18F-sodium fluoride positron emission tomography and coronary plaque radiomics derived from computed tomography angiography for prediction of myocardial infarction

Background

Assessments of coronary disease activity with 18F-sodium fluoride positron emission tomography (18F-NaF PET) and radiomics-based precision coronary plaque phenotyping derived from contrast-enhanced computed tomography (CT) have both been shown to enhance risk stratification in patients with coronary artery disease (CAD). To date, no study has investigated whether these two promising methods (which can be obtained during a single imaging session on a hybrid PET/CT scanner) are interchangeable or can provide superior predictive performance when used in combination.

Purpose

We sought to investigate whether the prognostic information provided by latent morphological radiomic coronary plaque features and assessments of disease activity by 18F-NaF PET are complementary in prediction of myocardial infarction.

Methods

Patients with known CAD underwent coronary 18F-NaF PET and CT angiography on a hybrid PET/CT scanner. Coronary 18F-NaF uptake was determined by the coronary microcalcification activity (CMA). We performed quantitative plaque analysis of coronary CT angiography datasets. Additionally, coronary plaque segmentations on CT angiography were used to extract 1103 radiomic features. Using weighted correlation network analysis we derived latent morphological features of coronary plaques which were aggregated to patient-level radiomic normograms to predict myocardial infarction using univariate and multivariate Cox proportional hazard models.

Results

The study cohort comprised of 260 patients with established CAD (age: 65±9 years; 84% men); 179 (69%) participants showed increased coronary 18F-NaF activity (CMA >0). Over 53 [40–59] months of follow-up 18 patients had a myocardial infarction. Using weighted correlation network analysis, from the 1103 radiomic features we derived 15 distinct eigen radiomic features representing latent morphological coronary plaque patterns. On univariate cox modelling 7 of these emerged as predictors of myocardial infarction (Figure). Following adjustments for calcified, noncalcified and low-density noncalcified plaque volumes and 18F-NaF CMA 4 radiomic features (related to texture and geometry) remained independent predictors of myocardial infarction (Figure).

Conclusion(s)

In patients with established CAD latent morphological features of coronary plaques are predictors of myocardial infarction above and beyond plaque volumes and 18F-NaF uptake. Comprehensive plaque analysis with radiomics may enhance risk stratification of CAD patients.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): NIH, Wellcome Trust

Non-invasive characterization of pancoronary inflammation by computed tomography angiography in patients with recent spontaneous coronary dissection

Background

Spontaneous coronary artery dissection (SCAD) is a non-atherosclerotic cause of myocardial infarction of unclear aethiology. Histopathological analyses have identified increased coronary inflammation in patients with SCAD [1]. Recently the peri-coronary adipose tissue attenuation (PCAT) derived from standard computed tomography angiography (CTA) has been established as a reproducible method for measuring vascular inflammation which enhances risk stratification in patients with coronary atherosclerosis [2].

Purpose

To characterize the pancoronary and vessel-specific inflammation by means of CTA-derived PCAT in patients with recent SCAD compared with individuals without prior SCAD.

Methods

Patients with confirmed SCAD referred to a tertiary center between 2017 and 2021 who underwent CTA as a routine cardiac evaluation were included in this retrospective study. Subjects were matched 1:1 with individuals with no prior SCAD who underwent CTA within the same timespan, using the same scanner and imaging protocol, with coronary arteries free of obstructive disease and similar clinical characteristics (Table 1). PCAT was analyzed on end-diastolic CTA reconstructions with a semi-automated software using standard methodology (Figure 1A) [3]. Proximal 40 mm of all major coronary vessels >2 mm in diameter as well as the SCAD-related vessel were included. The primary outcome was pancoronary PCAT defined as mean PCAT in the right (RCA), left anterior descending (LAD) and circumflex (LCX) artery. Secondary outcome was vessel-specific PCAT defined as PCAT in RCA and averaged PCAT in LAD and LCX (PCAT LCA).

Results

The final cohort comprised 35 patients with recent SCAD (median 6.1 mo. [4.0–16.8] since SCAD, 94.3% female) and 35 patients in the non-SCAD group. Pancoronary PCAT was higher in patients with SCAD compared with non-SCAD group (−80.1 [IQR: −74.5, −84.6] vs. −83.4 HU [−78.7, −88.0], P=0.008) suggestive of increased coronary inflammation. Vessel-specific PCAT was higher for the RCA (−80.7 [−70.4, −86.9] vs. −85.3 [−80.4, −90.6] HU, P<0.001) and borderline higher for the LCA (−79.2 [−73.9, −83.2] vs. −83.4 [−78.0, −88.3] HU, P=0.056) in patients with SCAD compared with non-SCAD respectively (Figure 1B). In patients with SCAD, PCAT in previously dissected vessel was not significantly different from averaged PCAT in unaffected vessels (−78.4 [−73.7, −89.0] vs. −80.9 [−74.9, −83.3], P=0.77; Figure 1C). While PCAT numerically decreased with time since SCAD, the association was not statistically significant when patients were stratified into tertiles according to time from SCAD (Figure 1D).

Conclusions

Patients with recent SCAD have higher pericoronary adipose tissue attenuation compared with non-SCAD patients suggesting increased perivascular inflammatory activity. This association is not restricted to the dissected vessel, nor reflected in routine serum inflammatory analysis and persists over time.

Funding Acknowledgement

Type of funding sources: None.

