Stress Imaging Research Articles

ROLE OF STRESS CARDIAC MRI IN THE EVALUATION OF SUSPECTED CORONARY ARTERY DISEASE.

Background: Cardiovascular magnetic resonance (CMR) has emerged in recent years as an essential tool in the imaging of coronary artery disease(CAD) and its preclinical detection. Our study aims at describing CMR imaging features of CAD, including CINE and perfusion imaging. We performed Stress perfusion CMR with Methods: pharmacologic stress(Adenosine) in 26patients of suspected CAD with intermediate cardiac chest pain. Results: All patients showed maintained wall thickness.The mean wall thickness of LV was 7.3mm ± 0.6 SD. 5 (6.4%) coronary territories showed regional wall motion abnormality on CINE imaging. No patient had hyperintensity on T2/STIR images. 9 patients (34.6%)showed subendocardial perfusion defect in coronary distribution on stress imaging, without matched defect on rest perfusion or LGE on delayed imaging (reversible inducible ischemia). 17 patients (73.4%) showed no perfusion defect on stress imaging. Out of 26, only 15 patients underwent catheter coronary angiography (CCA). This included all the 9 patients with stress inducible perfusion defect, of which 7(78%) showed significant CAD (>70% stenosis) in the corresponding artery and 2(22%) showed no significant CAD and 6 patients without stress inducible perfusion defect of which 5(83%) patients showed no significant CAD and 1(17%) showed significant CAD. Using CCA as a gold standard, the sensitivity of stress perfusion CMR in our study was 87.5%, specificity was 71.4% and accuracy was 80%. Stress Perfusion CMR is a noninvasive technique capable of detecting obstructive C Conclusion: AD with excellent diagnostic accuracy. It has high sensitivity and moderate specificity for diagnosing significant obstructive CAD compared with CCA.

ASSESSMENT OF PATIENTS WITH KNOWN CORONARY ARTERY DISEASE BY STRESS CARDIAC MRI.

Background: Signicant coronary artery lesions can be detected by evaluating regional myocardial perfusion by Cardiac MRI (CMR). This study aims to determine the usefulness of this technique in “known” patients of coronary artery disease (CAD). Our study aims at describing CMR featur Methods: es of CAD, including CINE and perfusion imaging. Stress perfusion imaging with pharmacologic stress (Adenosine) was performed on 22 patients with known CAD. These patients also underwent Catheter angiography (CAG). A total of 66 coronary territories were assessed for perfusion abnormalities and corresponding CAG ndings. Regional wall motion abnormalities were Results: seen in 28(42.4%) coronary territories and regional myocardial thinning in 11(16%) territories. Hypokinesia (68%) was the most commonly observed wall motion abnormality. Wall motion abnormality was present in most (91%; n=20) of the infarcted territories and some (18.2%;n=8) of the non-infarct territories. Regional myocardial thinning was present in some of the infarcted (27%; n=6) territories and none of the non-infarcted territories. The mean wall thickness in infarct territories was 5.1mm±0.4 and in non-infarct territories was 7.1mm±0.6. T2/STIR hyperintensity was present in 5 (23%) infarct related coronary territories and none of the non-infarcted territories. In all 5 cases, MRI was done within 10 days of symptom onset. 32 (49%) coronary territories showed perfusion defect on stress imaging, with 23 (35%) of them showing a matched defect on rest perfusion and 9 (14%) showing stress inducible perfusion defect. No perfusion defect was seen in 34(51%) territories. All 22 patients underwent CAG. 15patients had signicant disease (>70%) in a single vessel, 5 had in two vessels and none had in all the three vessels.2 patients had non-occlusive coronaries (MINOCA). Using CAG as gold standard, the sensitivity of stress perfusion CMR in detecting signicant CAD in non-infarct territory in these patients was 70%, with a specicity of 94% and accuracy of 88.3%. Visual analysis of rst-pass gadolinium CMR perfusion images to detect reg Conclusion: ional myocardial perfusion defect has a moderate sensitivity and high specicity for diagnosing signicant obstructive CAD in non-infarct related coronaries, as compared to CAG.

