Pulmonary Transit Time Derived from First-Pass Perfusion Cardiac MR Imaging: A Potential New Marker for Cardiac Involvement and Prognosis in Light-Chain Amyloidosis

BACKGROUND

First-pass perfusion cardiac MR imaging could reflect pulmonary hemodynamics. However, the clinical value of pulmonary transit time (PTT) derived from first-pass perfusion MRI in light-chain (AL) amyloidosis requires further evaluation.

PURPOSE

To assess the clinical and prognostic value of PTT in patients with AL amyloidosis.

STUDY TYPE

Prospective observational study.

POPULATION

226 biopsy-proven systemic AL amyloidosis patients (age 58.62 ± 10.10 years, 135 males) and 43 healthy controls (age 42 ± 16.2 years, 20 males).

FIELD STRENGTH/SEQUENCE

SSFP cine and phase sensitive inversion recovery late gadolinium enhancement (LGE) sequences, and multislice first-pass myocardial perfusion imaging with a saturation recovery turbo fast low-angle shot (SR-TurboFLASH) pulse sequence at 3.0T.

ASSESSMENT

PTT was measured as the time interval between the peaks of right and left ventricular cavity arterial input function curves on first-pass perfusion MR images.

STATISTICAL TESTS

Independent-sample t test, Mann-Whitney U test, Chi-square test, Fisher's exact test, analysis of variance, or Kruskal-Wallis test, as appropriate; univariable and multivariable Cox proportional hazards models and Kaplan-Meier curves, area under receiver operating characteristic curve were used to determine statistical significance.

RESULTS

PTT could differentiate AL amyloidosis patients with (N = 188) and without (N = 38) cardiac involvement (area under the curve [AUC] = 0.839). During a median follow-up of 35 months, 160 patients (70.8%) demonstrated all-cause mortality. After adjustments for clinical (Hazard ratio [HR] 1.061, confidence interval [CI]: 1.021-1.102), biochemical (HR 1.055, CI: 1.014-1.097), cardiac MRI-derived (HR 1.077, CI: 1.034-1.123), and therapeutic (HR 1.063, CI: 1.024-1.103) factors, PTT predicted mortality independently in patients with AL amyloidosis. Finally, PTT could identify worse outcomes in patients demonstrating New York Heart Association class III, Mayo 2004 stage III, and transmural LGE pattern.

DATA CONCLUSION

PTT may serve as a new imaging predictor of cardiac involvement and prognosis in AL amyloidosis.

LEVEL OF EVIDENCE

2 TECHNICAL EFFICACY: Stage 2.

Quantitative analysis of abdominal aortic blood flow by 99mTc-DTPA renal scintigraphy in patients with heart failure

OBJECTIVE

This study aimed to explore the characteristics of abdominal aortic blood flow in patients with heart failure (HF) using 99mTc-diethylenetriaminepentaacetic acid (DTPA) renal scintigraphy. We investigated the ability of renal scintigraphy to measure the cardiopulmonary transit time and assessed whether the time-to-peak of the abdominal aorta (TTPa) can distinguish between individuals with and without HF.

METHODS

We conducted a retrospective study that included 304 and 37 patients with and without HF (controls), respectively. All participants underwent 99mTc-DTPA renal scintigraphy. The time to peak from the abdominal aorta's first-pass time-activity curve was noted and compared between the groups. The diagnostic significance of TTPa for HF was ascertained through receiver operating characteristic (ROC) analysis and logistic regression. Factors influencing the TTPa were assessed using ordered logistic regression.

RESULTS

The HF group displayed a significantly prolonged TTPa than controls (18.5 [14, 27] s vs. 11 [11, 13] s). Among the HF categories, HF with reduced ejection fraction (HFrEF) exhibited the longest TTPa compared with HF with mildly reduced (HFmrEF) and preserved EF (HFpEF) (25 [17, 36.5] s vs. 17 [15, 23] s vs. 15 [11, 17] s) (P < 0.001). The ROC analysis had an area under the curve of 0.831, which underscored TTPa's independent diagnostic relevance for HF. The diagnostic precision was enhanced as left ventricular ejection fraction (LVEF) declined and HF worsened. Independent factors for TTPa included the left atrium diameter, LVEF, right atrium diameter, velocity of tricuspid regurgitation, and moderate to severe aortic regurgitation.

