Time-related aortic inflammatory response, as assessed with 18F-FDG PET/CT, in patients hospitalized with severely or critical COVID-19

Aim

Arterial involvement has been implicated in the coronavirus disease of 2019 (COVID-19). Fluorine 18-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) imaging is a valuable tool for the assessment of aortic inflammation and is a predictor of outcome. We sought to prospectively assess the presence of aortic inflammation and its time-dependent trend in patients with COVID-19.

Methods

Between November 2020 and May 2021, in this pilot, case-control study, we recruited 20 patients with severe or critical COVID-19 (mean age of 59±12 years), while 10 age and sex-matched individuals served as the control group. Aortic inflammation was assessed by measuring 18F-FDG uptake in PET/CT performed 20–120 days post-admission. Global aortic target to background ratio (GLA-TBR) was calculated as the sum of TBRs of ascending and descending aorta, aortic arch, and abdominal aorta divided by 4. Index aortic segment TBR (IAS-TBR) was designated as the aortic segment with the highest TBR.

Results

There was no significant difference in aortic 18F-FDG PET/CT uptake between patients and controls (GLA-TBR: 1.46 [1.40–1.57] vs. 1.43 [1.32–1.70], respectively, p=0.422 and IAS-TBR: 1.60 [1.50–1.67] vs. 1.50 [1.42–1.61], respectively, p=0.155). There was a moderate correlation between aortic TBR values (both GLA and IAS) and time distance from admission to 18F-FDG PET-CT scan (Spearman's rho=−0.528, p=0.017 and Spearman's rho=−0.480, p=0.032, respectively), Figure 1. Patients who were scanned less than or equal to 60 days from admission (n=11) had significantly higher GLA-TBR values compared to patients that were examined more than 60 days post-admission (GLA-TBR: 1.53 [1.42–1.60] vs. 1.40 [1.33–1.45], respectively, p=0.016 and IAS-TBR: 1.64 [1.51–1.74] vs. 1.52 [1.46–1.60], respectively, p=0.038). There was a significant difference in IAS-TBR between patients scanned ≤60 days and controls (1.64 [1.51–1.74] vs. 1.50 [1.41–1.61], p=0.036), Figure 2.

Conclusion

This is the first study suggesting that aortic inflammation, as assessed by 18F-FDG PET/CT imaging, is increased in the early post-COVID phase in patients with severe or critical COVID-19 and largely resolves over time. Our findings may have important implications for the understanding of the course of the disease and for improving our preventive and therapeutic strategies.

Funding Acknowledgement

Type of funding sources: None.

Effect of 1st line treatment on aortic inflammation as assessed by 18 FDG PET/CT in patients with Hodgkin and non-Hodgkin lymphoma

Background

Despite advances in the treatment of oncology patients, therapy-related side effects may lead to premature morbidity among cancer survivors. Inflammatory activation that has been linked to cardiovascular disease is particularly crucial for the pathogenesis of both Hodgkin (HL) and non-Hodgkin lymphoma (NHL).

Objectives

To assess the vascular effects of chemotherapy in patients with HL and NHL by 18-Fluorodeoxyglucose (FDG PET/CT) and to investigate possible interactions with systemic inflammation as assessed by circulating inflammatory markers.

Methods

Between July 2015 and July 2019, sixty-five consecutive patients (37 males, mean age 56±17.8 years) with histologically confirmed new diagnosis of either HL (n=33) or NHL (n=32), were prospectively studied. PET/CT imaging was performed at baseline, at an interim phase and after 1st line treatment. Aortic FDG uptake was assessed by measuring global aortic TBR. Serum interleukin-6 (IL6) and interleukin-1b (IL1b) were measured at each phase for all patients and served as circulating inflammatory markers.

Results

Patients with HL demonstrated significant reduction in aortic TBR after 1st line treatment (aortic TBRbaseline=1.98, aorticTBR3rdscan=1.75, p=0.001, F=8.335), which remained significant after adjustment for 10-year cardiovascular risk (Framingham risk score), dyslipidemia, hypertension and diabetes (p=0.002, F=7.664). In contrast, patients with NHL did not demonstrate a significant aortic inflammation response (aortic TBRbaseline = 2.13, aorticTBR3rd scan=2.015, p=0.596, F=0.527), Figure 1. Regarding inflammatory markers, after 1st line treatment IL6 levels were reduced significantly in both HL and NHL groups (IL6baseline HL=3.25, IL6 post 1st line treatment HL=0.448, p=0.00; IL6baseline NHL=0.475, IL6 post 1st line treatment NHL=0.144, p=0.001); IL1b levels did not change significantly in either group, Table 1.

Conclusions

We demonstrate for the first time that aortic inflammation as assessed by 18-FDG PET-CT is reduced in HL patients after 1st line treatment but not in NHL patients. These findings imply that different pathophysiological pathways and different therapies might affect the arterial bed in different ways in lymphoma patients. Further, a strong potential role of molecular imaging in cardio-oncology emerges, offering valuable information on disease prognosis and progression with a single examination.

