Relationship between coronary arterial 18F-sodium fluoride uptake and epicardial adipose tissue analyzed using computed tomography

Predicting major adverse cardiovascular events within 3 years by optimization of radiomics model derived from pericoronary adipose tissue on coronary computed tomography angiography: a case-control study

BACKGROUND

Coronary inflammation induces changes in pericoronary adipose tissue (PCAT) can be detected by coronary computed tomography angiography (CCTA). Our aim was to investigate whether different PCAT radiomics model based on CCTA could improve the prediction of major adverse cardiovascular events (MACE) within 3 years.

METHODS

This retrospective study included 141 consecutive patients with MACE and matched to patients with non-MACE (n = 141). Patients were randomly assigned into training and test datasets at a ratio of 8:2. After the robust radiomics features were selected by using the Spearman correlation analysis and the least absolute shrinkage and selection operator, radiomics models were built based on different machine learning algorithms. The clinical model was then calculated according to independent clinical risk factors. Finally, an overall model was established using the radiomics features and the clinical factors. Performance of the models was evaluated for discrimination degree, calibration degree, and clinical usefulness.

RESULTS

The diagnostic performance of the PCAT model was superior to that of the RCA-model, LAD-model, and LCX-model alone, with AUCs of 0.723, 0.675, 0.664, and 0.623, respectively. The overall model showed superior diagnostic performance than that of the PCAT-model and Cli-model, with AUCs of 0.797, 0.723, and 0.706, respectively. Calibration curve showed good fitness of the overall model, and decision curve analyze demonstrated that the model provides greater clinical benefit.

CONCLUSION

The CCTA-based PCAT radiomics features of three major coronary arteries have the potential to be used as a predictor for MACE. The overall model incorporating the radiomics features and clinical factors offered significantly higher discrimination ability for MACE than using radiomics or clinical factors alone.

Relationship Between Clinical Parameters and Histological Features of Epicardial Adipose Tissue and Aortic Valve Calcification Assessed on Computed Tomography

BACKGROUND

The relationships of the clinical and biological attributes of epicardial adipose tissue (EAT) with aortic valve calcification (AVC) have not been characterized. We evaluated the relationships of the clinical and histological features of EAT with AVC assessed using computed tomography (CT).Methods and Results: We enrolled 43 patients undergoing cardiac CT examination prior to elective cardiac surgery in whom AVC was identified on CT. EAT volume and density, coronary calcium score (CCS), AVC score (AVCS), and coronary atherosclerosis on CT angiography were evaluated in each patient. During cardiac surgery, 2 EAT samples were obtained for immunohistochemistry. The number of CD68- and CD11c-positive macrophages and osteocalcin-positive cells was counted in 6 random high-power fields of EAT sections. EAT density, but not EAT volume normalized to body surface area, was positively correlated with the number of macrophages and osteocalcin-positive cells in EAT. There was a positive correlation between ln(AVCS), but not ln(CCS+1), and the number of macrophages and osteocalcin-positive cells in EAT. Multivariate analysis revealed significant positive correlations for ln(AVCS) with EAT density (β=0.42; P=0.0072) and the number of CD68-positive macrophages (β=0.57; P=0.0022), CD11c-positive macrophages (β=0.62; P=0.0003), and osteocalcin-positive cells (β=0.52; P=0.0021) in EAT.

CONCLUSIONS

Inflammation and osteogenesis in EAT, reflected by high CT density, are associated with the severity of AVC representing aortic valve degeneration.

Novel PET Applications and Radiotracers for Imaging Cardiovascular Pathophysiology

PET allows the assessment of cardiovascular pathophysiology across a wide range of cardiovascular conditions. By imaging processes directly involved in disease progression and adverse events, such as inflammation and developing calcifications (microcalcifications), PET can not only enhance our understanding of cardiovascular disease, but also, as shown for 18F-sodium fluoride, has the potential to predict hard endpoints. In this review, the recent advances in disease activity assessment with cardiovascular PET, which provide hope that this promising technology could be leveraged in the clinical setting, shall be discussed.

