Purpose To evaluate surgical success after pulmonary endarterectomy (PEA) by means of cardiopulmonary magnetic resonance (MR) imaging. Materials and Methods In this institutional review board-approved study, 20 patients with chronic thromboembolic pulmonary hypertension were examined at 1.5 T with a dynamic contrast material-enhanced three-dimensional fast low-angle shot sequence before and 12 days after PEA (25th-75th percentile range, 11-16 days). Lung segments were evaluated visually before PEA for parenchymal hypoperfused segments. Pulmonary blood flow (PBF), first-pass bolus kinetic parameters, and biventricular mass and function were determined. Mean pulmonary artery pressure (mPAP) and 6-minute walking distance were measured before and after PEA. The Shapiro-Wilk test, paired two-sided Wilcoxon rank sum test, Spearman ρ correlation, and multiple linear regression analysis were performed. Results Two weeks after PEA, regional PBF increased 66% in the total lung from 32.7 to 54.2 mL/min/100 mL (P = .0002). However, after adjustment for cardiac output, this change was not evident anymore (increase of 7% from 7.03 to 7.54 mL/min/100 mL/L/min, P = .1). Only in the lower lobes, a significant increase in PBF after cardiac output adjustment remained: a 16% increase in the right lower lobe from 7.53 to 8.71 mL/min/100 mL (P = .01) and a 14% increase in the left lower lobe from 7.42 to 8.47 mL/min/100 mL/L/min (P < .05). Right ventricular mass and function also improved. mPAP decreased from 46 to 24 mm Hg (P < .0001). Six-minute walking distance increased from 390 to 467 m (P = .02) 5 months after PEA. Percentage change of mPAP and PBF in the lower lobe tended to be significant predictors of percentage change in 6-minute walking distance (β = -1.79 [P = .054] and β = 0.45 [P = .076], respectively) in multiple linear regression analysis. Conclusion Improvement of PBF after PEA was observed predominantly in the lower lungs, and the magnitude of improvement of PBF in the lower lobes correlated with the improvement in exercise capacity, reflecting surgical success. (©) RSNA, 2016.

Objectives To evaluate quantitative and semi-quantitative measures of regional pulmonary parenchymal perfusion in patients with COPD in relationship to global lung perfusion (GLP) and lung diffusing capacity (DLCO). Materials and Methods One hundred and forty three participants in the MESA COPD Study were examined by dynamic contrast-enhanced pulmonary perfusion MRI at 1.5 T. Pulmonary blood flow (PBF) was calculated on a pixel-by-pixel basis by using a dual-bolus technique and the Fermi function model. Semi-quantitative parameters for regional lung perfusion were calculated from signal-intensity time curves in the lung parenchyma. Intra- and inter-observer coefficients of variation (CV) and correlations between quantitative and semi-quantitative MRI parameters and with GLP and DLCO were determined. Results Quantitative and semi-quantitative parameters of pulmonary parenchymal perfusion were reproducible with CVs for all <10%. Furthermore, these MRI parameters were correlated with GLP and DLCO and there was good agreement between PBF and GLP. Quantitative and semi-quantitative MRI parameters were closely correlated (e.g., r=0.86 for maximum signal increase with PBF). In participants without COPD, the physiological distribution of pulmonary perfusion could be determined by regional MRI measurements. Conclusion Regional pulmonary parenchymal perfusion can reliably be quantified from dynamic contrast-enhanced MRI. MRI-derived quantitative and semi-quantitative perfusion measures correlate with GLP and DLCO.

BackgroundThe translation of phase‐resolved functional lung (PREFUL)‐MRI to routine practice in monitoring chronic thromboembolic pulmonary hypertension (CTEPH) still requires clinical corresponding imaging biomarkers of pulmonary vascular disease.PurposeTo evaluate successful pulmonary endarterectomy (PEA) via PREFUL‐MRI with pulmonary pulse wave transit time (pPTT).Study TypeRetrospective.PopulationThirty CTEPH patients and 12 healthy controls were included.Field Strength/SequenceFor PREFUL‐MRI a 2D spoiled gradient echo sequence and for DCE‐MRI a 3D time‐resolved angiography with stochastic trajectories (TWIST) sequence were performed on 1.5T.AssessmentEight coronal slices of PREFUL‐MRI were obtained on consecutive 13 days before and 14 days after PEA. PREFUL quantitative lung perfusion (PREFULQ) phases over the whole cardiac cycle were calculated to quantify pPTT, the time the pulmonary pulse wave travels from the central pulmonary arteries to the pulmonary capillaries. Also, perfusion defect percentage based on pPTT (QDPpPTT), PREFULQ (QDPPREFUL), and V/Q match were calculated. For DCE‐MRI, pulmonary blood flow (PBF) and QDPPBF were computed as reference. For clinical correlation, mean pulmonary arterial pressure (mPAP) and 6‐minute walking distance were evaluated preoperatively and after PEA.Statistical TestsThe Shapiro–Wilk test, paired two‐sided Wilcoxon rank sum test, Dice coefficient, and Spearman's correlation coefficient (ρ) were applied.ResultsMedian pPTT was significantly lower post PEA (139 msec) compared to pre PEA (193 msec), P = 0.0002. Median pPTT correlated significantly with the mPAP post PEA (r = 0.52, P < 0.008). Median pPTT was distributed more homogeneously after PEA: IQR pPTT decreased from 336 to 281 msec (P < 0.004). Median PREFULQ (P < 0.0002), QDPpPTT (P < 0.0478), QDPPREFUL (P < 0.0001) and V/Q match (P < 0.0001) improved significantly after PEA. Percentage change of PREFULQ correlated significantly with percentage change of 6‐minute walking distance (ρ = 0.61; P = 0.0031) 5 months post PEA.Data ConclusionPerioperative perfusion changes in CTEPH can be detected and quantified by PREFUL‐MRI. Normalization of pPTT reflects surgical success and improvement of PREFULQ predicts 6‐minute walking distance changes.Level of Evidence3Technical Efficacy Stage2 J. Magn. Reson. Imaging 2020;52:610–619.

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