Funding Acknowledgement

Type of funding sources: Foundation. Main funding source(s): Hellenic Society of Hypertension

Radiomics-based analysis by machine learning techniques improves characterization of functionally significant coronary lesions

Background

Computed Tomography Coronary Angiography (CTCA) is an effective non-invasive imaging modality for anatomo-functional assessment of coronary artery disease (CAD). Radiomics features have been used for diagnosis or outcome prediction, however, their potential value for characterizing flow limiting coronary lesions has not been explored.

Purpose

To assess whether application of novel radiomics and machine learning (ML) techniques on CTCA derived datasets improves characterization of functionally significant coronary lesions.

Methods

Consecutive patients with stable chest pain and intermediate pre-test likelihood for CAD, who underwent CTCA and PET-or SPECT-Myocardial Perfusion Imaging (MPI) respectively, were prospectively evaluated and included in the analysis. PET-MPI was considered abnormal when >1 contiguous segments showed both stress Myocardial Blood Flow ≤2.3mL/g/min and Myocardial Flow Reserve (MFR) ≤2.5 for 15O-water or <1.79 mL/g/min and ≤2.0 for 13N-ammonia respectively. Defect reversibility (DR) was defined as a summed difference score (SDS) between stress and rest images ≥2. CTCA and functional images were fused to assign each myocardial segment to the pertinent coronary territory. Stenosis severity, plaque characteristics and radiomic plaque features were assessed in the total length of the 3 main coronary vessels. In total, 1765 features were extracted from each vessel and a feature reduction and model creation pipeline was constructed [Figure 1]. Two separate datasets: a) coronary stenosis (≥50%) + plaque characteristics and b) coronary stenosis (≥50%) + plaque characteristics + radiomics were formulated and compared in terms of AUCs accordingly.

Results

A total of 292 coronary vessels (140 with corresponding PET-MPI data and 152 with SPECT MPI data) were analysed. Plaque burden and stenosis severity were the only independent predictors of impaired myocardial perfusion on PET-MPI, with an AUC = 0.749, (95% CI: 0.658–0.826). Stenosis severity, kurtosis, contrast, interquartile range and entropy were predictors of an abnormal PET-MPI result and their combination resulted in an AUC = 0.854, (95% CI: 0.775–0.914). The difference between the 2 models was statistically significant (p-diff: 0.02, 95% CI: 0.0165–0.194). Stenosis severity was the only predictor of a DR on SPECT-MPI, AUC = 0.624 (95% CI: 0.542–0.702). Small Dependence High Gray Level Emphasis, Cluster Prominence, Region Length, wavelet Median and square Median were predictors of a positive SPECT result, with AUC = 0.816, (95% CI: 0.745–0.875). The difference between the two models was statistically significant (p-diff: 0.006, 95% CI: 0.152–0.329)

Conclusion

Radiomic futures can be combined with anatomical and morphological characteristics of coronary lesions in CTCA imaging and provide valuable complementary information for characterizing functionally significant coronary lesions.

Funding Acknowledgement

Type of funding sources: Public grant(s) – EU funding. Main funding source(s): This work was supported from European Regional Development Fund, Operational Programme “Competitiveness, Entrepreneurship and Innovation 2014-2022 (EPAnEK)”, titled: The Greek Research Infrastructure for Personalized Medicine (pMED-GR)

Arterial stiffness improves with effective chemotherapy in patients with lymphoma

Introduction

Arterial stiffness independently predicts cardiovascular risk and has been associated with the presence of inflammation. Chemotherapy-induced cardiac dysfunction is a major contributor to adverse morbidity and mortality rates in cancer patients. There is extensive literature describing the cardiotoxic effects of anti-cancer treatment on left ventricular systolic function, that may be the result of direct effects of the cancer treatment on heart function, or due to an indirect acceleration of atherosclerosis. However there is only little evidence regarding chemotherapy effects on arterial elastic properties. The gold standard for measuring arterial stiffness is carotid femoral pulse wave velocity (cfPWV) and it is calculated as a function of transit time and distance of the pulse wave derived from the carotid and femoral arteries.

Purpose

Our aim was to investigate the effect of chemotherapy in aortic stiffness in patients with lymphoma, a malignancy with known high metabolic burden.

Methods

Sixty-six patients (22 male, mean age 56 years) with Hodgkin (n=34) or non-Hodgkin lymphoma (n=32) were enrolled in the study. Patients with Hodgkin Lymphoma underwent therapy with Doxorubicin, bleomycin, vinblastine and dacarbazine (ABVD). The interim of their treatment was set at 1 to 3 days prior to initiating the 3rd chemotherapy cycle. Patients with non Hodgkin Lymphoma underwent therapy with cyclophosphamide, doxorubicin, vincristine, and prednisone+rituximab (R-CHOP). Blood pressure (BP) and carotid-femoral pulse wave velocity (c-f PWV) were measured at baseline, interim and after completion of chemotherapy.

