Intraoperative Ultrasound Technology in Neuro-Oncology Practice-Current Role and Future Applications

BACKGROUND: Surgery for cranial and spinal tumors has evolved tremendously over the years. Not only have neuro-oncologists been able to better understand tumor biology and thereby improve multimodality therapy, but advances in surgical techniques have also directly equipped neurosurgeons with the armamentarium necessary to achieve more radical resections safely. Intraoperative imaging tools are one such adjunct. Though intraoperative magnetic resonance (MR) has emerged as the "gold standard" among these, logistical challenges make it difficult to implement across all centers. On the other hand, the use of ultrasound (US) intraoperatively predates the use of MR. Over the past 4 decades, technologic improvements have refined and expanded the scope and application of intraoperative US technology. Strategies to maximize its efficacy and overcome the various limitations have evolved. A large volume of clinical experience has accumulated with respect to its role as an adjunct specifically in tumor surgery. METHODS: We performed a literature review to evaluate the role of IOUS in tumor surgery. This review traces the evolution of intraoperative US over the years and reviews the current scope and applications with respect to neurooncologic surgery, as well as potential future applications. RESULTS: IOUS has evolved over the years since its introduction. Advances in technology have provided real-time navigated and 3-D techniques, which overcome many of the limitations of older IOUS techniques. This has shown to be very useful in not only localization of lesions, but also in improving resection rates as well as survival. CONCLUSIONS: IOUS is a powerful and versatile multipurpose intraoperative adjunct in tumor surgery, especially for resection control. The learning curve is relatively easy to climb and future improvements in technology are likely to widen the scope of its use.