Stimuli‐Responsive Sponge for Imaging and Measuring Weak Compression Stresses

Imaging and measuring compression stresses secure a safe and healthy life. Compression stresses in kPa range are not easily detected by conventional mechanoresponsive materials because microscopic molecular motion of the chromophores is not induced by such weak stresses. Moreover, imaging of the stress distribution is not achieved so far. The present study shows a sponge device combining two stimuli-responsive materials, a capsule releasing interior liquid and color-changing polymer in responses to compression stress and chemical stimulus, respectively. The stimuli-responsive capsule is dispersed on a melamine sponge comprised of the fibers with coating the layered polydiacetylene (PDA). The application of weak compression stresses induces collapse of the capsules, outflow of the interior liquid, and subsequent irreversible color change of PDA. The cascading response in the sponge device colorimetrically enables imaging of the distribution and measuring the strength of the compression stresses in kPa range. Furthermore, the device demonstrates imaging and measuring unknown weak compression stresses applied by the irregular-shaped objects. A couple of clinical issues in surgical operation of intestine are studied using the stress-imaging sponge device. The device and its design strategy can be applied to stress imaging in a variety of fields.

Real-Time Imaging of Stress in Single Spherulites and Its Relaxation at the Single-Particle Level in Semicrystalline Polymers.

Crystallization-induced microscopic stress and its relaxation play a vital role in understanding crystallization behavior and mechanism. However, the real-time measurements for stress and its relaxation seem to be an unachievable task due to difficulties in simultaneous labeling, spatiotemporal discrimination, and continuous quantification. We designed a micron-sized fluorescent probe, whose fluorescence can respond to stress-induced environmental rigidity and whose three-dimensional (3D) flow can respond to stress relaxation. Using the as-prepared fluorescent probe, we established a versatile strategy to realize the real-time 3D imaging of stress and its relaxation in the crystallization process. The rigidity-responsive fluorescence clearly indicated the stress, while the 3D flow movement could quantify the stress relaxation. It is revealed that stress in spherulites increased dramatically as a result of the suppression of stress relaxation in polymer melts. The developed method provides a novel avenue to simultaneously detect stress and its relaxation in various semicrystalline polymers at the single-particle level. This success would achieve the microscopic ways to guide the development of advanced crystallization-dependent materials.

ASCENDING AORTIC ANEURYSMS: SURGERY, RMODELLING & AI

ASCENDING AORTIC ANEURYSMS: SURGERY, RMODELLING & AI

Use of cardiac imaging in chronic coronary syndromes: the EURECA Imaging registry.

The prospective, multicentre EURECA registry assessed the use of imaging and adoption of the European Society of Cardiology (ESC) Guidelines (GL) in patients with chronic coronary syndromes (CCS). Between May 2019 and March 2020, 5156 patients were recruited in 73 centres from 24 ESC member countries. The adoption of GL recommendations was evaluated according to clinical presentation and pre-test probability (PTP) of obstructive coronary artery disease (CAD). The mean age of the population was 64 ± 11 years, 60% of patients were males, 42% had PTP >15%, 27% had previous CAD, and ejection fraction was <50% in 5%. Exercise ECG was performed in 32% of patients, stress imaging as the first choice in 40%, and computed tomography coronary angiography (CTCA) in 22%. Invasive coronary angiography (ICA) was the first or downstream test in 17% and 11%, respectively. Obstructive CAD was documented in 24% of patients, inducible ischaemia in 19%, and 13% of patients underwent revascularization. In 44% of patients, the overall diagnostic process did not adopt the GL. In these patients, referral to stress imaging (21% vs. 58%; P < 0.001) or CTCA (17% vs. 30%; P < 0.001) was less frequent, while exercise ECG (43% vs. 22%; P < 0.001) and ICA (48% vs. 15%; P < 0.001) were more frequently performed. The adoption of GL was associated with fewer ICA, higher proportion of diagnosis of obstructive CAD (60% vs. 39%, P < 0.001) and revascularization (54% vs. 37%, P < 0.001), higher quality of life, fewer additional testing, and longer times to late revascularization. In patients with CCS, current clinical practice does not adopt GL recommendations on the use of diagnostic tests in a significant proportion of patients. When the diagnostic approach adopts GL recommendations, invasive procedures are less frequently used and the diagnostic yield and therapeutic utility are superior.

