Perfusion Imaging Research Articles

Vasospasm in Pediatric Subarachnoid Hemorrhage.

Cerebral vasospasm (CV) is a common severe complication of subarachnoid hemorrhage (SAH), a severe type of intracranial bleeding that is uncommon in children. The purpose of this article is to review the current literature regarding this potentially devastating complication. CV may be asymptomatic and is less common in children compared to adults. Several molecular phenomena, including inflammatory ones, contribute to its pathophysiology. Better collateral circulation and higher cerebral blood flow are protective factors in children. When clinically apparent, CV may manifest as a change in the child's neurologic status or vital signs. CV can be diagnosed using brain vessel imaging, such as computed tomography angiography, magnetic resonance angiography, digital subtraction angiography, transcranial Doppler ultrasonography, and computed tomography perfusion. A reduction of < 50% in the artery's caliber confirms the diagnosis. Besides general supportive measures and causative treatment of SAH, CV management options include the administration of calcium channel blockers and neurointerventional approaches, such as intra-arterial vasodilators and balloon angioplasty. Long-term outcomes in children are usually favorable.

A New Acquisition Protocol for Optimized Dynamic Susceptibility Perfusion Imaging of Brain Tumors.

A New Acquisition Protocol for Optimized Dynamic Susceptibility Perfusion Imaging of Brain Tumors.

Safety and efficacy of intravenous thrombolytic therapy in the extended window up to 24 hours: A systematic review and meta-analysis.

About 25% of patients with acute ischemic stroke (AIS) present within the intravenous thrombolytic (IVT) therapeutic window of <4.5 h. This study is to elucidate the safety and efficacy of IVT in the extended therapeutic window (ETW) in patients with AIS. Using PRISMA guidelines, a systematic review was conducted using PubMed, Embase, and Scopus. A rigorous risk of bias assessment was conducted using the RoB2 tool. Rates of excellent and good functional outcome (mRS 0-1 and mRS 0-2) at 90 days, symptomatic intracranial hemorrhage (sICH), and mortality at 90 days were pooled using generalized linear mixed model and compared with controls. Meta-analyses were conducted employing random-effect models with risk ratio (RR) and 95% confidence intervals (CIs). Subgroup analysis was performed to assess the effect of imaging modalities used for patient selection. Eight randomized controlled trials (n = 2221, 59% male) were included. At 90 days IVT showed higher rates of functional recovery: mRS 0-1: RR 1.21 95% CI 1.1-1.34, p < 0.001, and mRS 0-2: RR 1.11 95% CI 1.03-1.18, p = 0.004. Rate of mortality at 90 day was not different between groups: RR 1.17 95% CI 0.93-1.48, p = 0.17. However, the rate of sICH was higher among IVT group: RR 2.93 95% CI 1.53-5.6, p = 0.001. Subgroup analysis showed higher mRS 0-1 among patients who were selected based on perfusion imaging (p < 0.05). The use of IVT in AIS in ETW is beneficial especially with the use of perfusion imaging for patients' selection.

Lesion Characterization by 99mTc-MIBI Myocardial Perfusion Imaging (MPI) &amp; 18F-FDG Cardiac PET Following Myocardial Infarction Before Revascularization &amp; Outcome Prediction: Initial Experience in Bangladesh

99mTc-MIBI SPECT myocardial perfusion imaging (MPI) and 18F-FDG cardiac positron emission tomography (Cardiac PET) can assess the extent and severity of myocardial perfusion and metabolic defect following myocardial infarction (MI) and also able to predict the outcome before revascularization in known coronary artery disease patients. About 135 cases of known coronary artery disease patients were enrolled here for combined nuclear imaging tests, rest only ECG gated MPI and FDG cardiac PET to assess myocardial perfusion and viability status following MI prior to revascularization. In this study we want to figure out the utility of this combined protocol for myocardial lesion characterization and its role for clinical decision-making in-patient selection prior to revascularization and treatment planning. We are also intended to share the initial outcome in available follow up cases. J Inv Clin Cardiol 2023; 5(2): 45-52

Myocardial perfusion SPECT radiomic features reproducibility assessment: Impact of image reconstruction and harmonization.

