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To investigate whether hyperpolarised xenon-129 MRI (HXeMRI) enables regional and physiological resolution of diffusing capacity limitations in chronic obstructive pulmonary disease (COPD), we evaluated 34 COPD subjects and 11 healthy volunteers. We report significant correlations between airflow abnormality quantified by HXeMRI and per cent predicted forced expiratory volume in 1 s; HXeMRI gas transfer capacity to red blood cells and carbon monoxide diffusion capacity (%DLCO); and HXeMRI gas transfer capacity to interstitium and per cent emphysema quantified by multidetector chest CT. We further demonstrate the capability of HXeMRI to distinguish varying pathology underlying COPD in subjects with low %DLCO and minimal emphysema. [ABSTRACT FROM AUTHOR]

Purpose: To assess the effect of lung volume on measured values and repeatability of xenon 129 ( 129 Xe) gas uptake metrics in healthy volunteers and participants with chronic obstructive pulmonary disease (COPD)., Materials and Methods: This Health Insurance Portability and Accountability Act-compliant prospective study included data (March 2014-December 2015) from 49 participants (19 with COPD [mean age, 67 years ± 9 (SD)]; nine women]; 25 older healthy volunteers [mean age, 59 years ± 10; 20 women]; and five young healthy women [mean age, 23 years ± 3]). Thirty-two participants underwent repeated 129 Xe and same-breath-hold proton MRI at residual volume plus one-third forced vital capacity (RV+FVC/3), with 29 also undergoing one examination at total lung capacity (TLC). The remaining 17 participants underwent imaging at TLC, RV+FVC/3, and residual volume (RV). Signal ratios between membrane, red blood cell (RBC), and gas-phase compartments were calculated using hierarchical iterative decomposition of water and fat with echo asymmetry and least-squares estimation (ie, IDEAL). Repeatability was assessed using coefficient of variation and intraclass correlation coefficient, and volume relationships were assessed using Spearman correlation and Wilcoxon rank sum tests., Results: Gas uptake metrics were repeatable at RV+FVC/3 (intraclass correlation coefficient = 0.88 for membrane/gas; 0.71 for RBC/gas, and 0.88 for RBC/membrane). Relative ratio changes were highly correlated with relative volume changes for membrane/gas ( r = -0.97) and RBC/gas ( r = -0.93). Membrane/gas and RBC/gas measured at RV+FVC/3 were significantly lower in the COPD group than the corresponding healthy group ( P ≤ .001). However, these differences lessened upon correction for individual volume differences ( P = .23 for membrane/gas; P = .09 for RBC/gas)., Conclusion: Dissolved-phase 129 Xe MRI-derived gas uptake metrics were repeatable but highly dependent on lung volume during measurement. Keywords: Blood-Air Barrier, MRI, Chronic Obstructive Pulmonary Disease, Pulmonary Gas Exchange, Xenon Supplemental material is available for this article © RSNA, 2023., Competing Interests: Disclosures of conflicts of interest: W.J.G. No relevant relationships. K.Q. No relevant relationships. M.H. No relevant relationships. L.Z. National Key R&D Program of China 2022ZD0118004, the Alzheimer’s Association through AARF-18-566347, the Zhejiang Provincial Natural Science Foundation of China under grant no. LGJ22H180004, 2020R01003, 2022C03057, the Fundamental Research Funds for the Central Universities 2021FZZX002-05, MOE Frontier Science Center for Brain Science & Brain-Machine Integration, Zhejiang University, DOBI Medical; systems and methods for accelerated MR thermometry. US10722137B2. Samuel Fielden, Li Zhao, Wilson Miller, Xue Feng, Max Wintermark, Kim Butts Pauly, Craig H. Meyer. 2020-07-28 System and Method for Improved Spin-Echo-Based Magnetic Resonance Imaging. US16498672. David C. Alsop, Li Zhao. 2021-11-02. N.J.T. No relevant relationships. J.T.P. No relevant relationships. J.F.M. No relevant relationships. Y.M.S. NIH funding HL132177. A.M.R. No relevant relationships. T.A.A. Grant/contract for Polarean Clinical Trial, consultant for Polarean, speaker for Polarean. J.P.M. NIH-NHLBI R01 HL109618 grants; research grant from Siemens Medical Solutions not related to the content of this manuscript. G.W.M. Grants from National Institutes of Health (R01 HL109618, R01 HL105586, R01 CA172595; payments paid to University of Virginia)., (© 2023 by the Radiological Society of North America, Inc.)

Background Apparent diffusion coefficient (ADC) maps of inhaled hyperpolarized gases have shown promise in the characterization of emphysema in patients with chronic obstructive pulmonary disease (COPD), yet an easily interpreted quantitative metric beyond mean and standard deviation has not been established. Purpose To introduce a quantitative framework with which to characterize emphysema burden based on hyperpolarized helium 3 ( 3 He) and xenon 129 ( 129 Xe) ADC maps and compare its diagnostic performance with CT-based emphysema metrics and pulmonary function tests (PFTs). Materials and Methods Twenty-seven patients with mild, moderate, or severe COPD and 13 age-matched healthy control subjects participated in this retrospective study. Participants underwent CT and multiple b value diffusion-weighted 3 He and 129 Xe MRI examinations and standard PFTs between August 2014 and November 2017. ADC-based emphysema index was computed separately for each gas and b value as the fraction of lung voxels with ADC values greater than in the healthy group 99th percentile. The resulting values were compared with quantitative CT results (relative lung area <-950 HU) as the reference standard. Diagnostic performance metrics included area under the receiver operating characteristic curve (AUC). Spearman rank correlations and Wilcoxon rank sum tests were performed between ADC-, CT-, and PFT-based metrics, and intraclass correlation was performed between repeated measurements. Results Thirty-six participants were evaluated (mean age, 60 years ± 6 [standard deviation]; 20 women). ADC-based emphysema index was highly repeatable (intraclass correlation coefficient > 0.99) and strongly correlated with quantitative CT ( r = 0.86, P < .001 for 3 He; r = 0.85, P < .001 for 129 Xe) with high AUC (≥0.93; 95% confidence interval [CI]: 0.85, 1.00). ADC emphysema indices were also correlated with percentage of predicted diffusing capacity of lung for carbon monoxide ( r = -0.81, P < .001 for 3 He; r = -0.80, P < .001 for 129 Xe) and percentage of predicted residual lung volume divided by total lung capacity ( r = 0.65, P < .001 for 3 He; r = 0.61, P < .001 for 129 Xe). Conclusion Emphysema index based on hyperpolarized helium 3 or xenon 129 diffusion MRI provides a repeatable measure of emphysema burden, independent of gas or b value, with similar diagnostic performance as quantitative CT or pulmonary function metrics. © RSNA, 2020 Online supplemental material is available for this article. See also the editorial by Schiebler and Fain in this issue.

Objective: The purpose of this article are to review scapular anatomy and function, describe imaging features of traumatic scapular injury, and discuss the role of diagnostic imaging in clinical decision making after shoulder trauma., Conclusion: Knowledge of scapular anatomy, function, injury patterns, imaging appearance, and clinical management is important for the radiologist to the care of patients who present with acute shoulder trauma.