Effects of respiratory cycle and body position on quantitative pulmonary perfusion by MRI

Cao, Jie J; Wang, Yi; Schapiro, William; McLaughlin, Jeannette; Cheng, Joshua; Passick, Michael; Ngai, Nora; Marcus, Philip; Reichek, Nathaniel

doi:10.1002/jmri.22527

Cited by 19 publications

(19 citation statements)

References 19 publications

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“…However, visual assessment of iodine distribution maps is reader-dependent and more time-consuming. It is known from MR lung perfusion studies that pulmonary blood flow is doubled in expiration compared to inspiration [25]. This is largely because the ratio of air to tissue per volume is decreased, thus increasing perfusion per volume [26].…”

mentioning

confidence: 99%

Automated Quantification of Pulmonary Perfused Blood Volume by Dual-Energy CTPA in Chronic Thromboembolic Pulmonary Hypertension

Meinel¹,

Graef²,

Thierfelder³

et al. 2013

Fortschr Röntgenstr

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Zusammenfassung !Zielsetzung: Ziel der Studie war es zu untersuchen, ob die automatisierte Quantifizierung des perfundierten Lungenblutvolumens (PBV) in der dual-energy CT Pulmonalis-Angiografie (DE-CTPA) zur Beurteilung des Schweregrades einer chronisch-thromboembolischen pulmonalen Hypertonie (CTEPH) genutzt werden kann. Methoden: Die automatisierte Quantifizierung des PBV wurde bei 25 konsekutiven Patienten mit CTEPH durchgeführt, die mittels DE-CTPA untersucht wurden. Die PBV-Werte wurden mit Parametern aus Rechtsherzkatheteruntersuchung (pulmonalarterieller Druck, Herzindex und pulmonalem Gefäßwiderstand) sowie der 6-Minuten-Gehstrecke korreliert. Hierbei wurde der Korrelationskoeffizient nach Pearson verwendet und mittels multivariater linearer Regression für Alter und Geschlecht adjustiert. Ergebnisse: Die aus der DE-CTPA ermittelten PBVWerte korrelierten negativ mit dem systolischen (r = -0,64, p = 0,001) und mittleren (r = -0,57, p = 0,004) pumonalarteriellen Blutdruck. Es zeigte sich ein Trend zu einer negativen Korrelation zwischen PBV-Werten und dem pulmonalen Gefäßwiderstand (r = -0,20, p = 0,35). Zwischen PBV und Herzindex sowie 6-Minuten-Gehstrecke wurden keine signifikanten Korrelationen gefunden. Durch multivariate lineare Regression wurde bestätigt, dass diese Korrelationen von Alter und Geschlecht unabhänig waren. Schlussfolgerung: Die DE-CTPA kann bei Patienten mit CTEPH für eine automatisierte Quantifizierung des perfundierten Lungenblutvolumens genutzt werden. Deren Ergebnisse korrelieren invers mit systolischem und mittlerem pulmonalarteriellen Druck und können daher den Schweregrad der pulmonalen Hypertonie bei diesen Patienten abschätzen. Abstract !Objectives: The aim of the study was to determine whether automated quantification of pulmonary perfused blood volume (PBV) in dual-energy computed tomography pulmonary angiography (DE-CTPA) can be used to assess the severity of chronic thromboembolic pulmonary hypertension (CTEPH). Methods: Automated quantification of PBV was performed in 25 consecutive CTEPH patients undergoing DE-CTPA. PBV values were correlated with cardiac index and pulmonary vascular resistance quantified by right heart catheterization and walking distance in the 6-minute walk test using Pearson's correlation coefficient and multivariate linear regression analysis to control for age and gender. Results: DE-CTPA derived PBV values inversely correlated with systolic (r = -0.64, p = 0.001) and mean (r = -0.57, p = 0.004) pulmonary arterial pressure. There was a trend for PBV values to inversely correlate with pulmonary vascular resistance (r = -0.20, p = 0.35). No significant correlation was found between PBV values and cardiac index or 6-minute walking distance. These correlations were confirmed to be independent of age and gender on multivariate linear regression analysis. Conclusion: DE-CTPA can be used for an automated quantification of pulmonary PBV in chronic thromboembolic pulmonary hypertension. PBV values correlate inversely with systolic and mean pulmonary arteria...