Unsupervised machine learning improves risk stratification of patients with visual normal SPECT myocardial perfusion imaging assessments

Background

Unsupervised machine learning has the potential to identify new cardiovascular phenotypes and more accurately assess individual risk in an unbiased fashion.

Purpose

We aimed to use unsupervised learning to identify, analyze, and risk-stratify subgroups of patients with normal perfusion by visual interpretation on single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI).

Methods

We included consecutive patients with visual normal clinical assessment (summed stress score of 0) from the multicenter (9 sites), REFINE SPECT registry. We considered 23 clinical, 17 image-acquisition, and 26 imaging variables. Optimal dimensionality reduction (Uniform Manifold Approximation and Projection), clustering (Gaussian Mixture Model), and number of clusters were selected to maximize the silhouette coefficient (how similar a patient is to those in their own cluster compared to other clusters). Risk stratification for all-cause mortality (ACM) and major adverse cardiac events (MACE) was assessed within these clusters and compared to risk stratification by quantitative ischemia (<5%, 5–10%, >10%) using Kaplan-Meier curves and Cox Proportional-Hazards analysis.

Results

In total, 17,527 (of 30,351) patients in the registry had visually normal perfusion, 49.7% female, median age of 64 [55, 72] years. There were 1,138 ACM events and 2,091 MACE events with a median follow-up of 4.1 [2.9, 5.7] years. Unsupervised learning provided better risk stratification for both ACM and MACE compared to quantitative ischemia (Figure). Notably, the high-risk cluster by unsupervised learning had a hazard ratio (HR) of 9.5 (95% confidence interval [CI]: 7.7–11.7) compared to 1.4 (95% CI: 1.1–1.9) for quantitative ischemia >10%. The high-risk cluster had proportionally more women (45% [low-risk], 51% [medium-risk], 57% [high-risk], all p<0.001), higher body mass indices (26.9, 27.4, 29.6, all p<0.001), prevalence of diabetes (17%, 22%, 33%, all p<0.001), and abnormal rest ECGs (30%, 43%, 64%, p<0.001); with lower rates of family history of coronary artery disease (40%, 33%, 24%, p<0.001). Patients in the low-risk cluster were more likely to undergo exercise stress (100%, 38%, 0%, all p<0.001), had lower rest peak systolic blood pressure (130, 131, 140 mmHg, all p<0.001), and higher stress peak systolic blood pressure (164, 150, 131 mmHg, all p<0.001). Patients in the high-risk cluster had higher left ventricular mass (129, 135.45, 143.9 g, all p<0.001) and stress volume (57, 59, 66 ml, all p<0.001).

Conclusion

Unsupervised learning identified new phenotypic clusters for SPECT MPI patients with visual normal assessments which provided improved risk stratification for ACM and MACE compared to SPECT ischemia. Such individualized risk assessment may allow better targeted management of patients with visually normal perfusion.

Funding Acknowledgement

Type of funding sources: Public Institution(s). Main funding source(s): Research reported in this publication was supported by the National Heart, Lung, And Blood Institute of the National Institutes of Health under Award Number R01HL089765. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.

18F-Sodium fluoride positron emission tomography, aortic disease activity and ischaemic stroke risk

Background

Arterial 18F-sodium fluoride (18F-NaF) activity on positron emission tomography (PET) is a marker of active microcalcification and atherosclerosis. Coronary 18F-NaF activity (CMA) predicts coronary artery disease progression and subsequent myocardial infarction.

Objective

To investigate whether aortic 18F-NaF activity (AMA) predicts thoracic aortic atherosclerotic disease progression and subsequent ischaemic stroke or myocardial infarction in patients with established cardiovascular disease.

Methods

In a post-hoc observational cohort study, we evaluated AMA and CMA in patients with stable coronary artery disease (n=239) or aortic stenosis (n=158) who had underwent thoracic 18F-NaF PET and computed tomography (CT). We assessed the associations between AMA or CMA and progression of calcified atherosclerotic plaque in both thoracic aortic and coronary territories on follow up CT, as well as subsequent ischaemic stroke or myocardial infarction.

Results

In 141 and 231 patients with repeat aortic and coronary CT imaging respectively at 12.7±2.7 months, AMA correlated with log progression of thoracic aortic calcium scores (r=0.21, p=0.011), volume (r=0.29, p<0.01) and mass (r=0.29, P<0.01) as well as log coronary calcium score progression (r=0.21, p=0.03). CMA correlated with log coronary (r=0.42, p<0.01), but not log aortic (p>0.80) calcium score progression. In 397 patients, 16 had an ischaemic stroke and 25 had a myocardial infarction after 4.7±1.6 years. After adjusting for clinical risk factors, CMA and calcium scoring, AMA was associated with stroke (hazard ratio, 1.71 [95% confidence interval 1.00–2.90], p=0.048]). AMA was superior to clinical risk and calcium scores in identifying patients with stroke (c-statistic 0.76 versus 0.58 versus 0.63 respectively, p<0.05). Survival analysis demonstrated that AMA was associated with ischaemic stroke (p<0.001) but not myocardial infarction (p=0.45), whereas CMA was associated with myocardial infarction (p<0.001) but not stroke (p=0.39).

Conclusions

In patients with established cardiovascular disease, AMA is associated with progression of aortic atherosclerosis and future ischaemic stroke. Arterial 18F-NaF identifies localised areas of atherosclerotic disease activity that relate to regional atherothrombotic events.

