Double DANTE-PRESS: Development of a 1H-MRS Multifrequency-Selective Sequence for Simultaneous In Vivo Quantification
Kesavi Kanagasabai1,2,3, Omer Oran4, Lena Palaniyappan1,2,3,5
1Imaging Program, Lawson Research Institute, London, Ontario, Canada.
Abstract:
Glutamate and glutathione share a complex and tightly regulated cycle where imbalances can be a symptom of neurocognitive disorders. Magnetic resonance spectroscopy (1H-MRS) is a noninvasive in vivo imaging technique used to quantify the concentration of human brain metabolites. Metabolite-targeted techniques produce simple brain spectra that use simple fitting models. This reduces algorithmic variability and increases the precision of measurements of the metabolite(s) of interest. Common metabolite-targeted techniques using spectral editing have drawbacks such as increased scan time and low signal-to-noise ratio efficiency and are prone to motion-related subtraction artifacts. We introduce a custom single-shot multifrequency-selective sequence known as double-DANTE-PRESS that does not involve spectral editing. This sequence uses narrowband refocusing pulses allowing the users to refocus the signal from within two frequency passbands of interest while suppressing unwanted signals from outside the passbands. This produces simpler spectra mostly containing signals from metabolites of interest. In this study, we use double-DANTE-PRESS to acquire measurements of glutamate and glutathione simultaneously and report on its precision at 7 Tesla in phantoms and in vivo human brain. Double DANTE-PRESS (TE/TR = 96 ms/3000 ms) was programmed within the software environment of the Siemens Magnetom 7 Tesla MR scanner at the Centre for Functional Metabolic Mapping of Western University (VE12U). Two scans were obtained on phantoms and in five healthy volunteers (20 × 20 × 20 mm3 voxel at the dorsal anterior cingulate cortex) as an in vivo proof-of-concept to refocus the glutamate multiplet at 2.35 ppm and glutathione singlet at 3.77 ppm simultaneously. In vivo, the mean inter-individual %CV of glutathione and glutamate were less than 10% and 7%, respectively, and the mean %CRLBs of glutathione and glutamate were 10% and 5%. Double-DANTE-PRESS can allow for the simultaneous detection of glutamate and glutathione. This technique simplifies spectral quantification allowing for precise and simultaneous measurements. Future work includes a formal in vivo test-retest study and application to clinically driven research in patients with neurocognitive disorders.
