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QUESTION 21 10 points Save Answer 9 An MPRAGE image of the brain was acquired at 3T using the following parameters: TE/TRRAGE = 3/20 ms, pulse angle 10 , TI 1600 ms, matrix 256 x 128 x 64 (Re x Ph x SI), slice selective adiabatic inversion pulse BW 10000 Hz, 3D phase encoding order Sl then Ph, inter- MPRAGE loop delay TD 1000 ms. Sketch a feasible version of the sequence, including RF, all gradient pulses, delays, echo times and signals as provided above. (include first RF pulse of second pass only) (3 marks) a b. Calculate the effective inversion time Tleff for this image acquisition. (2 marks) c. Calculate the MPRAGE TR time, TRMPRAGE (2 marks) d. Calculate the total imaging acquisition time (in min) for the 3D image. (1 mark) e. Briefly explain how this sequence can be used to enhance T1-weighting of the FLASH sequence in brain imaging. Refer to the contrast produced for CSF, WM and GM in your answer. (2 marks) QUESTION 21 10 points Save Answer 9 An MPRAGE image of the brain was acquired at 3T using the following parameters: TE/TRRAGE = 3/20 ms, pulse angle 10 , TI 1600 ms, matrix 256 x 128 x 64 (Re x Ph x SI), slice selective adiabatic inversion pulse BW 10000 Hz, 3D phase encoding order Sl then Ph, inter- MPRAGE loop delay TD 1000 ms. Sketch a feasible version of the sequence, including RF, all gradient pulses, delays, echo times and signals as provided above. (include first RF pulse of second pass only) (3 marks) a b. Calculate the effective inversion time Tleff for this image acquisition. (2 marks) c. Calculate the MPRAGE TR time, TRMPRAGE (2 marks) d. Calculate the total imaging acquisition time (in min) for the 3D image. (1 mark) e. Briefly explain how this sequence can be used to enhance T1-weighting of the FLASH sequence in brain imaging. Refer to the contrast produced for CSF, WM and GM in your answer. (2 marks)

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