Funding Acknowledgement

Type of funding sources: Other. Main funding source(s): British Heart Foundation AMA, disease progression and outcomesVariables associated with stroke

Association of coronary artery calcium score groups with qualitative and quantitatively assessed adverse plaque

Introduction

Coronary artery calcification is a marker of cardiovascular risk, but its association with qualitatively and quantitatively assessed plaque subtypes on coronary computed tomography (CT) angiography (CCTA) is unknown.

Methods

In this post-hoc analysis, CT images and clinical outcomes were assessed in SCOT-HEART trial participants. Agatston coronary artery calcium score (CACS) was measured on non-contrast CT and was stratified as zero (0 Agatston units, AU), minimal (1 to 9AU), low (10 to 99AU), moderate (100 to 399AU), high (400 to 999AU) and very high (≥1000AU). Adverse plaques were investigated with qualitative (visual categorisation of positive remodelling, low-attenuation plaque, spotty calcification, napkin ring sign) and quantitative (calcified, non-calcified, low-attenuation and total plaque burden) methods.

Results

Images of 1769 patients were assessed (mean age 58±9 years, 56% male, median Agatston score 21 [interquartile range 0 to 230] AU). Of these 36% had a zero, 9% minimal, 20% low, 17% moderate, 10% high and 8% very high CACS. Amongst patients with a zero CACS, 14% had nonobstructive disease, 2% had obstructive disease, 2% had visually assessed adverse plaques and 13% had quantitative low-attenuation plaque (LAP) burden >4% (Figure 1). Non-calcified and low-attenuation plaque burden increased between patients with zero, minimal and low CACS (p<0.001), but there was no difference between those with medium, high and very high CACS. Over a median follow-up of 4.8 [4.1 to 5.7] years, fatal or non-fatal myocardial infarction occurred in 41 patients, 10% of whom had zero CACS. CACS ≥1000AU (Hazard ratio (HR) 4.55 [1.20 to 17.3], p=0.026) and low-attenuation plaque burden (HR 1.74 [1.19 to 2.54], p=0.004) were the only predictors of myocardial infarction, independent of obstructive disease and cardiovascular risk score. Figure 2 shows example CCTA images in a patient with zero CACS, non-calcified plaque (red), low attenuation plaque (orange) burden >4% and obstructive disease in the left anterior descending coronary artery.

Conclusions

In patients with stable chest pain, a zero CACS is associated with a good prognosis, but 1 in 6 have coronary artery disease, including the presence of adverse plaques.

Funding Acknowledgement

Type of funding sources: Private grant(s) and/or Sponsorship. Main funding source(s): British Heart Foundation, National Institute of Health/National Heart, Lung, and Blood Institute

Thoracic aortic parallel stent-graft behaviour when subjected to radial loading

To manage complex aortic arch disease using minimally invasive techniques, interventionalists have reported the use of multiple stent-graft devices deployed in a parallel configuration. The structural device-device and device-artery interactions arising during aortic arch parallel endografting, also known as chimney thoracic endovascular aortic repair (ch-TEVAR), is not well understood. Through the use of a radial force testing system we sought to characterise both the loading and deformation behaviour of parallel endografts in representative ch-TEVAR configurations. Four commercially available devices (Bentley BeGraft, Gore TAG, Gore Viabahn, and Medtronic Valiant) were subjected to uniform radial load individually, and in six combinations, to quantify loading profiles. Image data collected during testing were analysed to evaluate mechanical deformations in terms of gutters, chimney and main endograft compression, as well as graft infolding. Parallel endografting was found to increase radial loads when compared to standard TEVAR. Chronic outward force during ch-TEVAR was dependent on main endograft manufacturer, with TAG combinations leading to consistently higher loads than Valiant, but independent of chimney graft type. Endograft deformations were dependent on chimney graft type, with Viabahn combinations presenting with lower gutter areas and increased lumen compression than BeGraft. Chimney graft deformations were also influenced by deployment arrangement in the case of double ch-TEVAR. This study emphasizes the significant variability in both radial loads and mechanical deformations between clinically relevant ch-TEVAR configurations.

18F-Sodium fluoride PET/CT detects transcatheter aortic valve degeneration

Funding Acknowledgements

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): This work was supported by the British Heart Foundation, London, United Kingdom

Background

Early detection of transcatheter aortic valve implantation (TAVI) degeneration is challenging and only feasible when advanced haemodynamic valve dysfunction is apparent. 

Purpose

We tested whether 18F-sodium fluoride (18F-NaF) positron emission tomography and computed tomography (PET/CT) could detect structural TAVI degeneration and haemodynamic valve dysfunction. 

Methods

After TAVI implantation, patients underwent baseline echocardiography, CT angiography and 18F-NaF PET/CT (Figure). We assessed for morphological changes, stenosis or regurgitation on Doppler echocardiography, CT (hypoattenuated leaflet thickening [HALT] or spotty calcification) and PET (18F-NaF uptake; maximum target-to-background ratio, TBRmax). We categorised structural valve degeneration (SVD) according to the standardised definition for surgical and transcatheter bioprosthetic valves, as proposed in a recent consensus statement. 

Results

We recruited 47 patients (81 ± 6 years old, 79% male) 1 month (n = 9), 2 years (n = 22) or 5 years (n = 16) after TAVI: 25 (53%) had received a balloon expanded bioprosthesis and 22 (47%) a self-expanding valve. There was moderate valve dysfunction on Doppler echocardiography in 3 (6%) patients, HALT on CT in 6 (13%) patients, spotty calcification in one patient and 18F-NaF uptake in 7 patients (15%) (TBRmax range: 1.59-5.88); all enrolled 5 years post-TAVI.

