The development and optimization of spin-echo-based, single-slab, three-dimensional techniques for magnetic resonance imaging of the whole brain are described. T1-weighted and T2-weighted image sets with a volume resolution of 1 mm(3) and fluid-attenuated inversion-recovery image sets with a volume resolution of 3 mm(3) were obtained in acquisition times of less than 10 minutes per image set.

An optimized interleaved‐spiral pulse sequence, providing high spatial and temporal resolution, was developed for dynamic imaging of pulmonary ventilation with hyperpolarized ³He, and tested in healthy volunteers and patients with lung disease. Off‐resonance artifacts were minimized by using a short data‐sampling period per interleaf, and gradient‐fidelity errors were compensated for by using measured k‐space trajectories for image reconstruction. A nonsequential acquisition order was implemented to improve image quality during periods of rapid signal change, such as early inspiration. Using a sliding‐window reconstruction, cine‐movies with a frame rate of 100 images per second were generated. Dynamic images demonstrating minimal susceptibility‐ and motion‐induced artifacts were obtained in sagittal, coronal, and axial orientations. The pulse sequence had the flexibility to image multiple slices almost simultaneously. Our initial experience in healthy volunteers and subjects with lung pathology demonstrated the potential of this new tool for capturing the features of lung gas‐flow dynamics. Magn Reson Med 4:667–677, 2001.

This pilot study evaluated the effect of short- and long-term ivacaftor treatment on hyperpolarized 3He-magnetic resonance imaging (MRI)-defined ventilation defects in patients with cystic fibrosis aged ≥12years with a G551D-CFTR mutation. Part A (single-blind) comprised 4weeks of ivacaftor treatment; Part B (open-label) comprised 48weeks of treatment. The primary outcome was change from baseline in total ventilation defect (TVD; total defect volume:total lung volume ratio). Mean change in TVD ranged from -8.2% (p=0.0547) to -12.8% (p=0.0078) in Part A (n=8) and -6.3% (p=0.1953) to -9.0% (p=0.0547) in Part B (n=8) as assessed by human reader and computer algorithm, respectively. TVD responded to ivacaftor therapy. 3He-MRI provides an individual quantification of disease burden that may be able to detect aspects of the disease missed by population-based spirometry metrics. Assessments by human reader and computer algorithm exhibit similar trends, but the latter appears more sensitive. www.clinicaltrials.gov identifier: NCT01161537.

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.

The phase‐encoding strategy plays a critical role in determining the quality of gradient‐ and spin‐echo (GRASE) images. Phase‐encoding methods developed for two‐dimensional GRASE imaging strive to achieve a balance between artifacts from T2‐dependent signal amplitude modulations and off‐resonance‐dependent signal phase shifts, although no current method provides smooth and nonperiodic evolutions for both of these signal changes. In three‐dimensional GRASE imaging, the use of two phase‐encoding directions presents the opportunity for improved phase‐encoding strategies. In this report a phase‐encoding strategy for three‐dimensional GRASE, termed SORT, is described; this strategy separates off‐resonance and T2 effects, mapping one along each of the two phase‐encoding directions. Thus, off‐resonance‐induced artifacts can be minimized while eliminating T2‐dependent periodic signal modulations and allowing complete flexibility in the selection of echo time. The performance of the SORT phase‐encoding method for T2‐weighted GRASE imaging was compared with that of existing methods based on calculated point spread functions and simulated images. The predicted performance of SORT phase encoding was verified experimentally using T2‐weighted three‐dimensional GRASE imaging of the brain. Generally artifact‐free images were obtained even in the presence of fat, susceptibility interfaces, and a wide range of T2 values.J. Magn. Reson. Imaging 1999;9:604–612.

3D Single-breath Chemical Shift Imaging (3D-SBCSI) is a hybrid MR-spectroscopic imaging modality that uses hyperpolarized xenon-129 gas (Xe-129) to differentiate lung diseases by probing functional characteristics. This study tests the efficacy of 3D-SBCSI in differentiating physiology among pulmonary diseases. A total of 45 subjects—16 healthy, 11 idiopathic pulmonary fibrosis (IPF), 13 cystic fibrosis (CF), and 5 chronic obstructive pulmonary disease (COPD)—were given 1/3 forced vital capacity (FVC) of hyperpolarized Xe-129, inhaled for a ~7 s MRI acquisition. Proton, Xe-129 ventilation, and 3D-SBCSI images were acquired with separate breath-holds using a radiofrequency chest coil tuned to Xe-129. The Xe-129 spectrum was analyzed in each lung voxel for ratios of spectroscopic peaks, chemical shifts, and T2* relaxation. CF and COPD subjects had significantly more ventilation defects than IPF and healthy subjects, which correlated with FEV1 predicted (R = −0.74). FEV1 predicted correlated well with RBC/Gas ratio (R = 0.67). COPD and IPF had significantly higher Tissue/RBC ratios than other subjects, longer RBC T2* relaxation times, and greater RBC chemical shifts. CF subjects had more ventilation defects than healthy subjects, elevated Tissue/RBC ratio, shorter Tissue T2* relaxation, and greater RBC chemical shift. 3D-SBCSI may be helpful in the detection and characterization of pulmonary disease, following treatment efficacy, and predicting disease outcomes.