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mentioning

confidence: 99%

Automated Quantification of Pulmonary Perfused Blood Volume by Dual-Energy CTPA in Chronic Thromboembolic Pulmonary Hypertension

Meinel¹,

Graef²,

Thierfelder³

et al. 2013

Fortschr Röntgenstr

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“…In healthy human lungs, perfusion is affected by body position and the respiratory cycle. 12,13 Furthermore, lung perfusion follows a linear gravitational gradient such that perfusion is highest in the posterior lung and lowest in the anterior lung in the supine position. 12 It is not clear how the gravitational perfusion gradient responds to increased left ventricular (LV) filling pressure and resultant increases in pulmonary arterial pressure.…”

Section: Editorial See P 689 Clinical Perspective On P 699mentioning

confidence: 99%

“…Parallel imaging was applied with an acceleration factor of 2. Although low-dose gadopentetate dimeglumine (0.01 mmol/ kg) was adequate for perfusion quantification, 12 higher dose (0.025 mmol/kg) was required to generate perfusion parameter maps that were acquired using the same settings used for the low-dose imaging series after at least a 15-minute washout period. A lung perfusion parameter map (Siemens Medical Solution) was used to visualize the relative perfusion distribution (Figures 1 and 2).…”

Section: Image Acquisitionmentioning

confidence: 99%

“…The mean signal intensities in the main PA and the lung parenchyma were transferred to a custom model-independent deconvolution program in Matlab (MathWorks Inc, Natick, MA) to assess absolute pulmonary perfusion. 12 Global lung perfusion was taken as the average of the left and right lung perfusion in anterior, mid, and posterior lung fields.…”

Section: Image Analysismentioning

confidence: 99%

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Effects of Hemodynamics on Global and Regional Lung Perfusion

Cao

Wang

McLaughlin

et al. 2012

Circ: Cardiovascular Imaging

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Background-Cardiac hemodynamics affect pulmonary vascular pressure and flow, but little is known of the effects of hemodynamics on lung perfusion at the tissue level. We sought to investigate the relationship between hemodynamic abnormalities in patients with left heart failure and global and regional lung perfusion using lung perfusion quantification by magnetic resonance imaging. Methods and Results-Lung perfusion was quantified in 10 normal subjects and 28 patients undergoing clinically indicated left and right heart catheterization and same day research cardiac magnetic resonance imaging. A total of 228 lung slices were evaluated. Global lung perfusion, determined as the average of 6 coronal lung slices through the anterior, mid, and posterior left and right lungs, was significantly lower in patients with reduced cardiac index (<2.5 L/min per m 2 ): 94±30 mL/100 mL per minute versus 132±40 mL/100 mL per minute in those with preserved cardiac index (≥2.5 L/min per m 2 ; P=0.003). The gravitational anterior to posterior perfusion gradient was inversely associated with left ventricular enddiastolic pressure (r=−0.728; P<0.001), resulting in a blunted perfusion gradient in patients with elevated left ventricular end-diastolic pressure, a finding largely attributed to the perfusion reduction in posterior lung regions. In a multivariate regression analysis adjusting for all hemodynamic variables, altered lung perfusion gradient was most closely associated with increased mean pulmonary arterial pressure (P=0.016). Conclusions-Increased left ventricular filling pressure and the resultant increase in pulmonary arterial pressure are associated with disruption of the normal gravitational lung perfusion gradient. Our findings underscore the complexity of heart-lung interaction in determining pulmonary hemodynamics in left heart failure.