All patients with increased 18F-NaF uptake (TBRmax ≥1.59) demonstrated either SVD without haemodynamic valve dysfunction (stage 1, n = 4) or structural valve dysfunction with moderate valve dysfunction and mean transprosthetic pressure gradients >20 mmHg (stage 2, n = 3). In patients without increased 18F-NaF uptake there was no evidence of structural valve degeneration (n = 40).

Within the increased 18F-NaF uptake (n = 7) group, patients with stage 2 SVD (n = 3) demonstrated higher uptake compared to patients with stage 1 SVD (TBRmax 4.3 [3.02-5.88] versus 1.8 [1.59-2.28]). Patients with stage 2 SVD (n = 3) had over 3 times higher TBRmax than those without SVD (n = 40) (4.30 [3.02, 5.88] versus 1.31 [1.21, 1.46]; p < 0.001); Figure).

Conclusion

18F-NaF PET/CT detects patients with SVD and potentially identifies those at risk of valve failure.

Abstract Figure.

Infarct-related artery and long-term mortality following recurrent ST-elevation myocardial infarction; insights from a Polish nationwide registry

Background

Recurrent ST-elevation myocardial infarction (rSTEMI) occurs either as an acute thrombotic event in the same (target-vessel, TV-STEMI) or different vessel (non-target, nonTV-STEMI) compared with the first infarction. Little is known about the frequency of rSTEMI in the era of primary percutaneous coronary intervention (PCI) and about the impact of the infarct-related artery (IRA) on long-term prognosis.

Purpose

We hypothesized that long-term mortality after rSTEMI varies according to IRA (either same or different compared with first STEMI).

Methods

We retrospectively analysed data from the Polish Registry of Acute Coronary Syndromes (PL-ACS) and identified survivors of first STEMI treated with PCI who experienced rSTEMI and were discharged home. We divided rSTEMI into TV-STEMI and nonTV-STEMI group. We compared baseline clinical, angiographic and procedural characteristics and utilized propensity score matching to adjust for baseline differences. 1-, 3- and 5-year all-cause mortality was obtained from the Polish National Health Fund. Categorical variables were presented as counts and percentages and compared using Chi2 test. Continuous variables were presented as medians and interquartile ranges and compared using Mann-Whitney test. The registry was approved by local Ethics Committee and meets the conditions of the Declaration of Helsinki

Results

Between January 2003 and August 2019 a total of 3517 patients (mean age 62.9 years, 75% male) had rSTEMI, of whom 1941 (55%) had TV- and 1576 (45%) had nonTV-STEMI after 615 (77, 1683) days since first infarction (Figure 1). Patients with nonTV-STEMI had higher BMI (27.2 vs 26.8 kg/m2, p=0.03), more hypertension (76.9 vs. 73.5%, p=0.02) and atrial fibrillation (4.7 vs. 3.3%, p=0.04), but had lower left ventricular ejection fraction (43 [35,50] vs. 45 [38,50], p<0.001) compared with TV-STEMI. On coronary angiography nonTV-STEMI had more frequently TIMI flow ≥1 (44.9 vs. 28.0%, p<0.001), multivessel disease (51.8 vs. 41.1%, p=0.003), culprit lesion located in circumflex artery (15.2 vs. 4.8, p<0.001) and more frequently underwent stenting (88.4 vs. 76.1%, p<0.001) compared with TV-STEMI. There was no difference in unadjusted 1-, 3- and 5-year mortality between nonTV-STEMI and TV-STEMI group (14.9 vs. 14.7%, p=0.9; 23.4 vs. 24.2%, p=0.64 and 29.6 vs. 32.9%, p=0.1 respectively). The propensity-score matching of 825 patients with TV- and 826 patients with nonTV STEMI suppressed all baseline differences, but adjusted mortality remained similar between study groups (Figure 1).

Conclusion

While patients with recurrent nonTV-STEMI have different clinical and angiographic characteristics compared with TV-STEMI, the long-term mortality in these groups is similar.

Figure 1

Funding Acknowledgement

Type of funding source: None

18F-sodium fluoride coronary uptake in patients with coronary artery bypass grafts

 

18F-Sodium fluoride (18F-NaF) positron emission tomography (PET) provides an assessment of active calcification (microcalcification) across a wide range of cardiovascular conditions including coronary artery disease, carotid and penile atherosclerosis, aortic and mitral valve disease, and abdominal aortic aneurysms. To date the significance of 18F-NaF uptake in patients with coronary artery bypass grafts (CABG) is unknown.

We aimed to characterize 18F-NaF activity in CABG patients.

We performed 18F-NaF PET (30-min long single bed position acquisition 1h after a 250mB injection of 18F-NaF) and coronary CT angiography in patients with multivessel coronary artery disease and followed them for fatal or non-fatal myocardial infarction over 42 [31,49] months. On motion-corrected datasets we quantified the whole-vessel coronary 18F-NaF PET uptake (the coronary microcalcification activity (CMA)) by measuring the activity of voxels above the background (right atrium activity) + 2 * standard deviations threshold. All study subjects underwent a comprehensive baseline clinical assessment including evaluation of their cardiovascular risk factor profile with the SMART [Secondary Manifestations of Arterial Disease] risk score calculated, and the coronary calcium burden assessed with calcium scoring (CCS).