CONCLUSIONS

Based on 99mTc-DTPA renal scintigraphy, TTPa may be used as a straightforward and non-invasive tool that can effectively distinguish patients with and without HF.

Pulmonary Transit Time Assessment by CEUS in Healthy Rabbits: Feasibility, and the Effects of UCAs Dilution Concentration

To evaluate the inter-observer variability and the intra-observer repeatability of pulmonary transit time (PTT) measurement using contrast-enhanced ultrasound (CEUS) in healthy rabbits, and assess the effects of dilution concentration of ultrasound contrast agents (UCAs) on PTT. Thirteen healthy rabbits were selected, and five concentrations UCAs of 1:200, 1:100, 1:50, 1:10, and 1:1 were injected into the right ear vein. Five digital loops were obtained from the apical 4-chamber view. Four sonographers obtained PTT by plotting the TIC of right atrium (RA) and left atrium (LA) at two time points (T1 and T2). The frame counts of the first appearance of UCAs in RA and LA had excellent inter-observer agreement, with intra-class correlations (ICC) of 0.996, 0.988, respectively. The agreement of PTT among four observers was all good at five different concentrations, with an ICC of 0.758-0.873. The reproducibility of PTT obtained by four observers at T1 and T2 was performed well, with ICC of 0.888-0.961. The median inter-observer variability across 13 rabbits was 6.5% and the median variability within 14 days for 4 observers was 1.9%, 1.7%, 2.2%, 1.9%, respectively; The PTT of 13 healthy rabbits is 1.01 ± 0.18 second. The difference of PTT between five concentrations is statistically significant. The PTT obtained by a concentration of 1:200 and 1:100 were higher than that of 1:1, while there were no significantly differences in PTT of a concentration of 1:1, 1:10, and 1:50. PTT measured by CEUS in rabbits is feasible, with excellent inter-observer and intra-observer reliability and reproducibility, and dilution concentration of UCAs influences PTT results.

Association of pulmonary transit time by cardiac magnetic resonance with heart failure hospitalization in a large prospective cohort with diverse cardiac conditions

BACKGROUND

Longer pulmonary transit time (PTT) is closely associated with hemodynamic abnormalities. However, the implications on heart failure (HF) risk have not been investigated broadly in patients with diverse cardiac conditions. In this study we examined the long-term risk of HF hospitalization associated with longer PTT in a large prospective cohort with a broad spectrum of cardiac conditions.

METHODS

All subjects were prospectively recruited to undergo cardiac magnetic resonance (CMR). The dynamic images of first-pass perfusion were acquired to assess peak-to-peak pulmonary transit time (PTT) which was subsequently normalized to RR interval duration. The risk of HF was examined using Cox proportional hazards models adjusted for baseline confounding risk factors.

RESULTS

Among 506 consecutively consented patients undergoing clinical cardiac MR with diverse cardiac conditions, the mean age was 63 ± 14 years and 373 (73%) were male. After a mean follow up duration of 4.5 ± 3.0 years, 70 (14%) patients developed hospitalized HF and of these 6 died. A normalized PTT ≥ 8.2 was associated with a significantly increased adjusted HF hazard ratio of 3.69 (95% CI 2.02, 6.73). The HF hazard ratio was 1.26 (95% CI 1.18, 1.33) for each 1 unit increase in PTT which was higher among those preserved (1.70, 95% CI 1.20, 2.41) compared to those with reduced left ventricular ejection fraction (< 50%) (1.18, 95% CI 1.09, 1.27). PTT remained a significant risk factor of hospitalized HF after additional adjustment for N-terminal pro-hormone brain natriuretic peptide (NT-proBNP) or left ventricular global longitudinal strain with additionally demonstrated incremental model improvement through likelihood ratio testing.

