Introduction: In 2004 the European Federation of Societies for Ultrasound in Medicine and Biology (EFSUMB) published the first guidelines on the use of ultrasound contrast agents (UCA) in clinical settings. Since then, several updates have been published, starting from widely studied organs such as the liver to more recent intra-operative applications. For the first time the recently released EFSUMB guidelines on the applications of non-hepatic contrast-enhanced ultrasound (CEUS) deals with the use of microbubble ultrasound contrast in neurosurgery.

Methods: The EFSUMB guidelines on CEUS represents a condensation of current findings on CEUS applications in various organs, pathologies and clinical settings. The guidelines are formulated by a group of experts and are primarily based on published literature. Levels of evidence and grades of recommendations are assigned according to the Oxford Centre for Evidence-based Medicine criteria. A consensus opinion was established by vote as follows: strong consensus (>?95?%), broad consensus (75?–?95?%), with approval, disapproval or abstaining from each participant.

Results: The EFSUMB document describes the methodology of CEUS exam and the recognized application relying on levels of evidence (LoE) and grade of recommendations (GoR). Intraoperative CEUS (iCEUS) is indicated in neuro-oncological procedures for tumor identification, assessment of boundaries, perfusion pattern and evaluation of residual tumor (LoE 4, GoR C). Strong consensus (19/0/0, 100?%). iCEUS is indicated in angiosonography for neurovascular procedures (LoE 4, GoR C). Strong consensus (19/0/0, 100?%). iCEUS is indicated in traumatic brain surgery to demonstrate tissue viability (LoE 4, GoR C). Strong Consensus (18/0/1, 100?%).

Conclusions: A panel of experts evaluated iCEUS available data regarding its use in neurosurgical procedures agreeing with a strong consensus that iCEUS is a valuable tool in neurosurgery for vascular and oncological applications. It allows for excellent perfusion evaluation with distinct enhancement phases and good delineation between lesions/vessels and healthy structures with high temporal and spatial resolution. Indeed larger number are needed for further validation, as well as specific training on this technique.

Patient Care: The EFSUMB guidelines provide general advice for the use of UCAs. They are intended to create standard protocols for the use and administration of UCAs and improve the patient management: a wider adoption of contrast enhanced ultrasound will lead, as already happened for other organs, to the improvement of US image guidance during neurosurgical procedures, improving patient’s outcome and safety. Due to the inherently dynamic nature of US this will allow a true real-time imaging, with reduced time and resources consumption compared to iMRI and also without the use of harmful radiation as in case of iCT and iAngio. Furthermore UCA are still used off-label in neurosurgery: the EFSUMB guidelines will provide a substrate for regulatory bodies towards UCAs approval.

Learning Objectives: By the conclusion of this session participants shuld be able to: 1) describe the current applications of iCEUS in neurosurgery 2) appreciate the strong agreement of iCEUS usage in neurosurgery among expert users and their recommendations 3) understand how ultrasound contrast agents, similarly to Gadolinium for magnetic resonance, improve stanard B-mode 4) identify iCEUS advantages over other intra-operative imaging techniques and 5) recognize the necessity of specific training to properly perform the examination and gather homogeneous data.

References: - Albrecht T, Blomley M, Bolondi L, et al.; EFSUMB Study Group. Guidelines for the use of contrast agents in ultrasound. January 2004. Ultraschall Med. 2004 Aug;25(4):249-56. - Sidhu PS, Cantisani V, Dietrich CF, et al. The EFSUMB Guidelines and Recommendations for the Clinical Practice of Contrast-Enhanced Ultrasound (CEUS) in Non-Hepatic Applications: Update 2017 (Long Version). Ultraschall Med. 2018 Mar 6. - Seitz K, Strobel D. A Milestone: Approval of CEUS for Diagnostic Liver Imaging in Adults and Children in the USA. Ultraschall Med. 2016 Jun;37(3):229-32. - Holscher T, Ozgur B, Singel S et al. Introoperative ultrasound using phase inversion harmonic imaging: first experiences. Neurosurgery 2007; 60: 382 – 386. - Prada F, Vitale V, Del Bene M, Boffano C, Sconfienza LM, Pinzi V, Mauri G, Solbiati L, Sakas G, Kolev V, D'Incerti L, DiMeco F. Contrast-enhanced MR Imaging versus Contrast-enhanced US: A Comparison in Glioblastoma Surgery by Using Intraoperative Fusion Imaging. Radiology. 2017 Oct;285(1):242-249. - Prada F, Del Bene M, Fornaro R, Vetrano IG, Martegani A, Aiani L, Sconfienza L, Mauri G, Solbiati L, Pollo B, DiMeco F. Identification of residual tumor with intraoperative contrast-enhanced ultrasound during glioblastoma resection. Neurosurgical Focus, March 2016. - Prada F, DelBene M, Ferroli P, Saini M, DiMeco F. Intra-operative cerebral angio-sonography with ultrasound contrast agents: how I do it. Acta Neurochir(Wien). 2015 Jun;157(6):1025-9. - Prada F, Perin A, Martegani A, Aiani L, Solbiati L, Lamperti M, Casali C, Legnani F, Mattei L, Saladino A, Saini M, DiMeco F. Intraoperative contrast-enhanced ultrasound for brain tumor surgery. Neurosurgery. 2014 May;74(5):542-52; discussion 552. - He W, Wang L, Li HZ et al. Intraoperative contrast-enhanced ultra- sound in traumatic brain surgery. Clin Imaging 2013; 37: 983 – 988.