Among 293 study participants (65±9 years; 84% male), 48 (16%) had a history of CABG. Although the majority 124/128 (97%) of coronary bypass grafts showed no uptake, 4 saphenous vein grafts presented with a CMA>0 (range: 2.5–11.5, Figure). While a similar proportion of patients with and without prior CABG showed increased coronary 18F-NaF uptake (CMA>0) (58.3% versus 71.4%, p=0.11) overall prior-CABG subjects had higher CMA (2.0 [0.3, 6.6] versus 0.6 [0, 2.7], p=0.001) and CCS (1135 [631, 2120] versus 225 [59, 542], p<0.001), respectively. In line with the differences in the calcification activity and the coronary calcium burden, the SMART risk scores were higher in CABG patients (23 [17, 28] versus 17 [12, 24], p=0.01), and these patients were also older (68±8 versus 64±8, p=0.01). Despite the aforementioned differences the incidence of myocardial infarction 5/48 (9%) versus 15/245 (6%) and MACE 6/48 (12%) versus 34/245 (14%) during follow-up between subjects with and without prior CABG was similar (p=0.44 and p=0.80, respectively).

CABG patients have a higher coronary microcalcification activity on 18F-NaF PET than multivessel coronary artery disease patients without prior CABG. Despite evidence of higher 18F-NaF uptake there is no difference in outcome between these two groups.

Figure 1. 18F-NaF uptake in CABG patients. (A) 63-year old male with prominent uptake in stented saphenous vein bypass grafts and native coronary arteries who experienced a non-fatal non ST elevation myocardial infarction during follow-up. (B) 70-year old male with evident uptake in native coronary arteries and only little 18F-NaF activity within coronary bypasses.

Funding Acknowledgement

Type of funding source: Other. Main funding source(s): National Heart, Lung, and Blood Institute/National Institute of Health (NHLBI/NIH), British Heart Foundation

Non-invasive quantitative characterization of aortic valve tissue composition from computed tomography angiography improves patient risk stratification in transcatheter aortic valve implantation

Background

Computed tomography angiography (CTA) performed for procedural planning of transcatheter aortic valve implantation (TAVI) can be used for a more complete characterization of aortic valve tissue beyond calcium assessment. Combining quantitative data on both noncalcified and calcified tissues may improve differentiation of aortic stenosis (AS) subtypes and prognostication post-TAVI.

Purpose

We sought to noninvasively assess aortic valve tissue composition with quantitative cardiac CTA in patients with AS and its prognostic vaalue in those who underwent TAVI.

Methods

In 185 consecutive AS patients in a prospective registry who underwent cardiac CTA before TAVR and 90 matched controls with normal aortic valves, non-luminal aortic valve tissue were identified using semi-automated software as non-calcified (low-attenuation [−30 to 30 Hounsfield Units (HU)], fibro-fatty (31 to 130 HU), fibrous (131 to 350 HU) and calcified (>650 HU) tissue; with total tissue as (non-calcified + calcified components). Volumes of each component and composition [(tissue component volume/total tissue volume) ×100%] were quantified. The association of aortic valve composition and clinical outcomes post-TAVI including all-cause mortality was evaluated using Valve Academic Research Consortium (VARC)-2 definitions.

Results

AS patients had greater aortic valve tissue volume (median 2000.2, vs 527.8 mm3, p<0.001) with a higher calcified tissue composition (41.8% vs 3.4%, p<0.001) compared to controls. Total aortic valve tissue (noncalcified and calcified) volume yielded the highest area under the operating curve (AUC) for diagnosing severe AS (0.93,95% CI:0.93–0.99) as compared to calcified tissue volume alone (0.87,95% CI:0.81–0.94, p=0.002). Low-flow low-gradient AS was associated with increase in total tissue volume compared to controls (1515.3 vs 527.8 mm3, p<0.001), with lower volumes of calcified tissue than high-gradient AS (412.5 vs 829.6 mm3, p<0.001). Device success was achieved in 88% (164 of 185) patients and prevalence of moderate or severe paravalvular leak was 3.8%, however no differences between in aortic valve composition were observed in patients with and without device success. Early safety endpoints occurred in 16.1% (29 of 180) patients and 30-day all-cause mortality was 4.4%. Whereas only calcified tissue volume was related to VARC-2 early safety, AUC for prediction of 30-day mortality post-TAVI was 0.793 (95% CI:0.685–0.901) for total tissue volume and 0.776 (95% CI:0.676–0.876) for calcified tissue volume.

Conclusions

Quantitative CTA assessment of aortic valve tissue volume and composition can improve identification of high-gradient AS and low-flow low-gradient AS patients referred for TAVI and predict 30-day mortality post-TAVI.

Funding Acknowledgement

Type of funding source: Public grant(s) – National budget only. Main funding source(s): National Heart, Lung, and Blood Institute (NHLBI)

5963Automated quantification of epicardial adipose tissue from non-contrast CT on multi-center and multi-vendor data using deep learning

Background

Epicardial adipose tissue (EAT), a metabolically active visceral fat depot surrounding the coronary arteries, has been shown to promote the development of atherosclerosis in underlying coronary vasculature.

Purpose

We evaluate the performance of deep learning (DL), a sub-group of machine learning algorithms, for robust and fully automated quantification of EAT on multi-center cardiac CT data.

Methods

In this study, 850 non-contrast calcium scoring CT scans, from multiple cohorts, scanners and protocols, with manual measurements of EAT from 3 different readers were considered. The DL method was based on a convolutional neural network trained to reproduce the expert measurement. DL global performance was first assessed using all the scans, and then compared to inter-observer variability on a subset of 141 scans. Finally, automated EAT progression was compared to manual measurement using baseline and follow-up serial scans available for 70 subjects. The proposed model was validated using 10-fold cross validation.

