FDA Accepts SonoClear System 510(k) Submission for Brain Tumor Resection Imaging

The FDA has accepted for substantive review the 510(k) submission for the SonoClear® System, a sterile ultrasound acoustic coupling fluid for brain tumor resections, according to a news release from the developer, SonoClear AS.¹ The FDA previously granted breakthrough device designation to the system for intracranial ultrasound procedures in July 2025.² The product is not cleared for sale or distribution.

The SonoClear System is a sterile, biocompatible, bio-excretable fluid designed to match the acoustic properties of brain tissue. Conventional irrigation fluids can create bright signal artifacts and visual noise in the resection cavity, which can obscure residual tumor at the end of the procedure. The system is intended to improve intraoperative ultrasound imaging by reducing these artifacts.

“Acceptance of this submission brings us an important step closer to our goal of making the SonoClear System available to US neurosurgeons,” said Peter Balmforth, chief executive officer of SonoClear, in the press release.¹ “Our aim is to give surgeons a clearer view of the surgical cavity to support decision-making in certain types of brain tumor surgery.”

What data were presented at the EANS Congress?

Data from the pivotal multicenter study (NCT04734444) were presented in an oral session at the 2026 Annual Congress of the European Association of Neurosurgical Societies (EANS), by Francesco DiMeco, MD, a professor of neurosurgery at the University of Milan and director of the Department of Neurological Surgery at the Carlo Besta Neurological Institute in Milan, Italy.

SonoClear met its primary and secondary safety end points in the 44-patient study, while also showing an indication of improved overall image quality compared with standard irrigation.

“There was considerable excitement around the pivotal trial data presented earlier this month at the EANS Congress,” Balmforth added.¹ “We collected feedback from future users of the SonoClear technology and anticipate a strong opportunity as we proceed toward commercialization.”

In a preprint of the study, a prospective, nonrandomized trial at 5 centers, investigators reported that no device-related serious adverse event and no device-related major MRI finding occurred within 30 days of surgery.³ The primary safety event rate criterion was met. All patients were alive at 30 days, and 3 deaths occurred beyond 30 days, all deemed related tp tumor progression.

The system reduced below-cavity artifacts (irrigation/SonoClear contrast-to-noise ratio, 1.70; 95% CI, 1.48-1.95). Five neurosurgeons masked to the fluid rated image quality better with SonoClear, with a mean paired Surgeon Image Rating improvement of 1.96 points (95% CI, 1.80-2.11) among 40 patients who contributed to paired comparisons. The authors said the effects on extent of resection and patient outcomes require further study.

“In conclusion, this study supports that SonoClear [acoustic coupling fluid] provides statistically superior reduction of [intraoperative ultrasound] artefact and improved interpretability for intraoperative decision-making compared with standard sterile irrigation fluids, while maintaining an acceptable safety profile,” wrote DiMeco and coauthors in the preprint.³

How was the trial designed?

Across 5 centers at tertiary neurological centers in Italy, Germany, and Slovakia, investigators acquired intraoperative ultrasound images at predefined time points. These time points were after craniotomy and dural opening, at around 80% resection when residual tumor was expected in the deeper parts of the cavity, and at the completion of resection per surgeon declaration. At the second and third time points, the ultrasound acquistition was performed two times, once with standard sterile irrigation fluid and then with SonoClear acoustic coupling fluid.

Eligible patients for the study were 18 years or older receiving intraoperative ultrasound-guided resection of a suspected de novo diffuse glioma, as well as a Karnofsky performance status of at least 70 and an expected survival of at least 30 days.

References

1. SonoClear® System 510(k) submission accepted for FDA review. News release. SonoClear AS. October 21, 2026. Accessed October 22, 2026. https://tinyurl.com/ynjfhbpb
2. SonoClear AS receives FDA breakthrough designation for SonoClear® system. News release. SonoClear AS. July 1, 2025. Accessed October 22, 2026. https://tinyurl.com/2vm529me
3. DiMeco F, Del Bene M, Carone G, Piccardi A, et al; SonoClear ACF Investigators. An acoustic coupling fluid improves intraoperative ultrasound image quality during glioma surgery: results of a pivotal multicenter study (NCT04734444). Preprint. Research Square. doi:10.21203/rs.3.rs-11017633/v1