T Kaireit

MR Imaging–derived Regional Pulmonary Parenchymal Perfusion and Cardiac Function for Monitoring Patients with Chronic Thromboembolic Pulmonary Hypertension before and after Pulmonary Endarterectomy

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.

Low-pass imaging of dynamic acquisitions (LIDA) with a group-oriented registration (GOREG) for proton MR imaging of lung ventilation

To compare low‐pass imaging dynamic acquisitions (LIDA) approach in combination with a group‐oriented registration (GOREG) scheme with conventional Fourier decomposition (FD).

Quantification of pathologic air trapping in lung transplant patients using ct density mapping: Comparison with other ct air trapping measures

To determine whether density mapping (DM) is more accurate for detection and quantification of pathologic air trapping (pAT) in patients after lung transplantation compared to other CT air trapping measures. One-hundred forty-seven lung and heart-lung transplant recipients underwent CT-examinations at functional residual capacity (FRC) and total lung capacity (TLC) and PFT six months after lung transplantation. Quantification of air trapping was performed with the threshold-based method in expiration (EXP), density mapping (DM) and the expiratory to inspiratory ratio of the mean lung density (E/I-ratio MLD). A non-rigid registration of inspiration-expiration CT-data with a following voxel-to-voxel mapping was carried out for DM. Systematic variation of attenuation ranges was performed for EXP and DM and correlated with the ratio of residual volume to total lung capacity (RV/TLC) by Spearman rank correlation test. AT was considered pathologic if RV/TLC was above the 95th percentile of the predicted upper limit of normal values. Receiver operating characteristic (ROC) analysis was performed. The optimal attenuation range for the EXP method was from -790 HU to -950 HU (EXP-790 to -950HU ) (r = 0.524, p<0.001) to detect air trapping. Within the segmented lung parenchyma, AT was best defined as voxel difference less than 80 HU between expiration and registered inspiration using the DM method. DM correlated best with RV/TLC (r = 0.663, p<0.001). DM and E/I-ratio MLD showed a larger AUC (0.78; 95% CI 0.69–0.86; 0.76, 95% CI 0.67–0.85) than EXP -790 HU to -950 HU (0.71, 95% CI 0.63–0.78). DM and E/I-ratio MLD showed better correlation with RV/TLC and are more suited quantitative CT-methods to detect pAT in lung transplant patients than the EXP-790HU to -950HU.

Feasibility of quantitative regional ventilation and perfusion mapping with phase-resolved functional lung (PREFUL) MRI in healthy volunteers and COPD, CTEPH, and CF patients: Phase-Resolved Functional Lung MRI

In this feasibility study, a phase‐resolved functional lung imaging postprocessing method for extraction of dynamic perfusion (Q) and ventilation (V) parameters using a conventional 1H lung MRI Fourier decomposition acquisition is introduced.

Comparison of quantitative regional ventilation-weighted fourier decomposition MRI with dynamic fluorinated gas washout MRI and lung function testing in COPD patients: Comparison of FD-MRI With 19F-MRI

Ventilation‐weighted Fourier decomposition‐MRI (FD‐MRI) has matured as a reliable technique for quantitative measures of regional lung ventilation in recent years, but has yet not been validated in COPD patients.

Free-breathing Dynamic 19F Gas MR Imaging for Mapping of Regional Lung Ventilation in Patients with COPD

Purpose To quantify regional lung ventilation in patients with chronic obstructive pulmonary disease (COPD) by using free-breathing dynamic fluorinated (fluorine 19 [19F]) 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 19F gas wash-in MR imaging during inhalation of a normoxic fluorinated gas mixture (perfluoropropane) and by using free-breathing dynamic 19F 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 19F 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 (FEV1) was observed; correspondingly median FV (r = 0.86; P < .0001) correlated positively with percentage predicted FEV1. 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 (VDPinitial) significantly correlated with percentage predicted FEV1 (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 VDPinitial (5.8% [25th-75th percentile, 4.0%-7.4%]; P < .0001). Conclusion Quantification of regional lung ventilation by using dynamic 19F gas washout MR imaging in free breathing is feasible at 1.5 T even in obstructed lung segments.

Regional investigation of lung function and microstructure parameters by localized 129Xe chemical shift saturation recovery and dissolved-phase imaging: A reproducibility study

To evaluate the reproducibility and regional variation of parameters obtained from localized 129Xe chemical shift saturation recovery (CSSR) MR spectroscopy in healthy volunteers and patients with chronic obstructive pulmonary disease (COPD) and to compare the results to 129Xe dissolved‐phase MR imaging.

