Assessment Of Pulmonary Flow Research Articles

Kiosk 3R-TB-06 - Assessment of Pulmonary Flow in Congenital Heart Disease-associated Pulmonary Arterial Hypertension: A Comparative Study Between 4D Flow CMR and Invasive Catheterization

Kiosk 3R-TB-06 - Assessment of Pulmonary Flow in Congenital Heart Disease-associated Pulmonary Arterial Hypertension: A Comparative Study Between 4D Flow CMR and Invasive Catheterization

Exercise cardiovascular magnetic resonance: feasibility and development of biventricular function and great vessel flow assessment, during continuous exercise accelerated by Compressed SENSE: preliminary results in healthy volunteers

PurposeExercise cardiovascular magnetic resonance (Ex-CMR) typically requires complex post-processing or transient exercise cessation, decreasing clinical utility. We aimed to demonstrate the feasibility of assessing biventricular volumes and great vessel flow during continuous in-scanner Ex-CMR, using vendor provided Compressed SENSE (C-SENSE) sequences and commercial analysis software (Cvi42).Methods12 healthy volunteers (8-male, age: 35 ± 9 years) underwent continuous supine cycle ergometer (Lode-BV) Ex-CMR (1.5T Philips, Ingenia). Free-breathing, respiratory navigated C-SENSE short-axis cines and aortic/pulmonary phase contrast magnetic resonance (PCMR) sequences were validated against clinical sequences at rest and used during low and moderate intensity Ex-CMR. Optimal PCMR C-SENSE acceleration, C-SENSE-3 (CS3) vs C-SENSE-6 (CS6), was further investigated by image quality scoring. Intra-and inter-operator reproducibility of biventricular and flow indices was performed.ResultsAll CS3 PCMR image quality scores were superior (p < 0.05) to CS6 sequences, except pulmonary PCMR at moderate exercise. Resting stroke volumes from clinical PCMR sequences correlated stronger with CS3 than CS6 sequences. Resting biventricular volumes from CS3 and clinical sequences correlated very strongly (r > 0.93). During Ex-CMR, biventricular end-diastolic volumes (EDV) remained unchanged, except right-ventricular EDV decreasing at moderate exercise. Biventricular ejection-fractions increased at each stage. Exercise biventricular cine and PCMR stroke volumes correlated very strongly (r ≥ 0.9), demonstrating internal validity. Intra-observer reproducibility was excellent, co-efficient of variance (COV) < 10%. Inter-observer reproducibility was excellent, except for resting right-ventricular, and exercise bi-ventricular end-systolic volumes which were good (COV 10–20%).ConclusionBiventricular function, aortic and pulmonary flow assessment during continuous Ex-CMR using CS3 sequences is feasible, reproducible and analysable using commercially available software.

Pulmonary flow assessment by phase-contrast MRI can predict short-term mortality of fibrosing interstitial lung diseases.

Phase-contrast magnetic resonance imaging (PC-MRI) can determine pulmonary hemodynamics non-invasively. Pulmonary hypertension causes changes in pulmonary hemodynamics and is a factor for acute exacerbation and death in interstitial lung diseases (ILD). To determine associations between pulmonary hemodynamics measured by PC-MRI and short-term mortality in patients with ILD. Pulmonary hemodynamics, measured by PC-MRI in 43 patients with ILD, were reviewed retrospectively. Evaluation parameters included heart rate, right cardiac output, average flow, average velocity, acceleration time, acceleration volume (AV), maximal change in flow rate during ejection (M), M/AV, maximum area, minimum area, and relative area change in the pulmonary artery (PA). All causes of death within one year from the day of the MRI examination were assessed by reviewing medical records. Associations between evaluation parameters and outcome were determined by univariate and multivariate Cox regression analysis. Six patients (13.9%) died by the one-year follow-up. Age (hazard ratio [HR] 1.116, 95% confidence interval [CI] 1.015-1.269), average flow (HR 0.932, 95% CI 0.870-0.984), average velocity (HR 0.778, 95% CI 0.573-0.976), right cardiac output (HR 0.870, 95% CI 0.758-0.967), AV (HR 0.840, 95% CI 0.669-0.985), M/AV (HR 1.008, 95% CI 1.001-1.014), and PA relative area change (HR 0.715, 95% CI 0.459-0.928) predicted death in univariate Cox analysis. Multivariate Cox analysis showed decreased right cardiac output (HR 0.547, 95% CI 0.160-0.912) and decreased PA relative area change (HR 0.538, 95% CI 0.177-0.922) were independently associated with death. Reduction in right cardiac output and decreased PA relative area change, detected by PC-MRI, were associated with increased mortality in ILD.

