MR-Spektroskopie bei Hirntumoren

Abstract

MRT allows the anatomical visualization of intracerebral space-occupying lesions, and when magnetic resonance spectroscopy (MRS) is used in routine clinical practice it can give more information and be helpful in the diagnosis of such lesions. In MRS with long echo times for nerve tissue there are five metabolites that are particularly significant: N-acetyl aspartate (NAA), creatine, choline, lactate, and lipids. NAA levels are lowered in the presence of intracerebral tumors. Creatine is lowered in situations of hypermetabolic metabolism and elevated in hypometabolic conditions, but remains constant in many pathologic states and can be used as a reliable reference value. With malignant tumors there are usually elevated choline concentrations, reflecting increased membrane synthesis and a higher cell turnover. The lactate level rises following a switch in metabolism from aerobic to anaerobic glycolysis, and this is frequently observed in the presence of malignant tumors. The occurrence of lipid peaks in a tumor spectrum suggests the presence of tissue necroses or metastases. There are typical constellations that are seen on MRS for individual tumors, which are discussed in detail in the present paper.

The value of proton mr-spectroscopy in the differentiation of brain tumours from non-neoplastic brain lesions

“…rotransmitter, generally increased in Wilson disease, Ala peak is generally shown in meningiomas and involves in partial oxidation (8,13), but in our In the benign cystic cranial masses of non-neoplastic group, we had also strong lipid resonances. MR-Spectroscopy has also an important diagnostic role, especially when it reveals reduced NAA without increased Cho, in these instances MRS findings may spare the patient from biopsy (4,16,17).…”

“…disorders except for the cystic cranial masses, Perfusion MR and Diffusion Weighted MR imaging could also be added to MRS findings in order to get more beneficial results (2,4,7,10,16). When we look at the literature; Elevated Cho levels and reduced NAA levels had been reported in acute MS plaques and had been explained by reactive astrogliosis, inflammation and early axonal degeneration, MI at short TE was also a discriminating metabolite for the acute MS and also increased in cases of glial activation or gliosis, represented dominancy in low-grade astrocytomas related to abnormal astrocyte proliferation, nevertheless might also be seen in Encephalitis, Dementia, Epilepsy and SSPE-PML like brain disorders (1,7,10,13,14), but in high grade gliomas, metastases and more malignant tumours, its peak sharply declined (1,2,4,15,17). In our study, we had also elevated MI peaks in non-neoplastic demyelinating group.…”

“…In MRSI; Resonances of brain metabolites as mentioned above, are briefly analysed for correct diagnosis of brain disorders especially for tumours and non-neoplastic lesions. NAA is a marker of functional neurons and decreases in all kinds of brain damages whether infiltrative, degenerative or destructive processes (3,5,8,(11)(12)(13). Cho resonances increase in all brain tumours, acute MS plaques and tuberculous abcesses due to increased cell membrane synthesis and turnover, reflect the abnormal processes like proliferating tumoral cells and active demyelinating plaques (1-3, 7, 11, 13).…”

Proton magnetic resonance spectroscopy of periventricular white matter and hippocampus in obstructive sleep apnea patients

“…NAA decreases in all forms of infltrative, degenerative or destructive brain damage [15–19]. MR spectroscopy provides in vivo quantitative analysis of neuronal loss or damage, which is one of the most important benefits of this technique [20,21].…”

Neuroradiological Viewpoint on the Diagnostics of Space-Occupying Brain Lesions

“…therefore, a characteristic feature of brain tumors is the reduction of the NAA and an increase of the cho signals [12]. A spectrum showing normal NAA concentrations is very unlikely for a cerebral tumor especially when partial volume effects can be excluded [33]. However, it has to be emphasized that there is no specific spectroscopic pattern for brain tumors.…”