Measurement and analysis of nonexponential signal decay curves in brain diffusion and muscle relaxation magnetic resonance studies in humans
✍ Scribed by Hale Pinar Zengingonul; Robert V. Mulkern
- Publisher
- John Wiley and Sons
- Year
- 1999
- Tongue
- English
- Weight
- 205 KB
- Volume
- 10
- Category
- Article
- ISSN
- 0899-9457
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✦ Synopsis
Detailed measurement and analysis of two important processes in magnetic resonance imaging (MRI) are described. The processes of interest are the apparent diffusion coefficient (ADC) behavior of water protons in the brain and the transverse relaxation (T2) behavior of water protons in muscle. The method described for the brain water diffusion study allows for more detailed sampling of the brain signal decay with b-factor than is usually performed. Prolonged scan times are avoided using a line scan format with the tradeoff being reduced volume coverage. The method described for the muscle studies also provides greater sampling of the T2 decay curves than is generally performed. The main advantage of the line scan format in this case, however, lies in the ability to perform "single-shot" sampling of the decay curve which may prove useful for studying temporal changes of muscle during exercise. In either case, the high sampling of the relevant decay curves allows us to explore the limits of the usual assumption of monoexponential decay with two complimentary computational methods. These are discrete and continuum exponential signal modeling, respectively. For both processes studied, the assumption of monoexponential decay is found lacking. The results indicate the potential for greater tissue characterization and highlight the need for biophysical modeling of multicomponent decay behavior in vivo.