Rapid hyperpolarized 3He diffusion MRI of healthy and emphysematous human lungs using an optimized interleaved‐spiral pulse sequence

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Abstract
Purpose: To develop and validate an interleaved‐spiral diffusion pulse sequence capable of hyperpolarized 3He MR imaging of the whole lung in less than 10 seconds.Materials and Methods: Hyperpolarized 3He diffusion measurements were performed in seven healthy volunteers and five patients with emphysema using an interleaved‐spiral pulse sequence that provided 11 contiguous 15‐mm thick coronal ADC maps, with an in‐plane resolution of 3.9 mm, covering the whole lung in 5.5 seconds. The resulting means and SDs of ADC values were compared statistically to those from a gradient‐echo pulse sequence with identical resolution and diffusion‐weighting gradients that acquired five ADC maps in 10.5 seconds.Results: High‐quality diffusion‐weighted interleaved‐spiral images covering the whole lung were obtained, and showed no significant susceptibility‐induced image degradation compared to corresponding gradient‐echo images. On a subject‐by‐subject basis, the means and SDs of ADC values for the interleaved‐spiral technique were not statistically different from those for the gradient‐echo technique. The mean ADC values from the two techniques were highly correlated on a section‐by‐section basis (R = 0.99).Conclusion: The interleaved‐spiral diffusion pulse sequence permits rapid acquisition of contiguous ADC maps covering the whole lung during a short breath‐hold period, and provides ADC values that are statistically equivalent to those from standard gradient‐echo techniques. J. Magn. Reson. Imaging 2003;17:581–588.