Results

Changes in systolic and diastolic BP from baseline, to interim phase and 6 weeks post therapy were insignificant (decrease by 3.87±1.37 mmHg p-0.277 and 3.05±0.92 mmHg p-0.422 respectively). Figure illustrates c-f PWV changes from baseline to interim and 6 weeks after completion of chemotherapy. As figure shows, c-f PWV progressively decreased at the interim phase and at 6–8 weeks after chemotherapy completion (by 0.37±0.14 m/s), (overall P-0.010, by ANOVA) The progressive decrease in c-f PWV remained statistically significant after adjustment for age, systolic BP and diabetes (F=5.173, P-0.009). Patients' baseline characteristics are demonstrated in table 1.

Conclusion

Carotid-Femoral PWV decreased at 6–8 weeks post chemotherapy in patients with lymphoma, suggesting that aortic elastic properties improve with chemotherapy in these patients. Considering that aortic stiffness increases due to systemic inflammation and that lymphomas are increased metabolic burden tumors, the significant improvement in arterial stiffness implies that the presence of inflammation caused by the malignancy may play a significant role in the arterial stiffness progression.

Funding Acknowledgement

Type of funding sources: None.

CCTA-derived functional and morphological features and their comparative performance in predicting impaired coronary vasodilatation by PET-myocardial perfusion imaging

Funding Acknowledgements

Type of funding sources: Public grant(s) – EU funding. Main funding source(s): This work was supported in part from European Regional Development Fund, Operational Programme “Competitiveness, Entrepreneurship and Innovation 2014-2020 (EPAnEK)”, titled: The Greek Research Infrastructure for Personalized Medicine (pMED-GR) , no. GR 5002802 ,and by Greece and the European Union (European Social Fund-ESF) through the Operational Programme «Human Resources Development, Education and Lifelong Learning 2014-2020» in the context of the project “Assessment of coronary atherosclerosis: a new complete, anatomo-functional, morphological and biomechanical approach”, Project no. 504776

onbehalf

EVINCI-SMARTOOL

Background/Objectives: The relationship between biomechanical characteristics of a coronary lesion with myocardial blood flow has not been studied. We investigated the relationship between local endothelial shear stress (ESS) and computed tomography coronary angiography (CTCA)-derived anatomical and plaque characteristics data with impaired vasodilating capability assessed by positron emission tomography myocardial perfusion imaging (PET-MPI).

Methods

A total of 92 coronary vessels of 53 patients who have undergone both CTCA and PET-MPI with 15O-water or 13N-ammonia were analysed. PET was considered abnormal when > 1 contiguous segments showed both stress Myocardial Blood Flow (MBF) ≤2.3mL/g/min and Myocardial Flow Reserve (MFR) ≤2.5 for 15O-water or <1.79 mL/g/min and ≤2.0 for 13N-ammonia respectively.  CTCA images were used to assess stenosis severity, lesion specific total plaque volume (PV), non-calcified PV and calcified PV as well as plaque phenotype. ESS was calculated for the full length of a lesion (total), as well as in the proximal, minimum lumen area and distal lesion segments.

Results

ESS was weakly correlated with total PV (rho = 0.273, p = 0.008), non-calcified PV (rho = 0.247, p = 0.017) and the volume of necrotic core (rho = 0.242, p = 0.02). ESS increased progressively with stenosis severity (p ≤ 0.001). ΕSS was also higher in functionally significant vs. non-significant lesions (10.4 [8.04-54.4] Pa vs. 3.9 [2.32-7.29] Pa, p ≤0.001). Addition of ESS to stenosis severity improved prediction (Δ[AUC]:0.113, 95% CI: 0.055 to 0.171, p = 0.0001) of functionally significant lesions.

Conclusion

There is a weak positive association between lesion-specific ESS and plaque volume. ESS increases progressively with stenosis severity and is higher in functionally significant lesions by PET-MPI. The addition of ESS to CTCA-anatomical information improves prediction of an abnormal PET-MPI result.

Prediction of impaired myocardial blood flow (MBF) with the use of machine learning techniques on CTCA based parameters

Funding Acknowledgements

Type of funding sources: Public grant(s) – EU funding. Main funding source(s): This work was supported in part from European Regional Development Fund, Operational Programme “Competitiveness, Entrepreneurship and Innovation 2014-2020 (EPAnEK)”, titled: The Greek Research Infrastructure for Personalized Medicine (pMED-GR) , no. GR 5002802 ,and by Greece and the European Union (European Social Fund-ESF) through the Operational Programme «Human Resources Development, Education and Lifelong Learning 2014-2020» in the context of the project “Assessment of coronary atherosclerosis: a new complete, anatomo-functional, morphological and biomechanical approach”, Project no. 504776

Background

Computed Tomography Coronary Angiography (CTCA) is a non-invasive imaging modality, used effectively for anatomo-functional assessment of coronary artery disease (CAD). Machine learning (ML) processes can effectively allow the extraction of useful information from multidimensional feature spaces for evaluation of coronary lesions.

Purpose

To investigate the ability of ML for predicting impaired myocardial blood flow (MBF) by combining computational fluid dynamics (CFD) derived parameters with quantitative plaque burden, plaque morphology and anatomical characteristics obtained from CTCA.

