• Wei Zha, Sean B Fain, Mark L Schiebler, Michael D Evans, Scott K Nagle, and Fang Liu.
• Department of Medical Physics, University of Wisconsin-Madison, Madison, Wisconsin, USA.
• J Magn Reson Imaging. 2019 Oct 1; 50 (4): 1169-1181.

BackgroundUltrashort echo time (UTE) proton MRI has gained popularity for assessing lung structure and function in pulmonary imaging; however, the development of rapid biomarker extraction and regional quantification has lagged behind due to labor-intensive lung segmentation.PurposeTo evaluate a deep learning (DL) approach for automated lung segmentation to extract image-based biomarkers from functional lung imaging using 3D radial UTE oxygen-enhanced (OE) MRI.Study TypeRetrospective study aimed to evaluate a technical development.PopulationForty-five human subjects, including 16 healthy volunteers, 5 asthma, and 24 patients with cystic fibrosis.Field Strength/Sequence1.5T MRI, 3D radial UTE (TE = 0.08 msec) sequence.AssessmentTwo 3D radial UTE volumes were acquired sequentially under normoxic (21% O2 ) and hyperoxic (100% O2 ) conditions. Automated segmentation of the lungs using 2D convolutional encoder-decoder based DL method, and the subsequent functional quantification via adaptive K-means were compared with the results obtained from the reference method, supervised region growing.Statistical TestsRelative to the reference method, the performance of DL on volumetric quantification was assessed using Dice coefficient with 95% confidence interval (CI) for accuracy, two-sided Wilcoxon signed-rank test for computation time, and Bland-Altman analysis on the functional measure derived from the OE images.ResultsThe DL method produced strong agreement with supervised region growing for the right (Dice: 0.97; 95% CI = [0.96, 0.97]; P < 0.001) and left lungs (Dice: 0.96; 95% CI = [0.96, 0.97]; P < 0.001). The DL method averaged 46 seconds to generate the automatic segmentations in contrast to 1.93 hours using the reference method (P < 0.001). Bland-Altman analysis showed nonsignificant intermethod differences of volumetric (P ≥ 0.12) and functional measurements (P ≥ 0.34) in the left and right lungs.Data ConclusionDL provides rapid, automated, and robust lung segmentation for quantification of regional lung function using UTE proton MRI.Level Of Evidence2 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2019;50:1169-1181.© 2019 International Society for Magnetic Resonance in Medicine.

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