Coronary artery disease (CAD) has one of the highest mortality rates in humans worldwide. Single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) provides clinicians with myocardial metabolic information non-invasively. However, there are some limitations to interpreting SPECT images performed by physicians or automatic quantitative approaches. Radiomics analyzes images objectively by extracting quantitative features and can potentially reveal biological characteristics that the human eye cannot detect. However, the reproducibility and repeatability of some radiomic features can be highly susceptible to segmentation and imaging conditions. We aimed to assess the reproducibility of radiomic features extracted from uncorrected MPI-SPECT images reconstructed with 15 different settings before and after ComBat harmonization, along with evaluating the effectiveness of ComBat in realigning feature distributions. A total of 200 patients (50% normal and 50% abnormal) including rest and stress (without attenuation and scatter corrections) MPI-SPECT images were included. Images were reconstructed using 15 combinations of filter cut-off frequencies, filter orders, filter types, reconstruction algorithms, number of iterations and subsets resulting in 6000 images. Image segmentation was performed on the left ventricle in the first reconstruction for each patient and applied to 14 others. A total of 93 radiomic features were extracted from the segmented area, and ComBat was used to harmonize them. The intraclass correlation coefficient (ICC) and overall concordance correlation coefficient (OCCC) tests were performed before and after ComBat to examine the impact of each parameter on feature robustness and to assess harmonization efficiency. The ANOVA and the Kruskal-Wallis tests were performed to evaluate the effectiveness of ComBat in correcting feature distributions. In addition, the Student's t-test, Wilcoxon rank-sum, and signed-rank tests were implemented to assess the significance level of the impacts made by each parameter of different batches and patient groups (normal vs. abnormal) on radiomic features. Before applying ComBat, the majority of features (ICC: 82, OCCC: 61) achieved high reproducibility (ICC/OCCC ≥ 0.900) under every batch except Reconstruction. The largest and smallest number of poor features (ICC/OCCC<0.500) were obtained by IterationSubset and Order batches, respectively. The most reliable features were from the first-order (FO) and gray-level co-occurrence matrix (GLCM) families. Following harmonization, the minimum number of robust features increased (ICC: 84, OCCC: 78). Applying ComBat showed that Order and Reconstruction were the least and the most responsive batches, respectively. The most robust families, in a descending order, were found to be FO, neighborhood gray-tone difference matrix (NGTDM), GLCM, gray-level run length matrix (GLRLM), gray-level size zone matrix (GLSZM), and gray-level dependence matrix (GLDM) under Cut-off, Filter, and Order batches. The Wilcoxon rank-sum test showed that the number of robust features significantly differed under most batches in the Normal and Abnormal groups. The majority of radiomic features show high levels of robustness across different OSEM reconstruction parameters in uncorrected MPI-SPECT. ComBat is effective in realigning feature distributions and enhancing radiomic features reproducibility.

Fractional flow reserve in saphenous vein grafts for the detection of myocardial ischemia determined by perfusion imaging

Abstract Background Fractional flow reserve (FFR) is recommended to guide revascularization of native coronary arteries. Revascularization decision-making for saphenous vein grafts (SVGs), however, is based on angiographic estimation of lesion severity, as studies exploring the value of FFR to detect perfusion imaging defined myocardial ischemia in SVGs are scarce. Purpose We aimed to define an optimal FFR threshold and compare its diagnostic performance with the traditional FFR cutoff and with percentage diameter stenosis (%DS) in patients evaluated for SVG disease using myocardial perfusion imaging (MPI) as the reference standard. Methods Symptomatic patients with prior coronary artery bypass grafting (CABG) who underwent single-photon emission computed tomography, positron emission tomography or stress perfusion cardiac magnetic resonance imaging, and had FFR measurements of one or more SVGs were included. Angiographic lesion severity of the SVG was measured using 2D quantitative invasive coronary angiography. We allocated and matched the myocardial territory subtended by the SVG to compare the values of FFR and %DS with ischemia determined by MPI. Results Included were 77 patients (mean age 72 ± 7 years; 86% male) with 91 SVGs. A total of 38 SVGs (42%) supplied an ischemic coronary territory. FFR and %DS correlated moderately (r= -0.51, P&amp;lt;0.001). The optimal cutoff value of FFR was ≤0.94, resulting in a sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy of 63%, 75%, 65%, 74% and 70%, respectively (Figure 1). Corresponding values of FFR≤0.80 and DS%≥50 are shown in Figure 1 as well. Sensitivity, NPV and accuracy of FFR ≤0.94 outperformed that of FFR≤0.80, whereas specificity was lower. FFR≤0.94 outperformed %DS≥50 only in terms of sensitivity. Conclusions The optimal cutoff value of FFR for the detection of MPI-defined disease in SVGs is higher than the traditional FFR cutoff used to guide native coronary artery revascularization. Importantly, the increased sensitivity led to a higher diagnostic performance of the adjusted cutoff. However, the high prevalence of ischemia in post-CABG patients questions whether the optimal cutoff reflects ischemia caused by SVG obstruction.Diagnostic performance of FFR and %DS