Methods

53 patients (31 male, mean age 64.7 ± 7.1 years) with intermediate pre-test likelihood of CAD who underwent CTCA and PET-MPI were included. PET was considered positive when > 1 contiguous segment demonstrated MBF ≤ 2.3 mL/g/min for 15O-water or ≤ 1.79 for 13N-ammonia respectively. CFD derived parameters such as a previously validated, virtual functional assessment index (vFAI), segmental endothelial shear stress (ESS), as well as anatomical and plaque characteristics were assessed. Seven classifiers were implemented and internally validated using 5-fold cross validation, repeated 1000 times. Using sequential forward selection (SFS), the highest rank features combination, based on appearances in the highest mean area under curve (AUC) classification scheme, was selected and features performance was evaluated following exhaustive search (ES).

Results

92 coronary segments were analyzed and 34 features derived from CTCA were extracted. Classifiers performance are depicted in Figure A. k-NN was the best classifier with AUCmean = 0.791 (SENSmean= 0.622, SPECmean = 0.840, p < 0.05). Clusters of features and number of appearances are presented in Figure B. The combination of vFAI, stenosis severity and lumen area demonstrated the highest AUC (1473 times). ES results are depicted in Figure C. The combination of vFAI and lumen area was the best predictor among all the combinations (AUCmean = 0.830, SENSmean =0.61, SPECmean =0.83, p < 0.05) followed by vFAI and stenosis severity (AUCmean = 0.81, SENSmean =0.72, SPECmean = 0.87, p < 0.05) and vFAI alone (AUCmean = 0.806, SENSmean =0.61, SPECmean =0.87, p < 0.05).

Conclusion

ML analysis is feasible for predicting with reasonable specificity abnormal MBF by PET, using a combination of CFD derived parameters and anatomical features. vFAI as a single characteristic was a specific predictor of impaired MBF, whilst in combination with stenosis severity, maintained almost the same AUC and specificity values and resulted in improved sensitivity. On the other hand, addition of lumen area to vFAI, increases the AUC and provides a relatively good specificity but low  sensitivity.

Abstract Figure 1

Coronary CT angiography derived features for predicting an abnormal pet myocardial perfusion imaging: a machine learning approach

Background

Computed Tomography Coronary Angiography (CTCA) is an effective non-invasive imaging modality for anatomo-functional assessment of coronary artery disease (CAD). Machine learning (ML) algorithms allow extraction and process of useful information from multidimensional spaces for evaluation of coronary lesions.

Purpose

To investigate the ability of ML to integrate computational fluid dynamics (CFD) derived parameters with quantitative plaque burden, plaque morphology and anatomical characteristics for predicting impaired myocardial flow reserve by PET myocardial perfusion imaging (MPI).

Methods

49 patients (29 male, mean age 65.3±6.3 years) with intermediate pre-test likelihood of CAD who underwent CTCA and PET-MPI were included. PET was considered positive when >1 contiguous segment demonstrated Myocardial flow reserve (MFR) ≤2.5 mL/g/min for 15O-water or ≤2.0 for 13N-ammonia respectively. CDF derived parameters such as a previously validated CT-FFR surrogate, virtual functional assessment index (vFAI), segmental endothelial shear stress (ESS), as well as anatomical and plaque characteristics were assessed. k-nearest neighbor (k-NN), support vector machines (SVM) and feedforward neural networks (FF-NN) were implemented. ML was internally validated using 5-fold cross validation, repeated 100 times. Using sequential forward selection (SFS), the 5 highest rank features based on appearances in each classification scheme were selected and following exhaustive search (ES) the best features combinations were identified. Each classifier's performance was evaluated using an area-under-receiver operating characteristic curve (AUC) analysis.

Results

85 coronary segments were analyzed and 28 features derived from CTCA were extracted. The features ranking for every classifier are depicted in Figure 1. k-NN using a combination only of ESS in the proximal (ESSprox) and distal segment achieved an AUC=0.78 (Sens=0.71, Spec=0.77, p<0.05) for predicting a positive PET result. Combining ESSprox with burden fibrofatty tissue and non-calcified plaque burden, SVM achieved an AUC=0.75 (Sens=0.74, Spec=0.67, p<0.05) whilst for FF-NN, the corresponding AUC was 0.79 (Sens=0.76, Spec=0.7, p<0.05) using ESSprox, vFAI and % Fibrofatty volume. Among the best features combinations, ESSprox was the most consistent one achieving an AUC=0.75 (Sens=0.66, Spec=0.73, p<0.05) for k-NN, AUC=0.73 (Sens=0.58, Spec=0.59, p<0.05), for SVM and an AUC=0.73 (Sens=0.63, Spec=0.62, p<0.05) for FF-NN respectively.

Conclusion

ML analysis is feasible for predicting abnormal MFR by PET using a combination of CFD derived parameters, anatomical and morphological features. ESSprox was present in every combination of best features. As a single characteristic was a moderate predictor of impaired MFR, whilst in combination with plaque characteristics and CFD derived features resulted in improved sensitivity and specificity.