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“…Although better spatial resolution would help assess inhomogeneity of lung perfusion at the segmental level, the current technique has produced comparable results to 3D acquisition and provides adequate resolution to assess perfusion at the lobar level. 9,11 The faster imaging time and lower gadolinium requirement are especially important if sick patients are to be studied.…”

Section: Article See P 693mentioning

confidence: 99%

Heart Failure

Little

Vasu

2012

Circ: Cardiovascular Imaging

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Dyspnea is the major symptom experienced by patients with heart failure (HF) and points to the important role of the lungs in this syndrome. Article see p 693Normal left ventricular diastolic function keeps the left atrial and pulmonary venous pressures low (<12 mm Hg), both at rest and during submaximal exercise.1 With this normal low pulmonary venous pressure, only a small amount of fluid and protein are filtered through gaps in the pulmonary capillary endothelial cells and into the alveolar interstitial space because the hydrostatic pressure is mostly offset by the protein osmotic pressure.2 Thus, normally the small amount of fluid and protein entering the interstitial space is cleared by lymphatic drainage into the venous circulation.An elevation of left ventricular diastolic and pulmonary venous pressures is a characteristic of HF, regardless of the ejection fraction.3 Mild elevations of pulmonary venous pressure (18-25 mm Hg) increase the flow into the interstitial space.2 When this flow exceeds the clearance ability of the lymphatics, edema accumulates in the lung interstitial space. This can be seen on a chest x-ray as Kerley B lines. The accumulation of interstitial fluid enhances the stiffness of the lungs, leading to an increase in work required to breathe, and produces the perception of dyspnea. With higher pulmonary venous pressures (>25 mm Hg), the accumulating fluid enters the alveolar space, producing pulmonary edema. This interferes with gas exchange and results in intrapulmonary shunting, leading to hypoxia. In this way, acute pulmonary edema can produce life-threatening respiratory failure.Chronic elevation of pulmonary venous pressures, as occurs in mitral stenosis, stimulates fibrosis, which decreases fluid transudation. This impairs pulmonary function, but makes it possible for some patients to chronically tolerate high pulmonary venous pressures without developing overt pulmonary edema. 4 The elevated pulmonary venous pressure in HF also increases the pressure in the pulmonary arteries, both due to the passive effects of increased downstream pressure and due to pulmonary vasoconstriction. 5,6 In addition, the elevated pulmonary venous pressure contributes to the pulsatile load, raising systolic pulmonary artery pressure. 7 The resulting pulmonary hypertension increases the load on the right ventricle, contributes to exercise intolerance, and indicates a poor prognosis.The study by Cao et al 8 in this issue of Circulation: Cardiovascular Imaging used an innovative magnetic resonance technique to provide detailed information on the important interaction of the heart and lungs in HF. Using gadolinium first-pass perfusion imaging, the time variations in signal intensity were converted to a contrast concentration time curve. With the assumption that pulmonary perfusion is a linear system, indicator dilution theory was used to assess the pulmonary blood flow by assessing the maximum signal intensity and the time course of the signal change. The rate of blood flow (perfusion) into small regions o...

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Effects of respiratory cycle and body position on quantitative pulmonary perfusion by MRI

Abstract: Lung perfusion imaging using a 2D saturation recovery SSFP perfusion MRI coupled with a model-independent deconvolution algorithm demonstrated physiologically consistent dynamic heterogeneity of lung perfusion distribution.

Cited by 19 publications

References 19 publications

Automated Quantification of Pulmonary Perfused Blood Volume by Dual-Energy CTPA in Chronic Thromboembolic Pulmonary Hypertension

Automated Quantification of Pulmonary Perfused Blood Volume by Dual-Energy CTPA in Chronic Thromboembolic Pulmonary Hypertension

Effects of Hemodynamics on Global and Regional Lung Perfusion

Heart Failure

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