CT-perfusion quantitation of cardiac infarct size - a novel technique

Abstract Introduction Cardiac infarct size is associated with cardiac prognosis after AMI. Cardiac CT is able to delineate both coronary anatomy and myocardial pefusion. Thus far, CT identification of infarction has been qualitative. We describe a novel technique for quantitation of myocardial infarct size in CT-perfusion imaging. Methods Patient Population comprised 51 patients that were previously clinically diagnosed with myocardial infarction on the basis of clinical presentation, ECG findings and elevated cardiac enzymes. CTP Imaging All patients had undergone dynamic rest, vasodilator-stress, rest, delayed enhancement CT perfusion imaging performed on a dual-source, third generation scanner (FORCE, Siemens Healthcare). Image Analysis 2 trained investigators independently quantified the infarct volume in 51 patient studies using Siemens SmartSimulator software. Mean ± SD HU were taken from a 1cm² circular ROI of normal myocardium used in a thresholding method. The epicardium and endocardium of infarcted areas were manually contoured from apex to base. Volumetric measurements were obtained of the infarct and total myocardium. Interpolation of contours for segmentation objects was performed. Subtraction of left ventricle cavity from total left ventricle allowed volumetric measurements of total left ventricular myocardium. ROIs of the infarct were estimated using SDs above mean HU of normal myocardium (0.5, 1, 1.5 and 2 SDs) in delayed imaging. Selection of optimal threshold HU was based on visual assessment that best mapped the hyperenhanced infarct area. This allowed volumetric asessment of infarct and total myocardium. Inter-investigator variability was evaluated with Bland-Altman and Intra-Class Correlation Coefficient (ICC). Results Patient characteristics are follow: Age 60.20±11.35 years, 41(89%)male, BMI 25.41±4.17kg/m², Hypertension 23(50%), diabetes 10(22%), hyperlipidemia 40(87%), smoking 7(15%), family history of premature CAD 4(8.7%), previous PCI 45(97.8%). In 51 patients, 23(41%), 24 (46%) &amp; 5(10%) of the infarctions were quantitated as being medium-sized (10%-20%), large (20% -30%) and very large (&amp;gt;30%). Thirty-seven (70%), 6 (11%) &amp; 10(19%) involved the LAD, LCx and RCA territories respectively. 49 (94%) of infarctions were transmural. Identical thresholding was selected by both investigators for each SD above mean (mean 1.42; SD 0.46). 93% of the total cases were within a set threshold of 1 to 2 SDs above the mean HU for both. Interclass correlation coefficient was 0.95, CI range 0.90 – 0.97. Bland-Altman analysis did not demonstrate systemic variations or proportional bias from the plot. Conclusion The study suggests that a method of quantifying cardiac infarct size using a threshold technique and delayed hyperenhancement images with dynamic perfusion imaging is clinically feasible and consistent.Rest-Stress-Delayed Enhancement infarct

CCTA and CTP imaging for detecting clinically suspected in-stent restenosis: a meta-analysis

Abstract Background The evaluation of coronary artery stents via Coronary Computed Tomography Angiography (CCTA) can be compromised by artefacts, potentially undermining its diagnostic accuracy. The integration of CT Perfusion (CTP) with CCTA (CCTA+CTP) has been proposed to enhance the diagnostic yield in detecting in-stent restenosis (ISR). Purpose This meta-analysis aims to assess the diagnostic performance of CCTA and combined CCTA+CTP in detecting ISR. Methods A comprehensive literature search of studies from 2005 to 2022 identified 13,747 articles. Inclusion criteria comprised the utilization of multidetector CT scanners with ≥64 slices and invasive coronary angiography as the reference standard. Studies that systematically evaluated stent patency in asymptomatic patients as part of their protocol were excluded. Results After removing duplicates, screening titles and abstracts, and conducting full-text reviews, 20 studies met the inclusion criteria (17 CCTA, 3 CCTA+CTP). Data on 2,674 CCTA-assessed stents and 752 CCTA+CTP-assessed stents were analyzed. The meta-analysis revealed that CCTA alone achieved a sensitivity of 90% (95% CI; 84-94%) and a specificity of 89% (95% CI; 86-92%)(Figure 1). CCTA+CTP exhibited comparable diagnostic performance, with a per-stent sensitivity of 88% (95% CI; 80-94%) and a specificity of 88% (95% CI; 84-93%) (Figure 2). The summary Receiver Operating Characteristic (sROC) Area Under the Curve (AUC) was 0.96 (95% CI; 0.94-0.97) for CCTA and 0.96 (95% CI; 0.89-1.00) for CCTA+CTP, indicating a high overall performance for both diagnostic modalities. Conclusion Utilizing contemporary imaging hardware, both CCTA and CCTA+CTP demonstrate high diagnostic performance in evaluating ISR. The findings suggest that the presence of coronary artery stents should not preclude the use of these non-invasive diagnostic tests in clinical practice.Figure 1Figure 2

Deep learning detection of subclinical cardiovascular dysfunction in type 2 diabetes through retinal photography

Abstract Background Type 2 diabetes (T2D) is associated with excess atherosclerotic coronary disease and heart failure risk, with several cardiac abnormalities described in asymptomatic patients. Routine digital retinal photography performed for screening of diabetic retinopathy (DR) has the potential to identify patients with underlying cardiovascular disease (CVD). We aimed to determine whether features extracted from digital retinal photographs could detect subclinical cardiovascular dysfunction in asymptomatic people with T2D. Methods We prospectively enrolled adults with T2D and no history or symptoms of CVD to undergo extensive phenotyping with multiparametric stress perfusion cardiac MRI and CT coronary artery calcium scoring. Digital retinal photographs acquired for routine diabetic eye screening and performed within one year of cardiac evaluation were interrogated for retinopathy grading and using four deep learning (DL) models (Xception, Inception, EfficientNet, and MobileNet) to capture complex patterns within the retinal vasculature. Each subject had four retinal photographs (two of each eye) for DL analysis. Cardiac image analysis was performed blinded to participant details and independent of retinal images. Subjects with and without DR were compared. Participants were divided into training (80%) and validation datasets (20%) prior to DL analysis. DL models employed to predict from retinal images: presence or absence of coronary artery calcium on non-contrast CT, myocardial perfusion reserve &amp;lt;2.5, left ventricular (LV) global longitudinal strain &amp;lt;16%, absolute stress and rest myocardial blood flood (mL/g/min) used as continuous variables. AUC was used to assess the ability of DL models to discriminate between those without and without subclinical CVD. Results An initial 254 subjects (comprising 1,016 retinal photographs) were included in the analysis: 212 (83%) with no DR, 42 (17%) with grade 1 (mild background) DR. Key cardiac imaging parameters in subjects with and without DR are displayed in Table 1. The groups were well matched for age, sex, body mass index and blood pressure. Overall, those with grade 1 DR had higher atheroma burden, evidence of increased LV filling pressures (E/e’) and poorer systolic function, but no differences in stress and rest myocardial blood flow or myocardial perfusion reserve. However, all four DL models failed to achieve sufficient discrimination of any of the evaluated cardiac imaging parameters, with the majority achieving AUC scores below 50% for all cardiac parameters. Conclusion Asymptomatic adults with grade 1 DR exhibit more subclinical atherosclerosis and cardiovascular dysfunction than those without DR. However, DL transfer models could not discriminate between subjects with and without cardiovascular disease. Further work is needed to better define whether retinal screening may be used to identify those people with T2D most at risk of underlying cardiovascular disease.Subjects demographics

