A Study to Test a New Fluid to Improve the Quality of Images Obtained by Using Sound Waves (Ultrasound) During Surgery

Ultrasound images will be obtained at different timepoints during the operation. First timepoint being after craniotomy (no fluids involved). Second timepoint being when some tumour is left in the bottom of the deeper part of the resection cavity (approximately 80% of tumour removed), and third timepoint being when the surgeon deems resection of the tumour to be completed. At the second and third timepoint ultrasound acquisition will be performed twice at each timepoint. Once with routinely used irrigation fluids (physiologic saline 0.9% / ringer's / lactated ringers' solution) and once with SonoClear® as part of the SonoClear® System There are two performance related primary endpoints, based on core lab assessments: 1. To assess ultrasound images obtained with SonoClear® as part of the SonoClear® System are less influenced by image artefacts compared to images obtained with standard of care irrigation fluid, by measuring the contrast-to-noise ratio (CNR). The CNR is a measure of the relative noise in the image. 2. To assess ultrasound images obtained with SonoClear® as part of the SonoClear® System compared to images obtained with standard of care irrigation fluids, by using a qualitative assessment, called the Surgeons Image Rating (SIR) scale. A Panel of Experts will assess the quality of the obtained images by answering 3 questions for each image. For SIR a 1-10 numeric rating scale, is used to measure the quality of the image according to three questions to be answered at the three different timepoints during the operation. This SIR is designed to explore whether SonoClear® as part of the SonoClear® System having shown to provide better quantitative image quality in the CNR analysis, allows surgeons to detect this improved image quality. Eventually this improved image quality should result in better decision-making during surgery about margins of excision and residual tumour resection. The primary safety event is defined as any core lab determined major Magnetic Resonance Imaging (MRI) finding when post-operative MRI is compared to pre-operative MRI that was found by the Data Monitoring Committee (DMC) to be serious and probably or definitely related to the study device OR any DMC determined serious adverse event that is probably or definitely related to the study device that occurs within 30 days of the procedure. The primary safety hypothesis declared in ACF-03 study is to prove the primary safety event rate is less than 10%. Success is demonstrated by observing 0 of these events out of 37 subjects exposed to SonoClear® ACF, i.e. the event rate is 0% with an upper two-sided 95% confidence limit less than 10%. With an event rate of less than 10% for major neurotoxicity events that are serious and probably or definitely related to the device, the benefit of a clearer image for the neurosurgeon balances the potentially increased risk. This study expands the number of patients to evaluate the safety outcome. The primary safety event rate will be evaluated also in a total group of 60 patients, 45 using SonoClear® ACF and 15 using the SonoClear® System.