Abstract #1853

The Goldilocks zone for 3T MRS studies using semi-LASER: Determining the optimal balance between repetition time and scan time using FSL-MRS

Alex Ensworth^1,2, Laura Barlow^3,4, Piotr Kozlowski^1,2,3,4, Erin MacMillan^3,4,5, and Cornelia Laule^1,2,3,6

¹Physics and Astronomy, University of British Columbia, Vancouver, BC, Canada, ²International Collaboration on Repair Discoveries (ICORD), University of British Columbia, Vancouver, BC, Canada, ³Radiology, University of British Columbia, Vancouver, BC, Canada, ⁴UBC MRI Research Centre, University of British Columbia, Vancouver, BC, Canada, ⁵Philips Canada, Mississauga, ON, Canada, ⁶Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC, Canada

Synopsis

Keywords: Spectroscopy, Spectroscopy, MRS, T1 weighting, FSL-MRS, repetition time, TR, semi-LASER, 3T, metabolite concentration, brain, grey matter

Motivation: A short TR is often used in clinical MRS brain studies, leading to T₁-weighting of metabolites and inaccurate T₁ correction.

Goal(s): To determine the optimal balance between scan time and TR that minimizes T₁-weighting effects when using semi-LASER MRS.

Approach: SNR and metabolite concentrations were compared for TRs of 2, 5 and 8s using FSL-MRS.

Results: A TR of 5s provides a good balance of scan time, SNR and signal recovery. For a similar scan time, TR of 2s leads to incomplete signal recovery and thus heavy T₁ weighting, while a TR of 8s results in complete signal recovery but reduced SNR.

Impact: For MRS studies using semi-LASER, our work informs scientists and clinicians on the issues of using a short TR, and recommends the optimal scan parameters to use while implementing the newly available FSL-MRS analysis package.

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