Direct comparisons of left ventricular volume and function by simultaneous cardiac magnetic resonance imaging and gated 13N-ammonia positron emission tomography

Application of three-dimensional speckle tracking technique in measuring left ventricular myocardial function in patients with diabetes

BACKGROUND

Diabetic cardiomyopathy is considered as a chronic complication of diabetes mellitus (DM). Therefore, early detection of left ventricular systolic function (LVSF) damage in DM is essential.

AIM

To explore the use of the three-dimensional speckle tracking technique (3D-STI) for measuring LVSF in DM patients via meta-analysis.

METHODS

The electronic databases were retrieved from the initial accessible time to 29 April 2023. The current study involved 9 studies, including 970 subjects. We carried out this meta-analysis to estimate myocardial function in DM compared with controls according to myocardial strain attained by 3D-STI.

RESULTS

Night articles including 970 subjects were included. No significant difference was detected in the left ventricular ejection fraction between the control and the diabetic group (P > 0.05), while differences in global longitudinal strain, global circumferential strain, global radial strain, and global area strain were markedly different between the controls and DM patients (all P < 0.05).

CONCLUSION

The 3D-STI could be applied to accurately measure early LVSF damage in patients with DM.

Simultaneous assessment of left ventricular mechanical dyssynchrony using integrated 13N-ammonia PETMR system: direct comparison of PET phase analysis and MR feature tracking

BACKGROUND

To compare phase analysis with positron emission tomography (PA) and magnetic resonance feature tracking derived myocardial strain (FT) for left ventricular (LV) mechanical dyssynchrony using PETMR system in patients with ischemic heart disease.

METHODS AND RESULTS

Patients who underwent rest-pharmacological stress 13N ammonia PETMR were enrolled. Histogram bandwidth (BW) and phase standard deviation (PSD) were compared to global longitudinal, long axis radial, short axis circumferential, and radial strain (GLS, GRS, SA Circ, and SA Rad) obtained from FT. LV dyssynchrony index (SDI) derived from PA and FT were compared. BW and PSD showed significant correlations with FT (a Pearson's coefficient r = 0.64, P < .0001, and r = 0.51, P < .0001 for SA Circ; r = 0.67, P < .0001, and r = 0.74, P < .0001 for GLS; r = - 0.60, P < .0001, r = - 0.61, P < .0001 for SA Rad; r = - 0.62, P < .0001, and r = - 0.68, P < .0001 for GRS, respectively). Bland-Altman plots for SDI showed a preferable agreement (95% limit of agreement - 0.12 to 0.075, - 0.20 to 0.098, - 0.38 to 0.077, and - 0.37 to 0.032; bias 0.0068 ± 0.056, 0.026 ± 0.068, 0.11 ± 0.088, and 0.13 ± 0.079 for SA Circ, SA Rad, GLS, and GRS, respectively).

CONCLUSION

In simultaneous acquisition using PETMR, comparison of PET phase analysis and MR strain showed a good correlation.

Left-ventricular volumes and ejection fraction from cardiac ECG-gated 15O-water positron emission tomography compared to cardiac magnetic resonance imaging using simultaneous hybrid PET/MR

BACKGROUND

15O-water PET is the gold standard for noninvasive quantification of myocardial blood flow. In addition to evaluation of ischemia, the assessment of cardiac function and remodeling is important in all cardiac diseases. However, since 15O-water is freely diffusible and standard uptake images show little contrast between the myocardium and blood pool, the assessment of left-ventricular (LV) volumes and ejection fraction (EF) is challenging. Therefore, the aim of the present study was to investigate the feasibility of calculating LV volumes and EF from first-pass analysis of 15O-water PET, by comparison with cardiac magnetic resonance imaging (CMR) using a hybrid PET/MR scanner.

METHODS

Twenty-four patients with known or suspected CAD underwent a simultaneous ECG-gated cardiac PET/MR scan. The 15O-water first-pass images (0-50 seconds) were analyzed using the CarPET software and the CMR images were analyzed using the software Segment, for LV volumes and EF calculations. The LV volumes and EF were compared using correlation and Bland-Altman analysis. In addition, inter- and intra-observer variability of LV volumes and EF were assessed for both modalities.

