Scanner
Enter the ¹H frequency your scanner reports for the best accuracy. Siemens “3 T” systems run near 2.89 T.
Larmor frequencies
| Nucleus | γ/2π (MHz/T) | Frequency (MHz) |
|---|
Scaled from the ¹H frequency by γ ratios. Chemical shift spreads each nucleus over several kHz, so treat these as where to start a frequency search.
Tap a peak to put the transmit frequency on it. Axis runs high to low ppm, as on a spectrum.
Offsets from transmit
| Peak | ppm | Offset |
|---|
Convert
Hyperpolarized acquisition
Enter T1 as 0 to ignore relaxation between pulses.
Signal per excitation
Excitation number across, signal as a fraction of the starting polarization up. Signal is sin θ times the remaining longitudinal magnetization.
Hyperpolarized acquisition
Constant-signal schedule
θₙ = arctan(1/√(N−n)) uses all the magnetization in N equal-signal excitations and ends at 90°. It ignores T1 decay, which makes later signals smaller.
Thermally polarized acquisition
θ = arccos(e−TR/T1) gives the most steady-state signal per unit time, for example natural-abundance ¹³C glycogen. Not for hyperpolarized signals.