Psychological distress and body image disturbances after modified radical mastectomy among breast cancer survivors: A cross-sectional study from a tertiary care centre in North India.

Breast cancer (BC) diagnosis and treatment can affect women both physically and psychologically. Women with BC undergo various painful and debilitating therapies as well as emotional trauma. Additionally, treatment modalities can bring about multiple changes, causing distress and alteration in one's appearance. This study aimed to assess the psychological distress and body image disturbances after modified radical mastectomy (MRM) among BC survivors. A descriptive, cross-sectional study was conducted at a tertiary care centre in North India on 165 female survivors of BC who underwent MRM and attended outpatient follow-up. The median (interquartile range) age was 42 (36-51) years. Patients were evaluated using MINI 6·0·0 to assess for psychiatric comorbidities. The Depression Anxiety and Stress Scale (DASS-21) was used to measure psychological distress. Additionally, the ten-item Body Image Satisfaction (BIS-10) scale was used to evaluate body image disturbances. The rates of depression, anxiety, and stress were 27·8%, 31·5%, and 24·8%, respectively. Most patients (92%) experienced body image disturbances, and BC survivors who completed treatment within 12 months were more likely (p<0·01) to have body image disturbances than women who had a long time since completion of treatment. Body image disturbances were not associated with age or psychological distress. Depression, anxiety, stress, and body image issues are common among BC survivors. Follow-up management plans for BC survivors should also include evaluation and treatment of psychological distress and addressing body image disturbances in patients undergoing mastectomy. Not applicable.

Augmented stress weightbearing CT for evaluation of subtle tibiofibular syndesmotic injuries in the elite athlete.

We aim to present a novel imaging technique utilizing weight-bearing CT with syndesmotic stress to identify subtle, unstable syndesmotic injuries. We illustrate this with a case presentation of such an injury in an elite athlete that ultimately required operative fixation. In order to perform an augmented stress weightbearing CT, the patient is in the standing position, feet facing forward, and with weight distributed equally. The patient is then coached to internally rotate the shin and knee. This places an external rotational moment on the TFS due to the planted foot and ankle. The augmented stress images undergo 3D reconstruction and post-processing to render coronal and sagittal images. These are subsequently compared to standard, conventional weightbearing CT images performed without the external rotation stress. We illustrate this technique by presenting a case in which a 21-year-old collegiate athlete sustained a Grade II syndesmotic injury, diagnosed by MRI and clinical exam without evidence of instability by standard weightbearing CT or weightbearing radiographs. After undergoing the augmented stress weightbearing CT, the instability was noted. This prompted subsequent operative fixation and ultimately return to sport. We propose this technique for diagnosing unrecognized, subtle dynamically unstable syndesmosis injuries where clinical suspicion persists despite negative imaging, particularly in the elite athlete.

Abstract 12499: Anomalous Coronary Arteries Are Associated With Ischemia in the Ischemia Trial

Introduction: Coronary anomalies are detected in 0.3-2.3% of patients undergoing coronary computed tomography angiography (CCTA). Data are scarce on atherosclerosis severity in anomalous arteries and relationship to ischemia on stress testing. Hypothesis: High risk features of anomalous coronary arteries are associated with ischemia, even in the absence of coronary stenosis on CCTA. Methods: 5,903 participants enrolled in the ISCHEMIA trial program with site-determined moderate or severe ischemia underwent CCTA. A core laboratory assessed atherosclerosis severity and made note of anomalous coronary origin. A single reader at the CCTA core laboratory re-evaluated all identified anomalies to assess high risk features and origin, blinded to stress test results. Patients were excluded if stress test results were unavailable. We assessed the relationship between type of anomaly and vessel with ischemia in the subtended territory on stress imaging, and stenosis severity. Results: There was anomalous origin of a coronary artery in 56 of 5,903 CCTA cases (0.9%). Age, sex and CAD risk factors were similar between patients with vs. without anomalies. Anomalous origin affected the left circumflex (LCX) in 28, right coronary artery (RCA) in 21, left main (LM) in 4, and left anterior descending (LAD) in 3. Ischemia was severe on stress testing in 58.2%, moderate in 34.5%, mild in 3.6% and absent in 3.6%. High risk anomalies were present in 17/56 (30.3%, 16/21 RCA and 1/4 LM), including inter-arterial course in 28.6%, intra-mural course in 1.8%, and slit-like orifice in 12.5%. Most anomalous coronaries (82.9%) were associated with ischemia in the subtended territory. Among anomalies associated with ischemia, 37.9% had &lt;50% stenosis and 62.1% had &lt;70% stenosis (Figure). Of those with &lt;70% stenosis, 27.6% had high risk features. Conclusions: Anomalous coronary arteries in stable patients are associated with ischemia, even in the absence of severe atherosclerotic disease.

