Brain ultrasound during tumor surgery matches pre-op MRI guidance and then some

Italian researchers have shown how surgeons resecting glioblastomas, the most common and aggressive brain tumors, can use contrast-enhanced ultrasound to guide their view of tumor location, morphologic features, margins and dimensions in real time and for the duration of the entire surgery.

Radiology has published their findings online, ahead of print.

Francesco Prada, MD, of the Carlo Besta Neurological Institute in Milan and colleagues reviewed the cases of 10 patients who had glioblastoma multiforme and underwent tumor resection surgery with fusion guidance, which allowed the team to combine and then compare intraoperative ultrasound imaging against gadolinium-enhanced T1-weighted MR images obtained preoperatively.

The researchers found that, in all cases, the two sets of images were superimposable with correct scaling and a positional discrepancy of less than two millimeters.

In one patient, the imaging did differ meaningfully between the two modalities: The ultrasound showed the full bulk of the tumor while the MRI supplied peripheral contrast enhancement.

The authors conclude that intraoperative contrast-enhanced ultrasound enables surgeons to access, in real time, key tumor information that compares favorably with targeting information from preoperative gadolinium MRI—and therefore “can be used as an intraoperative guidance tool.”

They note that, compared with neuro navigation guided by static pre-op images, the ultrasound technique is “dynamic, economic and repeatable” throughout the surgery.

“Future studies should investigate the role of intraoperative ultrasound in the evaluation of residual tumor, usually a great challenge for neurosurgeons,” Prada et al. write. “The synergistic use of contrast-enhanced ultrasound with navigation systems and other imaging modalities, such as intraoperative MR imaging, fluorescence imaging and optical imaging, might help maximize resection of glioblastoma multiforme, thereby minimizing the risks for our patients.”