Multiple regression method for pulmonary apparent diffusion coefficient measurement by hyperpolarized 3He MRI
✍ Scribed by Jiangsheng Yu; Masaru Ishii; Stephen Kadlecek; David A. Lipson; Kiarash Emami; Timothy W. Clark; Sheeva Rajaei; Rahim R. Rizi
- Publisher
- John Wiley and Sons
- Year
- 2007
- Tongue
- English
- Weight
- 727 KB
- Volume
- 25
- Category
- Article
- ISSN
- 1053-1807
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✦ Synopsis
Abstract
Purpose
To develop and validate a new multiple regression technique for the separation of flip angle effect in pulmonary apparent diffusion coefficient (ADC) measurement.
Materials and Methods
Hyperpolarized ^3^He MRI (HP ^3^He MRI) ADC measurements were performed on phantom, pig, and human models. The diffusion‐sensitization sequence is modified from a standard gradient echo (GRE) sequence with a nonlinear progression in the bipolar gradient amplitude with each image. In the self‐diffusion phantom experiment, four images were acquired with base gradient factor b~0~ = 0.15 second/cm^2^; in the pig and human experiment, six images were acquired with base gradient factor b~0~ = 1.4 second/cm^2^.
Results
The self‐diffusion coefficient measured in the phantom experiment was 1.98 ± 0.16 cm^2^/second. The measured uncertainty curve was consistent with the theoretically predicted curve. The measured in vivo ADC values (three coronal slices in the supine direction) were 0.20/0.16/0.13 cm^2^/second and 0.20/0.18/0.16 cm^2^/second for pig and human experiments, respectively.
Conclusion
With the introduction of a nonlinear progression in the diffusion‐sensitization gradients, the multiple regression technique is capable of separating the flip angle effect in ADC measurement. In addition, this technique can perform a rigorous measurement uncertainty analysis and provide the optimal scan parameters that yield best noise performance. J. Magn. Reson. Imaging 2007;25:982–991. © 2007 Wiley‐Liss, Inc.