Pulmonary blood volume measured by cardiovascular magnetic resonance: influence of pulmonary transit time methods and left atrial volume

Abstract

Background Increased pulmonary blood volume (PBV) is a measure of congestion and is associated with an increased risk of cardiovascular events. PBV can be quantified using cardiovascular magnetic resonance (CMR) imaging as the product of cardiac output and pulmonary transit time (PTT), the latter measured from the contrast time-intensity curves in the right and left side of the heart from first-pass perfusion (FPP). Several methods of estimating PTT exist, including pulmonary transit beats (PTB), peak-to-peak, and center of gravity (CoG). The aim of this study was to determine the accuracy and precision for these methods of quantifying the PBV, taking the left atrium volume (LAV) into consideration. Methods Fifty-eight participants (64 ± 11 years, 24 women) underwent 1.5 T CMR. PTT was quantified from (1) a basal left ventricular short-axis image (FPP), and (2) the reference method with a separate contrast administration using an image intersecting the pulmonary artery (PA) and the LA (CoG(PA-LA)). Results Compared to the reference, PBV for (a) PTB(FPP) was 14 ± 17% larger, (b) peak-peak(FPP) was 17 ± 16% larger, and (c) CoG(FPP) was 18 ± 10% larger. Subtraction of the LAV (available for n = 50) decreased overall differences to − 1 ± 19%, 2 ± 18%, and 3 ± 12% for PTB(FPP), peak-peak(FPP), and CoG(FPP), respectively. Lowest interobserver variability was seen for CoG(FPP) (− 2 ± 7%). Conclusions CoG(PA-LA) and FPP methods measured the same PBV only when adjusting for the LAV, since FPP inherently quantifies a volume consisting of PBV + LAV. CoG(FPP) had the best precision and lowest interobserver variability among the FPP methods of measuring PBV. Graphical abstract

Prognostic value of pulmonary transit time by cardiac magnetic resonance imaging in ST-elevation myocardial infarction

“…Although patients with MACE exhibited slightly larger PBVI in our cohort, differences did not reach statistical significance and PBVI was not an independent predictor of MACE. We evaluated left atrial volume in a subgroup of 135 patients with 7 MACE in the subgroup, to adjust for left atrial size variation, as the left atrium contributes to the total PBVI with our method of PTT measurement [ 25 ]. Even after correction for left atrial volumes in the subgroup, PBVI did not significantly predict MACE; however, the number of events in subgroup analysis might be too little to draw conclusions.…”

Stress and Rest Pulmonary Transit Times Assessed by Cardiovascular Magnetic Resonance

“…While the CMR-derived pulmonary circulation parameters do not assess cardiac pathology, recent studies [14][15][16][17]22,23,28 demonstrate their potential as supplementary tools for stratifying patients…”

“…While the CMR-derived pulmonary circulation parameters do not assess cardiac pathology, recent studies 14–17,22,23,28 demonstrate their potential as supplementary tools for stratifying patients with known cardiovascular diseases and highlight their potential as additional testing methods. The possibility of assessing pulmonary circulation parameters from first-pass perfusion images also offers an interesting perspective, especially for centers with moderate to high levels of adenosine stress perfusion tests.…”

“… 17 When a missed triggering occurs during the acquisition, it may result in an underestimated PTB, and in this case, the center of gravity method has proved more robust. 26 , 28 A comprehensive comparison of the precision and accuracy of the peak-to-peak and center-of-gravity methods has been published elsewhere. 28 The peak-to-peak approach works well when the signal or contrast intensity curves have well-defined peaks; however, two peaks might have similar intensity, making it sometimes challenging to define precisely the maximum.…”

“… 26 , 28 A comprehensive comparison of the precision and accuracy of the peak-to-peak and center-of-gravity methods has been published elsewhere. 28 The peak-to-peak approach works well when the signal or contrast intensity curves have well-defined peaks; however, two peaks might have similar intensity, making it sometimes challenging to define precisely the maximum. Additionally, every trigger should be accounted for during the acquisition, which cannot be assured beforehand.…”