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Hyperpolarized 129Xe magnetic resonance imaging (MRI) is a method for studying regionally resolved aspects of pulmonary function. This work presents an end-to-end standardized workflow for hyperpolarized 129Xe MRI of lung ventilation, with specific attention to pulse sequence design, 129Xe dose preparation, scan workflow, and best practices for subject safety monitoring.
Hyperpolarized 129Xe MRI comprises a unique array of structural and functional lung imaging techniques. Technique standardization across sites is increasingly important given the recent FDA approval of 129Xe as an MR contrast agent and as interest in 129Xe MRI increases among research and clinical institutions. Members of the 129Xe MRI Clinical Trials Consortium (Xe MRI CTC) have agreed upon best practices for each of the key aspects of the 129Xe MRI workflow, and these recommendations are summarized in a recent publication. This work provides practical information to develop an end-to-end workflow for collecting 129Xe MR images of lung ventilation according to the Xe MRI CTC recommendations. Preparation and administration of 129Xe for MR studies will be discussed and demonstrated, with specific topics including choice of appropriate gas volumes for entire studies and for individual MR scans, preparation and delivery of individual 129Xe doses, and best practices for monitoring subject safety and 129Xe tolerability during studies. Key MR technical considerations will also be covered, including pulse sequence types and optimized parameters, calibration of 129Xe flip angle and center frequency, and 129Xe MRI ventilation image analysis.
Hyperpolarized 129Xe MRI is an exciting tool for non-invasive, spatially-resolved characterization and quantification of specific aspects of pulmonary function1,2,3. Acquisition and reconstruction approaches similar to those used in anatomical proton MRI yield images of inhaled 129Xe in the lungs, permitting visualization of non-ventilated lung regions and region-resolved quantification of ventilation distribution4,5,6,
All research involving human subjects must be approved by an institutional review board (IRB). IRB involvement is not necessary for regulatory-approved clinical use of 129Xe MRI. Before participating in a research study, prospective subjects must be provided with an approved informed consent document. The person obtaining consent must explain the contents of the document, including the purpose, procedures, benefits, and risks of the study, must answer any questions, and must obtain consent from the subject to .......
Figure 1 shows representative ventilation and three-plane localizer images from a healthy individual. High 129Xe signal can be observed throughout the lungs in the ventilation images, and no ventilation impairment is evident in this individual.
Figure 2, Figure 3, and Figure 4 show representative ventilation and anatomical images from diseased individuals.
The ventilation and anatomical MRI approaches outlined above are designed to maximize image quality and SNR while maintaining simplicity of implementation - these sequence protocols can in general be adapted from vendor product pulse sequences, provided multinuclear operation is enabled, and images will automatically reconstruct on the scanner computer. One disadvantage of the 2D approaches described here is the use of slice-selective excitation RF pulses, which introduces signal differences between slices collected earl.......
This work was funded by the National Institutes of Health (grant numbers R01-CA172595-01, R01-HL132177, R01-HL167202, S10-OD018079, and UL1-TR003015) and by Siemens Medical Solutions.
....Name | Company | Catalog Number | Comments |
1.5T or 3T human MRI scanner | Siemens | MAGNETOM Symphony (1.5T) or Vida (3T); older models fine, as long as multinuclear option is/can be installed; scanners also available from GE and Philips | |
129Xe hyperpolarizer | Polarean | 9820 | |
129Xe MRI phantom | |||
129Xe MRI vest coil | Clinical MR Solutions | Also available from other vendors | |
129Xe polarization measurement station | Polarean | 2881 | |
1H MRI phantom | |||
Coil file for 129Xe MRI vest coil | Also available from other vendors for their respective coils | ||
ECG machine | |||
Helium buffer gas | |||
Interface box from coil to scanner | May be built into coil, but needs to be included separately if not | ||
Liquid nitrogen | |||
MRI-safe pulse oximeter | Philips | Expression MR200 | |
Nitrogen buffer gas | |||
PFT machine | |||
Programming/image analysis software | MATLAB | R2023a | Various other options available |
Pulse sequence design software | Siemens | IDEA software package; also available from GE and Philips for their respective scanners | |
Scanner multinuclear option | Siemens | Scanner integrated hardware/software package; also available from GE and Philips for their respective scanners | |
Tedlar gas sampling bags (500, 750, 1000, 1250, 1500 mL) | |||
Xenon gas (129Xe isotopically enriched) |
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