The clinical utility of magnetic resonance elastography in differentiating tumor recurrence from pseudoprogression in glioblastoma

Glioblastoma (GBM) is the most common malignant primary brain tumor in adults with nearly universal progression despite aggressive treatment. Distinguishing true tumor recurrence from treatment-related effects (pseudoprogression) remains challenging with conventional contrast-enhanced MRI, as both can produce similar imaging findings. Magnetic resonance elastography (MRE), which measures tissue stiffness, has shown that gliomas are less stiff than normal brain parenchyma and that stiffness inversely correlates with tumor grade. We hypothesized that MRE could differentiate true tumor progression from treatment effects in post-treatment GBM patients. This retrospective pilot study included 13 patients with pathology-confirmed GBM who demonstrated imaging findings suspicious for recurrence on surveillance MRI. MRE was performed as an add-on sequence requiring less than 7 min of additional scan time. Regions of interest (ROIs) were manually delineated by a single neuroradiologist blinded to progression status and compared to contralateral control regions. Progression status was determined by pathologic confirmation when available or by clinical history and imaging characteristics. Among 18 analyzed lesions from 13 patients, a linear mixed effects model revealed a significant interaction between progression status (true progression or pseudoprogression) and ROI (lesion or contralateral control) on tissue stiffness (coef = -0.174 kPa, z = -12.75, p < 0.001). True tumor progression demonstrated significantly reduced stiffness compared to contralateral control tissue, while the majority of pseudoprogression lesions showed no significant stiffness reduction. MRE-derived stiffness measurements may serve as a useful imaging biomarker to distinguish GBM recurrence from treatment effects, potentially complementing perfusion MRI in guiding clinical decision-making for post-treatment GBM patients.