RESULTS

The correlation between PET and CMR was strong for volumes (r > 0.84) and moderate for EF (r = 0.52), where the moderate correlation for EF was partly due to the small range of EF values. Agreement was high for all parameters, with a slight overestimation of PET values for end-diastolic volume but with no significant mean bias for other parameters. Inter- and intra-observer agreement of volumes was high and comparable between PET and CMR. For EF, inter-observer agreement was higher for PET and intra-observer agreement was higher for CMR.

CONCLUSION

LV volumes and EF can be calculated by first-pass analysis of a 15O-water PET scan with high accuracy and comparable precision as with CMR.

Value of PET ECG gating in a cross-validation study of cardiac function assessment by PET/MR imaging

BACKGROUND

This work investigated the impact of different cardiac gating methods on the assessment of cardiac function by FDG-PET in a cross-validation PET/MR study.

METHODS AND RESULTS

MR- and PET-based left ventricular end-diastolic, end-systolic volumes, and ejection fraction (EDV, ESV, and EF) were delineated in 30 patients with a PET/MR examination. Cardiac PET imaging was performed using three ECG gating methods: fixed number of gates per beat (STD), STD with a beat acceptance window (STD-BR), and fixed gate duration (FW). High MR-PET correlations were found in all the values. ESVs correlated better than EDVs and EFs: Pearson's r coefficient [0.92, 0.92, 0.92] in ESV vs [0.75, 0.81, 0.80] in EDV and [0.79, 0.91, 0.87] in EF, for each method [STD, STD-BR, FW]. Biases with respect to MRI for all the evaluated PET methods were less than 13% in EDV, 5% in ESV, and 14% in EF, but with wide limits of agreements, in the range (59-68)% in EDV, (65-70)% in ESV, and (49-71)% in EF. STD showed the strongest disagreement, while there were no marked differences between STD-BR and FW.

CONCLUSION

Based on these findings, PET- and MR-based cardiac function parameters were highly correlated but in substantial disagreement with variabilities introduced by the selected PET ECG gating method. The most significant differences were associated with the ECG gating method susceptible to highly irregular beats, while similar performance was observed in the methods using uniform adjustment of gates width per beat with the beat acceptance window, and fixed gate width along all the beats. Thus, strict quality controls of R peak detection are needed to minimize its impact on the function assessment.

Left ventricular function and volumes from gated [13N]-ammonia positron emission tomography myocardial perfusion imaging: A prospective head-to-head comparison against CMR using a hybrid PET/MR device

BACKGROUND

Positron emission tomography (PET) myocardial perfusion imaging (MPI) can be used to evaluate left ventricular (LV) volumes and function. We performed a head-to-head comparison of LV function and volumes obtained simultaneously using [13N]-ammonia-PET and cardiac magnetic resonance (CMR), with the latter serving as the reference standard.

METHODS AND RESULTS

In this prospective study, 51 patients underwent [13N]-ammonia-PET MPI and CMR using a hybrid PET/MR device. Left ventricular end-systolic volumes (LVESV), end-diastolic volumes (LVEDV), stroke volumes (LVSV), ejection fractions (LVEF), and segmental wall motion were analyzed for both methods and were compared using correlational and Bland-Altman (BA) analysis; segmental wall motion was compared using ANOVA. The agreement between [13N]-ammonia-PET and CMR for LVEF was good, with minimal bias (- .6%) and narrow BA limits of agreement (- 7.9% to 6.8%), but [13N]-ammonia-PET systematically underestimated LV volumes, with high bias in LVESV (- 11.2 ml), LVEDV (- 28.9 ml), and LVSV (- 17.5 ml). Mean segmental wall motion in [13N]-ammonia-PET differed significantly among the corresponding normokinetic (6.6 ± 2 mm), hypokinetic (5.1 ± 2 mm), and akinetic (3.3 ± 2 mm) segments in CMR (P < .01).