Patients with Polyvascular Disease: A Very High-risk Group.

Polyvascular disease (PolyvascDis) with atherosclerosis occurring in >2 vascular beds (coronary, carotid, aortic, visceral and/or peripheral arteries) is encountered in 15-30% of patients who experience greater rates of major adverse cardiovascular (CV) events. Every patient with multiple CV risk factors or presenting with CV disease in one arterial bed should be assessed for PolyvascDis clinically and noninvasively prior to invasive angiography. Peripheral arterial disease (PAD) can be readily diagnosed in routine practice by measuring the ankle-brachial index. Carotid disease can be diagnosed by duplex ultrasound showing % stenosis and/or presence of plaques. Coronary artery disease (CAD) can be screened by determining coronary artery calcium score using coronary computed tomography angiography; further, non-invasive testing includes exercise stress and/or myocardial perfusion imaging or dobutamine stress test, prior to coronary angiography. Abdominal ultrasound can reveal an abdominal aortic aneurysm. Computed tomography angiography will be needed in patients with suspected mesenteric ischemia to assess the mesenteric arteries. Patients with the acute coronary syndrome and concomitant other arterial diseases have more extensive CAD and poorer CV outcomes. Similarly, PolyvascDis in patients with carotid disease and/or other PAD is independently associated with an increased risk for all-cause and CV mortality during long-term follow-up. Treatment of patients with PolyvascDis should include aggressive management of all modifiable risk factors by lifestyle changes and drug therapy, with particular attention to patients who are commonly undertreated, such as those with PAD. Revascularization should be reserved for symptomatic vascular beds, using the least aggressive strategy in a multidisciplinary vascular team approach.

Neural correlates linking trauma and physical symptoms

Trauma and chronic pain frequently co-occur, but the underlying neurological mechanisms are poorly understood. The current study investigated the neural correlates of stress and physical symptoms in trauma patients using functional magnetic resonance imaging (fMRI) and follow-up smartphone surveys. Participants were 10 patients diagnosed with Trauma- and Stressor-Related Disorders and 18 demographically-matched healthy controls who completed a fMRI stress provocation task in which they viewed stressful and neutral-relaxing images. Subsequently, participants completed daily smartphone surveys which prospectively monitored their stress and physical symptoms for 30 days. The trauma group experienced a significantly higher frequency of physical symptoms than controls during the follow-up period. During stress, trauma patients exhibited increased activity in the hippocampus, insula, and sensorimotor areas, but decreased activity in the ventromedial prefrontal cortex (vmPFC), lateral prefrontal cortex (LPFC), and dorsal striatum relative to controls. In all participants, higher physical symptom frequency was significantly associated with a hyperactive left hippocampal response to stress. The current study reports that trauma is characterized by greater physical symptoms and decreased prefrontal but increased limbic responses to stress. Our findings suggest that trauma may increase physical health symptoms by compromising hippocampal function, which could also increase vulnerability to stress- and pain-related disorders.

Examining the perceived stress and body image in burn patients: A cross-sectional study.

