Open MATLAB, change to ./code folder and run the m-file batch_process.m
Scan Descriptions
Scan Name
Scan Time mm:ss
TI ms
TR ms
TE ms
Max Flip Angle
Repetition Delay ms
TFE Inversion Delay ms
TFE Shot Interval ms
Dynamics
Spiral Duration ms
Spiral Interleaves
Reconstructed
VUMC_MRF_1000_TE3.3_FSC
10:14.0
20
16
3.3
70
N/A
8012.00
26000
24
6.7578
24
YES
VUMC_MRF_1000_TE3.3_US
00:16.0
20
16
3.3
70
N/A
8012.00
26000
1
6.7578
24
YES
VUMC_MRF_1000_TE5.0_FSC
10:14.0
20
16
5.0
70
N/A
8012.00
26000
24
6.7578
24
YES
VUMC_MRF_1000_TE5.0_US
00:16.0
20
16
5.0
70
N/A
8012.00
26000
1
6.7578
24
YES
VUMC_MRF_210_TE3.3_FSC
03:04.8
28
28
3.3
70
1000
2953.96
6880
27
6.8843
27
YES
VUMC_MRF_210_TE3.3_US
00:26.6
28
28
3.3
70
1000
2953.96
6880
4
6.8288
24
YES
VUMC_MRF_210_TE4.0_FSC
03:04.8
28
28
4.0
70
1000
2953.96
6880
27
6.8843
27
YES
VUMC_MRF_210_TE4.0_US
00:26.6
28
28
4.0
70
1000
2953.96
6880
4
6.8288
24
YES
VUMC_MRF_500_TE3.3_FSC
07:01.5
15
15
3.3
60
N/A
3757.49
18000
24
5.8876
24
YES
VUMC_MRF_500_TE3.3_US
00:07.5
15
15
3.3
60
N/A
3757.49
18000
1
5.8876
24
YES
VUMC_MRF_500_TE5.2_FSC
07:01.5
15
15
5.2
60
N/A
3757.49
18000
24
5.8876
24
YES
VUMC_MRF_500_TE5.2_US
00:07.5
15
15
5.2
60
N/A
3757.49
18000
1
5.8876
24
YES
Notes
US stands for "undersampled", i.e., a single spiral interleaf per readout of the fingerprint pattern.
FSC stands for "fully sampled center", i.e., 24 spiral interleaves avaialble per readout of the fingerprint pattern.
Spirals are variable density with the change to x2 additional undersampling (24 to 48 interleaves) at 60% from k-space center.
Dynamics are used for two purposes in the above scans.
Repeated dynamics achieved the short relaxation time interval feature (length 210 pattern) by using the first 3 dynamics as the "dummy" repetitions.
Repeated dynamics collected additional interleaves to fully sample the spiral trajectory.
Spirals are rotated by the Golden Angle, which is 180 * (3 - sqrt(5)) = 137.50776405 degrees (full projection radial MRI golden angle is 111.246117975 degrees)
FSC 210 scans had an incorrect setting of 27 spiral interleaves and therefore have a mismatch between acquired and trajectory-measured spiral. Reconstructions were performed by synthesizing the trajectory from the gradient waveform values along with eddy current constants and gradient delay time estimated from the measured spiral trajectory for the undersampled 210 scans. The method of calibration was a slightly tweaked version of the approach described in this paper.
Excitation RF was selected to have a higher time-bandwidth product (RFex rf_shape = sg_500_200_0).
No off-resonance correction is applied in current reconstructions. A single delta B0 fieldmap was acquired at the end of the scan session and appears to not agree with most scans. Center frequency was selected once at the beginning of the scan session with "selective F0" and likely drifted over the long scan session duration.
Alternating RF phase in length 1000 pattern is removed during corrections applied to raw k-space data and the alternating phase is added back into the even numbered complex images before matching to the dictionary.
ROI measurements use a circular shape with radius of 7 pixels yielding 149 samples in each ROI.