Results

Automated quantification was performed in 1.57±0.49 seconds compared to 15 minutes for manual measurement. DL provided high agreement with expert manual quantification for all scans (R=0.974, p<0.001) with no significant bias (0.53 cm3, p=0.13). EAT volume was higher in patients with hypertension (+18.02 cm3, p<0.001, N=442), with diabetes (+18.33 cm3, p<0.001, N=75) and with hypercholesterolemia (+7.33 cm3, p=0.039, N=508). Manual EAT volumes measured by two experienced readers on 141 scans were highly correlated (R=0.984, p<0.001) but presented a significant difference of 4.35 cm3 (p<0.001). On these 141 scans, DL quantifications were highly correlated to both experts' measurements (R=0.973, p<0.001; R=0.979, p<0.001) with significant and non-significant bias for readers 1 and 2 (5.19 cm3, p<0.001; 0.84 cm3, p=0.26), respectively. In 70 subjects, EAT progression quantified by DL correlated strongly with EAT progression measured by the expert reader (R=0.905, p<0.001) with no significant bias (0.64 cm3, p=0.43), and was related to increased non-calcified plaque burden quantified from coronary CT angiography (5.7% vs 1.8%, p=0.026).

Automated vs. manual EAT volume

Conclusion

Deep learning allows rapid, robust and fully automated quantification of EAT from calcium scoring CT. It performs as an expert reader and can be implemented for routine cardiovascular risk assessment.

Acknowledgement/Funding

1R01HL133616/01EX1012B/Adelson Medical Research Foundation

5966Whole-vessel coronary 18F-sodium fluoride coronary microcalfication activity is associated with Low density plaque

Background

18F-sodium fluoride (18F-NaF) showed promise in imaging vulnerable coronary plaques. To date reporting of the highest per patient target to background ratio (TBR), total number of lesions with visual uptake and whole-heart tracer activity have been proposed. Unfortunately, each of these approaches has limitations which become especially prominent in patients with multiple foci of uptake, where reproducible global per-vessel measures are required. In oncology, the total metabolic active tumor volume has been found to be a significant prognostic factor for disease progression, recurrence and death. We evaluated if such methodology could be applied to coronary PET imaging.

Purpose

To quantify whole-vessel coronary 18F-NaF PET activity by utilizing automatically derived coronary vessel regions of interest (ROI) from CT angiography and assess the relationship between coronary microcalcification activity (CMA) and per vessel quantitative plaque characteristics on coronary CT angiography (CTA).

Methods

Twenty patients (68±6 years old, 70% males) with multivessel coronary artery disease underwent a 30 min single bed position PET 1h after a 250mB injection of 18F-NaF and CTA on a hybrid PET/CT scanner. We assessed coronary 18F-NaF uptake using novel whole-vessel tubular and tortuous 3D ROIs which were automatically extracted from CTA datasets. Within such ROIs we measured mean standard uptake value (SUV), maximum TBR (TBRmax) and the activity of voxels (CMA) above 1.25 the background SUV (left atrium activity). We used a previously established 1.25 TBRmax threshold to distinguish vessels positive and negative for 18F-NaF uptake. Coronary CTA datasets were analyzed by semi-automated software to quantify volumes and percentage lesion content of non-calcified plaque (NCP), low-density non-calcified plaque (LD-NCP, attenuation <30 Hounsfield units) and calcified plaque (CP).

Results

13 (65%) patients and 24 (40%) out of 60 main epicardial vessels presented with 18F-NaF uptake exceeding the 1.25 TBRmax threshold. While coronaries positive for uptake had higher CMA 0.92 [0.17, 2.03] vs 0.0, p<0.001 and TBRmax 1.42 [1.35, 1.74] vs 1.09 [1.0, 1.19], there was no difference in whole-vessel SUVmean 0.90 [0.77, 1.17] vs 0.87 [0.78, 0.96], p=0.33 compared to 18F-NaF negative arteries. Of the quantitative plaque characteristics vessels positive for uptake had higher NCP 278.4 [145.6, 576.9] vs 184.6 [63.8, 367.0]mm3, p=0.030; and LD-NCP 8.4 [0.3, 11.0] vs 2.7 [12.1, 43.5]mm3, p=0.01. CMA showed a stronger correlation with LD-NCP (r=0.70, p<0.001) than TBRmax (r=0.52, p<0.001). On regression analysis LD-NCP acted as an independent predictor of CMA after adjustments for CP and vessel SUVmean (p<0.001).

Figure 1

Conclusions

Whole-vessel 18F-NaF coronary microcalcification activity assessment with CT angiography automatically derived 3-dimensional ROIs is feasible and the measured coronary microcalcification burden correlates well with low density plaque.

