Shear Wave Elastography Better than MRI, Surgeons at Detecting Residual Brain Tumor Tissue

Shear wave elastography can outperform MRI in pinpointing whether any malignant tissue has been left behind after brain surgery.

While MRI is currently considered the gold standard for determining whether a patient might have a relapse after having a brain tumor surgically removed, it is both costly and time-consuming, sometimes adding up to two additional hours to a procedure. In a new study published in Frontiers in Oncology, a multi-institutional team discovered shear wave elastography was a much more sensitive technique.

The team, led by Jeffrey Bamber, Ph.D., professor of physics applied to medicine at The Institute of Cancer Research in London, compared shear wave scans to standard 2D ultrasound and a surgeon’s opinion. They, then, compared those results to MRI outcomes.

“We have shown for the first time that this new tool is better than either a standard 2D ultrasound or a surgeon’s judgment on its own,” Bamber said, “and has the potential to supplement a surgeon’s opinion as a means of improving outcomes from operations.”

This study, the team said, is the first to unearth shear wave’s real-time efficacy as a neurosurgical tool that can be used during procedures for cancerous tissue identification. Because brain tumor tissue tends to be stiffer than normal brain tissue, shear wave elastography is to optimal technique for identifying tissue that still needs to be removed, they added.

In a study with 26 patients, the team performed shear wave and 2D ultrasound before, during, and after the tumor removal. In addition, prior to showing surgeons any images, they asked surgeons to assess whether any malignant tissue remained. To get a clear idea of performance, the team also compared results to post-surgery MRI scans.

Based on their analysis, shear wave elastography was more sensitive in pinpointing residual tumor tissue than either standard ultrasound or surgeon opinion – it offered 94-percent sensitivity compared to 73 percent with standard ultrasound and 36 percent with the surgeon. With this performance, Barber said, shear wave was 2.5 times more likely to pick up remaining malignant tissue than a surgeon.

But, the technique’s specificity was only middle of the road, he explained. It offered 77-percent specificity, compared with 63 percent with standard ultrasound and 100 percent for surgeons. What that translates into is, given shear wave’s propensity for more false positives, it could be best used in concert with a surgeon’s professional analysis.

“This technique provides a very practical means of detecting areas of potentially removable tumor that are not readily visible to the operating surgeon,” said Neil Dorward, MB, BSc, a consultant neurosurgeon and co-researcher at the National Hospital for Neurology and Neurosurgery. “The surgeon must use his or her experience to decide whether the area of abnormality should be resected. This has the potential to substantially improve the outcome of such operation.”

While these results are encouraging and could potentially improve patient outcomes, the team said, additional, larger studies are needed to validate whether shear wave elastography can be offered as a standard practice.

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