Connecting epicardial adipose tissue and heart failure with preserved ejection fraction: mechanisms, management and modern perspectives

Obesity is very common in patients with heart failure with preserved ejection fraction (HFpEF) and it has been suggested that obesity plays an important role in the pathophysiology of this disease. While body mass index defines the presence of obesity, this measure provides limited information on visceral adiposity, which is probably more relevant in the pathophysiology of HFpEF. Epicardial adipose tissue is the visceral fat situated directly adjacent to the heart and recent data demonstrate that accumulation of epicardial adipose tissue is associated with the onset, symptomatology and outcome of HFpEF. However, the mechanisms by which epicardial adipose tissue may be involved in HFpEF remain unclear. It is also questioned whether epicardial adipose tissue may be a specific target for therapy for this disease. In the present review, we describe the physiology of epicardial adipose tissue and the pathophysiological transformation of epicardial adipose tissue in response to chronic inflammatory diseases, and we postulate conceptual mechanisms on how epicardial adipose tissue may be involved in HFpEF pathophysiology. Lastly, we outline potential treatment strategies, knowledge gaps and directions for further research.

Associations between coronary/aortic 18F-sodium fluoride uptake and pro-atherosclerosis factors in patients with multivessel coronary artery disease

BACKGROUND

18F-NaF PET/CT is a novel approach to detect and quantify microcalcification in atherosclerosis. We aimed to explore the underlying systematic vascular osteogenesis in the coronary artery and aorta in patients with multivessel coronary artery disease (CAD).

METHODS

Patients with multivessel CAD prospectively underwent 18F-NaF PET/CT. The coronary microcalcification activity (CMA) and aortic microcalcification activity (AMA) were calculated based on both the volume and intensity of 18F-NaF PET activity. Peri-coronary adipose tissue (PCAT) density was measured in adipose tissue surrounding the coronary arteries and the 18F-NaF tissue-to-blood ratio (TBR) was measured in the coronary arteries.

RESULTS

100 patients with multivessel CAD were prospectively recruited. The CMA was significantly associated with the AMA (r = 0.70; P < .001). After multivariable adjustment, the CMA was associated with the AMA (Beta = 0.445 per SD increase; P < .001). The coronary TBR was also significantly associated with the PCAT density (r = 0.56; P < .001). The PCAT density was independently associated with the coronary TBR after adjusting confounding factors.

CONCLUSIONS

Coronary 18F-NaF uptake was significantly associated with the PCAT density. There was a significant relationship between the coronary and the aortic 18F-NaF uptake. It might indicate an underlying systematic vascular osteogenesis in patients with multivessel CAD.

Left atrial epicardial adipose tissue is associated with low voltage zones in the left atrium in patients with non-valvular atrial fibrillation

Objective

Epicardial adipose tissue (EAT) is related to atrial fibrillation (AF), but the specific mechanism is still unclear. Left atrial (LA) low voltage zones (LVZ) can well reflect atrial fibrosis. This study investigated the relationship between EAT and LVZ in non-valvular AF (NVAF) patients.

Methods

This observational study including patients with NVAF (n = 214) undergoing radiofrequency ablation (RFCA) for the first time in our hospital and 62 matched controls. The EAT volume and attenuation were measured by contrast-enhanced computed tomography. A three-dimensional mapping system was used to map the left atrial endocardium and evaluate LA-LVZ. Patients were divided into LVZ and non-LVZ groups according to the presence or absence of LVZ.

Results

Patients with AF showed higher LA-EAT volume and lower attenuation value than controls (29.7 ± 11.2 cm³ vs. 20.9 ± 8.6 cm³, P = 0.021; −91.2 ± 5.6 HU vs. −88.7 ± 5.9 HU, P < 0.001). Compared with the group without LVZ, there were significant differences in age [65 (59–71) vs. 60 (52–69), P = 0.006], LAVI [75.1 ± 20.7 ml/m² vs. 67.2 ± 20.9 ml/m², P = 0.018], LA-EAT volume (34.8 ± 11.5 cm³ vs. 28.1 ± 10.6 cm³, P < 0.001) and LA-EAT attenuation (−93.9 ± 5.3 HU vs. −90.4 ± 5.5 HU, P < 0.001). Multivariate regression analysis showed that age (OR = 1.040; 95%CI: 1.001–1.078, P = 0.042), LAVI (OR = 1.019; 95%CI: 1.002–1.037, P = 0.032), LA-EAT volume (OR = 1.193; 95%CI: 1.015–1.402, P = 0.034) and attenuation value (OR = 0.801; 95%CI: 0.701–0.916 P = 0.001) were independent predictors of LVZ. After LA-EAT attenuation was incorporated into the clinical model, the comprehensive discrimination and net reclassification tended to improve (IDI and NRI > 0, P < 0.05).