Comparison of quantitative regional perfusion-weighted phase resolved functional lung (PREFUL) MRI with dynamic gadolinium-enhanced regional pulmonary perfusion MRI in COPD patients: Comparison of PREFUL-MRI With DCE-MRI

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.

Cardio-pulmonary MRI for detection of treatment response after a single BPA treatment session in CTEPH patients

ObjectivesChronic thromboembolic pulmonary hypertension (CTEPH) can be treated with balloon pulmonary angioplasty (BPA) in inoperable patients. Sensitive non-invasive imaging methods are missing to detect treatment response after a single BPA treatment session. Therefore, the aim of this study was to measure treatment response after a single BPA session using cardio-pulmonary MRI.Materials and methodsOverall, 29 patients with CTEPH were examined with cardio-pulmonary MRI before and 62 days after their initial BPA session. Pulmonary blood flow (PBF), first-pass bolus kinetic parameters, and biventricular mass and function were determined. Multiple linear regression analysis was implemented to estimate the relationship of PBF change in the treated lobe with treatment change of full width at half maximum (FWHM), cardiac output (CO), ventricular mass index (VMI), pulmonary transit time (PTT) and PBF change in the non-treated lobes. Paired Wilcoxon rank sum test and Spearman rho correlation were used.ResultsAfter BPA regional PBF increased in the treated lobe (p < 0.0001) as well as in non-treated lobes (p = 0.015). PBF treatment changes in the treated lobe were significantly larger compared with the non-treated lobes (p = 0.0049). Change in NT proBNP, MRI-derived mean pulmonary artery pressure (mPAP), PTT, FWHM, right ventricular (RV) ejection fraction, RV stroke volume, CO, VMI and PBF in the non-treated lobes correlated with PBF change in the treated lobe (p < 0.05). PBF changes in the treated lobe were independently predicted by PTT as well as PBF change in the non-treated lobes.ConclusionCardio-pulmonary MRI detects and quantifies treatment response after a single BPA treatment session.Key Points• Two months after BPA regional parenchymal pulmonary perfusion (PBF) increased in the total lung parenchyma (p = 0.005), the treated lobes (p < 0.0001) and non-treated lobes (p = 0.015).• The PBF treatment changes in the treated lobe were significantly larger than in the non-treated lobes (p = 0.0049).• Change in NT proBNP, MRI-derived mean pulmonary artery pressure, pulmonary transit time, full width at half maximum, right ventricular (RV) ejection fraction, RV stroke volume, cardiac output, ventricular mass index and PBF in the non-treated lobes correlated with PBF change in the treated lobe (p < 0.05).

Lobe-wise assessment of lung volume and density distribution in lung transplant patients and value for early detection of bronchiolitis obliterans syndrome

PURPOSE To evaluate quantitative computed tomography (CT) measurements of the lung parenchyma in lung transplant (LTx) patients for early detection of the bronchiolitis obliterans syndrome (BOS). MATERIALS AND METHODS 359 CT scans of 122 lung transplant patients were evaluated. Measurements of lung volume and density were performed for the whole lung and separately for each lobe. For longitudinal analysis the difference between the baseline at 6 months after LTx and follow-up examinations was calculated. Patients with and without BOS (matched 1:2) were compared at two different time points, the last examination before the BOS onset and the first examination within one year after BOS onset. RESULTS 30 patients developed BOS during the follow-up period. Longitudinal changes in the lung volume and lung density measured on CT differed significantly between those patients with and without early BOS, in particular the difference of the inspiratory and expiratory lung volume (p < 0.001), the ratio of the expiratory and inspiratory lung volume (p < 0.001-p = 0.001) and MLD (p < 0.001-p = 0.001), the volume on expiration (p < 0.001-p = 0.007), the MLD on expiration (p < 0.001-p = 0.007), and the percentiles on expiration (p < 0.001-p = 0.002) with an increase of lung volume and a decrease of lung density. Changes were pronounced in the lower lobes. Before BOS onset, patients with and without future development of BOS showed no significant differences. CONCLUSION Longitudinal changes of lung volume and lung density measured on CT start markedly at BOS onset with increased lung volume and decreased lung density indicating increased inflation levels. Even though this method may help to diagnose BOS at onset it is not useful as a predictor for BOS before disease onset.