Key result
13N-ammonia PET accurately measures LVEF vs. CMR, but systematically underestimates LV volumes.
Why the study?
ECG-gated 13N-ammonia PET MPI is validated for LV volumes and function assessment, but its accuracy compared with CMR in INOCA patients was unknown.
Does 13N-ammonia PET accurately quantify left ventricular volumes and function compared to cardiac magnetic resonance in patients with INOCA?
Cross-Sectional (n=75)
No
Does 13N-ammonia PET accurately quantify left ventricular volumes and function compared to cardiac magnetic resonance in patients with INOCA?
Mean Difference: -0.57 (95% CI -1.97–0.83)
Absolute Event Rate: 60.56% vs 61.13%
p-value: p=0.420
ECG-gated 13N-ammonia PET allows reliable assessment of left ventricular ejection fraction and regional wall motion in patients with INOCA, making it a valuable alternative when CMR is contraindicated.
May support 13N-ammonia PET for LVEF in INOCA when CMR unavailable; leaves open prospective validation for volumes and outcomes.
Background: Electrocardiogram (ECG)-gated 13 N-ammonia positron emission tomography (PET) myocardial perfusion imaging (MPI) has been widely validated for the assessment of left ventricular (LV) volumes and function. This study aimed to compare the accuracy of LV volumes and functional parameters derived from 13 N-ammonia PET with those obtained by cardiac magnetic resonance (CMR), using CMR as the reference standard. Methods: A total of 75 consecutive patients with known or suspected ischemia with no obstructive coronary arteries (INOCA) who simultaneously underwent ECG-gated 13 N-ammonia PET and CMR using a hybrid PET/magnetic resonance (MR) scanner were enrolled in this prospective study. Left ventricular end-diastolic volume (LVEDV), left ventricular end-systolic volume (LVESV), left ventricular stroke volume (LVSV), left ventricular ejection fraction (LVEF), and regional wall motion score (RWMS) were derived from both imaging modalities and compared using correlation and Bland-Altman (BA) analyses. Additionally, inter- and intraobserver variability in LV volumetric parameters and LVEF were evaluated for both imaging modalities. Results: The correlation between PET and CMR was strong for LV volumes (r>0.83) and moderate for LVEF (r=0.65). The moderate LVEF correlation may be partially explained by the narrow range of LVEF values across the study cohort. Moreover, the agreement between 13 N-ammonia PET and CMR for LVEF was good, with minimal bias (−0.57%); however, 13 N-ammonia PET systematically underestimated LV volumes, with negative biases for LVEDV (−7.76 mL), LVESV (−3.28 mL), and LVSV (−5.33 mL). Similar, strong correlations and good agreement were observed in patients with reduced myocardial flow reserve (MFR). For both PET and CMR, inter- and intraobserver agreement for LV volumes and LVEF was high and comparable between the two modalities. In addition, RWMSs derived from ECG-gated 13 N-ammonia PET and CMR also exhibited good agreement (kappa =0.84±0.02). Conclusions: LVEF and RWMS can be reliably and accurately quantified by ECG-gated 13 N-ammonia PET, although LV volumes are systematically underestimated compared with those quantified by CMR. ECG-gated 13 N-ammonia PET may serve as a complementary modality for the assessment of LV systolic function; however, CMR remains the benchmark for LV volumetric measurement and myocardial tissue assessment.
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Wen et al. (2026) conducted a cross-sectional in Ischemia with no obstructive coronary arteries (INOCA) (n=75). 13N-ammonia PET vs. Cardiac magnetic resonance (CMR) was evaluated on Left ventricular ejection fraction (LVEF) (MD -0.57%, 95% CI -1.97 to 0.83, p=0.420). 13N-ammonia PET accurately quantified LVEF compared with CMR (mean difference -0.57%, p=0.420), although it systematically underestimated left ventricular volumes.
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