior cerebral artery required 14 ± 6 minutes. Preregistration of these targets and detection by neuronavigation alone shortened examination times significantly to 8 ± 2 minutes. Registering the optimal examination trajectories on the neuronavigational device and applying navigational pilot software shortened times for repetitive examination further to 4 ± 1 minutes and ensured that the examination was done at the exact same spot under the same angle as in previous examinations.

Image guidance can be applied easily and efficiently to TCD. It provides anatomic orientation and may help to standardize investigation protocols, define pathological vascular territories for repeat investigations, and thus reduce interinvestigator variations. Image guidance may also extend the use of TCD to situations of a pathological or variant vascular anatomy.