The role of semi-quantitative parameters of thallium-201 myocardial perfusion imaging in predicting mortality rate among CKD population

Abstract Background Chronic kidney disease (CKD) is a major public health concern worldwide, with high morbidity and mortality rates. Myocardial perfusion imaging (MPI) is a non-invasive diagnostic tool that can detect early-stage cardiovascular disease in CKD patients. Purpose This study aimed to investigate the role of semi-quantitative parameters of Thallium-201 MPI in predicting mortality rates among CKD patients. Methods This retrospective study included 579 CKD patients who underwent Thallium-201 MPI between October 2005 and December 2019. Semi-quantitative parameters were analyzed using automation software, including transient ischemic dilation (TID), lung-to-heart ratio (LHR), total perfusion deficit (TPD), summed stress score (SSS), summed rest score (SRS), summed difference score (SDS), summed thickening percent (ST%), summed motion percent (SM%), stress end-diastolic volume (EDV), stress end-systolic volume (ESV), and stress left ventricular ejection fraction (LVEF). The primary endpoint was overall mortality. Results During a median follow-up of 52 months, 148 patients died. The older age group, lower hemoglobin levels, and lower estimated glomerular filtration rate (eGFR) were associated with higher mortality rates. The semi-quantitative parameters that predicted overall mortality included LHR above 0.4, elevated ST% , increased stress EDV and ESV, and reduced stress LVEF in a multivariable Cox regression model. Conclusion Thallium-201 MPI with semi-quantitative parameters can predict mortality rates in CKD patients without a definite diagnosis of coronary artery disease. The identified parameters, including LHR above 0.4, elevated ST levels, increased stress EDV and ESV, and reduced stress LVEF can assist in early detection the mortality risk in CKD patients.Characteristics of CKD PatientsMultivariable Analysis

Assessment of impact of left ventricular flow state on myocardial blood flow using positron emission tomography and echocardiography

Abstract Background The relationship between left ventricular (LV) mass and myocardial blood flow (MBF) has been recognized as an important physiological measure of myocardial perfusion to match global metabolic demand. However, there is little information on the association between LV flow state and MBF. Purpose To investigate impact of LV flow state on MBF. Methods The study included 104 patients undergoing cardiac positron emission tomography (PET) and echocardiography for chest pain and/or dyspnoea. CT attenuation corrected rest/regadenoson stress 13N-ammonia myocardial perfusion imaging was acquired with a PET CT camera. All images were acquired in 3-D list mode. Sixteen dynamic frames were reconstructed and analyzed with QPET software to obtain rest quantitative MBF measurements adjusted for rate-pressure product in ml/min/g, with a myocardial flow reserve (MFR) derived as the ratio of stress MBF/resting MBF. All patients had no ischaemia or infarction with LV ejection fraction ≥55%. Echocardiography was performed within 6 months of PET in clinically stable conditions allowing for. SV was measured by Doppler echocardiography using the continuity equation and was indexed by body surface area (SVi). The patients were divided to normal flow group (NFS: SVi &amp;gt; 35 ml/m2) and low flow group (LFS: SVi≤35 ml/m2). Results The mean SVi was 40 ml/m2 for NFS and 29 ml/m2 for LFS (p&amp;lt;0.001). LFS group was younger (57 ± 11 vs. 67 ± 11 years, p&amp;lt;0.001) with higher body mass index (43±8 vs. 37±8 kg/m2, p&amp;lt;0.001) and lower resting MBF (0.84±0.22 vs. 1.02±0.34 ml/min/g, p&amp;lt;0.01) than NFS groups. There were no significant differences of hypertension (81% vs. 82%, p&amp;gt; 0.05), LV mass index (82±21 vs. 88±82 g/m2, p&amp;gt;0.05), LVEF (63% vs. 65%, p&amp;gt;0.05) between LFS and NFS groups. SVi was positively associated with MBF as a whole group (r= 0.38, p&amp;lt;0.01). However, this significant association was only observed in NFS group (r=0.62, p &amp;lt;0.001), but not in LFS group (r=0.048, p= 0.46, Figure). Conclusion LFS expressed low MBF and the dissociation between SVi and MBF in comparison with NFS group suggesting potential alterations in relationships between myocardial work (SV) and oxygen consumption (MBF) in LFS. Further studies are warranted to investigate the pathophysiology behind the findings and to correlate with a long-term clinical outcome.

