Matthieu Pelletier-Galarneau

Purpose Data on the use of fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) in non-granulomatous myocarditis are limited, and no study has evaluated the diagnostic performance of combined FDG-PET and rest myocardial perfusion imaging (rMPI). Methods We conducted a multicenter prospective observational feasibility study of patients who underwent combined FDG-PET/CT with rMPI as well as cardiac magnetic resonance (CMR) for suspected myocarditis. When available, endomyocardial biopsy (EMB) established the diagnosis according to consensus criteria. Otherwise, the final adjudicated clinical diagnosis served as the reference standard. All patients had a minimum follow-up of 12 months following PET imaging. Results Twenty-five patients were included, of whom 18 (72%) were diagnosed with myocarditis. FDG-PET and rMPI demonstrated a sensitivity/specificity of 61%/100%, and 59%/71%, respectively. Inter-reader agreement for FDG-PET was excellent (κ = 0.84, 95% CI 0.62–1.00). The combination of FDG-PET and rMPI yielded a sensitivity of 82% (95% CI: 50–93%) and a specificity of 71% (95% CI: 29–96%). Late gadolinium enhancement (LGE), excluding isolated subendocardial patterns, showed a sensitivity/specificity of 72%/57%. Spatial agreement between rMPI perfusion defects and LGE on CMR was modest (κ = 0.35, 95%CI: 0.23–0.47). Conclusion Combining FDG-PET with rMPI may be a feasible imaging modality for detecting non-granulomatous myocarditis by capturing both inflammatory and fibrotic components across different disease stages.

Angina with non-obstructive coronary arteries (ANOCA) is increasingly recognized as a common cause of chest pain. We observed that some ANOCA patients undergoing dipyridamole rubidium-82 positron emission tomography (PET)/computed tomography (CT) myocardial perfusion imaging (MPI) develop ST-segment depression despite preserved or elevated stress myocardial blood flow (MBF). This study sought to characterize this phenomenon. We analyzed patients referred for rubidium-82 PET/CT MPI without obstructive coronary artery disease for evaluation of microvascular function between 2017 and 2023 (ANOCA) and a propensity-matched control group at very low likelihood of obstructive disease. Stress MBF was categorized as low (< 2.0 mL/min/g), normal (2.0-3.5 mL/min/g), or high (> 3.5 mL/min/g). ST-segment depression was defined as ≥ 1 mm horizontal or downsloping depression in two contiguous leads. The final cohort comprised 136 ANOCA patients and 533 controls. A total of 37 (5.5%) patients presented ST-segment depression, 25 (4.7%) in the control group and 12 (8.8%) in the ANOCA group; all were female. Its prevalence was significantly higher among patients with high vs. normal stress MBF in both the ANOCA group (37.5% vs. 6.1%, p = 0.0016) and the Control group (16.7% vs. 3.4%, p < 0.0001). At any given stress MBF, ANOCA patients had a higher probability of developing ST-segment depression compared with controls (p = 0.0037). In multivariable analyses, ST-segment depression was significantly associated with high stress MBF in ANOCA patients (OR:4.85, 95%CI:1.07-21.93). Vasodilator-induced ST-segment depression was observed more frequently at higher stress MBF, particularly in ANOCA, raising the possibility of a paradoxical "high-flow ischemia" phenotype. These observations are hypothesis-generating and highlight the need for further studies to clarify underlying mechanisms and prognostic relevance.

Consumption of ultra-processed foods has been linked to various adverse health effects; however, the mechanisms underlying these effects remain poorly understood. This study aimed to evaluate the impact of a single ultra-processed meal on myocardial blood flow (MBF), measured using positron emission tomography/computed tomography (PET/CT), and its effects on cognitive performance. Fourteen healthy adult males were enrolled in a randomized crossover trial, receiving either a non-ultra-processed meal (comprising foods from NOVA groups 1 to 3) or an ultra-processed meal (comprising foods from NOVA groups 1 to 4) before crossing over to the alternate meal. After each meal, rubidium-chloride PET/CT scans were conducted at baseline and during intermediate (80 µg/kg/min) and high-dose adenosine (140 µg/kg/min). Neuropsychological testing followed each meal. MBF and MFR at intermediate-dose adenosine was significantly higher after the ultra-processed meal compared to the non-ultra-processed meal (1.62 vs. 1.22 mL/min/g, p = 0.015, and 2.43 vs. 1.88, p = 0.012, respectively), with a mean relative difference of 40.7%. No significant differences were observed between the meals at baseline or high-dose adenosine for both MBF and MFR. When considering carry-over and learning effects, overall performance on neuropsychological testing was worse following the ultra-processed meal during the first period. In healthy adult males, a single ultra-processed meal enhanced adenosine-mediated MBF and MFR at intermediate-dose adenosine and was associated with potentially reduced cognitive performance compared to a non-ultra-processed meal.Trial registration number: NCT06353009 (ClinicalTrials.gov ID). Trial registration Date: 08/04/2024 https://clinicaltrials.gov/study/NCT06353009 .