Radiation-Induced Brain Metabolic Changes in the Acute and Early Delayed Phase Detected With Quantitative Proton Magnetic Resonance Spectroscopy

Abstract

Radiation-induced changes in brain metabolism were well detected with quantitative MRS in the early delayed phase. Quantitative MRS is a novel tool for estimating radiation-induced neurotoxicity.

Radiation Injury to the Normal Brain Measured by 3D‐Echo‐Planar Spectroscopic Imaging and Diffusion Tensor Imaging: Initial Experience

“…Several studies have reported the potential of 1 H MRS in evaluating both short and long-term effects of radiation therapy to normal brain parenchyma in patients with brain tumors. [7][8][9][10][11][12] All of these studies have reported significant reduction in the NAA and few of these studies 8,9 have reported elevation in the Cho levels from several different regions including the periventricular white matter, thalamus or the occipital lobe. In the present study, we observed a significant increase in Cho/Cr from the hippocampus and genu of corpus callosum.…”

“…Elevated Cho from the normal brain after irradiation has also been reported earlier. 8,9 Cho containing phospholipids are abundant in myelin and the cell membranes 39 and neurodegeneration and demyelination have been described in irradiated brains. 40 It is postulated that irradiation induced damage of oligodendrocytes may cause breakdown of myelin sheath and the cell membranes, resulting in rapid membrane turnover and increased Cho levels following irradiation.…”

“…1 H MRS has been used to demonstrate abnormal metabolite pattern from the normal brain, secondary to irradiation. [7][8][9][10][11][12] However, these studies suffered from limited volumetric coverage of the brain since a majority of these studies either used a single voxel or a single slice two-dimensional chemical shift imaging method. The only study that used a 3D 1 H MRS method, reported increased averaged Cho from normal brain areas in patients with gliomas treated with radiation therapy, 13 however, regional differences in the Cho levels were not reported in this study.…”

Diffusion Tensor Imaging Screening of Radiation-Induced Changes in the White Matter after Prophylactic Cranial Irradiation of Patients with Small Cell Lung Cancer: First Results of a Prospective Study

“…24 DTI and proton MR spectroscopy allow quantitative investigation of changes in the metabolite level and water diffusion parameters of normal-appearing WM on conventional T2-weighted MR images. 20,25 In studies of proton magnetic reso- Fig 1. A, Change in mean fractional anisotropy in patients with 0 or 1 vascular risk factor (n ϭ 10). *1 indicates significant reduction from baseline (P Ͻ .05); *2 indicates significant improvement from baseline (P Ͻ .05).…”

Early Differential Neurometabolite Response of Hippocampus on Exposure to Graded dose of Whole Body Radiation: An in Vivo 1H MR Spectroscopy Study

“…The tCr concentration was used as a normalising factor since its concentration in normal brain is relatively constant, which is reported in earlier studies 13,20 . Earlier MRS studies have also observed no change in the concentration of creatine during acute or delayed response of radiation exposure 21,22 . Significant change was observed only in two metabolite ratios, tau/tCr and mI/tCr in 5 Gy and 8 Gy radiation dose group animals compared to sham irradiated controls.…”