Implementation of 3 T Lactate-Edited 3D 1H MR Spectroscopic Imaging with Flyback Echo-Planar Readout for Gliomas Patients

Abstract

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. 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. Over-prescription factor of PRESS voxels was optimized using phantom to minimize chemical shift artifacts. 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. The results demonstrated the feasibility of detecting lactate within a short scan time of 9.5 min in both phantoms and patients. Over-prescription of voxels gave less chemical shift artifacts allowing detection of lactate on the majority of the selected volume. The normalized SNR of brain metabolites using the flyback encoding were comparable to the SNR of brain metabolites using conventional phase encoding MRSI. The specialized lactate-edited 3D MRSI sequence was able to detect lactate in brain tumor patients at 3 T. 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.

Metabolic Profiling of IDH Mutation and Malignant Progression in Infiltrating Glioma

“…Subsequent in vitro work has revealed differential 2HG production based on the subcellular localization of IDH2 enzymes in the mitochondria, providing evidence that IDH2 mutations are robust to the absence of the wild-type enzyme while IDH1 mutations are not41. Although limited in sample size, a recent in vivo study at ultra-high field strength supports this result by demonstrating an over three-fold increase in 2HG levels in IDH2 -mutated lesions42434445. Taken together, these studies support further investigation into the metabolic differences between IDH1 and IDH2 mutations that are downstream of 2HG.…”

Acute Tumor Lactate Perturbations as a Biomarker of Genotoxic Stress: Development of a Biochemical Model

“…(5, 7) HP-MRI provides a powerful imaging platform, with greatly improved signal-to-noise ratio compared to traditional proton magnetic resonance spectroscopy. (16, 48, 49) Xu et al utilized this imaging platform to differentiate between cell lines with high and low metastatic potential. (15) Thind et al demonstrated that HP-MRI can be used to detect acute normal tissue radiation toxicity in a lung model.…”

Quantitative multi-modal MR imaging as a non-invasive prognostic tool for patients with recurrent low-grade glioma

“…3D Lactate-edited proton MR spectroscopic imaging ( 1 H MRSI) was acquired with (CHESS) water suppression, point-resolved spectroscopic selection (PRESS) localization, and very selective saturation (VSS) pulses for outer volume suppression with TE/TR = 144/1104ms, matrix size = 16x16x16 and a nominal voxel size of 1x1x1 cm 3 . A flyback echo-planar k-space trajectory was used to sample data in the SI direction in order to decrease the total acquisition time [24]. …”