Figure 1

Funding Acknowledgement

Type of funding source: Public grant(s) – EU funding. Main funding source(s): This research is co-financed by Greece and the European Union (European Social Fund-ESF) through the Operational Programme “Human, Resources Development, Education and Lifelong Learning 2014-2020” in the context of the project “Assessment of coronary atherosclerosis: a new complete, anatomo-functional, morphological and biomechanical approach” and from p-Med GR 5002802

Vascular inflammation and cardiovascular burden in metastatic breast cancer female patients receiving hormonal treatment and CDK 4/6 inhibitors or everolimus

Background

Chemotherapy regimens for breast cancer treatment can promote vascular dysfunction and lead to high cardiovascular risk.

Purpose

The aim of this study was to investigate the cardiovascular burden and vascular inflammation in metastatic breast cancer patients receiving either CDK 4/6 inhibitors and hormonal treatment or standard everolimus and hormonal treatment.

Methods

22 consecutive female patients with metastatic breast cancer that expressed estrogen and /or progesteron receptor and were HER2-negative were enrolled. Patients with active infection, chronic autoimmune disease and history of chemotherapy for the metastatic disease and/or adjuvant chemotherapy during the past 3 years were excluded. All subjects received hormonal treatment and of those, 10 received everolimus and 12 received therapy with CDK 4/6 inhibitors. The two groups were matched for age, history of hypertension, diabetes, dyslipidemia, smoking and all were free of major cardiovascular events for the past 6 months. Regional wall thickness (RWT) and left ventricle mass (LVM) measurements by transthoracic echocardiographic study were obtained followed by 24 hour ambulatory blood pressure monitoring, and 18F-fluorodeoxyglucose positron-emission tomography/computed tomography imaging. Radiotracer uptake in the aortic wall (ascending, arch, descending, abdominal), was quantified as tissue-to-background ratio (TBR).Each patient was assessed for the aforementioned parameters before the initiation and after 6 months of treatment.

Results

At follow up, patients assigned to CDK4/6 treatment demonstrated increased measurements of 24 hour systolic blood pressure (SBP) (p=0.004), daytime SBP(p=0.004) and night time SBP (p=0.012) (Group effect). The 24 hour mean arterial pressure measurements were also higher in CDK 4/6 population, in comparison to everolimus that displayed firm values. (Group effect- p=0.035, Interaction effect-p=0.023).Additionally, 24 hour diastolic blood pressure recordings in CDK 4/6 therapy were higher opposed to everolimus that remained consistent (Interaction effect- p=0.010). In CDK 4/6 group, TBR aorta measurements also increased significantly, whereas TBR values in everolimus remained stable. (Interaction effect-p=0.049). Both therapeutic regimens displayed statistically significant damaging effect with regards to the following variables: Night-time SBP (p=0.032), RWT (p<0.001), and LVM (p<0.001).

Conclusion

Chemotherapy with novel CDK 4/6 inhibitors and hormonal treatment can lead to increased vascular inflammation, and higher blood pressure values compared to the combination of everolimus and hormonal treatment in female patients with HR-positive HER2-negative metastatic breast cancer. Moreover, both treatment strategies promote remodelling of the left ventricle by means of increased RWT and mass. Further research and longitudinal studies in this field are required to validate the above findings.

Funding Acknowledgement

Type of funding source: None

The effects of chemotherapy on arterial inflammation assessed by 18 FDG PET-CT in patients with Lymphoma

Introduction

Anti-cancer treatment can lead to increased cardiovascular morbidity among lymphoma survivors. This may be the result of direct effect of treatment on heart function, or indirect acceleration of atherosclerosis. 18F-fluorodeoxyglucose (FDG) uptake is a sensitive and robust marker for assessment of atherosclerotic inflammation.

Purpose

To investigate the effects of chemotherapy on arterial inflammation using FDG-PET CT in patients with lymphoma.

Methods

Fifty nine (mean age 58±17 years) patients with Hodgkin (n=39) or non-Hodgkin lymphomas (n=20) underwent 18FDG PET-CT imaging at baseline, interim and after completion of chemotherapy as part of their routine protocol. Arterial inflammation was assessed by arterial target to background ratio (TBR) of the aortic wall along the entire aorta. The index vessel TBR (the vessel with the higher value at baseline) was used for assessment of arterial inflammation. Patients with Hodgkin Lymphomas (HL) underwent therapy with Doxorubicin, bleomycin, vinblastine and dacarbazine (ABVD). The interim of their treatment was set at 1 to 3 days prior to initiating the 3rd chemotherapy cycle. Patients with non Hodgkin Lymphomas (NHL) underwent therapy with cyclophosphamide, doxorubicin, vincristine, and prednisone+rituximab (R-CHOP). The interim of their treatment was set at 2 weeks post the 4th chemotherapy cycle. All patients we reassessed 6 weeks after chemotherapy completion.

Results

There were no differences in age and atherosclerotic risk factors (hypertension, diabetes, dyslipidemia and smoking), between the two groups (all P>0.05). Similarly, there were no differences in mean (±SD) index vessel TBR between HL and NHL patients (2.4±0.7 vs 2.7±0.9, respectively, P=0.65). In the whole study population the index vessel TBR progressively decreased after the end of therapy (by 0.53±0.11, from baseline to 6 weeks following the end of therapies) (F=10.94, P<0.001, ANOVA). The index vessel TBR decreased in both HL and NHL patients at 6 weeks after therapy compared to baseline level (all P<0.01, ANOVA, figure). The decrease at the interim scan was more pronounced in NHL compared to HL patients, however at 6 weeks after chemotherapy completion the index vessel TBR decreased further in patients with HL, while it increased slightly compared to interim levels in NHL patients (figure 1).

