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Updated: May 25, 2025
Hyperpolarized Xenon for NMR and MRI Applications
Published on: September 6, 2012
Hyperpolarized 129Xe diffusion-weighted MRI of the lung with 3D golden-angle radial sampling and keyhole
Luyang Shen1, Haidong Li1,2, Yuan Fang1
1State Key Laboratory of Magnetic Resonance Spectroscopy and Imaging, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences-Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan, China.
Background:
Hyperpolarized (HP) 129Xe multiple b-values diffusion-weighted imaging (DWI) facilitates the assessment of pulmonary morphology. However, conventional DWI method, such as 2D GRE DWI, is limited in its application due to the long acquisition time and relatively thick slice.
Purpose:
To develop a method combining 3D golden-angle radial sampling with keyhole reconstruction (GRSK) for accelerating 129Xe multiple b-values DWI and obtaining thinner slice.
Methods:
For 3D GRSK DWI, 3D kooshball golden-angle radial sampling was used for image acquisition, with each spoke assigned to 1 of 4 b-values, and keyhole method was applied for reconstructing DW images under different b-values. 2D fully sampled GRE DWI and 3D GRSK DWI were obtained in five healthy young volunteers (HYV; 25 [24-26] years). Lung morphological parameter maps, including mean linear intercept (Lm) and surface-to-volume ratio (SVR), were generated using a cylinder model (CM) from the four b-values DW images, and apparent diffusion coefficient (ADC) maps were derived through mono-exponential fitting. Spearman correlation and Bland-Altman analysis were performed to compare Lm, SVR and ADC from 2D GRE and 3D GRSK DWI. In addition, 3D GRSK DWI was applied in five emphysema patients (66 [60-69] years) and five age-matched healthy controls (AMC; 59 [54-68] years), and Lm, SVR and ADC maps were also derived. Wilcoxon rank-sum test was utilized to contrast Lm, SVR and ADC from patients with those from AMC.
Results:
DW images with an isotropic resolution (5 mm) were obtained with 3D GRSK DWI within 11.4 s. In comparison, 2D GRE DWI acquired four slices with 30 mm thickness in 15.9 s. For Lm, SVR and ADC from 2D GRE and 3D GRSK DWI, the Spearman correlation coefficients were 0.975, 0.900, and 1.000, with corresponding p-values of 0.005, 0.037, and < 0.001, and the Bland-Altman analysis had biases of -3.19%, 1.44%, and -3.71%, respectively. Furthermore, Lm and ADC in patients were significantly higher (p = 0.008 and p = 0.008) than those in AMC, while SVR was notably reduced (p = 0.008).
Conclusion:
The proposed method could obtain isotropic resolution DW images with four b-values within an 11.4 s breath-hold duration, mitigating the problems of long scan time and large slice thickness in conventional DWI.
Insights
This study introduces a faster 3D golden-angle radial sampling with keyhole reconstruction (GRSK) method for hyperpolarized 129Xe diffusion-weighted imaging (DWI), enabling thinner slices and improved pulmonary morphology assessment.
Area of Science:
- Medical Imaging
- Pulmonary Medicine
- Physics
Background:
- Hyperpolarized (HP) 129Xe multiple b-values diffusion-weighted imaging (DWI) is crucial for assessing lung morphology.
- Conventional 2D GRE DWI methods are limited by long acquisition times and thick slices.
Purpose of the Study:
- To develop an accelerated 3D golden-angle radial sampling with keyhole reconstruction (GRSK) method for 129Xe multiple b-values DWI.
- To enable thinner slice acquisition for enhanced pulmonary imaging.
Main Methods:
- 3D kooshball golden-angle radial sampling was employed for image acquisition, with keyhole reconstruction used for different b-values.
- Lung morphological parameters (Lm, SVR) and apparent diffusion coefficient (ADC) were derived and compared between 2D GRE DWI and 3D GRSK DWI in healthy volunteers.
- The 3D GRSK DWI method was further applied to emphysema patients and controls.
Main Results:
- 3D GRSK DWI acquired isotropic resolution images in 11.4 seconds, significantly faster than conventional 2D GRE DWI.
- High correlations (Spearman's ρ: 0.900-1.000) and small biases were observed for Lm, SVR, and ADC between the two methods.
- Emphysema patients showed significantly higher Lm and ADC, and reduced SVR compared to controls.
Conclusions:
- The proposed 3D GRSK DWI method successfully accelerates 129Xe multiple b-values DWI acquisition.
- This technique overcomes limitations of long scan times and thick slices, offering improved pulmonary imaging.
- The method demonstrates potential for differentiating lung disease characteristics, such as in emphysema.
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