Prognostic value of quantitative anatomical and functional measures of coronary artery disease in diabetic and non-diabetic patients

Abstract Background Diabetes is associated with increased risk of coronary artery disease (CAD). However, the relative prognostic importance of anatomical and functional findings of CAD in the presence vs. absence of diabetes is incompletely understood. Technological advances have made quantitative analysis of coronary artery plaques and stenosis feasible by coronary computed tomography angiography (CTA). In turn, positron emission tomography (PET) enables absolute quantification of myocardial blood flow (MBF). Purpose To study long-term prognostic value of quantified severity of coronary atherosclerosis and myocardial perfusion in non-diabetic vs. diabetic patients with suspected CAD. Methods From two academic medical centres, we identified symptomatic patients with suspected CAD who had undergone coronary CTA and [15O]H2O PET myocardial perfusion imaging during adenosine stress. Based on artificial intelligence -guided quantitative analysis of coronary CTA scans, the anatomical severity of CAD was measured as the presence of obstructive CAD (≥50% diameter stenosis) and percent atheroma volume (PAV; higher vs. lower than median). The functional severity of CAD was measured as the presence of regional myocardial ischemia (≥2 adjacent segments with stress MBF &amp;lt;2.3 ml/g/min) and global stress MBF (&amp;lt;2.2 ml/g/min vs. ≥ 2.2 ml/g/min) by PET. Annual rates of adverse events (AER) including all-cause mortality, myocardial infarction (MI), and unstable angina pectoris (UAP) were evaluated. Results Among 1311 patients, 251 (19%) had diabetes. Patients with diabetes had more frequently obstructive CAD (55% vs. 43%, p&amp;lt;0.001) and regional myocardial ischemia (51% vs. 43%, p=0.015), higher plaque burden by PAV (12% vs. 7%, p&amp;lt;0.001), and lower global stress MBF (2.78 ml/g/min vs. 3.05 ml/g/min, p&amp;lt;0.001). During median follow-up of 7.1 years, 171 (13.0%) patients experienced AE (85 deaths, 56 MIs, and 30 UAPs). Patients with diabetes had higher AER than non-diabetic patients (3.1% vs. 1.6%, p&amp;lt;0.001). The presence of obstructive stenosis was associated with increased AER in non-diabetic (2.6% vs. 1.0%, p&amp;lt;0.001) and diabetic patients (4.2% vs. 1.9%, p&amp;lt;0.001). High plaque burden by PAV was associated with increased AER in non-diabetic (2.8% vs. 0.7%, p&amp;lt;0.001) and diabetic patients (3.9% vs. 1.7%, p&amp;lt;0.001). The presence of regional myocardial ischemia was associated with increased AER in non-diabetic (2.5% vs. 1.1%, p&amp;lt;0.001), but not in diabetic patients (3.4% vs. 2.7%, p=0.238). Low global stress MBF was associated with increased AER in non-diabetic (2.9% vs. 1.3%, p&amp;lt;0.001), but not among diabetic patients (3.2% vs. 3.0%, p=0.286). Conclusions Diabetes was associated with more advanced CAD. Quantified severity of anatomical findings predicted long-term adverse outcome in non-diabetic and diabetic patients. In contrast, functional imaging risk stratified non-diabetic patients, whereas diabetic patients had impaired long-term outcome irrespective of perfusion findings.

Endogen microvascular dysfunction is associated with worse outcomes in heart transplantation

Abstract Background Cardiac allograft vasculopathy (CAV) affects the health of both epicardial and microvascular blood vessels in heart transplants. Coronary microvascular dysfunction (CMD) has been associated with poor outcomes in the non-transplant population. Two patterns of microvascular dysfunction have been characterized, classical (low stress flow) and endogen (high rest flow). Whether these patterns of microvascular dysfunction are associated with outcomes in the transplant population has not been thoroughly evaluated. Purpose The purpose of the study was to assess the relationship between microvascular dysfunction and adverse outcomes in patients with heart transplants. Methods Patients with no history of angiographic CAV who underwent positron emission tomography myocardial perfusion imaging and were found to have normal perfusion (summed stress score = 0) were included in the study. Patients were then classified by microvascular dysfunction: normal (flow reserve ≥ 2.0) versus abnormal (flow reserve &amp;lt;2.0). Patients were further subclassified based on pattern of microvascular dysfunction, classical (stress myocardial flow &amp;lt;1.7 mL/min/g) and endogen (stress myocardial flow ≥1.7 mL/min/g). The two primary outcomes were all-cause mortality and a composite of death, heart failure hospitalization, acute coronary syndrome, and revascularization. Kaplan-Meier survival and Cox proportional regression were used to assess the relationship between microvascular function and outcomes. Results In total, 359 patients were enrolled in the study, of which 29 (8%) had classical CMD and 78 (22%) had endogen CMD. Patients with endogen CMD were more likely to be women (46%) compared to 31% for normal microvascular function and 24% for classical CMD. During a median follow up period of 2.0 years (Q1 1.7, Q3 2.3), 36 patients had an adverse event and 19 patients died. Endogen CMD was associated with a significantly higher risk of both the composite outcome, HR 2.30 (1.15 – 4.61), and all-cause mortality, 4.19 (1.64 – 10.73). Classical CMD was not associated with either the composite outcome, HR 0.88 (0.20 – 3.84) or death, HR 1.02 (0.12 – 8.33), however assessment of classical CMD was limited by small sample size. Conclusions Endogen-type CMD is associated with worse intermediate-term outcomes in transplant patients compared to normal microvascular function and classical-type CMD, although comparison to classical-type CMD was limited by small sample size.Table 1:DemographicsFigure 1:KM Survival Curves