Conclusion

Arterial inflammation is reduced during and post-chemotherapy in patients with lymphoma. The index vessel TBR changes at the interim phase and 6 weeks after therapy completion indicate a different effect of specific treatment regimes in arterial inflammation between HL and NHL patients.

Figure 1

Funding Acknowledgement

Type of funding source: None

Relationship between endothelial shear stress, plaque burden and stenosis severity and their comparative performance in predicting impaired coronary vasodilation by pet myocardial perfusion imaging

Background

Advances in CTCA imaging enable assessment of coronary plaque burden, a predictor of myocardial perfusion abnormalities and more recently, with the use of computational fluid dynamics (CFD) of endothelial shear stress (ESS), an established contributor to atherosclerotic plaque development and progression.

Purpose

To investigate the relationship of local endothelial shear stress (ESS) and plaque burden (PB) between them and with stenosis severity as well as their comparative performance in predicting impaired coronary vasodilating capability assessed by PET myocardial perfusion imaging (MPI).

Methods

49 patients (29 males, mean age 65.3±6.3 years, intermediate pre-test likelihood of coronary artery disease, CAD), who underwent PET-MPI with 15O-water or 13N-ammonia and CTCA were included. PET was considered abnormal when >1 contiguous segment showed both stress Myocardial Blood Flow ≤2.3 mL/g/min and Myocardial Flow Reserve ≤2.5 for 15O-water or <1.79 mL/g/min and ≤2.0 for 13N-ammonia respectively. On CTCA, stenosis (sten) severity was classified as: <30%, 31–50%, 51–70% and 71–90%. CFD were applied to every vessel, assuming a mean pressure of 100 mmHg as the inlet boundary condition and a coronary velocity profile of 1 ml/sec as the outlet. ESS was calculated for the full length of a stenosis (total), as well as in the proximal (prox), minimum lumen area (MLA) and distal (dist) stenotic segments. Atherosclerotic PB was defined as lesion plaque volume/lesion vessel volume ×100.

Results

85 coronary vessels were evaluated. There was a positive correlation between ESS and PB (r(total)=0.544, r(prox)=0.528, r(MLA)=0.529, r(dist)=0.474, p<0.001 for all). All ESS indices and PB increased progressively with stenosis severity compared to segments with a <30% stenosis (p≤0.004 for all comparisons). ESS indices and PB were also higher in lesions demonstrating impaired vasodilating capacity compared to those without (p≤0.02 for all comparisons, figure 1). All ESS indices performed equally with PB and sten >50% in predicting an abnormal PET MPI, (AUC: from 0.682 to 0.780, p-diff >0.5 for all comparisons). The pairwise combination of sten >50% with the ESS segments, except the distal one, increased the predictive ability of the model over stenosis alone (AUC (sten >50% + ESS(total)) = 0.80, AUC (sten >50% + ESS(prox)) = 0.797, AUC (sten >50% + ESS(MLA)) = 0.822, p-diff ≤0.01 for all comparisons, AUC (sten >50% + ESS(dist)) = 0.768, p-diff=0.07).

Conclusion

There is a low to moderate positive association between lesion plaque burden and ESS indices. Like PB, ESS increases progressively with stenosis severity and is higher in lesions paired with abnormal PET results. ESS is a moderate predictor of impaired vasodilating capability, performing equally with PB and stenosis severity. The addition of ESS to stenosis severity can improve prediction of an abnormal PET result.

Figure 1

Funding Acknowledgement

Type of funding source: Public grant(s) – EU funding. Main funding source(s): This study is co-financed by Greece and the European Union (European Social Fund-ESF) through the Operational Programme “Human Resources Development, Education and Lifelong Learning 2014-2020” in the context of the project “Assessment of coronary atherosclerosis: a new complete, anatomo-functional, morphological and biomechanical approach” and from p-Med GR 5002802

P3363Severity of lymphoma is associated with aortic FDG uptake assessed by FDG PET/CT imaging

Introduction

There is increasing evidence that metabolic disease burden in lymphoma modifies patients' outcome. However, the impact of disease severity on cardiovascular system remains unknown.

Purpose

To investigate whether lymphoma is associated with arterial inflammation by examining the relationship between disease burden and arterial F-18 Fluorodeoxyglucose (FDG) uptake assessed by positron emission tomography/computed tomography (PET/CT) in Hodgkin and non-Hodgkin sub-types.

Methods

Sixty-two patients (43 male, mean age 58±18 years) with Hodgkin (n=29) or non-Hodgkin lymphoma (n=33) underwent FDG PET/CT imaging before chemotherapy. Disease severity was quantified by total metabolic tumor volume (TMTV) that represents the volume exhibiting standard uptake values (SUV) ≥41% or ≥2.5 of maximum SUV within lymphoma regions, while aortic FDG uptake assessment was based on target-to-background ratio (TBR). Serum high sensitivity-C-reactive protein (hs-CRP), white blood count (WBC), ratio of neutrophils to lymphocytes (N/L), albumin and lactic acid dehydrogenase (LDH) values were recorded in all the patients.

