gms | German Medical Science

Objective: Neurosurgical ICU-treatment requires sedation over prolonged periods. ICP-monitoring and frequent CCT scans are mandatory to diagnose adverse events. CCT-scanning is time-consuming and endangers patients with elevated ICP. ICP-monitoring provides no structural information. Imaging by intracranial endosonography may offer an alternative. Generally the skull limits sonography for intracranial imaging. Imaging through cranial defects has been shown to provide high resolution images of intracranial structures, but with a limited imaging window. We investigated a navigation image-guided intracranial B-scan image catheter for intracranial monitoring.

Methods: We applied the system in a porcine model of intracranial hemorrhage (n=2). Following anaesthesia and MRI for image-guidance, an endosonography catheter was introduced into the frontal lobe via a 3 mm bur whole. After imgaing anatomical sites and vascular territiories, a hemorrhage was placed via a second bur hole on the contralateral side. For ultrasound imagingm, we used an Acuson ultrasound unit with a 10 F B-scan image catheter. For sufficient anatomical orientation the ultrasound catheter was connected to a VectorVision2 neuronavigation device modified to overlay anatomical MRI images with the imaging plane of endosonography.

Results: Intracranial ultrasound demonstrated anatomical structures with high definition. By means of an overlay of sonographic images and MRI-based image guidance, the ultrasound-catheter could be directed to preselected structures and defined anatomical landmarks. Application of the doppler-mode allowed observation of blood-flow of intracranial vessels. Image-guidance provided orientation of specific bloodvessels. Ultrasound imaging demonstrated the formation of experimental hematoma and brain edema in real-time. Comparison of ultrasound scans with a posthemorrhagic MRI showed a high reliability of the overlay and high definition of endosonography.

Conclusions: We demonstrated that intracranial B-scan imaging provides high definition images of intracranial structures and allows real-time monitoring of intracranial lesions. We suggest that bold screw mounted B-scan image-catheters placed through bur holes into the ventricular system may prove to be a valuable tool for intracranial monitoring of ICU patients.