This study aimed to examine the perceived stress and body image in burn patients and the relationship between these two variables. This is a descriptive and cross-sectional study. The study included total of 144 patients who had burn injuries, received treatment in a research and training hospital and were scheduled to be discharged. The data were collected prospectively by the researchers, using descriptive methods, Kruskal Wallis test, paired samples t test, and Pearson's correlation analysis. Of the patients, 59% were between the ages of 18 and 35 years, 68.1% were male, 65.3% had second-degree burns, 77.1% had burn surfaces ranging between 10% and 20% of their body, and 54.9% had autograft surgery. The burn patients aged 51 years and over had higher perceived stress than younger patients, and the difference between them was statistically significant (P< 0.05). As the percentage of burn surface increased, the perceived stress increased, and the perceived body image weakened (P< 0.05). The burn patients with autograft surgery had lower perceived stress and higher perceived body image than those without autograft surgery, and the difference between them was statistically significant (P< 0.01). This study found an inverse relationship between perceived stress and body image in burn patients, which was affected by the percentage of burn surface and autograft surgery. Relevant interventions are suggested to increase perceived body image in burn patients and reduce their perceived stress.

Serum myostatin level is associated with myocardial scar burden by SPECT myocardial perfusion imaging

BackgroundMyostatin is a negative regulator of skeletal muscle and myocardial mass. The relationship between myocardial ischemia and scar burden and levels of myostatin has not been established. MethodsWe enrolled symptomatic patients with heart failure (HF) with a left ventricular ejection fraction (LVEF) < 45 % and controls (LVEF ≥ 45 %). Serum levels of myostatin were measured. Single-photon emission computed tomography (SPECT) imaging was interpreted, and summed scores of 17 stress and rest image segments in 5-point scale produced the summed stress score (SSS) and summed rest score (SRS), respectively. The summed difference score (SDS) was calculated as the difference between the SSS and SRS. ResultsNinety-six patients with HF and 103 controls were enrolled. The levels of myostatin were higher in the HF group. In linear regression analysis, myostatin level was positively correlated with SSS (β coefficient = 6.840, p = 0.013) and SRS (β coefficient = 5.557, p = 0.026), but not correlated with SDS. The areas under the receiver operating characteristic curves of myostatin levels for SSS ≥ 8 and SSS ≥ 13 were 0.6813 ± 0.04854 (p < 0.001) and 0.7498 ± 0.04402 (p < 0.001), respectively. ConclusionSerum levels of myostatin were correlated with the extent of myocardial scarring as defined by SPECT imaging. Serum levels of myostatin may be a predictor of myocardial scar burden.

Correlation of left ventricular mechanical dyssynchrony in patients with chronic kidney disease using phase analysis of gated single photon emission computed tomography myocardial perfusion imaging

Abstract Background Left ventricular mechanical dyssynchrony (LVMD) possesses deleterious effects that have been neglected in chronic kidney disease (CKD) as a cause of left ventricular dysfunction and further progression to heart failure, possibly contributing to sudden cardiac death in this population. Thus, cardiovascular risk assessment is essential in early stages of CKD as well as in the pre-transplant screening and this can be performed non-invasively by modalities including phase analysis Gated-SPECT myocardial perfusion imaging (MPI). This modality has emerged as a prognostic tool to predict mortality independent of MPI abnormalities as well as assessment of ventricular synchrony. Purpose The goal of this study is to evaluate the relationship of left ventricular mechanical dyssynchrony using phase analysis G-SPECT and chronic kidney disease severity and its predictors. Methods We included 567 patients who underwent one day rest/stress (dipyridamole) 99mTc-sestamibi myocardial perfusion imaging with G-SPECT for the following indications for testing: detection of CAD among asymptomatic patients, risk assessment during pre-operative evaluation for kidney transplantation and evaluation for noncardiac surgery without active cardiac conditions between January 2017 to January 2021. Data was collected including gender, age, risk factors resting heart rate and baseline blood pressure. Gated SPECT-MPI was performed according to the protocol rest followed by stress images (dipyridamole) 99mTc-sestamibi. The rest and stress phase analysis (histogram bandwidth, standard deviation of phase and entropy) parameters were compared between the five stages of chronic kidney disease. Data of the stress-rest difference in dyssynchrony was analyzed using McNemar's test; crude odds ratios and adjusted odds or multivariate analysis were done. Results Advanced CKD (Stage 4–5) shows statistically significant correlation with the Histogram bandwidth (HBW) both at stress (p=0.008) and rest (p=0.018), and stress entropy (p=0.007). As for the other stages, LVMD is present with similar results seen with the phase parameters HBW and PSD, the entropy values at rest than at stress for Stages I to IV (p&amp;lt;0.05). On further analysis, abnormal perfusion showed to be an independent predictor of left ventricular mechanical dyssynchrony across all arms. Other associated factors includes advanced CKD (stages 4–5), male sex, BMI ≥30 kg/m2, blood pressure and resting heart rate were significantly associated with increased odds of dyssynchrony across stress and rest tests. Overall, the full models were statistically significant, with R-squared ranging from 14.96% to 30.11% (p&amp;lt;0.001). Conclusion This study showed that CKD patients have left ventricular mechanical dyssynchrony on gated-SPECT MPI. Hence, it can be used as an alternative for early assessment and guide decision making for the treatment of patients with CKD to prevent further cardiovascular complication. Funding Acknowledgement Type of funding sources: None.