Results

TMTV measurements correlated significantly with hs-CRP, WBC, N/L ratio, albumin and LDH. (Table) Patients with advanced stage disease (III-IV) had higher aortic TBR values compared to those with stage I-II disease (median 2.19 interquartile range (1.96–2.54) vs. 2.04 (1.83–2.15) p=0.046 respectively). Aortic TBR was related with N/L ratio (R=0.370, p=0.009), while no significant correlation was observed with either WBC or hs-CRP values (p=0.930 and p=0.296, respectively). There were significant associations between aortic TBR uptake and TMTV values even after adjustment for age, sex, LDH, albumin, N/L ratio, as well as for the number of cardiovascular risk factors of each patient (β=0.353, p=0.001, adjusted R2=0.318 for TMTV41%, β=0.442, p=0.001, adjusted R2=0.269 for TMTV2.5).

Table 1. Pearson correlation between indices of lymphomas' severity and serum biomarkers PET derived measurements Hs-CRP P-value Neutrophils to lymphocytes ratio P-value MTV41% 0.306 0.016 0.317 0.026 MTV2.5 0.312 0.013 0.389 0.006 Albumin LDH MTV41% −0.281 0.044 0.465 <0.001 MTV2.5 −0.419 0.002 0.616 <0.001

Conclusions

Aortic wall FDG uptake is related with disease severity and subtype of lymphoma indicating a vascular effect of lymphoma, as well as a new potential role of molecular imaging in cardio-oncology by evaluation of disease severity and its consequences to vascular beds with a single examination.

P2702Assessment of endothelial shear stress and functional significance of coronary lesions by computed tomography coronary angiography (CTCA) and computational fluid dynamics: a comparison with PET

Background

The feasibility of assessing endothelial shear stress (ESS) in coronary lesions by non-invasive imaging and its potential role in different clinical settings has been recently explored. However, the relationship of ESS with functional indices derived by computed tomography coronary angiography (CTCA) and its value in predicting perfusion changes by quantitative positron emission tomography (PET) downstream stenotic vessels has not been assessed.

Purpose

To investigate the feasibility of calculating local ESS, its relationship with stenosis severity as well as with virtual functional assessment index (vFAI), and the comparative performance of the two parameters for predicting impaired coronary vasodilating capability in terms both of stress myocardial blood flow (MBF) and myocardial flow reserve (MFR) in patients submitted to CTCA.

Methods

Thirty-two patients (23 male-9 female, mean age 65.6±7.2 years) with intermediate pre-test likelihood of coronary artery disease (CAD), who were enrolled in the EVINCI and SMARTool projects, and had undergone CTCA with vFAI and PET myocardial perfusion imaging with 15 O-water or 13 N-ammonia were included in the study. PET was considered positive when >1 contiguous segments showed both stress MBF ≤2.3 mL/g/min and MFR ≤2.5 for 15 O-water or ≤1.79 mL/g/min and ≤2.0, for 13 N-ammonia respectively. A vFAI threshold of 0.85 was used as predictor of impaired vasodilating capability. ESS computation was based on a mean aortic pressure of 100 mmHg for the inlet and a mean blood flow at rest of 0.00105 kg/s for the outlet. ESS was calculated (Pa) in the full length of the stenosis and the mean value was obtained.

Results

Hybrid imaging analysis was performed in CTCA and PET datasets. 51 coronary segments were assessed. There were 27 lesions with stenosis 31–50% and 24 lesions with stenosis 51–70%. ESS was higher in the latter (20.4, IQ: 11.4–32.1 vs. 10.4, IQ: 5.5–15.7, p=0.04). Similarly, ESS was higher in stenoses with impaired vasodilating capacity compared to those without, although this difference did not reach statistical significance (22.8, IQ: 13.2–35.1 vs. 10.6, IQ: 5.7–22.1, p=0.10). The ROC curve analysis for prediction of both abnormal stress MBF and MFR followed the same pattern (AUC=0.668, 95% confidence interval (CI): 0.490–0.810, p=0.11).On the other hand, there was a moderate negative correlation (r=−0.41, p=0.004) between ESS and vFAI and the former was lower in stenoses with vFAI >0.85 compared to those below this threshold (7.35, IQ: 3.2–13.9 vs. 19.1, IQ: 14.1–32.8, p=0.012). vFAI was a good predictor of coronary flow capacity (AUC=0.737, CI: 0.58–0.85, p=0.02).

Conclusion

Calculation of ESS is feasible in CTCA datasets. ESS was related with stenosis severity and there was a trend to be higher in lesions with impaired coronary vasodilating capability. ESS is modestly related with vFAI and may also be an additional predictor of impaired regional myocardial flow obtained by PET imaging.