4D Flow versus Conventional 2D MRI for Measuring Pulmonary Flow after Tetralogy of Fallot Repair

After tetralogy of Fallot (TOF) repair, pulmonary regurgitation and right ventricular function must be monitored. Conventional (2D) cardiac magnetic resonance (CMR) is currently the clinical reference method for measuring pulmonary regurgitation. However, 4D CMR has been reported to provide a more comprehensive flow analysis than 2D CMR. We aimed to compare 4D CMR to 2D CMR for assessing pulmonary regurgitation and flow, as well as aortic flow, in children and adults after surgical repair of TOF. Retrospective analysis of patients with repaired TOF admitted for cardiac MRI with 4D flow acquisition from 2016 to 2018. Linear regression was used to assess correlations and Bland-Altman analyses were performed. The 60 included patients had a mean age of 18.2 ± 10.4 years (range, 2-54 years). Significant correlations between the two techniques were found for pulmonary regurgitant fraction (R 2 = 0.6642, P < 0.0001), net pulmonary flow (R 2 = 0.6782, P < 0.0001), forward pulmonary flow (R 2 = 0.6185, P < 0.0001), backward pulmonary flow (R 2 = 0.8192, P < 0.0001), and aortic valve flow (R 2 = 0.6494, P < 0.0001). The Bland-Altman analysis showed no significant bias, narrow limits of agreement, and few scattered points. The correlation between pulmonary and aortic flow was better with 4D CMR than with 2D CMR (R 2 = 0.8564, P < 0.0001 versus R 2 = 0.4393, P < 0,0001, respectively). Interobserver reliability was good. These results establish the feasibility and reliability of 4D CMR for assessing pulmonary flow in a large paediatric and adult population with repaired TOF. 4D CMR may be more reliable than 2D MRI for pulmonary flow assessment after TOF repair.

4D flow MRI versus conventional 2D for measuring pulmonary flow after Tetralogy of Fallot repair

BackgroundAfter tetralogy of Fallot (TOF) repair, pulmonary regurgitation and right ventricular function must be monitored. Conventional (2D) cardiac magnetic resonance (CMR) is currently the clinical reference method for measuring pulmonary regurgitation. However, 4DFlow CMR has been reported to provide a more comprehensive flow analysis than 2D CMR. We aimed to compare 4DFlow CMR to 2D CMR for assessing pulmonary regurgitation and flow, as well as aortic flow, in children and adults after surgical repair of TOF. MethodsRetrospective analysis of patients with repaired TOF admitted for cardiac MRI with 4DFlow acquisition from 2016 to 2018. Linear regression was used to assess correlations and Bland-Altman analyses were performed. ResultsThe 60 included patients had a mean age of 18.2 ± 10.4 years (range, 2–54 years).Significant correlations between the two techniques were found for pulmonary regurgitant fraction (R [2] = 0.6642, p < 0.0001), net pulmonary flow (R [2] = 0.6782, p < 0.0001), forward pulmonary flow (R [2] = 0.6185, p < 0.0001), backward pulmonary flow (R [2] = 0.8192, p < 0.0001), and aortic valve flow (R [2] = 0.6494, p < 0.0001). The Bland-Altman analysis showed no significant bias, narrow limits of agreement, and few scattered points. The correlation between pulmonary and aortic flow was better with 4DFlow CMR than with 2D CMR (R [2] = 0.8564, p < 0.0001 versus R [2] = 0.4393, p < 0,0001, respectively). Interobserver reliability was good. ConclusionThese results establish the feasibility and reliability of 4DFlow CMR for assessing pulmonary flow in a large paediatric and adult population with repaired TOF. 4DFlow CMR may be more reliable than 2D MRI for pulmonary flow assessment after TOF repair.

4D Flow versus Conventional 2D MRI for Measuring Pulmonary Flow after Tetralogy of Fallot Repair

After tetralogy of Fallot (TOF) repair, pulmonary regurgitation and right ventricular function must be monitored. Conventional (2D) cardiac magnetic resonance (CMR) is currently the clinical reference method for measuring pulmonary regurgitation. However, 4D CMR has been reported to provide a more comprehensive flow analysis than 2D CMR. We aimed to compare 4D CMR to 2D CMR for assessing pulmonary regurgitation and flow, as well as aortic flow, in children and adults after surgical repair of TOF. Retrospective analysis of patients with repaired TOF admitted for cardiac MRI with 4D flow acquisition from 2016 to 2018. Linear regression was used to assess correlations and Bland-Altman analyses were performed. The 60 included patients had a mean age of 18.2 ± 10.4 years (range, 2–54 years). Significant correlations between the two techniques were found for pulmonary regurgitant fraction (R 2 = 0.6642, P < 0.0001), net pulmonary flow (R 2 = 0.6782, P < 0.0001), forward pulmonary flow (R 2 = 0.6185, P < 0.0001), backward pulmonary flow (R 2 = 0.8192, P < 0.0001), and aortic valve flow (R 2 = 0.6494, P < 0.0001). The Bland-Altman analysis showed no significant bias, narrow limits of agreement, and few scattered points. The correlation between pulmonary and aortic flow was better with 4D CMR than with 2D CMR (R 2 = 0.8564, P < 0.0001 versus R 2 = 0.4393, P < 0,0001, respectively). Interobserver reliability was good. These results establish the feasibility and reliability of 4D CMR for assessing pulmonary flow in a large paediatric and adult population with repaired TOF. 4D CMR may be more reliable than 2D MRI for pulmonary flow assessment after TOF repair.

