For PRC use only
Date of approval:
Signature of Chair:
Siemens Vision 1.5T Sequence Description
Sequence name: UNFAIR and FAIR v2.0
Developer: Jan Hrabe, NKI
Date: 10/21/1999
Filenames:
Location: /usr/appl/sequence/local
fair_v20_180.ekc
unfair_v20_180.ekc
Other files: fu_rf.dat, fu_spl.sph, fu_tables.dat
Brief description: Implements FAIR/UNFAIR perfusion imaging in a single slice. Inversion pulses
are HS-type, 1.8 times wider than the imaging slice, acquisition is high BW EPI with resolution from
32x64 up to 128x128. Fat saturation is optional. Two images are acquired during every acquisition
loop: control (with NS inversion pulses) and PW image (with a slice-selective inversion).
Measurement repetitions are implemented as Acquisitions, not as Number of Measurements. All
images will have the same series number, interleaving control and PW image.
Parent sequence: These sequences are based on Siemens standard sequence
ep2d_fid_22b2080_62.ekc, although only the readout remained relatively unchanged.
RF safety: Dr. D. Lewis designed the inversion HS pulse especially for these sequences.
1. HSM10D10A.004_200: Hyperbolic secant inversion pulse, duration 10 ms, BW 3.41 kHz,
gradient 20 mT/m for 4 mm slice, threshold B1 amplitude for inversion 0.30 G,  1.05 ms-1,
 10.2, 1% truncation at the ends of the pulse, 1000 support points.
2. The imaging 90 degree pulse is a standard Siemens-generated filtered sinc pulse 4.096 ms
long with slice reference gradient 10 mT/m for 10 mm slice.
Computed Partial Body SAR: 1.46 W/kg
Computed Energy Dose: 0.25 J/kg
Gradient safety: The gradients used do not exceed the switching rate of the standard Siemens
parent sequence ep2d_fid_22b2080_62.ekc. It is the maximum rate at which the machine can
operate (25 mT/m maximum amplitude, sinusoidal shape with period 1.2 ms, giving maximum
derivative 130.9 T/m/s).
Parameter meanings, limits and defaults:
 BW: max. 2752.8 Hz/pixel, average 2083.3 Hz/pixel (variable sampling rate)
 Matrix: 64x64 or 128x128 (default), min. of 32 PE lines
 Alpha: max. 200, default 180, manipulates the RF power for the HS inversion pulses
 TR: min. 1s, default 4s, every acquisition takes 2xTR (control + perf. image)
 TI: min. 20 ms, default 600 ms (from the end of inversion pulse to the end of imaging pulse)
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TE: it is computed and reported by the dialog box and can be changed only indirectly by adding
TD delay time. Minimum TE is computed as 5.71 + (Npe / 2) * 0.3, where Npe is the number of
PE lines. For 128x128 matrix we get 24.91 ms, which brings the echo to line 32 = 128/4.
TD: it makes the echo time longer (which is correctly reported next to the TE button)
FOV: minimum voxel size is approximately 2.62 mm, independent of resolution (gradient
strength limitation), the default is 3 mm voxels, 5 mm slice thickness (with 4 mm min.)
RFOV: min. 4/8, default 8/8.
Usage notes: Slice can be double oblique but not off-center. Tests show good results for 5 cm axial
shift combined with oblique acquisition but unreliable results for 10cm shift. Try to position the
subject so that the slice intersects the coil isocenter for reproducible results. Number of
measurements can be selected bigger than 1 but it will not work in most cases (Siemens problem).
Repetitions are implemented as Acquisitions and all images have the same series number. Control
images are interleaved with perfusion images, and the control comes first.
Appendices: 1. Complete sequence code listing. 2. Listing of all changes in the sequence SPL code.
3. Sequence diagram (UNFAIR shown).