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

Abstract 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 &amp;gt;1 contiguous segments showed both stress Myocardial Blood Flow ≤2.3mL/g/min and Myocardial Flow Reserve (MFR) ≤2.5 for 15O-water or &amp;lt;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)

Differential association of high-sensitive cardiac Troponin T and Troponin I with coronary atherosclerotic burden, inducible ischemia and long-term prognosis in patients with chronic coronary syndrome

Abstract Background High-sensitivity (hs) assays for the measurement of cardiac troponin T (cTnT) and cardiac troponin I (cTnI) are now used widely for the diagnosis of myocardial infarction. However, it is also increasingly apparent that troponin concentrations well below the thresholds used in acute coronary syndromes may provide diagnostic and prognostic information also for patients with chronic coronary syndromes (CCS). Purpose This study is aimed at evaluating the association of hs-cTnT and hs-cTnI with clinical/molecular profiles, measures of myocardial ischemia and coronary artery disease (CAD), and their potential role as predictors of adverse cardiovascular events in a population of patients with CCS. Methods Hs-cTnT and hs-cTnI were measured in 365 patients with CCS (mean age 61±8, 217 males) as part of the multicenter Evaluation of Integrated Cardiac Imaging (EVINCI) European study. Patients were characterized for clinical and molecular profile and underwent stress imaging to detect myocardial ischemia and coronary computed tomographic angiography (CTA) to assess the presence of CAD. An individual coronary CTA score was calculated combining extent, severity, composition, and location of plaques. All patients entered a clinical follow-up (1600±369 days). The composite cardiovascular outcome measure included all-cause mortality, non-fatal myocardial infarction, and hospitalization for unstable angina or heart failure. Clinical, molecular, and imaging parameters were used in a multivariate step-wise analysis to identify those associated with hs-cTnT and hs-cTnI. The possible role of troponins as independent predictors of adverse cardiovascular events was evaluated by Kaplan-Meier and Cox analysis. Results The median values (IQR) of hs-cTnT and of hs-cTnI were 6.4 (4.9) ng/L and 4.4 (10.3) ng/L, respectively. In a multivariate model, age, gender, diabetes, NT-proBNP, and CTA score were independently associated with plasma hs-cTnT; triglycerides, HDL-cholesterol, and ischemia were independently associated with hs-cTnI (Table 1); interleukin-6 was associated with both troponins. At Kaplan-Meier analysis, event-free survival was significantly worse in patients with levels higher than the median values of both hs-cnT and hs-cTnI (Figure 1A, B). At Cox analysis, after correction for age, gender, and risk factors (EUROscore), only high hs-cTnI remained an independent predictor of cardiovascular events (hs-cTnT: HR 2.17, 95% CI, 0.87–5.41, P=ns; hs-cTnI: HR 2.65, 95% CI, 1.09–6.44, P=0.031). Conclusion In patients with CCS, the presence and extent of coronary atherosclerosis is related with circulating levels of hs-cTnT, while the presence of ischemia is related with circulating levels of hs-cTnI, suggesting different mechanisms of release. Only high levels of hs-cTnI were independent predictors of cardiovascular events. Funding Acknowledgement Type of funding sources: Public grant(s) – EU funding. Main funding source(s): Grant from the European Union FP7-CPFP506-2007 (Evaluation ofIntegrated Cardiac Imaging for the Detection and Characterisation of Ischemic Heart Disease).

