title: Helium-3 MR q-space imaging with radial acquisition and iterative highly constrained back-projection.
abstract: An undersampled diffusion-weighted stack-of-stars acquisition is combined with iterative highly constrained back-projection to perform hyperpolarized helium-3 MR q-space imaging with combined regional correction of radiofrequency- and T1-related signal loss in a single breath-held scan. The technique is tested in computer simulations and phantom experiments and demonstrated in a healthy human volunteer with whole-lung coverage in a 13-sec breath-hold. Measures of lung microstructure at three different lung volumes are evaluated using inhaled gas volumes of 500 mL, 1000 mL, and 1500 mL to demonstrate feasibility. Phantom results demonstrate that the proposed technique is in agreement with theoretical values, as well as with a fully sampled two-dimensional Cartesian acquisition. Results from the volunteer study demonstrate that the root mean squared diffusion distance increased significantly from the 500-mL volume to the 1000-mL volume. This technique represents the first demonstration of a spatially resolved hyperpolarized helium-3 q-space imaging technique and shows promise for microstructural evaluation of lung disease in three dimensions.
authors: Department of Medical Physics, University of Wisconsin, Madison, Wisconsin 53792, USA.
authors: Rafael L
authors: RL
authors: O'Halloran
authors: James H
authors: JH
authors: Holmes
authors: Yu-Chien
authors: YC
authors: Wu
authors: Andrew
authors: A
authors: Alexander
authors: Sean B
authors: SB
authors: Fain
mesh_terms: D000280:Administration, Inhalation; D000465:Algorithms; D003287:Contrast Media / Q000008:administration & dosage; D006371:Helium / Q000008:administration & dosage; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D007554:Isotopes / Q000008:administration & dosage / Q000627:therapeutic use; D008168:Lung / Q000033:anatomy & histology*; D008279:Magnetic Resonance Imaging / Q000295:instrumentation / Q000379:methods*; D019047:Phantoms, Imaging; D019275:Radiopharmaceuticals / Q000008:administration & dosage; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D003287:Contrast Media; D007554:Isotopes; D019275:Radiopharmaceuticals; D006371:Helium