Quantitative MRI using relaxometry in malignant gliomas detects contrast enhancement in peritumoral oedema

Abstract

Malignant gliomas are primary brain tumours with an infiltrative growth pattern, often with contrast enhancement on magnetic resonance imaging (MRI). However, it is well known that tumour infiltration extends beyond the visible contrast enhancement. The aim of this study was to investigate if there is contrast enhancement not detected visually in the peritumoral oedema of malignant gliomas by using relaxometry with synthetic MRI. 25 patients who had brain tumours with a radiological appearance of malignant glioma were prospectively included. A quantitative MR-sequence measuring longitudinal relaxation (R1), transverse relaxation (R2) and proton density (PD), was added to the standard MRI protocol before surgery. Five patients were excluded, and in 20 patients, synthetic MR images were created from the quantitative scans. Manual regions of interest (ROIs) outlined the visibly contrast-enhancing border of the tumours and the peritumoral area. Contrast enhancement was quantified by subtraction of native images from post GD-images, creating an R1-difference-map. The quantitative R1-difference-maps showed significant contrast enhancement in the peritumoral area (0.047) compared to normal appearing white matter (0.032), p = 0.048. Relaxometry detects contrast enhancement in the peritumoral area of malignant gliomas. This could represent infiltrative tumour growth.

Advanced MR techniques in glioblastoma imaging—upcoming challenges and how to face them

“…An interesting study by Blystad et al (2020) analyzed peritumoral edema of malignant gliomas using quantitative analysis of T1 and T2 mapping sequences, concluding that mapping techniques may be suitable for identifying peritumoral infiltrative growth. These results are in line with other interesting observations made by using mapping techniques in analyzing the peritumoral zones of high-grade gliomas [8].…”

Quantitative Mapping of Individual Voxels in the Peritumoral Region of Glioblastoma to Distinguish Between Tumor Infiltration and Edema

“…Although the microscopic tumor contents of the PTR is not appreciated with standard MRI sequences, several groups have attempted identifying areas of microscopic disease using sequences like DWI, dynamic susceptibility-weighted contrast-enhanced perfusion imaging (DSC), diffusion tensor imaging (DTI), magnetic resonance spectroscopy, and relaxometry [5,[14][15][16]. While several studies have correlated the MRI ndings with targeted tissue specimens with reasonable radiology-histology agreement, temporal correlation with speci c areas of tumor progression has been lacking.…”

Synthetic MRI for Evaluation of Brain Gliomas Grade and Tumor Proliferative Activity：A Retrospective Study

“…However, conventional MRI offers only anatomical and morphological characteristic through visual comparison, which cannot obtain quantitative information. Synthetic MRI which is not affected by the scanner settings, inhomogeneity of the B1-eld and coil sensitivity pro le provided with additional quantitive information about gliomas grading [14]. We retrospectively explored the diagnostic performance of synthetic MRI in evaluating gliomas grading and tumor proliferative activity.…”

“…For example, some studies revealed that synthetic MRI with the method of measuring quantitively T1 values of before and after contrast enhancement contributed to detect the enhancement of peritumoral edema which re ected tumor proliferative activity. The enhancement was not usually visible on conventional MRI [14,15]. However, the prediction of gliomas grade and tumor proliferation by synthetic MRI has not been reported.…”