A Better Way to Keep an Eye on Glioblastoma Tumors

For people with glioblastoma brain tumors, it can be vital yet challenging to determine the precise size, location, and extent of the tumor. A company called Imaging Biometrics, LLC, has developed novel imaging strategies to address this issue. Here, our Curious Dr. George asks its president and CEO Michael Schmainda about these innovations.

Curious Dr. George: Determining the extent of an intracranial neoplasm can be as important as securing the diagnosis. This also applies to postoperative follow-up: Was the tumor fully or only partly extirpated? Is the tumor recurring or is the evolving positive imaging only locating organizing hematoma or scar tissue?

Michael, how is your company striving to help solve these vital clinical puzzles?

Michael Schmainda: You’ve highlighted a critical challenge in neuro-oncology: distinguishing between tumor progression and treatment effects like pseudo-progression or post-treatment radiation effect (PTRE) using imaging techniques. This distinction is vital for accurate diagnosis, treatment planning, and monitoring.

Contrast enhanced magnetic resonance imaging (CE-MRI) is the standard imaging method but has limitations in differentiating between tumor and PTRE. In fact, PTRE often mimics tumor on CE-MRI, further conflating the issue. This often necessitates invasive biopsies for confirmation, which can be problematic, especially in heterogeneous tumors like glioblastoma. Targeting a biopsy site that is not consistent with aggressive tumor can lead to suboptimal treatment plans.

Response assessment techniques for brain tumors, such as response assessment in neuro-oncology (RANO), rely on CE-MRI to measure tumor size, which can be misleading if PTRE is present, potentially resulting in overly aggressive treatments with severe side effects.

At Imaging Biometrics (IB), we have developed and validated an automated processing platform that overcomes these limitations. This advanced imaging platform uses two quantitative technologies. The first, called a Delta T1 map, helps delineate true regions of contrast enhancement. Delta T1 maps incorporate an exclusive image-intensity calibration step, removing variability and artifacts to objectively highlight the true contrast-enhancing region.

Within the enhancing region identified by the Delta T1 map, additional information is obtained using our IB Neuro product. This uses dynamic susceptibility contrast (DSC) MR perfusion to measure several parameters including relative cerebral blood volume (rCBV). As tumors form and grow, they need increased oxygen and nutrients, which are supplied via the blood. Before a tumor can be detected on standard imaging, IB Neuro can accurately measure this increase in rCBV. IB Neuro also incorporates a calibration step that standardizes the rCBV output (sRCBV) independent of how it was collected. This enables a direct comparison of sRCBV measurements across time, MR scanners and field strengths, and patients. Furthermore, the sRCBV values have been independently validated by multiple academic centers using spatially matched tissue samples to establish cutoff thresholds that differentiate tumor from PTRE.

Combining IB Delta T1 and IB Neuro enable the creation of fractional tumor burden (FTB) maps, providing a quantitative assessment of tumor progression and treatment response across time. The maps are also imported into surgical navigation systems to target biopsies, plan surgical resection and radiation and, more recently, to help plan laser interstitial thermal therapy (LITT).

Several recent and ongoing studies have demonstrated the clinical benefit of using FTB for treatment surveillance for both primary and metastatic brain tumors and for biopsy guidance such that the most aggressive part of the tumor is sampled. They also have been shown to result in the greatest inter-reader agreement and confidence for glioblastoma response assessment over other techniques to which they were compared.

I encourage interested readers to learn more by watching Imaging Biometrics’ video on getting more out of your MRI exam, as well as our webinars on Delta T1 and the clinical applications of perfusion MRI in neuro-oncology.

Michael Schmainda can be reached at mike@imagingbiometrics.com.

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