This study shows the feasibility of phase-resolved functional lung imaging to gain quantitative information regarding regional lung perfusion and ventilation without the need for ultrafast imaging, which will be advantageous for future clinical translation. Magn Reson Med 79:2306-2314, 2018. © 2017 International Society for Magnetic Resonance in Medicine.

Purpose To quantify regional lung ventilation in patients with chronic obstructive pulmonary disease (COPD) by using free-breathing dynamic fluorinated (fluorine 19 [F]) gas magnetic resonance (MR) imaging. Materials and Methods In this institutional review board-approved prospective study, 27 patients with COPD were examined by using breath-hold F gas wash-in MR imaging during inhalation of a normoxic fluorinated gas mixture (perfluoropropane) and by using free-breathing dynamicF gas washout MR imaging after inhalation of the gas mixture was finished for a total of 25-30 L. Regional lung ventilation was quantified by using volume defect percentage (VDP), washout time, number of breaths, and fractional ventilation (FV). To compare different lung function parameters, Pearson correlation coefficient and Fisher z transformation were used, which were corrected for multiple comparisons with the Bonferroni method. Results Statistically significant correlations were observed for all evaluated lung function test parameters compared with median and interquartile range of F washout parameters. An inverse linear correlation of median number of breaths (r = -0.82; P< .0001) and median washout times (r = -0.77; P < .0001) with percentage predicted of forced expiratory volume in 1 second (FEV) was observed; correspondingly median FV (r = 0.86; P < .0001) correlated positively with percentage predicted FEV. Comparing initial with late phase, median VDP of all subjects decreased from 49% (25th-75th percentile, 35%-62%) to 6% (25th-75th percentile, 2%-10%; P < .0001). VDP at the beginning of the gas wash-in phase (VDP) significantly correlated with percentage predicted FEV (r = -0.74; P = .0028) and FV (r = 0.74; P = .0002). Median FV was significantly increased in ventilated regions (11.1% [25th-75th percentile, 6.8%-14.5%]) compared with the defect regions identified by VDP (5.8% [25th-75th percentile, 4.0%-7.4%]; P < .0001). Conclusion Quantification of regional lung ventilation by using dynamic F gas washout MR imaging in free breathing is feasible at 1.5 T even in obstructed lung segments. RSNA, 2017 Online supplemental material is available for this article.

BackgroundPerfusion‐weighted (Qw) noncontrast‐enhanced proton lung MRI is a promising technique for assessment of pulmonary perfusion, but still requires validation.PurposeTo improve perfusion‐weighted phase‐resolved functional lung (PREFUL)‐MRI, to validate PREFUL with perfusion single photon emission computed tomography (SPECT) as a gold standard, and to compare PREFUL with dynamic contrast‐enhanced (DCE)‐MRI as a reference.Study TypeRetrospective.PopulationTwenty patients with chronic obstructive pulmonary disease (COPD), 14 patients with cystic fibrosis (CF), and 21 patients with chronic thromboembolic pulmonary hypertension (CTEPH) were included.Field Strength/SequenceFor PREFUL‐MRI, a spoiled gradient echo sequence and for DCE‐MRI a 3D time‐resolved angiography with stochastic trajectories sequence were used at 1.5T.AssessmentPREFUL‐MRI coronal slices were acquired in free‐breathing. DCE‐MRI was performed in breath‐hold with injection of 0.03 mmol/kg bodyweight of gadoteric acid at a rate of 4 cc/s. Perfusion SPECT images were obtained for six CTEPH patients. Images were coregistered. An algorithm to define the appropriate PREFUL perfusion phase was developed using perfusion SPECT data. Perfusion defect percentages (QDP) and Qw‐values were calculated for all methods. For PREFUL quantitative perfusion values (PREFULQ) and for DCE pulmonary blood flow (PBF) was calculated.Statistical TestsObtained parameters were assessed using Pearson correlation and Bland–Altman analysis.ResultsQw‐SPECT correlated with Qw‐DCE (r = 0.50, P < 0.01) and Qw‐PREFUL (r = 0.47, P < 0.01). Spatial overlap of QDP maps showed an agreement ≥67.7% comparing SPECT and DCE, ≥64.1% for SPECT and PREFUL, and ≥60.2% comparing DCE and PREFUL. Significant correlations of Qw‐PREFUL and Qw‐DCE were found (COPD: r = 0.79, P < 0.01; CF: r = 0.77, P < 0.01; CTEPH: r = 0.73, P < 0.01). PREFULQ/PBF correlations were similar/lower (CF, CTEPH: P > 0.12; COPD: P < 0.01) compared to Qw‐PREFUL/DCE correlations. PREFULQ‐values were higher/similar compared to PBF‐values (COPD, CF: P < 0.01; CTEPH: P = 0.026).Data ConclusionThe automated PREFUL algorithm may allow for noncontrast‐enhanced pulmonary perfusion assessment in COPD, CF, and CTEPH patients comparable to DCE‐MRI.Level of Evidence 3Technical Efficacy Stage 2J. Magn. Reson. Imaging 2020;52:103–114.