Predictive factors and gender insights into abnormal myocardial flow reserve in non-obstructive coronary artery disease: a CZT-SPECT analysis

Abstract Background Dynamic myocardial perfusion imaging (D-MPI) using cadmium-zinc-telluride (CZT) cardiac-dedicated SPECT has emerged as a valuable method for assessing coronary microcirculation, particularly compared to conventional SPECT. Additionally, gender-specific disparities in microvascular dysfunction require further investigation. Objective This study aims to identify predictive factors for abnormal myocardial flow reserve (MFR) in non-obstructive coronary artery disease (CAD) using CZT-SPECT, with a focus on gender differences in MFR dysfunction. Methods A retrospective analysis was conducted on clinical data from 393 patients presenting with symptoms of "chest pain and/or tightness," all of whom were confirmed to lack obstructive CAD by coronary angiography or CT angiography. MFR was measured using CZT-SPECT, with values ≥2.5 considered normal and values &amp;lt;2.5 considered abnormal. Results Of the patients, 49.1% (193/393) demonstrated abnormal MFR, with females representing 56.7% (223/393). Females with abnormal MFR exhibited higher averages in age, total cholesterol, LDL-C, creatinine, left atrial diameter, left ventricular posterior wall (LVPW) thickness in diastole, and E/e’ ratio (P &amp;lt; 0.05). Additionally, MDRD-eGFR and mitral annular septal velocity e’ were lower in the abnormal MFR cohort (P &amp;lt; 0.05). Multivariate logistic regression analysis identified elevated LDL-C levels (OR = 1.513, 95%CI: 1.122–2.041, P = 0.007) and increased LVPW thickness (OR = 1.717, 95%CI: 1.140–2.585, P = 0.010) as independent predictors of abnormal MFR in females. ROC analysis suggested optimal cutoff for LDL-C at 3.68 mmol/L (sensitivity 31%, specificity 84%, AUC = 0.586; 95%CI: 0.511–0.661) and LVPW thickness at 9.5 mm (sensitivity 62%, specificity 52%, AUC = 0.576; 95%CI: 0.501–0.652). A combined ROC analysis of LDL-C and LVPW thickness showed a sensitivity of 50% and specificity of 73% (AUC = 0.632, 95%CI: 0.559–0.705). In males, greater left ventricular end-diastolic diameter (LVEDD) was significantly associated with abnormal MFR (P = 0.014), with LVEDD identified as a predictor (OR = 1.130, 95%CI: 1.016–1.258, P = 0.025) and an optimal cutoff at 44.5 mm (sensitivity 88%, specificity 37%, AUC = 0.609; 95%CI: 0.524–0.694). No significant gender differences were observed in overall left ventricular resting myocardial blood flow (MBF) among patients with abnormal MFR (P = 0.072); however, female patients exhibited higher resting MBF in specific territories supplied by the left circumflex and right coronary arteries, and higher E/e’ ratios (P &amp;lt; 0.05). Furthermore, a negative correlation was found between resting MBF in the territory supplied by the right coronary artery and E/e’ in females (r = -0.210, P = 0.030). Conclusion Predictors of abnormal MFR in non-obstructive CAD show gender disparities, implicating an association with left ventricular diastolic function.

Opportunistic screening of coronary artery calcification on non-gated conventional CT scans using artificial intelligence

Abstract Background Recent advancements in artificial intelligence (AI) led to the development of automatic Coronary artery calcification (CAC) analysis based on chest CT scans. The objective of this study is to assess the impact of AI-based CAC evaluation on improving the allocation of add-on therapies and further evaluation. Methods We used a novel propriety AI software to estimate CAC from non-gated, non-contrast chest CT scans. Patients were categorized into groups: low CAC 0-99 Agatston unit (AU), moderate CAC 100-399AU, and high CAC ≥ 400 AU. Exclusion criteria included prior myocardial infarction, percutaneous coronary intervention (PCI), coronary artery bypass graft (CABG), and life expectancy &amp;lt; 2 years. Patients classified as high CAC were invited to a dedicated clinic to perform a risk factor and clinical assessment, initiate appropriate medication, and refer to further testing as needed. For low-moderate CAC, referring physicians were informed of CAC status, encouraging guideline-based optimal preventive management. Results 1272 eligible patients between January 1th, 2023 to February 29th, 2024 were evaluated for inclusion. 641/1272 (50.3%) were excluded. Out of 631 enrolled patients, 84 (13%) patients were classified as high CAC, 163 (26%) as moderate and 348 (61%) as low CAC. At the dedicated clinic, appropriate low-density lipoprotein (LDL) goals were assigned and statins were initiated or dose adjusted where necessary. Twenty patients were referred to myocardial perfusion imaging, of which 2 were referred for invasive coronary angiography, one of them underwent PCI (Figure), and the other was referred for CABG. Conclusion This ongoing study indicates routine CAC quantification using AI software on chest CT scans can identify patients who may benefit from preventive cardiology services and lead them to appropriate cardiac treatment pathway. Further follow-up is required to assess its clinical impact.

