Table 2.
Sequence | Transfer efficiency (b) | Localization accuracy | SNR | SAR (%) (d) |
---|---|---|---|---|
Z-TOCSY-LASER | 60% | ++++ | +++ | 100 |
Z-TOCSY-STEAM | 60% | − | +++ (c) | 72 |
Z-TOCSY-PRESS | 60% | − | +++ (c) | 72 |
TOCSY-LASER (a) | 12% | ++++ | + | 94 |
COSY-LASER | 100% | ++++ | ++++ | 28 |
L-COSY | 100% | − | ++++ (c) | 7 |
The sequence design from Ref. (29) was used;
The efficiency calculated as percentage for the same mixing time of 64 ms (close to 1/2J = 72 ms for lactate) and the low-power condition γB1,max = 0.76 kHz in the case of TOCSY;
when the signal is adjusted to the size of the real voxel selected by the localization;
SAR calculated and measured at 3T (transmit body RF coil) by the watchdog monitor in percentage from the maximum of 3W/kg allowed for the brain in a volunteer case when using the same TR = 2 s and 64 ms mixing time at the low power condition for TOCSY (for other organs with lower SAR limits shorter TR < 2s is possible with the most intense Z-TOCSY-LASER sequence, the semi-adiabatic sequences Z-TOCSY-STEAM and Z-TOCSY-PRESS can be run on brain with TR = 1.5 s). Plus (+) and minus (−) symbols are given as a qualitative measure for the performance (for localization minus indicates poor localization as proven by the presence of contaminating signal from lipids).