Color Doppler ultrasound imaging in the emergency management of an intracerebral hematoma caused by cerebral arteriovenous malformations: technical case report

Neuronavigation for arteriovenous malformation surgery by intraoperative three-dimensional ultrasound angiography

OBJECTIVE

Neuronavigational devices have traditionally used preoperative imaging with limited possibilities for adjustment to brain shift and intraoperative manipulation of the surgical lesions. We have used an intraoperative imaging and navigation system that uses navigation on intraoperatively acquired three-dimensional ultrasound data, as well as preoperatively acquired magnetic resonance imaging scans and magnetic resonance angiograms. The usefulness of this system for arteriovenous malformation (AVM) surgery was evaluated prospectively.

METHODS

Nine consecutive patients with Spetzler Grade 1 (n = 3), 2 (n = 3), 3(n = 2) or 4 (n = 1) AVMs underwent operation using this intraoperative imaging and navigation system. The system provides real-time rendering of three-dimensional angiographic data and can visualize such projections in a stereoscopic (virtual reality) manner using special glasses. The experiences with this technology were analyzed and the outcomes assessed. Angiographic reconstructions of three-dimensional images were obtained before and after resection.

RESULTS

Conventional navigation on the basis of preoperative magnetic resonance angiography was helpful to secure positioning of the bone flap; stereoscopic visualization of the same data represented a powerful means to construct a mental three-dimensional picture of the extent of the AVM and the feeder anatomy even before skin incision. Intraoperative ultrasound corresponded well to the intraoperative findings and allowed confirmation of feeding vessels in surrounding gyri and rapid identification of the perinidal dissection planes, regardless of brain shift. The latter feature was particularly helpful because the intraoperative navigational identification of surgical planes leads to minimal exploration into the nidus or dissection at a greater distance from the malformation. Application of the system was thought to increase surgical confidence. In two patients, postresection ultrasound prompted additional nidus removal. Ultrasound angiography seemed to allow some degree of resection control, although its sensitivity was not thought to be sufficient. All AVMs were radically removed without new permanent morbidity.

CONCLUSION

The complexities of handling the pathological vessels of AVMs were ameliorated by intraoperative three-dimensional ultrasound and navigation because the three-dimensional outline of the vasculature (feeders, nidus, and draining veins) provided a means to adapt resection strategies, define dissection planes, and interpret intraoperative findings. It is difficult to provide a scientifically valid definition of "added value." However, in our experience, the added confidence and the improved mental image of the lesion that resulted from this technology improved the quality and flow of surgery.

Operation of Arteriovenous Malformations Assisted by Stereoscopic Navigation-controlled Display of Preoperative Magnetic Resonance Angiography and Intraoperative Ultrasound Angiography

OBJECTIVE

To study the application of navigated stereoscopic display of preoperative three-dimensional (3-D) magnetic resonance angiography and intraoperative 3-D ultrasound angiography in a clinical setting.

METHODS

Preoperative magnetic resonance angiography and intraoperative ultrasound angiography are presented as stereoscopic images on the monitor during the operation by a simple red/blue technique. Two projections are generated, one for each eye, according to a simple ray casting method. Because of integration with a navigation system, it is possible to identify vessels with a pointer. The system has been applied during operations on nine patients with arteriovenous malformations (AVMs). Seven of the patients had AVMs in an eloquent area.

RESULTS

The technology makes it easier to understand the vascular architecture during the operation, and it offers a possibility to identify and clip AVM feeders both on the surface and deep in the tissue at the beginning of the operation. All 28 feeders identified on the preoperative angiograms were identified by intraoperative navigated stereoscopy. Twenty-five were clipped at the beginning of the operation. The other three were clipped at a later phase of the operation. 3-D ultrasound angiography was useful to map the size of the nidus, to detect the degree of brain shift, and to identify residual AVM.

CONCLUSION

Stereoscopic visualization enhances the surgeon's perception of the vascular architecture, and integrated with navigation technology, this offers a reliable system for identification and clipping of AVM feeders in the initial phase of the operation.

Intraoperative Color Doppler Sonography in the Surgical Treatment of Perimedullary Arteriovenous Fistula-Case Report-

A 36-year-old female was treated for a perimedullary arteriovenous fistula (AVF) using intraoperative color Doppler sonography monitoring. Color Doppler sonography before interruption of the fistulous point clearly demonstrated an abnormal hyperechoic lesion. After interruption of the shunting point, the lesion had disappeared. Intraoperative angiography confirmed the disappearance of the perimedullary AVF. Intraoperative color Doppler sonography is a noninvasive, reliable, and cost-effective method for monitoring the effect of interruption on perimedullary AVF.

Hemostasis of punctured vessels using Doppler-guided high-intensity ultrasound

The use of Doppler ultrasound was investigated to determine if it would aid in guiding the application of high-intensity focused ultrasound (HIFU) to stop bleeding from punctured vessels. Major vessels (abdominal aorta, illiac, carotid, common femoral and superficial femoral arteries and the jugular vein) were surgically exposed, punctured and treated in anesthetized pigs. Treatment was applied when the Doppler sounds indicated the focus coincided with the bleeding site. In 89 treatment trials, the average time to achieve major hemostasis (a point where bleeding was reduced to a level of only oozing) was 8 s, and for complete hemostasis was 13 s. These times were significantly shorter than those of an identical former study in which only visual guidance was used. In that study, the average times for major and complete hemostasis were 40 and 62 s, respectively. The advantage of Doppler guidance in applying HIFU in treating bleeding vessels was demonstrated.