Active surveillance for cardiac complications after major noncardiac surgery: implications on resource utilization and safety in high-risk patients

Abstract Background The 2022 ESC guidelines on cardiovascular assessment and management of patients undergoing noncardiac surgery recommend that high-risk patients should undergo active surveillance for cardiac complications, including perioperative myocardial infarction/injury (PMI), following major noncardiac surgery. Unfortunately, little is known about the resource use and safety of active surveillance compared to a control cohort (i.e. without active surveillance). Objective To quantify the impact of active surveillance for cardiac complications, by perioperative cardiac troponin (cTn) measurements and a systematic PMI work-up on working days, on resource usage and safety. Methods We did a retrospective comparison of non-randomised pre- vs post-implementation of an active surveillance program for cardiac complications in patients at elevated cardiovascular risk undergoing noncardiac surgery at two hospitals in Switzerland. The two cohorts' resource use and safety were compared. Resource use encompassed perioperative cTn measurements, ECGs, cardiac imaging, cardiology consultations as well as coronary angiography (CAG) and revascularisation procedures. Safety was assessed based on the number of "seemingly normal CAG" and complications arising from CAG and revascularisation procedures. Results A total of 13’147 patients, 10’346 in the active surveillance cohort and 2’805 in the standard-of-care (SOC) cohort, were eligible for this analysis. Patient characteristics between both cohorts were comparable (e.g. median age of 74 vs 73 and 44.8% vs 43% female, respectively). Patients in the active surveillance cohort underwent significantly more perioperative cTn measurements (86.4% vs 3.5%, respectively), postoperative ECGs (13.5% vs 5.7%), postoperative cardiac consultations (5.9% vs 2.4%), postoperative transthoracic echocardiogram (TTE) (7.5% vs 6.1%), postoperative myocardial perfusion imaging (MPI) (1.2% vs 0.6%), and postoperative CAG (0.8% vs 0.4%, all p &amp;lt;0.05). The increased resource use led to a substantial increase in detected cardiac complications within the first 48h after surgery: active surveillance 1’207 (12%) (95%CI 11%-12%) vs SOC 68 (2.4%) (95%CI 1.9%-3.1%). The active surveillance cohort generated an overall cardiac management cost of 236 Euros (95%CI 223–250) per patient vs 133 Euros (95%CI 110–160) per patient in the SOC cohort, resulting in an incremental cost for the active surveillance of 103 Euros (95%CI 110–160) per patient. Thereby the cost of detecting one additional cardiac complication within 48h was 989 Euros. Concerning safety, no significant differences in the number of "seemingly normal CAG" (6.4% vs 15%, p=0.1) and complications due to CAG and revascularisation (0.6% vs 5.1%, p=0.08) were observed. Conclusion The active surveillance for cardiac complications is safe when compared to a standard-of-care cohort while 989 Euros per additional detected cardiac complication seems reasonably priced.Resource-utilization tableOverview

Coronary artery disease screening in renal transplant candidates: insights from a large prospective cohort

Abstract Background There is currently no specific consensus regarding the screening strategy for CAD in renal transplant candidates. Purposes To describe in renal transplant candidates 1/ Strategies and results of CAD screening and 2/ renal and cardiovascular outcomes in this population Methods All patients registered on kidney transplant waiting list in our tertiary centre were classified into no screening for CAD (unscreened), screened, or with prior CAD. Unscreened was defined as no ischemia or anatomic testing while on waiting list or within the year prior to listing. Screening was considered as "positive" when it led to diagnostic of obstructive CAD (stenosis &amp;gt; 50%). Primary outcome was a composite outcome defined as [death or unplanned revascularization]. Primary outcome and renal transplant were analysed using multivariable Cox model. Results From 2005 to 2023, 3248 patients were registered as candidates for kidney transplantation, 228 (7.0%) patients had a history of CAD, 1987 (61.2%) patients were screened for CAD and 1033 (31.8%) were unscreened. Initial screening investigation were mainly stress cardiovascular MRI (33.7%), stress TTE (27.7%) or myocardial perfusion imaging (26.4%). Among screened patients, 133 (6.7%) patients had a positive screening for obstructive CAD. Within 4.7 [1.2 – 7.2] years, using patients with a negative screening as a reference, patients with positive screening and known CAD were less likely to receive renal transplant (aHR 0.70 [0.53 ; 0.93] and 0.64 [0.49 ; 0.84] respectively), while patients without screening were similarly transplanted (aHR 1.01 [0.89 ; 1.15]). Patients without screening or with a prior history of CAD were at higher risk of primary outcome compared with patients with negative screening (aHR 1.49 [1.16; 1.91]) and aHR 1.97 [1.48; 2.62] respectively), along with patients on dialysis at registration (1.37 [1.13; 1.66]), diabetic patients (1.79 [1.47; 2.18]) and smokers (1.25 [1.03; 1.53]). Age was an interaction factor between unscreening and primary outcome, as there was no association in younger patients (aHR 1.21 [0.81; 1.81]). Conclusion Among candidates for kidney transplantation, 2 out of 3 patients underwent non-invasive testing for obstructive CAD resulting in less than 10 % of positive cases. Positive testing and history of CAD were associated with a lower opportunity for kidney transplantation compared with negative testing or absence of screening. Nonetheless, absence of screening was associated with a higher risk of [death + unplanned revascularization], especially in older patients.Central illustration

Impact of CT attenuation correction on viable myocardium detection in combined SPECT and PET/CT: A retrospective cohort study.