Acknowledgement/Funding

This research was supported by grants R01HL135557 and R01HL133616 from the NHLBI/NIH and a grant from the Dr. Miriam & Sheldon G. Adelson MRF

Staphylococcus aureus Aggregation and Coagulation Mechanisms, and Their Function in Host-Pathogen Interactions

The human commensal bacterium Staphylococcus aureus can cause a wide range of infections ranging from skin and soft tissue infections to invasive diseases like septicemia, endocarditis, and pneumonia. Muticellular organization almost certainly contributes to S. aureus pathogenesis mechanisms. While there has been considerable focus on biofilm formation and its role in colonizing prosthetic joints and indwelling devices, less attention has been paid to nonsurface-attached group behavior like aggregation and clumping. S. aureus is unique in its ability to coagulate blood, and it also produces multiple fibrinogen-binding proteins that facilitate clumping. Formation of clumps, which are large, tightly packed groups of cells held together by fibrin(ogen), has been demonstrated to be important for S. aureus virulence and immune evasion. Clumps of cells are able to avoid detection by the host's immune system due to a fibrin(ogen) coat that acts as a shield, and the size of the clumps facilitates evasion of phagocytosis. In addition, clumping could be an important early step in establishing infections that involve tight clusters of cells embedded in host matrix proteins, such as soft tissue abscesses and endocarditis. In this review, we discuss clumping mechanisms and regulation, as well as what is known about how clumping contributes to immune evasion.

Pectus excavatum in mummies from ancient Egypt

Pectus excavatum is one of the common congenital anomalies, yet there seems to be a suspicious absence of any cases or descriptions of this deformity from antiquity. This could represent a real change in disease prevalence but is more likely just due to an inadequate reporting in medico-historical literature. The current study reviews reports of computed tomography (CT) scans of 217 ancient Egyptian mummies, revealing 3 presumed cases of this deformity. Therefore, pectus excavatum was in fact present already in ancient times, with prevalence roughly similar to the modern one.

No rheumatoid arthritis in ancient Egypt: a reappraisal

Antiquity of rheumatoid arthritis (RA) remains controversial, and its origins in Americas or in the Old World are disputed. Proponents of the latter frequently refer to RA in ancient Egypt, but validity of those claims has never been examined. Review of all reported RA cases from ancient Egypt revealed that none of them represent real RA, instead being either examples of changing naming conventions or of imprecise diagnostic criteria. Most cases represented osteoarthritis or spondyloarthropathies. Also review of preserved ancient Egyptian medical writings revealed many descriptions of musculoskeletal disorders, but none of them resembled RA. This suggests that RA was absent in ancient Egypt and supports the hypothesis of the New World origin of RA and its subsequent global spread in the last several centuries.

Biofilm formation by pathogenic Prototheca algae

Prototheca microalgae are the only plants known to cause infections in humans and animals. The mechanisms of Prototheca infections are poorly understood, and no good treatments are available. Biofilms-surface-attached, three-dimensional microbial communities contributing to chronic infections-are formed by many pathogenic bacteria and fungi, but it is not known if Prototheca algae also have this ability. This study shows that various Prototheca species form biofilms composed of surface-attached cells in all growth phases, linked together by matrix containing DNA and polysaccharides. Biofilm formation was modulated by the presence of host plasma or milk. Compared to planktonic cells, Prototheca biofilms caused decreased release of IL-6 by mononuclear immune cells and responded differently to treatment with antimicrobials. Prototheca biofilms possibly contribute to chronic and hard-to-treat character of those algal infections.

SIGNIFICANCE AND IMPACT OF THE STUDY

Prototheca algae are the only existing pathogenic plants. Almost nothing is known about mechanisms of Prototheca infections. This study identifies that, similar to pathogenic bacteria and fungi, Prototheca algae can form biofilms. These biofilms induce reduced immune cell activation relative to planktonic cells, and are also less susceptible to antimicrobials. Biofilm formation by Prototheca could be the first in vitro correlate of pathogenicity, opening a new research field for this pathogen.

Staphylokinase Control of Staphylococcus aureus Biofilm Formation and Detachment Through Host Plasminogen Activation

Staphylococcus aureus biofilms, a leading cause of persistent infections, are highly resistant to immune defenses and antimicrobial therapies. In the present study, we investigated the contribution of fibrin and staphylokinase (Sak) to biofilm formation. In both clinical S. aureus isolates and laboratory strains, high Sak-producing strains formed less biofilm than strains that lacked Sak, suggesting that Sak prevents biofilm formation. In addition, Sak induced detachment of mature biofilms. This effect depended on plasminogen activation by Sak. Host-derived fibrin, the main substrate cleaved by Sak-activated plasminogen, was a major component of biofilm matrix, and dissolution of this fibrin scaffold greatly increased susceptibility of biofilms to antibiotics and neutrophil phagocytosis. Sak also attenuated biofilm-associated catheter infections in mouse models. In conclusion, our results reveal a novel role for Sak-induced plasminogen activation that prevents S. aureus biofilm formation and induces detachment of existing biofilms through proteolytic cleavage of biofilm matrix components.

CTLA4 Immunoglobulin but Not Anti-Tumor Necrosis Factor Therapy Promotes Staphylococcal Septic Arthritis in Mice

BACKGROUND

The development of biologics has greatly increased the quality of life and the life expectancy of many patients with rheumatoid arthritis. However, a large number of these patients have an increased risk of developing serious infections. The aim of this study was to examine differential effects of anti-tumor necrosis factor (TNF) treatment and CTLA4 immunoglobulin (Ig) treatment on both immunological response and host defense in a murine model of septic arthritis.

METHODS

Abatacept (CTLA4-Ig), etanercept (anti-TNF), or phosphate-buffered saline were given to NMRI mice intravenously inoculated with Staphylococcus aureus. The clinical course of septic arthritis and histopathological and radiological changes of joints were compared among the groups.

