Non-invasive assessment of glioma microstructure using VERDICT MRI: correlation with histology.

Abstract

Abstract Purpose This prospective study evaluated the use of VERDICT MRI to investigate the tissue microstructure in glioma. VERDICT-derived parameters were correlated with both histological features and tumour subtype and were also used to explore the peritumoral region.

Methods Fourteen consecutive treatment-naïve patients (43.5±15.1 years, 6 males, 8 females) with suspected glioma underwent diffusion weighted imaging including VERDICT modelling. Tumour cell radius, intracellular and combined extracellular/vascular volumes were estimated using a framework based on linearization and convex optimization. An experienced neuroradiologist outlined the peritumoral edema, enhancing tumour and necrosis on T2W and contrast-enhanced T1W. The same regions-of-interest were applied to the co-registered VERDICT maps to calculate the microstructure parameters. Pathology sections were analyzed with semi-automated software to measure cellularity and cell size.

Results VERDICT parameters were successfully calculated in all patients. The imaging-derived results showed a larger intracellular volume fraction in high grade glioma compared to low grade glioma (0.13±0.07 vs. 0.08±0.02 respectively; p=0.05) and a trend towards a smaller extracellular/vascular volume fraction (0.88±0.07 vs. 0.92±0.04 respectively; p=0.10). The conventional apparent diffusion co-efficient was higher in low grade gliomas compared to high grade gliomas but this difference was not statistically significant (1.22±0.13x10-3 mm2/s vs. 0.98±0.38x10-3 mm2/s, respectively; p=0.18).

Conclusion This feasibility study demonstrated that VERDICT MRI can be used to explore the tissue microstructure of glioma using an abbreviated protocol. The VERDICT parameters of tissue structure correlated with those derived on histology. The method shows promise as a potential test for diagnostic stratification and treatment response monitoring in the future.