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One Minute Whole-Brain Magnetization Transfer Ratio Imaging with Intrinsic B1-Correction

Roya Afshari^1,2, Francesco Santini^1,2, Rahel Heule³, Craig H. Meyer⁴, Josef Pfeuffer⁵, and Oliver Bieri^1,2
¹Division of Radiological Physics,Department of Radiology, University Hospital Basel, University of Basel, Basel, Switzerland, ²Department of Biomedical Engineering, University of Basel, Basel, Switzerland, ³High Field Magnetic Resonance, Max Planck Institute for Biological Cybernetics, Tübingen, Germany, ⁴Department of Biomedical Engineering, University of Virginia, Charlottesville, VA, United States, ⁵Siemens Healthcare, Application Development, Erlangen, Germany

A one-minute whole-brain MTR imaging method with intrinsic B₁-correction was introduced. The new method makes use of three interleaved multi-slice acquisitions offering high reproducibility and excellent prospects for translation and application in the clinics.

Scheme of 2D interleaved multi-slice spiral MTR imaging approach. SEQ: the sequence features three repetitions. Each repetition features a single-shot spiral readout, followed by a dummy period to reach steady state conditions and an interleaved spiral readout for image encoding. I_1,3,5: Single shot spiral readout without MT-preparation pulses. Dummy: MT-preparation pulses, RF excitation and gradients are played out. No readout is performed. I_2,4,6: MT-preparation is played out. Image encoding is performed using spiral interleaves. Recovery: Only gradients are played out.

Whole brain MTR histograms for the B₁-uncorrected (black solid line) and for the B₁-corrected MT-saturation (red dotted line). Overall, B₁-correction leads to a shift of the histogram toward lower MTR values, lower spread and improved peak-discrimination.