Optimized Diffusion Time for Long-Time-Scale Helium-3 Diffusion MRI

Chengbo Wang¹, John P. Mugler, III^1,2, Eduard E. de Lange¹, Talissa A. Altes¹

Global long-time-scale helium-3 ADC values as a function of diffusion time were measured in 29 healthy volunteers and 14 subjects with COPD. The percentage difference in group mean ADC versus diffusion time had a well-defined maximum at a diffusion time of approximately 1 s, suggesting that this diffusion time affords the best ability to discriminate COPD and healthy subjects. Furthermore, the percentage difference between the two groups at the long-time scale (110%-150%) was much greater than that found at the short-time-scale (commonly, 20%-100%), which supports the premise that long-time-scale diffusion is more sensitive to COPD than short-time-scale diffusion.