Image-guided microneurosurgical management of vascular lesions using navigated computed tomography angiography. an advanced IGS technology application

Intraoperative visualization of cerebral aneurysms using navigated 3D-ultrasound power-Doppler angiography

BACKGROUND

The questions of whether the spatial resolution of navigated 3D-ultrasound (3D-US) power-Doppler angiography imaging rendered by existing 3D-US systems is sufficient for the intraoperative visualization of cerebral aneurysms, and in what percentage of cases, are largely unanswered. A study on this topic is lacking in the literature.

METHODS

From 2015 to 2022, we performed 86 surgeries on 83 aneurysm patients. Navigated 3D-US was used at the discretion of the operating neurosurgeons when available (i.e., not being used during parallel tumor surgeries). Twenty-five aneurysms (15 ruptured) were operated on using 3D-US; 22 aneurysms were located at the middle cerebral artery (MCA). Patient 3D-US power-Doppler angiography images and surgical reports were retrospectively reviewed to assess the intraoperative ultrasound visibility of aneurysms.

RESULTS

In 20 patients (80%) the aneurysms were successfully visualized. In five patients (20%), the aneurysms visualization was insufficient or absent. Nineteen of 22 aneurysms (86.4%) were visualized in the MCA aneurysm subgroup. We observed no association between aneurysm visibility and aneurysm size or the presence of subarachnoid hemorrhage. In the subgroup of MCA aneurysms, no association between aneurysm visibility and the presence of subarachnoid hemorrhage was found; a trend toward poor sonographic visibility of smaller aneurysms was observed (p = 0.09).

CONCLUSIONS

Our initial data show that intraoperative 3D-US power-Doppler angiography, rendered by current navigated 3D-US systems, clearly depicts the majority of aneurysms in the MCA aneurysm subgroup. However, future prospective studies performed on a higher number of aneurysms localized at various anatomic sites are needed to confirm our initial findings and determine their potential clinical relevance.

Fluorescence Angiography with Temporary Occlusion to Confirm the Distal Artery: Technical Notes

Confirming the patency of the proximal parent and distal artery is necessary in cerebral aneurysm surgery. To understand the relationship between the parent and distal arteries of the aneurysm, the blood vessels running through the subarachnoid space should be extensively dissected, which is time consuming. To examine the efficacy of a temporary clip with indocyanine green (ICG) technique, in which the parent artery is temporarily occluded using a temporary clip, an ICG videoangiography (ICGVAG) is performed to clarify the relationship between the distal artery and the proximal parent artery. Three patients with a distal aneurysm. This technique was used to confirm the connection of the parent and the distal artery in distal aneurysms. With regard to middle cerebral artery (MCA), the procedure is conducted as follows. First, the M2 within the Sylvian fissure is investigated to ensure the absence of atherosclerosis and perforators and that this vessel could undergo occlusion by temporary clipping. The subarachnoid space surrounding the distal artery of the lesion site suspected of an existent aneurysm is dissected. The image range of the ICGVAG is set sufficiently wide to accommodate the possibility that the distal artery is not the artery that was anticipated. Subsequently, after the temporary clip occlusion is completed, the ICGVAG is recorded. In the three distal aneurysms, the relationship between the aneurysm, the distal artery, and the parent artery was confirmed. This method was useful, suggesting that unnecessary dissection in the subarachnoid space might be reduced.

Image guidance for transcranial Doppler ultrasonography

BACKGROUND

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

OBJECTIVE

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.

METHODS

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.

RESULTS

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.

CONCLUSION

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.