Accelerated Fractional Ventilation Imaging with Hyperpolarized Gas MRI

作者：Emami Kiarash^*; Xu Yinan; Hamedani Hooman; Profka Harrilla; Kadlecek Stephen; Xin Yi; Ishii Masaru; Rizi Rahim R

来源：Magnetic Resonance in Medicine, 2013, 70(5): 1353-1359.

DOI：10.1002/mrm.24582

• pulmonary ventilation
• quantitative lung imaging
• fractional ventilation
• hyperpolarized gas MRI
• mechanical ventilation
• parallel MRI
• generalized auto-calibrating partially parallel acquisition
• accelerated ventilation imaging

PurposeTo investigate the utility of accelerated imaging to enhance multibreath fractional ventilation (r) measurement accuracy using hyperpolarized gas MRI. Undersampling shortens the breath-hold time, thereby reducing the O-2-induced signal decay and allows subjects to maintain a more physiologically relevant breathing pattern. Additionally, it may improve r estimation accuracy by reducing radiofrequency destruction of hyperpolarized gas.
MethodsImage acceleration was achieved using an eight-channel phased array coil. Undersampled image acquisition was simulated in a series of ventilation images and data was reconstructed for various matrix sizes (48-128) using generalized auto-calibrating partially parallel acquisition. Parallel accelerated r imaging was also performed on five mechanically ventilated pigs.
ResultsOptimal acceleration factor was fairly invariable (2.0-2.2x) over the range of simulated resolutions. Estimation accuracy progressively improved with higher resolutions (39-51% error reduction). In vivo r values were not significantly different between the two methods: 0.27 0.09, 0.35 +/- 0.06, 0.40 +/- 0.04 (standard) versus 0.23 +/- 0.05, 0.34 +/- 0.03, 0.37 +/- 0.02 (accelerated); for anterior, medial, and posterior slices, respectively, whereas the corresponding vertical r gradients were significant (P < 0.001): 0.021 +/- 0.007 (standard) versus 0.019 +/- 0.005 (accelerated) (cm(-1)).
ConclusionQuadruple phased array coil simulations resulted in an optimal acceleration factor of approximate to 2x independent of imaging resolution. Results advocate undersampled image acceleration to improve accuracy of fractional ventilation measurement with hyperpolarized gas MRI. Magn Reson Med 70:1353-1359, 2013.

• 出版日期2013-11