Introduction: Compared to diffusion-weighted imaging (DWI) with a conventional pulsed gradient spin echo (PGSE) sequence, DWI with an oscillating gradient spin echo (OGSE) sequence can shorten the diffusion time by changing the frequency. The purpose of this study was to investigate the suitability of n-alkanes as isotropic phantoms for estimation of the diffusion coefficient of an OGSE sequence. Methods: We investigated the changes in apparent diffusion coefficient (ADC) due to differences in the viscosity of 9 n-alkane phantoms with different numbers of carbon atoms(C₈H₁₈ to C₁₆H₃₄)using OGSE and PGSE sequences at 21°C. Effective diffusion times of 4.3, 4.6, 5.1, 5.7, 6.5, 7.6, 9.3 35.8, 40, 45, and 49.1 ms were used. Sphere regions of interest were placed manually within the alkane phantoms on ADC maps. Results: In each alkane phantom, the mean ADC value was approximately constant with the change in diffusion time. The viscosities and ADC values were inversely proportional, as theoretically expected. Conclusion: The ADC values of alkanes do not depend on the diffusion times. The n-alkane phantoms can be used to assess the clinical accuracy of DWI with an OGSE sequence.
MAEKAWA et al. (Mon,) studied this question.
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