Object ID: 00000018WIA30748970GYZ
Topic ID: id_40024820 Version: 1.4
Date: Mar 28, 2022 2:08:30 PM

Dynamic Susceptibility Contrast scan protocol

Consider these tradeoffs as you change scan parameters for images that are post-processed with these READY View applications: BrainStat, BrainStat AIF, and MR Standard. The tables below apply to the following MR field strengths:

1.5T

Table 1. 2D Single-Shot Gradient-Echo, Echo-Planar Imaging
Scan parameter	Value	Considerations
TR	1000- 1500 ms	TR affects T2* weighting, which is required to reduce T1 effect from leakage contamination.
TE	30-60 ms	Decrease the TE value for 3.0T protocols to 30-40 ms.
Flip angle	60 degrees	The value does not change for field strength.
Bandwidth	250 kHz	Select Ramp Sampling User CV.
FOV	24 - 28 cm	The value does not change for field strength.
Slice thickness	4 - 7 mm	As the slice thickness decreases: The magnetic susceptibility decreases. SNR decreases. Consider decreasing the matrix size to increase SNR.
Slice spacing	0-1 mm	The value does not change for field strength.
Matrix	7 mm slice = 128 x 128 4 mm slice = 64 x 64	As the matrix size increases, increase slice thickness to compensate for the SNR loss.
NEX	1	The value does not change for field strength.
Frequency direction	Right/Level	Swap phase and frequency to reduce Nyquist ghost artifact.
Imaging Options	Multi-phase, ASSET	Brainstat GVF requires a larger amount of time-points compared to Brainstat AIF.
Temporal resolution	determined by the TR	The shorter the TR the better. Brainstat requires high temporal resolution data (typically TR< or = 1500 ms).
Acquisition time	AIF is approximately 60 seconds GVF is 40% longer than AIF	Assumes a temporal resolution of 1.5 seconds.
Number of slices	Changes as TR changes	Be aware of the effect of the number of prescribed slices has on the TR value. The minimum TR can double when the number of slices is increased.

Table 2. 2D Single-Shot Spin-Echo Echo-Planar Imaging
Scan parameter	Value	Considerations
TR	1000- 1500 ms	TR affects T2* weighting, which is required to reduce T1 effect from leakage contamination.
TE	50-80 ms	Decrease the TE value for 3.0T protocols to 30-40 ms.
Flip angle	90 degrees	The value does not change for field strength.
Bandwidth	250 kHz	Select Ramp Sampling User CV.
FOV	24 - 28 cm	The value does not change for field strength.
Slice thickness	4 - 7 mm	As the slice thickness decreases: The magnetic susceptibility decreases. SNR decreases. Consider decreasing the matrix size to increase SNR.
Slice spacing	0-1 mm	The value does not change for field strength.
Matrix	7 mm slice = 128 x 128 4 mm slice = 64 x 64	As the matrix size increases, increase slice thickness to compensate for the SNR loss.
NEX	1	The value does not change for field strength.
Frequency direction	Right/Level	Swap phase and frequency to reduce Nyquist ghost artifact.
Imaging Options	Multi-phase, ASSET	Brainstat GVF requires a larger amount of time-points compared to Brainstat AIF.
Temporal resolution	determined by the TR	The shorter the TR the better. Brainstat requires high temporal resolution data (typically TR< or = 1500 ms).
Acquisition time	AIF is approximately 60 seconds GVF is 40% longer than AIF	Assumes a temporal resolution of 1.5 seconds.
Number of slices	Changes as TR changes	Be aware of the effect of the number of prescribed slices has on the TR value. The minimum TR can double when the number of slices is increased.