RESULTS

Mice receiving CTLA4-Ig treatment had more-severe septic arthritis, compared with controls and mice receiving anti-TNF treatment. Anti-TNF treatment led to more-severe weight loss and kidney abscesses, as well as a higher bacterial burden in the kidneys. Mice receiving CTLA4-Ig therapy had lower serum levels of interleukin 4, whereas mice receiving anti-TNF therapy had higher levels of TNF-α. Both iNOS and arginase-1 expression were reduced in peritoneal macrophages from mice receiving CTLA4-Ig, compared with expression in the anti-TNF group.

CONCLUSIONS

CTLA4-Ig therapy significantly increased the susceptibility to S. aureus septic arthritis in mice, whereas anti-TNF therapy deteriorated host bacterial clearance, resulting in more-severe weight loss and kidney abscesses.

Antibiotic-killed Staphylococcus aureus induces destructive arthritis in mice

OBJECTIVE

Permanent reduction in joint function is a severe postinfectious complication in patients with Staphylococcus aureus septic arthritis. We undertook this study to determine whether this reduction in joint function might be caused by persistent joint inflammation after the adequate eradication of bacteria by antibiotics.

METHODS

After intraarticular injection of cloxacillin-killed S aureus into mouse knee joints, we investigated whether antibiotic-killed S aureus induced joint inflammation and elucidated the molecular and cellular mechanisms of this type of arthritis.

RESULTS

Intraarticular injection of antibiotic-killed S aureus induced mild-to-moderate synovitis and bone erosions that lasted for a minimum of 14 days. Compared with wild-type animals, mice deficient in tumor necrosis factor receptor type I (TNFRI), receptor for advanced glycation end products (RAGE), or Toll-like receptor 2 (TLR-2) had a significantly reduced frequency and severity of synovitis. Combined depletion of monocytes and neutrophils also resulted in a significantly lower frequency of synovitis. Among bacterial factors, insoluble cell debris played a more important role than bacterial DNA or soluble components in inducing joint inflammation. Importantly, anti-TNF therapy abrogated joint inflammation induced by antibiotic-killed S aureus.

CONCLUSION

Antibiotic-killed S aureus induced and maintained joint inflammation mediated through TLR-2, TNFRI, and RAGE. The cross-talk between neutrophils and monocytes is responsible for this type of arthritis. Anti-TNF therapy might be used as a novel strategy, in combination with antibiotics, to treat staphylococcal septic arthritis.

Surface proteins of Staphylococcus aureus play an important role in experimental skin infection

Staphylococcus aureus is the most common cause of skin infections that range from mild diseases up to life-threatening conditions. Mechanisms of S. aureus virulence in those infections remain poorly studied. To investigate the impact of S. aureus surface proteins on skin infection, we used mouse models of skin abscess formation and skin necrosis, induced by a subcutaneous injection of bacteria. In the skin abscess model, a sortase-deficient S. aureus strain lacking all of its cell-wall anchored proteins was less virulent than its wild-type strain. Also, strains specifically lacking protein A, fibronecting binding proteins, clumping factor A or surface protein SasF were impaired in their virulence. When a model of dermonecrosis was studied, the S. aureus surface proteins could not be shown to be involved. In summary, surface proteins play an important role in virulence of S. aureus skin abscess infections, but not in formation of skin necrosis.

The dawn of medicine: ancient egypt and Athotis, the king-physician

The earliest physician recorded in history is Athotis (Aha), one of the first rulers of ancient Egypt. While it is debatable whether the story of a king-physician is a fact or just a legend, it is clear that ancient Egyptian medicine developed around the time of his reign. The fortunate combination of earlier medical observations, the development of script, and favorable social conditions made the dawn of ancient Egypt also the dawn of medicine.

The combination of a tumor necrosis factor inhibitor and antibiotic alleviates staphylococcal arthritis and sepsis in mice

BACKGROUND

Despite advances in medical practices, in recent decades permanent reductions in joint function have not been achieved, and the high mortality rate of patients with staphylococcal septic arthritis has not substantially improved.

METHODS

We evaluated the effects of a combined tumor necrosis factor (TNF) inhibitor and antibiotic therapy on the course of Staphylococcus aureus arthritis and sepsis in mice.

RESULTS

Treatment with the combination of a TNF inhibitor and an antibiotic resulted in a quicker relief of clinical arthritis in mice with septic arthritis, compared with an antibiotic monotherapy. Both histopathologically verified synovitis and the extent of joint destruction were reduced by this combined treatment. Importantly, anti-TNF treatment significantly improved the survival rate of mice with S. aureus sepsis and staphylococcal enterotoxin shock syndrome; this effect might be the result of a partial restoration of the hemostatic balance between coagulation and fibrinolysis. Finally, we demonstrated that anti-TNF treatment downregulates high-mobility group protein B1 in staphylococcal enterotoxin shock syndrome.

CONCLUSIONS

Thus, simultaneous systemic TNF inhibition and antibiotic therapy has beneficial effects on the outcome of S. aureus arthritis and sepsis in a mouse model, suggesting that the combination of a TNF inhibitor and antibiotics represents a novel therapeutic strategy for the treatment of staphylococcal infections.

Teaching developmentally disabled persons how to react to fires

Four elements of fire reaction are delineated: investigating, reporting, suppressing, and evacuating areas in which fires are present. Important issues in the acquisition, maintenance, and generalization of fire reaction skills for developmentally disabled persons are identified and reviewed. Learning-based treatment strategies and fire safety literature relevant to the authors' concerns are reviewed. The authors suggest that behavioral research on training should be congruent with fire safety experts' recommendations on fire reaction skills.