Reproducibility of pulmonary blood flow measurements by phase-contrast MRI using different 1.5 T MR scanners at two institutions.

BackgroundMagnetic resonance imaging (MRI) can be beneficial for diagnosis of disease by offering quantitative information. However, reproducibility can be a major problem when there is a numerical threshold in multi-institution, multi-vendor situations.PurposeTo measure pulmonary blood flow with phase-contrast (PC) imaging using two different MR scanners (1.5 T) at different institutions in the same participants and to examine the reproducibility of the measurements.Material and MethodsParticipants were 10 healthy volunteers (5 men; age range, 27–36 years). The measurements included the mean and maximal blood velocities, the mean blood flow volume, and the acceleration time and volume (AT and AV), derived from the time-flow curve of the PC-MRI. Simultaneously obtained maximal, minimal, and mean areas from regions of interest set in the pulmonary artery were also calculated. In order to calculate the reproducibility of the quantitative variables, intra-class correlation coefficients (ICCs) were employed. When an adequate ICC was obtained, Bland–Altman analysis was conducted to identify any systematic bias.ResultsThe ICCs were almost perfect for the mean blood flow volume and the AV (r = 0.82 and 0.80), and were substantial in the mean and maximal areas, and the AT (r = 0.63, 0.74, and 0.64, respectively). However, there was a fixed bias in the area measurement between the two scanners. Also, the AV had a proportional bias.ConclusionOur results reveal that various indices derived from PC-MRI on different MR scanners are promising as common indices for pulmonary flow assessment. Research and clinical use of PC-MRI for the pulmonary artery is expected to extend to multi-institution situations.

NT-proBNP as Marker of Ventricular Dilatation and Pulmonary Regurgitation After Surgical Correction of Tetralogy of Fallot: A MRI Validation Study.

The goal of this study is to evaluate whether NT-proBNP plasma levels may help as a screening biomarker for monitoring right ventricular dilatation, pulmonary regurgitation and the onset of heart failure in patients with repaired Tetralogy of Fallot. Our single-centre observational prospective study involved 43 patients (15.1years, SD=8) with corrected Tetralogy of Fallot. Data collection included: clinical parameters (electrocardiogram, chest X-ray, NYHA scale, time since last surgery), biochemistry (NT-proBNP levels) and MRI values (ventricular volumetry, pulmonary flow assessment). Mean time since last surgery was 13.5years (SD=7.8). There was a statistically significant correlation between the NT-proBNP levels (187.4pg/ml, SD=154.9) and right ventricular dilatation for both the right ventricular end-diastolic volume (124.9ml/m2, SD=31.2) (Pearson=0.19, p<0.01) and end-systolic volume (56.1ml/m2, SD=18.8) (Pearson=0.21, p<0.01) and also with the pulmonary regurgitation fraction (36.5%, SD=16, Pearson=0.12, p<0.01). No significant correlation was found between NT-proBNP and right ventricular ejection fraction (54.6%, SD=10.6, Pearson=-0.07), left ventricular ejection fraction (59.9%, SD=7.1, Pearson=-0.18) or any clinical parameters. The receiver operating curve analysis evidenced that a NT-proBNP cut-off value above 133.2pg/ml predicted the presence of dilated right ventricular end-diastolic and end-systolic volumes over centile 95 (sensitivity 82 and 83% and specificity 93 and 79%, respectively). In conclusion, in patients with surgically corrected Tetralogy of Fallot, NT-proBNP levels correlate with right ventricular dilatation and the degree of pulmonary regurgitation. Ambulatory determination of NT-proBNP might be an easy, readily available and cost-effective alternative for MRI follow-up evaluation of these patients.