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GOREG+LIDA can be used to calculate quantitative ventilation images with improved image quality, which is an important step toward clinical translation of this method. The presented method is also feasible at 3T. Magn Reson Med 78:1496-1505, 2017. © 2016 International Society for Magnetic Resonance in Medicine.

Background Chronic lung allograft dysfunction (CLAD) is a major cause for the low long‐term survival rates after lung transplantation (LTx). Early detection of CLAD may enable providing medical treatment before a nonreversible graft dysfunction has occurred. MRI is advantageous to pulmonary function testing (PFT) in the ability to assess regional function changes, and thus have the potential in detecting very early stages of CLAD before changes in global forced expiratory volume during the first second (FEV1%) occur. Purpose To examine whether early stages of CLAD (diagnosed based on PFT values) could also be detected using MRI‐derived parameters of regional flow‐volume dynamics. Study Type Retrospective. Population 62 lung transplantation recipients were included in the study, 29 of which had been diagnosed with CLAD at various stages. Field Strength/Sequence MRI datasets were acquired with a 1.5T Siemens scanner using a spoiled gradient echo sequence. Assessment MRI datasets were retrospectively preprocessed and analyzed by a blinded radiologist according to the phase resolved functional lung MRI (PREFUL‐MRI) approach, resulting in fractional ventilation (FV) maps and regional flow‐volume loops (rFVL). FV‐ and rFVL‐based parameters of regional lung ventilation were estimated. Statistical Tests Differences between groups were compared by Mann–Whitney U‐test with a Bonferroni correction for multiple comparisons (n = 2). Results rFVL‐CC‐based parameters discriminated significantly between the presence or absence of CLAD (P < 0.003). Data Conclusion Using the contrast media‐free PREFUL‐MRI technique, parameters of ventilation dynamics and its regional heterogeneity were shown to be sensitive for the detection of early CLAD stages. Level of Evidence: 3 Technical Efficacy Stage 3 J. Magn. Reson. Imaging 2019;50:1873–1882.

Background: Perfusion-weighted noncontrast-enhanced proton lung MRI during free breathing is maturing as a novel technique for assessment of regional lung perfusion, but has not yet been validated in chronic obstructive pulmonary disease (COPD) patients. Purpose: To compare pulmonary parenchymal perfusion assessed by noncontrast-enhanced perfusion-weighted phaseresolved functional lung (PREFUL)-MRI with lung perfusion determined with dynamic gadolinium-enhanced (DCE)-MRI and with lung function test parameters. Study Type: Prospective. Population: A single-center subset of the COPD cohort "COPD and SYstemic consequenzes-COmorbidities NETwork" (COSYCONET). Forty-seven patients with COPD (median age 66 [57-70] years) were studied. Field Strength/Sequence: For PREFUL-MRI a spoiled gradient echo sequence and for DCE-MRI, a 3D time-resolved spoiled gradient echo sequence was used at 1.5T. Assessment: PREFUL-MRI coronal slices were acquired in free breathing. DCE-MRI was performed in breath-hold with administration of 0.025 mmol/kg bodyweight of gadobutrol i.v. at a rate of 4 ml/s and pulmonary blood flow (PBF) maps were calculated. Slices of PREFUL and DCE-MRI were matched by their ventrodorsal position and corresponding slices were coregistered for evaluation. Perfusion defect percentages (QDP) were calculated for both methods. Statistical Tests: The obtained parameters were correlated using Spearman's correlation coefficient (r) and Bland-Altman plot analysis. Results: PREFUL-QDP showed an absolute and spatial agreement with PBF-QDP on a global (39.3 (31.8-45.5)% vs. 44.7 (35.4-50.0)% with a spatial overlap of 62.2 (57.2-67.2)%)) as well as on a lobar level and correlated with lung function test parameters (PREFUL-QDP vs. FEV 1 , r = -0.75, P < 0.0001). There was a systematic overestimation of PREFUL-QDP compared with PBF-QDP, mainly in the lower lobes, resulting in an overall overestimation for the whole lung with a mean difference of 5% (95% confidence interval [CI]: 3.0%; 7.0%; STD 6.8%). Data Conclusion: PREFUL-MRI is a promising noninvasive, radiation-free tool for quantification of regional perfusion in COPD patients. Level of Evidence: 1 Technical Efficacy: Stage 2

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