![]() ![]() 2, 26 In these cases, increased lactate was interpreted as an indication of increased tumor metabolism and growth. 15, 27 Elevated signals from lactate and lipid were associated with short survival in patients with glioblastoma multiforme (GBM) who were evaluated either prior to surgery or radiation treatment at 1.5 T. Previous studies performed at 1.5 Tesla (1.5 T) have shown that the presence of lactate and lipid peaks in 1H magnetic resonance spectroscopic imaging (MRSI) data is associated with a diagnosis of high-grade tumor. The potential for identifying regions of metabolic stress and ischemic area in brain means that in vivo measurements of lactate are of interest in patients with a number of different brain pathologies. 31 This means that lactate can be considered as an indicator of anaerobic glycolysis and reduced cellular oxygenation, which is of interest for evaluating response to radiation or other therapies. 8, 11 Neoplastic processes that are present in tumors have low oxygen supply and depend on non-oxidative glycolysis for energy production. Lactate is a metabolic marker that is observed in many brain pathologies. The implementation of this technique means that brain lactate can be evaluated in a routine clinical setting to study its potential as a marker for prognosis and response to therapy. The specialized lactate-edited 3D MRSI sequence was able to detect lactate in brain tumor patients at 3 T. The normalized SNR of brain metabolites using the flyback encoding were comparable to the SNR of brain metabolites using conventional phase encoding MRSI. Over-prescription of voxels gave less chemical shift artifacts allowing detection of lactate on the majority of the selected volume. The results demonstrated the feasibility of detecting lactate within a short scan time of 9.5 min in both phantoms and patients. The lactate-edited flyback sequence was compared with lactate-edited MRSI using conventional elliptical k-space sampling in a phantom and volunteers, and then applied to patients with gliomas. Over-prescription factor of PRESS voxels was optimized using phantom to minimize chemical shift artifacts. A 3D PRESS MRSI sequence incorporating shortened, high bandwidth 180° pulses, new dual BASING lactate-editing pulses, high bandwidth very selective suppression (VSS) pulses and a flyback echo-planar readout was implemented at 3 T. The purpose of this study was to implement a new lactate-edited 3D 1H magnetic resonance spectroscopic imaging (MRSI) sequence at 3 T and demonstrate the feasibility of using this sequence for measuring lactate in patients with gliomas. ![]()
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