Conclusion

LA-EAT volume and attenuation values can independently predict the presence of LVZ, and LA-EAT attenuation has a better predictive value than LA-EAT volume.

Association between epicardial adipose tissue density and characteristics of coronary plaques assessed by coronary computed tomographic angiography

To investigate the relationship between the epicardial adipose tissue density (EATD) and the coronary plaque components as assessed by coronary computed tomographic angiography (CCTA). The study cohort included 240 patients with chest pain or precardiac discomfort (mean age 62.01 ± 7.45 years, 55.83% male). Patients were assigned to the high-risk plaque (HRP) group (n = 133) or non-HRP group (n = 107). All patients underwent CCTA to assess plaque composition, and quantitative analysis of EATD and epicardial adipose tissue volume (EATV). Age, gender, EATV, EATD, diabetes history and family history were all correlated with HRP. There was no linear correlation between EATD and EATV among the subjects (R² = 0.008, p = 0.177), but there was a curvilinear correlation (R² = 0.102, p < 0.001). After adjusting other traditional factors, and we observed robust associations of EAT volume and density with HRP (all p < 0.05). For per 1 standard deviation increase in EATD, the risk of HRP was 3.120 times the risk than that of non-HRP. For per 1 standard deviation increase in EATV, the risk of HRP was 1.499 times the risk than that of non-HRP. The receiver operating characteristic curve showed that EATD was more predictive of HRP than EATV (AUC = 0.761, 95% CI 0.701-0.822). Our study found that EATD and EATV are both independent factors affecting the presence of HRPs, and EATD had a high predictive value for the presence of HRP.

Atherosclerosis Imaging with 18F-Sodium Fluoride PET

The evidence on atherosclerosis imaging with ¹⁸F-sodium-fluoride (NaF) positron emission tomography (PET) is hotly debated because of the different patient characteristics, methodology, vascular beds, etc. in reported studies. This review is a continuation of a previous review on this topic, which covered the period 2010-2018. The purpose was to examine whether some of the most important questions that the previous review had left open had been elucidated by the most recent literature. Using principles of a systematic review, we ended analyzing 25 articles dealing with the carotids, coronary arteries, aorta, femoral, intracranial, renal, and penile arteries. The knowledge thus far can be summarized as follows: by targeting active arterial microcalcification, NaF uptake is considered a marker of early stage atherosclerosis, is age-dependent, and consistently associated with cardiovascular risk. Longitudinal studies on NaF uptake, conducted in the abdominal aorta only, showed unchanged uptake in postmenopausal women for nearly four years and varying uptake in prostate cancer patients over 1.5 years, despite constant or increasing calcium volume detected by computed tomography (CT). Thus, uncertainty remains about the transition from active arterial wall calcification marked by increased NaF uptake to less active or consolidated calcification detected by CT. The question of whether early-phase atherosclerosis and calcification can be modified remains also unanswered due to lack of intervention studies.

An Update on [18F]Fluoride PET Imaging for Atherosclerotic Disease

Atherosclerosis is the leading cause of life-threatening morbidity and mortality, as the rupture of atherosclerotic plaques leads to critical atherothrombotic events such as myocardial infarction and ischemic stroke, which are the 2 most common causes of death worldwide. Vascular calcification is a complicated pathological process involved in atherosclerosis, and microcalcifications are presumed to increase the likelihood of plaque rupture. Despite many efforts to develop novel non-invasive diagnostic modalities, diagnostic techniques are still limited, especially before symptomatic presentation. From this point of view, vulnerable plaques are a direct target of atherosclerosis imaging. Anatomic imaging modalities have the limitation of only visualizing macroscopic structural changes, which occurs in later stages of disease, while molecular imaging modalities are able to detect microscopic processes and microcalcifications, which occur early in the disease process. Na[¹⁸F]-fluoride positron emission tomography/computed tomography could allow the early detection of plaque instability, which is deemed to be a primary goal in the prevention of cardiac or brain ischemic events, by quantifying the microcalcifications within vulnerable plaques and evaluating the atherosclerotic disease burden.