Simultaneous Measurement of Perfusion and T2* in Calf Muscle at 7T with Submaximal Exercise using Radial Acquisition

Figures

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  Figure 1. Schematic of pulse sequence and prescription of imaging slices. Pulse sequence consisted of two loops. The outer perfusion loop (top) was acquired with interleaved tagging (SS) and control (NS) adiabatic inversion pulse followed by PLD and radial acquisition of perfusion imaging slice (slice 1). Inner loop consisted of multi-echo GRE pulse sequence implemented during the PLD delay to get multi echo images for T2* calculation. Five echo images were acquired during one outer perfusion loop with echo times = 2.2, 5.0, 7.8, 10.6 and 13.4 ms. Perfusion slice was selected 3 cm proximal to the T2* slice which accounts for the incoming arterial blood flow direction.

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  Figure 2. Difference between radial image reconstruction without and with gradient delay error correction. (a) Phantom image shows artifacts without the correction of gradient delay errors. There are two vials on the top that disappear in the reconstructed image. (b) Image after correction for gradient delays.

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  Figure 3. (a) Image of the phantom. (b) Perfusion map showing absence of perfusion in phantom. (c) Correlation plot showing excellent correlation between T2* calculated from new sequence and GRE sequence. (d) Bland-Altman plot also showing very good agreement between two sequences.

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  Figure 4. Two slice locations for perfusion and T2* on calf muscle (a). Slice 1 is perfusion slice and slice 2 is T2* slice. Increased perfusion activated area on corresponding perfusion slice (b) and average perfusion with standard deviation of all the subjects during recovery period from selected ROI (green circle) (c). Decreased T2* activated area on corresponding T2* slice (d) and average relative T2* with standard deviation of all subjects during recovery period from selected ROI (e).

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  Figure 5. Sample slice selective (SS) signal time course from gastrocnemius muscle during recovery following exercise (a) and corresponding perfusion calculated without the non-selective (NS) acquisition plotted together with a sample perfusion calculated with NS acquisition (b).

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  Figure 6. Different muscle groups in perfusion slice (a) and corresponding muscle perfusion (b) during recovery period. Same muscle groups in T2* slice (c) and corresponding muscle T2* (d) during recovery period.