For PRC use only Date of approval: Signature of Chair: Siemens Vision 1.5T Sequence Description Sequence name: T1 measurement sequence version 1.0. Developer: Jan Hrabe Date: 8/2/2000 Filename: t1_v10_7inv.ekc and t1_v10_8inv.ekc Location: $SEQ/local Other files: t1_rf.dat, t1_tables.dat, t1_spl.sph, t1_8inv_tables.dat t1_8inv_spl.sph, all in $EXT/local directory. Brief description: Quantitative measurement of T1 using IR EPI (7 or 8 TI times) in a single slice. The sequence with 7 inversions uses the phase correction algorithm based on HW ADC window shift which leads to a longer adjustment time (algorithm is identical to the FAIR/UNFAIR sequences). The 8 inversions sequence uses 2-line phase correction collected with the longest TI time used. Adjustment time is shorter and there are no timeout problems. Parent sequence: fair_v20_225.ekc, RF pulses are identical but there are more inversions. RF safety: 1. HSM10D10B.004_200: Hyperbolic secant inversion pulse, duration 10 ms, BW 3.41 kHz, gradient 20 mT/m for 4 mm slice. 2. The imaging 90 degree pulse is a standard Siemensgenerated filtered sinc pulse 4.096 ms long with slice reference gradient 10 mT/m for 10 mm slice. Computed Partial Body: 0.76 W/kg Computed Energy Dose: 0.132 J/kg Gradient safety: The gradients used do not exceed the switching rate of the standard Siemens parent sequence ep2d_fid_22b2080_62.ekc. Parameter meanings, limits and defaults: Alpha operates on the inversion HS pulse voltage (default 180). TR is pertinent to the first TI time and identical post-acquisition delay is then used for other TI times (default is 15s in the 8 inversion sequence). TI sets the first TI time, other TI times are computed by adding the respective TD time to TI. Default inversion times are 93.75, 187.5, 375, 750, 1500, 3000, 6000, and 12000 ms. TE cannot be changed, is as small as possible. Usage notes: The sequence with 7 inversions is not appropriate for measuring T1 of CSF and is more prone to timeout errors. However, it resembles the perfusion sequence more closely. Use 3-5 acquisitions and leave the fat saturation on. Appendices: 1. Sequence code listing. 2. Listing of all changes in the sequence SPL code. 3. Sequence diagram (section of a 7 inversion sequence for one TI time shown).