CONCLUSIONS

Our findings support the role of PTT in assessing HF risk among patients with broad spectrum of cardiac conditions with reduced as well as preserved ejection fraction. Longer PTT duration is an incremental risk factor for HF when baseline global longitudinal strain and NT-proBNP are taken into consideration.

Pulmonary transit time has close relation with pulmonary pulse wave transit time in normal subjects

BACKGROUND

Pulmonary transit time (PTT) and pulmonary pulse wave transit time (pPTT) are useful parameters for the evaluation of cardiopulmonary circulation and vascular alterations, but their relationship remains unknown. The aim of this study was to investigate the correlation between PTT and pPTT.

METHODS

A total of 60 healthy volunteers were involved in this study. They were divided into two groups (30 participants per group): <50 years and >50 years. They all underwent Doppler echocardiography of pulmonary vein flow and contrast echocardiography with the measurement of pPTT and PTT, respectively. The correlation between PTT and pPTT was deduced.

RESULTS

Compared with Group of <50 years, there was a significant increment in left atrial volume index, left atrial pressure and pulmonary artery stiffness but a significant reduction in acceleration times of pulmonary artery flow in Group of >50 years (p < 0.05). Group >50 years had longer PTT and but reduced normalized PTT by R-R interval (NPTT), reduced normalized pPTT by R-R interval (NpPTT) than Group <50 years (p < 0.05), while there was no significant difference in pPTT between the two groups (p > 0.05). PTT and NPTT were all negatively correlated with pPTT and NpPTT. The statistically significant strongest correlation was observed between PTT and NpPTT (r = -0.886, p < 0.0001). The regression equation for them was y = 7.4396-13.095x (R²  = 0.785; p < 0.001), where x and y represent NpPTT and PTT, respectively.

CONCLUSION

PTT had close relation with pPTT in normal subjects. From the regression equation for them, we can get the value of PTT simply and easily by non-invasively measured pPTT.

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

OBJECTIVES

To investigate the prognostic value of pulmonary transit time (pTT) determined by cardiac magnetic resonance (CMR) after acute ST-segment-elevation myocardial infarction (STEMI).

METHODS

Comprehensive CMR examinations were performed in 207 patients 3 days and 4 months after reperfused STEMI. Functional parameters and infarct characteristics were assessed. PTT was defined as the interval between peaks of gadolinium contrast time-intensity curves in the right and left ventricles in first-pass perfusion imaging. Cox regression models were calculated to assess the association between pTT and the occurrence of major adverse cardiac events (MACE), defined as a composite of death, re-infarction, and congestive heart failure.

RESULTS

PTT was 8.6 s at baseline and 7.8 s at the 4-month CMR. In Cox regression, baseline pTT (hazard ratio [HR]: 1.58; 95% CI: 1.12 to 2.22; p = 0.009) remained significantly associated with MACE occurrence after adjustment for left ventricular ejection fraction (LVEF) and cardiac index. The association of pTT and MACE remained significant also after adjusting for infarct size and microvascular obstruction size. In Kaplan-Meier analysis, pTT ≥ 9.6 s was associated with MACE (p < 0.001). Addition of pTT to LVEF resulted in a categorical net reclassification improvement of 0.73 (95% CI: 0.27 to 1.20; p = 0.002) and integrated discrimination improvement of 0.07 (95% CI: 0.02 to 0.13; p = 0.007).

CONCLUSIONS

After reperfused STEMI, CMR-derived pTT was associated with hard clinical events with prognostic information independent of and incremental to infarct size and LV systolic function.

KEY POINTS

• Pulmonary transit time is the duration it takes the heart to pump blood from the right chambers across lung vessels to the left chambers. • This prospective single-centre study showed inferior outcome in patients with prolonged pulmonary transit time after myocardial infarction. • Pulmonary transit time assessed by magnetic resonance imaging added incremental information to established prognostic markers.

