Begin by creating a thermally polarized 129 xenon phantom. To do so, connect a glass pressure vessel to a xenon gas filled bag, having an appropriate size and volume aligning with the vessel's capacity. Then submerge the pressure vessel in a small amount of liquid nitrogen to allow xenon diffusion and freezing.
Seal the vessel after the xenon has formed frozen snow inside. Allow it to thaw while pressurizing the vessel before calculating the pressure in the vessel. To detect peak frequency, put the phantom inside the xenon 129 coil and place it similar to that of a loaded patient.
Perform a scan with proton frequency as some scanners may disallow multinuclear scans without initial proton frequency localizer. Use a broadband transmit pulse if available, high bandwidth and high resolution readout experiment, to accurately detect the xenon frequency peak. Once a well-defined peak is detected, record the frequency to full precision.
Repeat the new experiment at the new frequency with a low bandwidth of about 1000 hertz to maximize signal to noise ratio or SNR and peak frequency precision. Once a satisfactory high signal peak is detected, save the protocol for future quality control tests. Use a small amount of hyperpolarized xenon 129, which is well concentrated and free of oxygen for imaging.
Measure the xenon 129 dose equivalent or DE accurately immediately prior to imaging. Set the test imaging protocol to reflect desired in vivo parameters as closely as possible. Acquire and save the image of the xenon bag as a baseline measure of scanner performance.
Measure and record the SNR of the acquired images alongside all scan parameters and xenon DE.For measuring alpha, the flip angle, perform a full volume spoiled gradient echo scan in which the field of view is imaged twice in succession using identical sequence parameters. Measure the SNR at the DC offset of the two images S0 and S1.Count the number of phase encoding steps n, and calculate the flip angle.