Acknowledgement/Funding

This study has received funding from the EU H2020 research and innovation programme under grant agreement No 689068 and from p-Med GR 5002802

P5302Significant correlation of visceral adiposity and adipocytokines with arterial inflammation in genetic dyslipidaemias

Background

The adipose tissue is now established as a major regulator of cardiovascular status, mediated by the secretion of several bioactive molecules, including adipocytokines. Individuals with genetic dyslipidaemias of either familial combined hyperlipidemia (FCH) or heterozygous familial hypercholesterolemia (heFH) subtype are characterized by accelerated atherosclerosis. Nonetheless, limited data exists on the relationship between adiposity and arterial inflammation, a marker of cardiovascular risk, in this setting.

Purpose

To investigate the relationship between adiposity indices and arterial inflammation evaluated by 18F fluorodeoxyglycose positron emission tomography (PET/CT) in patients with hereditary lipid metabolism disorders.

Methods

Consecutive patients with either FCH or heFH, free of statin therapy, and normolipidaemic individuals underwent PET/CT imaging. Arterial FDG uptake was estimated as the average value of target-to-background ratio (TBR) within aortic and carotid wall. Volumes of subcutaneous adipose tissue (SAT) and visceral adipose tissue (VAT) were measured from CT images between the proximal (cephalic) end of the L1 and distal (caudal) end of the L3 vertebrae by selecting all voxels with attenuation between −190 and −30 Hounsfield Units (HU). Serum adiponectin and leptin levels were measured with ELISA by available commercial kits. For comparisons with arterial TBR, adiponectin and leptin concentrations above and below the 25th percentile, were stratified as high and low, respectively.

Results

In total, 60 individuals (20 FCH, 20 heFH and 20 controls) were included. A modest but significant correlation between SAT volume and arterial TBR (R=0.386, p=0.004) was detected. This relationship did not remain significant after controlling for VAT volume (p=0.303). A strong correlation between VAT volume and arterial TBR (R=0.621, p=0.001) was observed. This relationship remained significant after controlling for SAT volume (R=0.541, p<0.001). Arterial TBR values were higher in individuals with low plasma adiponectin levels (p=0.010). In addition, patients with higher leptin levels exhibited increased arterial FDG uptake compared to subjects with low serum leptin concentrations (p=0.05)

Conclusions

Abdominal adipose tissue imaging markers and serum adipocytokines correlate with arterial inflammation as assessed by PET/CT in patients with familial dyslipidaemias highlighting the role of abdominal adipose tissue for atherosclerosis progression in this population.

P730Decreased adiponectin levels and FDG uptake in visceral adipose tissue in familial combined hyperlipidemia compared to heterozygous familial hypercholesterolemia and normolipidemics

Background

Adipose tissue regulates energy balance and glucose homeostasis via the secretion of circulating molecules, termed adipokines, such as leptin and adiponectin. Excess adiposity and adipose tissue dysfunction have been involved in the pathogenesis of dyslipidemias. Positron emission tomography/computed tomography (PET/CT) with F-18-Fluorodeoxyglycose (FDG) has been used for the assessment of adiposity.

Purpose

To compare abdominal adipose tissue function assessed by FDG uptake with serum indices, such as plasma adipokines' levels in individuals with different subtypes of dyslipidemia and normolipidemics.

Methods

Seventy individuals (mean age 44±13 years, range 21–75, 43 men) with a clinical diagnosis of either heterozygous familial hypercholesterolemia (heFH) (n=38) or familial combined hyperlipidemia (FCH) (n=32), not under statins for at least one year, and 20 age and sex matched controls, were enrolled. Visceral (VAT) and subcutaneous adipose tissue metabolic activity (SAT) was assessed with FDG-PET/CT imaging and was quantified by calculating the target-to-background ratios (TBR) in consecutive axial fat images between the proximal (cephalic) end of the L1 and distal (caudal) end of the L3 vertebrae by dividing the average of the mean standard uptake value (SUV) to the mean SUV of the vena cava. Leptin and adiponectin were measured in all the subjects.

Results

There was no significant difference of plasma leptin values between FCH, heFH and non dyslipidemics subjects (p=0.204). FCH had reduced adiponectin values compared to heFH patients and controls [median 5.7 IQR (3.9–7.6) vs. 13.1 (9.2–23.3) vs. 10.9 (6.1–19.1) μg/mL, respectively, p<0.001]. There was no difference in FDG uptake in subcutaneous adipocytes (SATTBR) between FCH, heFH and controls (p=0.161). In contrast, patients with FCH had reduced VATTBR values compared to heFH patients and controls (0.63±0.14 versus 0.81±0.17 versus 0.86±0.28, p=0.005). This difference remained significant even after adjustment for age, sex and cardiovascular risk factors (b=-0.428, p=0.001, adjusted R2=0.219). SATTBR was inversely correlated to leptin levels (r=−0.484, p<0.001), while no significant association was observed with adiponectin values (p=0.167). No significant associations were observed between VATTBR and either serum leptin (p=0.066) or adiponectin levels (p=0.254).

Conclusions

Visceral adipose tissue FDG uptake is reduced in patients with FCH compared to those with heFH and normolipidemics. In addition, serum adiponectin levels are lower in patients with FCH. These findings highlight the different pathophysiological role of visceral fat function in the two most common types of familial dyslipidemia and suggest that visceral fat could be an attractive target for the treatment of FCH.