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Purpose: The purpose of this work was to establish a database of tissue sodium concentration (TSC) in the normal brain of healthy volunteers. Tissue sodium concentration can be used as a sensitive marker of tissue viability in stroke or radiation therapy monitoring. Material and methods: Thirty-seven volunteers were scanned with a 23Na protocol in the span of one year; within this group, 29 studies were of acceptable quality. The study was approved by the Local Bioethics Committee. Data were acquired during a single magnetic resonance (MR) scanner session. The single scanner session consisted of 23Na 3D radial gradient echo (GRE) acquisition, MPRage, SPACE-FLAIR, and Resolve-DTI. MPRage images were segmented to obtain masks of the grey matter (GM), white matter (WM), and cerebrospinal fluid (CSF), which were registered to the sodium image space for image analysis. Images were transformed into TSC maps - a signal calibration curve obtained from the reference phantom of known sodium concentration and known relaxation time. Results: The collected data were analysed in 2 different ways: volunteers were divided by sex and by age. No significant differences in TSC were found between sexes. In all comparisons there was a significant difference in TSC between younger and older volunteers. In healthy volunteers mean TSC were as follows: GM 33.21 ± 4.76 mmol/l, WM 28.41 ± 4.03 mmol/l and for CSF 41.3 ± 6.69 mmol/l. Conclusions: This preliminary work is a base for further work with sodium imaging in brain lesions. The entirety of the col-lected data will be useful in the future as a baseline brain TSC for comparison to values obtained from pathologies.
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INTRODUCTION: This study focuses on the challenge of distinguishing between tumour recurrence and radiation necrosis in glioma treatment using magnetic resonance imaging (MRI). Currently, accurate differentiation is possible only through surgical biopsy, which is invasive and may cause additional damage. The study explores non-invasive methods using dynamic susceptibility contrast (DSC) MR perfusion with parameters like relative peak height (rPH) and relative percentage of signal-intensity recovery (rPSR). MATERIAL AND METHODS: Among retrospectively evaluated patients (multicentre study) with an initial diagnosis of the primary and secondary brain tumour, 47 met the inclusion criteria and were divided into two groups, the recurrent glioblastoma (GBM) WHO IV group and the radiation necrosis group, based on MRI of the brain. All patients enrolled into the recurrent GBM group had a second surgical intervention. RESULTS: Mean, minimum and maximum rPH values were significantly higher in the recurrent GBM group than in the radiation necrosis group ( p < 0.001), while rPSR values were lower in the recurrent GBM group than in the radiation necrosis group ( p = 0.011 and p = 0.012). DISCUSSION: This study investigates the use of MR perfusion curve characteristics to differentiate between radiation necrosis and glioblastoma recurrence in post-treatment brain tumours. MR perfusion shows promising potential for distinguishing between the two conditions, but it also has certain limitations. Despite challenges in finding a sufficient cohort size, the study demonstrates significant differences in MR perfusion parameters between radiation necrosis and GBM recurrence. CONCLUSIONS: The results demonstrate the potential usefulness of these DSC perfusion parameters in discriminating between glioblastoma recurrence and radiation necrosis.
