publications by G. Allan Johnson.
- MD Shattuck, SL Gewalt, GH Glover, LW Hedlund, GA Johnson, MR microimaging of the lung using volume projection encoding.,
Magnetic resonance in medicine : official journal of the Society of Magnetic Resonance in Medicine / Society of Magnetic Resonance in Medicine, UNITED STATES, vol. 38 no. 6
pp. 938-42 .
(last updated on 2005/08/03)
Radial acquisition (RA) techniques have been extended to produce isotropic, three-dimensional images of lung in live laboratory animals at spatial resolution down to 0.013 mm3 with a signal-to-noise ratio of 30:1. The pulse sequence and reconstruction algorithm have been adapted to allow acquisition of image matrices of up to 256(3) in less than 15 min. Scan-synchronous ventilation has been incorporated to limit breathing motion artifacts. The imaging sequence permits randomizing and/or discarding selected views to minimize the consequences of breathing motion. The signal in lung parenchyma was measured as a function of flip angle (alpha) for different repetition times and found to follow the predictions for which there is an optimum excitation (Ernst) angle. A single T1 relaxation value of 780 +/- 54 ms fits all data from six guinea pigs at 2.0 T. This T1 value parameterizes the signal and allows for a priori optimization, such as calculation of the Ernst angle appropriate for lung imaging.
Animals • Guinea Pigs • Lung • Magnetic Resonance Imaging • anatomy & histology* • methods*