Corrected MRI Pulmonary Transit Time for Identification of Combined Precapillary and Postcapillary Pulmonary Hypertension in Patients With Left Heart Disease

BACKGROUND

The identification of combined precapillary and postcapillary pulmonary hypertension (CpcPH) in patients with pulmonary hypertension (PH) due to left heart disease (LHD) can influence therapy and outcome and is currently based on invasively determined hemodynamic parameters.

PURPOSE

To investigate the diagnostic value of MRI-derived corrected pulmonary transit time (PTTc) in PH-LHD sub-grouped according to hemodynamic phenotypes.

STUDY TYPE

Prospective observational study.

POPULATION

A total of 60 patients with PH-LHD (18 with isolated postcapillary PH [IpcPH] and 42 with CpcPH), and 33 healthy subjects.

FIELD STRENGTH/SEQUENCE

A 3.0 T/balanced steady-state free precession cine and gradient echo-train echo planar pulse first-pass perfusion.

ASSESSMENT

In patients, right heart catheterization (RHC) and MRI were performed within 30 days. Pulmonary vascular resistance (PVR) was used as the diagnostic "reference standard." The PTTc was calculated as the time interval between the peaks of the biventricular signal-intensity/time curve and corrected for heart rate. PTTc was compared between patient groups and healthy subjects and its relationship to PVR assessed. The diagnostic accuracy of PTTc for distinguishing IpcPH and CpcPH was determined.

STATISTICAL TESTS

Student's t-test, Mann-Whitney U-test, linear and logistic regression analysis, and receiver-operating characteristic curves. Significance level: P < 0.05.

RESULTS

PTTc was significantly prolonged in CpcPH compared with IpcPH and normal controls (17.28 ± 7.67 vs. 8.82 ± 2.55 vs. 6.86 ± 2.11 seconds), and in IpcPH compared with normal controls (8.82 ± 2.55 vs. 6.86 ± 2.11 seconds). Prolonged PTTc was significantly associated with increased PVR. Furthermore, PTTc was a significantly independent predictor of CpcPH (odds ratio: 1.395, 95% confidence interval: 1.071-1.816). The area under curve was 0.852 at a cut-off value of 11.61 seconds for PTTc to distinguish between CpcPH and IpcPH (sensitivity 71.43% and specificity 94.12%).

DATA CONCLUSION

PTTc may be used to identify CpcPH. Our findings have potential to improve selection for invasive RHC for PH-LHD patients.

EVIDENCE LEVEL

3 TECHNICAL EFFICACY: Stage 2.

The Role of Artificial Intelligence in Predicting Outcomes by Cardiovascular Magnetic Resonance: A Comprehensive Systematic Review

Background and Objectives: Interest in artificial intelligence (AI) for outcome prediction has grown substantially in recent years. However, the prognostic role of AI using advanced cardiac magnetic resonance imaging (CMR) remains unclear. This systematic review assesses the existing literature on AI in CMR to predict outcomes in patients with cardiovascular disease. Materials and Methods: Medline and Embase were searched for studies published up to November 2021. Any study assessing outcome prediction using AI in CMR in patients with cardiovascular disease was eligible for inclusion. All studies were assessed for compliance with the Checklist for Artificial Intelligence in Medical Imaging (CLAIM). Results: A total of 5 studies were included, with a total of 3679 patients, with 225 deaths and 265 major adverse cardiovascular events. Three methods demonstrated high prognostic accuracy: (1) three-dimensional motion assessment model in pulmonary hypertension (hazard ratio (HR) 2.74, 95%CI 1.73−4.34, p < 0.001), (2) automated perfusion quantification in patients with coronary artery disease (HR 2.14, 95%CI 1.58−2.90, p < 0.001), and (3) automated volumetric, functional, and area assessment in patients with myocardial infarction (HR 0.94, 95%CI 0.92−0.96, p < 0.001). Conclusion: There is emerging evidence of the prognostic role of AI in predicting outcomes for three-dimensional motion assessment in pulmonary hypertension, ischaemia assessment by automated perfusion quantification, and automated functional assessment in myocardial infarction.