The influence of computed tomography attenuation correction (CTAC) on the accuracy of diagnosing viable myocardium using Tc-99m-MIBI dedicated cardiac cadmium-zinc-telluride (CZT) single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) combined with F-18-FDG Positron Emission Tomography/Computed Tomography (PET/CT) metabolic imaging, compared with conventional SPECT MPI, remains to be fully elucidated. To evaluate the impact of CTAC on the accuracy of diagnosing viable myocardium using Tc-99m-MIBI dedicated cardiac CZT SPECT MPI combined with F-18-FDG PET/CT, compared to conventional SPECT MPI. 193 patients underwent CZT SPECT and F-18-FDG PET/CT imaging, while 39 patients underwent conventional SPECT and F-18-FDG PET/CT imaging, with both groups utilizing CT for attenuation correction. The injured myocardium (hibernating and scarring) was quantified using the Q.PET software. After CTAC, both groups showed significant improvements in perfusion of the injured myocardial areas, particularly in the inferior wall (INF). The reduction in perfusion was more notable in the CZT SPECT group than that in the conventional group, particularly in the inferior and lateral walls. Among patients with large cardiac chambers, those undergoing MPI with CZT, with normal weights, or males, hibernating myocardium (HM) and scar post-CTAC reductions were particularly significant in the INF. If HM ≥ 10% is considered an indicator for recommended revascularization, among the 87 patients without prior cardiac bypass, 25 (28.7%) might not require revascularization treatment. Dedicated cardiac CZT SPECT and conventional SPECT MPI combined with F-18-FDG PET/CT significantly influenced the assessment of viable myocardium. The impact of CTAC was more profound in dedicated cardiac CZT SPECT, particularly in the INF region. CTAC significantly enhances the accuracy of viable myocardial assessment and may influence clinical decisions regarding revascularization therapy. Therefore, CTAC should be routinely used in dedicated cardiac CZT SPECT MPI combined with F-18-FDG PET/CT for myocardial viability diagnosis.

Topical application of beta-blockers accelerates epithelialization to mesh skin grafted full-thickness burn in sheep

Aim : Beta-adrenergic receptor blockers are conventionally used for the treatment of hypertension, tachycardia, and glaucoma. Research has shown that beta-blockers can accelerate wound epithelialization. In this study, we tested the efficacy of the beta-blocker timolol in an ovine model of grafted full-thickness burn wound healing, which closely mimics clinical scenarios. Methods : Six full-thickness burn wounds were created on the sheep’s posterior surface. Twenty-four hours later, eschars were excised and meshed skin was grafted (Day0). The wounds in the treatment group received topical application of timolol. Blood flow was measured using a blood perfusion imager. Cardiovascular hemodynamics and blood glucose levels were recorded daily. The epithelialization rate on Day 14 was determined by planimetric assay and analyzed by paired t -test. The days that the epithelialization rate exceeded 85%, 90%, and 95% were analyzed by survival analysis. To assess the potential influence of TGFβ, epithelial-mesenchymal transition (EMT), or myofibroblast activation (MFA) on wound healing, the RNA abundance of gene products related to these pathways was measured by reverse transcription and quantitative polymerase chain reaction (RT-qPCR). Results : The epithelialization rate on Day 14 was significantly higher in the treatment group. The days that the epithelialization rate exceeded 85%, 90%, and 95% were significantly shorter in the treatment group. There was no significant difference in wound blood flow or RNA abundance related to TGFβ, EMT, or MFA-related pathways among the groups at any time point. Conclusion : The results demonstrate that the beta-blocker timolol accelerates epithelialization of mesh skin grafted full-thickness burn wounds through a mechanism other than improving wound blood flow.

Diagnostic value of routine CT perfusion imaging for radiology residents

To evaluate whether incorporating CT perfusion imaging can significantly enhance diagnostic CT accuracy in stroke detection. Two 3rd-year residents (3rd of 5 years of residency) reviewed CT scans of 200 patients with suspected stroke, consisting of 104 patients with a proven stroke and a control group with 96 patients. They analyzed each patient in a blinded and randomized manner in two runs. In one session, they had only non-contrast CT and CT angiography available for diagnosis; in the other session at a later time point, an additional CT perfusion imaging was available. The performance achieved by the two readers was determined in terms of AUC (area under the curve), accuracy, sensitivity, specificity, positive and negative predictive value and Cohen’s Kappa. Reader 1 achieved an AUC of 87.64% with the basic stroke-protocol vs. an AUC of 97.4% with an additional CT-perfusion given. Based on the DeLong test, these values differ significantly (p-value: 0.00017). Reader 2 achieved an AUC of 91.23% in basic stroke-protocol vs. an AUC of 96.42% with an additional CT-perfusion. These values also differ significantly (p-value: 0.02612).. The performance gain achieved with CT-perfusion is most evident in the decrease in the number of false classified cases (Reader 1: 24 to 5; Reader 2: 18 or 14 to 7) and the significant increase in Cohen’s kappa. Our study shows that additional CT-perfusion imaging in stroke diagnosis significantly improves the diagnostic reliability of residents. Therefore, it should be further investigated whether perfusion imaging should be a general standard of initial stroke diagnosis no matter of the onset.