Comparison of regional cerebral blood flow (rCBF) in patients with high-grade glioma against healthy volunteers measured using PET with radiolabelled water

Abstract

Abstract Glioma is an aggressive type of brain tumours which account for 24% of primary brain tumours (1). In glioma, the effective therapy requires adequate drug delivery. Therefore this study is aimed to measure and compare the regional cerebral blood flow (rCBF) in a group of glioma patients (GPs) against a group of healthy volunteers (HVs) using [15O]-labelled water positron emission tomography (PET). Additionally, it measures the perfusion within the tumour and in extra-tumour tissue. It evaluates the symmetry of perfusion in contralateral and ipsilateral tissue. The images are processed using FSL software and compared the segmentation with statistical parametric mapping (SPM) segmentation, to evaluate segmentation accuracy which affects the estimation of CBF. Methods: The CBF was measured using [15O]-labelled water PET in 15 HVs and 14 GPs. In addition to functional PET, structural MR images were used to localise the activity. The MR images were processed using FSL and segmentation comparison was performed with SPM. Results: In this study the comparison of segmentation methods showed that FSL segmentation was more accurate than SPM segmentation for HVs and GPs. The comparison of grey matter (GM) and white matter (WM) perfusion among HVs and GPs showed that the high-grade patients had lower perfusion values (CBF mean ±SD GM = 0.34 ±0.08 and WM = 0.27 ±0.05 ml/min/cm3 ), while the low-grade patients had similar perfusion values to the HVs (CBF mean ±SD GM =0.42 ± 0.04 and WM = 0.31 ± 0.03 ml/min/cm3). Moreover, rCBF of tumour regions was lower in the high-grade patients, but two patients had a perfused enhancing rim. In this study, the NLLS estimation showed that perfusion was comparable between contralateral and ipsilateral WM. Moreover, it showed that perfusion was heterogeneous in perilesional tissue Conclusion: In this study, high-grade patients had low perfusion values in the tumour region and in extra-tumour tissue with heterogeneity in perfusion in the perilesional areas.