Assessment of Pulmonary Flow Using Impedance Pneumography

There is a lack of noninvasive pulmonary function measurement techniques suitable for continuous long-term measurement of tidal breathing in mobile subjects, although tidal breathing analysis has been shown to contain information that relates to the level airway obstruction. This paper is the first to assess the suitability of impedance pneumography (IP) for measurement of continuous pulmonary flow and volume signals instead of only the respiration rate (RR) or tidal volume ( V(T)). We measured pneumotachograph (PNT) and IP signals simultaneously from 20 healthy male subjects in erect, dorsal supine, and lateral supine positions while voluntarily varying V(T). IP was measured using five different impedance lead configurations with electrodes integrated into a textile chest belt. The IP signals were compared with PNT signals to assess agreement of IP with a more well-established measurement method. The pulmonary flow signal waveform agreement was assessed with standard error of measurement (SEM) between the time-differentiated IP signal and the PNT signal as rho = 1-SEM. Additionally, we assessed the agreement of IP and PNT in V(T) estimation and the magnitude of the cardiogenic oscillation present in the impedance signal. The agreement in the pulmonary flow signal waveform shapes was found excellent at all tidal volumes and postures (mean rho > 0.90). The agreement between the PNT-derived and the IP-derived V(T) estimates was very high when IP values were calibrated per subject and posture (mean difference < 3%). The main source of error in visual inspection of the IP signal was the cardiogenic distortion. From the five novel electrode configurations tested, the lateral ones were found clearly better than the anteroposterior ones. IP potentially enables the development of a noninvasive ambulatory measurement device for long-term studies of certain tidal breathing parameters in mobile subjects.

Utility of phase contrast MR imaging for assessment of pulmonary flow and pressure estimation in patients with pulmonary hypertension: Comparison with right heart catheterization and echocardiography

To compare the utility of phase contrast MR imaging (PC-MRI) for assessment of pulmonary flow and pressure estimation with that of right heart catheterization and echocardiography (cardiac US) in patients with pulmonary arterial hypertension (PAH). Twenty consecutive patients with suspected PAH underwent PC-MRI, cardiac US, and right heart catheterization. In each patient, PC-MRI was acquired by cine 2D-PC method on a 1.5 Tesla scanner, and stroke volume (SV) and pulmonary arterial systolic pressure (PASP) were assessed by using the modified Bernoulli's equation. To evaluate the agreements of SV and PASP among the three methods, correlations and limits of agreement among the three methods were statistically assessed by using the Bland-Altman's analyses. The correlations and limits of agreement for SV and PASP between PC-MRI and catheterization (r = 0.96, r(2) = 0.94, 1.1 +/- 6.9 mL and r = 0.94, r(2) = 0.88, -3.2 +/- 14.5 mmHg, respectively) were better than between cardiac US and catheterization (r = 0.01, r(2) < 0.01, 8.9 +/- 42.1 mL and r = 0.86, r(2) = 0.72, -5.9 +/- 27.7 mmHg, respectively). PC-MRI is more compatible with right heart catheterization than cardiac US in pulmonary flow and pressure estimation.

Pediatric cardiac imaging: the beat goes on!

The publication of the paper “The accuracy of chest radiographs in the detection of congenital heart disease and in the diagnosis of specific congenital cardiac lesions” [1] provides an opportunity for me to reflect on my career as a pediatric cardiac imager, on past teaching strategies in cardiac imaging, and to comment on the current and future opportunities. I welcome this re-evaluation of cardiac imaging, and the new horizons. Nearly 40 years ago, prior to echocardiography, the gold standard for recognizing children with congenital heart disease consisted of findings on physical examination and a chest radiograph. Traditionally, the radiologist tried to decide based on the chest radiograph whether the infant or child had congenital or acquired heart disease and to suggest a differential diagnosis. Each new generation of residents would learn the list of congenital heart lesions associated with increased, decreased and normal flow, and after asking whether the patient was cyanotic or acyanotic, they would proceed with a list of lesions associated with the flow pattern. Despite the advancement of non-invasive modalities such as echocardiography, CT, and MRI, the approach to teaching and educational programs was based on the assessment of pulmonary flow. Retrospectively, this may have been a flawed approach to cardiac imaging and has resulted in many radiologists not understanding basic physiology and anatomy of the heart.

Radioisotope scanning of the lung in cyanotic congenital heart disease

Lung scanning was found to be a safe and useful method of studying pulmonary blood flow in cyanotic patients, and good correlation was obtained with angiocardiographic findings. At present, in addition to its proved value in thromboembolic pulmonary disease, radioisotope scanning of the lung appears indicated for the following groups of cyanotic patients: (1) In those suspected of major regional differences of pulmonary flow due to absence or hypoplasia of one pulmonary artery or its major branch, or to peripheral pulmonary arterial stenosis. (2) In those with severe chest deformity due to scoliosis or other skeletal anomalies in whom simple radiologic assessment of pulmonary flow is difficult or impossible. (3) In patients after operation to assess the patency of venous shunts, and in a few instances, to document the continuing patency of arterial shunts. Future quantitative studies comparing cyanotic patients with pulmonary hypertension and those with pulmonary stenosis are indicated. Further improvements in methods of quantitation and timing may make the technic useful in documenting bronchial flow and in assessing the velocity of pulmonary blood flow in selected cyanotic patients.