First-pass perfusion cardiovascular magnetic resonance parameters as surrogate markers for left ventricular diastolic dysfunction: a validation against cardiac catheterization

OBJECTIVES

The non-invasive assessment of left ventricular (LV) diastolic dysfunction remains a challenge. The role of first-pass perfusion cardiac magnetic resonance (CMR) parameters in quantitative hemodynamic analyses has been reported. We therefore aimed to validate the diagnostic ability and accuracy of such parameters against cardiac catheterization for LV diastolic dysfunction in patients with left heart disease (LHD).

METHODS

We retrospectively enrolled 77 LHD patients who underwent CMR imaging and cardiac catheterization. LV diastolic dysfunction was defined as pulmonary capillary wedge pressure (PCWP) or LV end-diastolic pressure (LVEDP) > 12 mmHg on catheterization. On first-pass perfusion CMR imaging, pulmonary transit time (PTT) was measured as the time for blood to pass from the left ventricle to the right ventricle (RV) through the pulmonary vasculature. Pulmonary transit beat (PTB) was the number of cardiac cycles within the interval, and pulmonary blood volume indexed to body surface area (PBVi) was the product of PTB and RV stroke volume index (RVSVi).

RESULTS

Of the 77 LHD patients, 53 (68.83%) were found to have LV diastolic dysfunction, and showed significantly higher PTTc, PTB, and PBVi (p < 0.05) compared with those without. In multivariate analyses, only PTTc and PTB were identified as independent predictors of LV diastolic dysfunction (p < 0.05). With an optimal cutoff of 11.9 s, PTTc yielded the best diagnostic performance for LV diastolic dysfunction (area under the curve = 0.83, p < 0.001).

CONCLUSIONS

PTTc may represent a non-invasive quantitative surrogate marker for the detection and assessment of diastolic dysfunction in LHD patients.

KEY POINTS

• PTTc yielded the best diagnostic accuracy for diastolic dysfunction, with an optimal cutoff of 11.9 s, and a specificity of 100%. • PTTc and PTB were found to be independent predictors of LV diastolic dysfunction across different multivariate models with high reproducibility. • PTTc is a promising non-invasive surrogate marker for the detection and assessment of diastolic dysfunction in LHD patients.

Prognostic Value of Pulmonary Transit Time and Pulmonary Blood Volume Estimation Using Myocardial Perfusion CMR

OBJECTIVES

The purpose of this study was to explore the prognostic significance of PTT and PBVi using an automated, inline method of estimation using CMR.

BACKGROUND

Pulmonary transit time (PTT) and pulmonary blood volume index (PBVi) (the product of PTT and cardiac index), are quantitative biomarkers of cardiopulmonary status. The development of cardiovascular magnetic resonance (CMR) quantitative perfusion mapping permits their automated derivation, facilitating clinical adoption.

METHODS

In this retrospective 2-center study of patients referred for clinical myocardial perfusion assessment using CMR, analysis of right and left ventricular cavity arterial input function curves from first pass perfusion was performed automatically (incorporating artificial intelligence techniques), allowing estimation of PTT and subsequent derivation of PBVi. Association with major adverse cardiovascular events (MACE) and all-cause mortality were evaluated using Cox proportional hazard models, after adjusting for comorbidities and CMR parameters.

RESULTS

A total of 985 patients (67% men, median age 62 years [interquartile range (IQR): 52 to 71 years]) were included, with median left ventricular ejection fraction (LVEF) of 62% (IQR: 54% to 69%). PTT increased with age, male sex, atrial fibrillation, and left atrial area, and reduced with LVEF, heart rate, diabetes, and hypertension (model r2 = 0.57). Over a median follow-up period of 28.6 months (IQR: 22.6 to 35.7 months), MACE occurred in 61 (6.2%) patients. After adjusting for prognostic factors, both PTT and PBVi independently predicted MACE, but not all-cause mortality. There was no association between cardiac index and MACE. For every 1 × SD (2.39-s) increase in PTT, the adjusted hazard ratio for MACE was 1.43 (95% confidence interval [CI]: 1.10 to 1.85; p = 0.007). The adjusted hazard ratio for 1 × SD (118 ml/m2) increase in PBVi was 1.42 (95% CI: 1.13 to 1.78; p = 0.002).

