Application of Intraoperative Ultrasound for Brain Surgery

Objective: Over the past decade, the use of intraoperative image guidance in neurosurgery has gradually gained in importance. Apart from some sophisticated and very expensive techniques, intraoperative ultrasound (IOUS) is a simple and economical technique that allows the surgeon to localize deep-seated lesions under a real-time ultrasonic image display without dissection. The purpose of this study was to present our own preliminary experiences in using this modality during surgery for various intraparenchymal brain lesions. Materials and Methods: In total, 37 patients were enrolled for IOUS monitoring in a recent year, which included 10 infratentorial lesions and 27 supratentorial lesions. All studies were performed using an ultrasound machine with variable 3.5-7.5 MHz sector transducers (B&K Medical, Denmark). The echogenicity and pathomorphology between IOUS and computed tomography/magnetic resonance imaging (CT/MRI) of various disease entities were compared. Results: Intracranial structures could be well demonstrated by ultrasound once the skull was opened. Most of the intracranial lesions were hyperechoic, except those with a cystic component. IOUS was more sensitive in demonstrating non-enhanced solid lesions and lesions with a cystic component than was preoperative CT/MRI. In addition, color Doppler IOUS could distinguish abnormal vessels from a hematoma, and could identify components of an arteriovenous malformation (AVM) without difficulty. Conclusions: High-resolution real-time IOUS is a convenient and user-friendly method for identifying, localizing, and characterizing the pathological focus during an operation. Such information is very important and can enhance surgical results.