CONCLUSION

LVEF and LV wall motion can be accurately assessed using [13N]-ammonia-PET MPI, although LV volumes are significantly underestimated compared to CMR.

Comparing the diagnostic accuracy of PET and CMR for the measurement of left ventricular volumes and ejection fraction: a system review and meta-analysis

BACKGROUND

Cardiac magnetic resonance (CMR) has been recognized as the gold standard for the evaluation of left ventricular (LV) function. Cardiac gated PET allows the simultaneous assessment of LV function with the evaluation of myocardial perfusion and metabolism. But the correlations between PET and CMR remain controversial.

METHODS

We conducted a systematic electronic search of PubMed, Embase and the Cochrane Library . Forest plot, spearman correlation analysis and Bland-Altman analysis were used to evaluate the correlations between PET and CMR.

RESULTS

Pooled analysis of 13 studies showed that PET underestimated left ventricular end-diastolic volumes (LVEDV) [mean difference (MD), -15.30; 95% confidence interval (CI), -23.10 to -7.50; P  < 0.001] and left ventricular end-systolic volumes (LVESV) (MD, -6.20; 95% CI, -12.58 to 0.17; P  = 0.06) but not left ventricular ejection fraction (LVEF) (MD, -0.35; 95% CI, -1.75 to 1.06; P  = 0.63). Overall, there were very good correlations between PET and CMR measurements for LVEDV ( r , 0.897), LVESV ( r , 0.924) and LVEF ( r , 0.898). Subgroup analysis indicated that LVEDV ≥180 ml and LVEF <40% reduced the accuracy of PET, especially the measurement of LVEF ( r , LVEDV ≥180 vs . r , LVEDV < 180 : 0.821 vs. 0.944; r , LVEF < 40% vs . r , LVEF ≥40% : 0.784 vs. 0.901).

CONCLUSIONS

Correlations between PET and CMR measurements of LVEDV, LVESV and LVEF were excellent, but these two methods could not be used interchangeably for accurate measurements of LV volume and LVEF in patients with significantly increased LV volume and decreased LVEF.

Low coronary flow relative to myocardial mass predicts heart failure in symptomatic hypertensive patients with no obstructive coronary artery disease

AIMS

The transition from hypertension to heart failure (HF) remains poorly understood. We hypothesized that insufficient perfusion to match global metabolic demand, reflected by a low ratio of myocardial blood flow to global myocardial mass, may be a HF risk marker.

METHODS AND RESULTS

A retrospective cohort (n = 346) of patients with hypertension who underwent clinical positron emission tomography (PET) myocardial perfusion imaging for chest pain and/or dyspnoea at Brigham and Women's Hospital (Boston, MA, USA) were studied. Patients without obstructive coronary artery disease by history or PET perfusion (summed stress score <3), HF, cardiomyopathy, or ejection fraction (EF) <40% were followed for HF hospitalization (primary outcome), all-cause death, and their composite. Myocardial blood flow, left ventricular (LV) mass, volumes, and EF were obtained from PET, and a 'flow/mass ratio' was determined as hyperaemic myocardial blood flow over LV mass indexed to body surface area. A lower flow/mass ratio was independently associated with larger end-diastolic (β = -0.44, P < 0.001) and end-systolic volume (β = -0.48, P < 0.001) and lower EF (β = 0.33, P < 0.001). A flow/mass ratio below the median was associated with an adjusted hazard ratio of 2.47 [95% confidence interval (CI) 1.24-4.93; P = 0.01] for HF hospitalization, 1.95 (95% CI 1.12-3.41; P = 0.02) for death, and 2.20 (95% CI 1.39-3.49; P < 0.001) for the composite.

CONCLUSION

An integrated physiological measure of insufficient myocardial perfusion to match global metabolic demand identifies subclinical hypertensive heart disease and elevated risk of HF and death in symptomatic patients with hypertension but without flow-limiting coronary artery disease.