CONCLUSIONS

Pulmonary transit time (and its derived parameter pulmonary blood volume index), measured automatically without user interaction as part of CMR perfusion mapping, independently predicted adverse cardiovascular outcomes. These biomarkers may offer additional insights into cardiopulmonary function beyond conventional predictors including ejection fraction.

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

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.

Pulmonary blood volume index as a quantitative biomarker of haemodynamic congestion in hypertrophic cardiomyopathy

Aims 

The non-invasive assessment of left ventricular (LV) diastolic function and filling pressure in hypertrophic cardiomyopathy (HCM) is still an open issue. Pulmonary blood volume index (PBVI) by cardiovascular magnetic resonance (CMR) has been proposed as a quantitative biomarker of haemodynamic congestion. We aimed to assess the diagnostic accuracy of PBVI for left atrial pressure (LAP) estimation in patients with HCM.

Methods and results 

We retrospectively identified 69 consecutive HCM outpatients (age 58 ± 11 years; 83% men) who underwent both transthoracic echocardiography (TTE) and CMR. Guideline-based detection of LV diastolic dysfunction was assessed by TTE, blinded to CMR results. PBVI was calculated as the product of right ventricular stroke volume index and the number of cardiac cycles for a bolus of gadolinium to pass through the pulmonary circulation as assessed by first-pass perfusion imaging. Compared to patients with normal LAP, patients with increased LAP showed significantly larger PBVI (463 ± 127 vs. 310 ± 86 mL/m², P < 0.001). PBVI increased progressively with worsening New York Heart Association functional class and echocardiographic stages of diastolic dysfunction (P < 0.001 for both). At the best cut-off point of 413 mL/m², PBVI yielded good diagnostic accuracy for the diagnosis of LV diastolic dysfunction with increased LAP [C-statistic = 0.83; 95% confidence interval (CI): 0.73–0.94]. At multivariable logistic regression analysis, PBVI was an independent predictor of increased LAP (odds ratio per 10% increase: 1.97, 95% CI: 1.06–3.68; P = 0.03).

Conclusion 

PBVI is a promising CMR application for assessment of diastolic function and LAP in patients with HCM and may serve as a quantitative marker for detection, grading, and monitoring of haemodynamic congestion.

Pulmonary blood volume estimation in mice by magnetic particle imaging and magnetic resonance imaging

This methodical work describes the measurement and calculation of pulmonary blood volume in mice based on two imaging techniques namely by using magnetic particle imaging (MPI) and cardiac magnetic resonance imaging (MRI). Besides its feasibility aspects that may influence quantitative analysis are studied. Eight FVB mice underwent cardiac MRI to determine stroke volumes and anatomic MRI as morphological reference for functional MPI data. Arrival time analyses of boli of 1 µl of 1 M superparamagnetic tracer were performed by MPI. Pulmonary transit time of the bolus was determined by measurements in the right and left ventricles. Pulmonary blood volume was calculated out of stroke volume, pulmonary transit time and RR-interval length including a maximal error analysis. Cardiac stroke volume was 31.7 µl ± 2.3 µl with an ejection fraction of 71% ± 6%. A sharp contrast bolus profile was observed by MPI allowing subdividing the first pass into three distinct phases: tracer arrival in the right ventricle, pulmonary vasculature, and left ventricle. The bolus full width at half maximum was 578 ms ± 144 ms in the right ventricle and 1042 ms ± 150 ms in the left ventricle. Analysis of pulmonary transit time revealed 745 ms ± 81 ms. Mean RR-interval length was 133 ms ± 12 ms. Pulmonary blood volume resulted in 177 µl ± 27 µl with a mean maximal error limit of 27 µl. Non-invasive assessment of the pulmonary blood volume in mice was feasible. This technique can be of specific value for evaluation of pulmonary hemodynamics in mouse models of cardiac dysfunction or pulmonary disease. Pulmonary blood volume can complement cardiac functional parameters as a further hemodynamic parameter.