Left ventricular strain analysis by positron emission tomography: Beyond myocardial perfusion

Background: Myocardial perfusion imaging by positron emission tomography (PET-MPI) is the current gold standard for quantification of myocardial blood flow. 18F-flurpiridaz was recently introduced as a valid alternative to currently used PET-MPI probes. Nonetheless, optimum scan duration and time interval for image analysis are currently unknown. Further, it is unclear whether rest/stress PET-MPI with 18F-flurpiridaz is feasible in mice. Methods: Rest/stress PET-MPI was performed with 18F-flurpiridaz (0.6-3.0 MBq) in 29 mice aged 7-8 months. Regadenoson (0.1 μg/g) was used for induction of vasodilator stress. Kinetic modeling was performed using a metabolite-corrected arterial input function. Image-derived myocardial 18F-flurpiridaz uptake was assessed for different time intervals by placing a volume of interest in the left ventricular myocardium. Results: Tracer kinetics were best described by a two-tissue compartment model. K1 ranged from 6.7-20.0 mL/cm3/min, while myocardial volumes of distribution (VT) were between 34.6 and 83.6 mL/cm3. Of note, myocardial 18F-flurpiridaz uptake (%ID/g) was significantly correlated with K1 at rest and following pharmacological stress testing for all time intervals assessed. However, while Spearman coefficients (rs) ranged between 0.478 and 0.672, R2 values were generally low. In contrast, an excellent correlation of myocardial 18F-flurpiridaz uptake with VT was obtained, particularly when employing the averaged myocardial uptake from 20-40 min post tracer injection (R2 ≥0.98). Notably, K1 and VT were similarly sensitive to pharmacological stress induction. Further, mean stress-to-rest ratios of K1, VT, and %ID/g 18F-flurpiridaz were virtually identical, suggesting that %ID/g 18F-flurpiridaz can be used to estimate CFR in mice. Conclusion: Our findings suggest that a simplified assessment of relative myocardial perfusion and coronary flow reserve (CFR), based on image-derived tracer uptake, is feasible with 18F-flurpiridaz in mice, enabling high-throughput mechanistic CFR studies in rodents.

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1043 Association of left ventricular global longitudinal strain with myocardial perfusion evaluated by 13N-ammonia positron emission tomography in hemodialysis patients with preserved ejection fraction

European Heart Journal - Cardiovascular Imaging ◽

10.1093/ehjci/jez319.635 ◽

2020 ◽

Vol 21 (Supplement_1) ◽

Author(s):

S Yamabe ◽

R Ito ◽

T Sakakibara ◽

A Yamada ◽

S Ohshima ◽

...

Keyword(s):

Positron Emission Tomography ◽

Myocardial Perfusion ◽

Cardiovascular Events ◽

Longitudinal Strain ◽

Global Longitudinal Strain ◽

Left Ventricular ◽

Emission Tomography ◽

Positron Emission ◽

Group A ◽

Group B

Abstract Background Global longitudinal strain (GLS) is an echocardiographic marker to detect subclinical left ventricular systolic dysfunction prior to the appearance of reduced left ventricular ejection fraction (LVEF). Reduced GLS identified in patients with maintenance hemodialysis (HD) has been reported to be a predictor of their higher mortality and cardiovascular events. On the other hand, pharmacological stress 13N-ammonia positron emission tomography (13N-NH3-PET) has been an established and reliable imaging modality to evaluate myocardial perfusion expressed as coronary flow reserve (CFR) or maximal stress myocardial blood flow (MBF). CFR and MBF are powerful parameters to detect coronary artery disease and to predict cardiovascular events and mortality. However, association between GLS and those myocardial perfusion parameters are not fully understood. Purpose：The aim of this study was to evaluate the relationship between GLS and the myocardial perfusion parameters of 13N-NH3-PET in HD patients with preserved LVEF. Methods We studied 24 HD patients (mean age 67 years, 67% male) who underwent ATP stress 13N-NH3-PET as well as transthoracic echocardiography including 2-dimensional speckle tracking imaging for suspected ischemic heart disease. Exclusion criteria were as follows: LVEF <50%, moderate to severe valvular diseases, and atrial fibrillation. Myocardial perfusion abnormality (MPA) was defined as CFR <2.0 and/or stress MBF <2.0. Results Mean GLS in all patients was -16.2 ± 3.6%. The patients were divided into 2 groups based on GLS: patients with reduced GLS (<-16%) (Group A, N = 11) and those with preserved GLS (≧-16%) (Group B, N = 14). There were no significant differences between 2 groups in age, gender, body mass index, left ventricular mass index, and average E/e’. Nevertheless, Group A had significantly lower stress MBF than Group B (1.7 ± 0.41 vs 2.0 ± 0.33, p = 0.031). In addition, Group A showed more frequent MPA compared with Group B (81.8% vs 42.9%, p = 0.043). There was a moderate correlation between GLS and stress MBF (r = 0.62, p = 0.0012), whereas no significant correlation was noted between GLS and CFR (r = 0.079, p = 0.71). Conclusion Reduced GLS was significantly associated MPA. MPA may be one of the major contributors to the reduction in GLS in HD patients with preserved LVEF.

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