Deep learning for evaluating left atrium stress echocardiography: a proof of principle study

Abstract Introduction Left atrial (LA) size is a dynamic variable that changes during stress echocardiography (SE) and provides valuable information within and beyond coronary artery disease. However, its measurement remains subjective, time-consuming and based on manual tracings. Recent advances in deep learning might save analysis time and deflate variability by removing the subjectivity of LA assessment. Purpose In this proof of principle study we aim to validate the potential of an automated machine learning system for the evaluation of LA in SE. Methods From the image data bank of Stress Echo 2030 study, we selected 20 consecutive patients who underwent SE (using a variety of stress methods) in 2 recruiting centers. Imaging data was acquired in DICOM format and anonymized. The studies were reviewed by an expert cardiologist trained in SE evaluation who selected apical four chamber (A4Ch) view images during stress and rest phases and marked end-systolic (ES) and end-diastolic frames to be used in further evaluation. Endocardial borders for LA were traced in ES. The tracings were repeated by three different evaluators (expert cardiologist [C1], cardiologist from external center [C2] and a machine learning [ML] model – a convolutional neural network trained on an unrelated set of images). LA area (LAA), volume (LAV) using area-length formula and proportional LAV changes between stress and rest (ΔLAV = [rest − stress] / rest) were calculated. Each evaluator was blinded from each other's measurements. Results In total, 40 A4Ch images were acquired (20 at rest and 20 at stress) of which all were of sufficient quality for performing LA measurements using an automated system. Pearson correlation coefficients (R) for LAA were 0.95 (C1-ML), 0.96 (C2-ML) at rest and 0.88 (C1-ML), 0.79 (C2-ML) at stress. The C1-C2 pair had R of 0.98 and 0.86 for LAA at rest and stress. LAV also showed good correlation between different raters with R values of 0.90 (C1-ML), 0.94 (C2-ML), 0.94 (C1-C2) at rest and 0.86 (C1-ML), 0.87 (C2-ML), 0.84 (C1-C2) at stress. Root mean squared errors (RMSEs) for LAV were 13.48 ml (C1-ML), 7.44 ml (C2-ML), 10.26 ml (C1-C2) at rest and 14.03 ml (C1-ML), 8.53 ml (C2-ML), 13.69 ml (C1-C2) at stress. There were high level correlations between all raters for ΔLAV with R values of 0.93, 0.94 and 0.95 for C1-ML, C2-ML and C1-C2 pairs respectively. Mean (95% CI) ΔLAV values were −20.1 (−51.59 to +11.39), −14.95 (−43.77 to +13.87) and −14.37 (−34.46 to +5.72) for ML, C1 and C2. Comparison with one-way ANOVA did not show significant differences in mean ΔLAV values between operators (p=0.94). Conclusions Automated ML based system produces LA measurements that are comparable to human operators and can reduce the need for manual tracing. There was a tendency for all operators to have lower levels of agreement in stress images compared to rest, further showing the need for additional standardization of SE evaluation for machine and human operators. Funding Acknowledgement Type of funding sources: None.

Oral N-acetylcysteine decreases IFN-γ production and ameliorates ischemia-reperfusion injury in steatotic livers.

Type 1 Natural Killer T-cells (NKT1 cells) play a critical role in mediating hepatic ischemia-reperfusion injury (IRI). Although hepatic steatosis is a major risk factor for preservation type injury, how NKT cells impact this is understudied. Given NKT1 cell activation by phospholipid ligands recognized presented by CD1d, we hypothesized that NKT1 cells are key modulators of hepatic IRI because of the increased frequency of activating ligands in the setting of hepatic steatosis. We first demonstrate that IRI is exacerbated by a high-fat diet (HFD) in experimental murine models of warm partial ischemia. This is evident in the evaluation of ALT levels and Phasor-Fluorescence Lifetime (Phasor-FLIM) Imaging for glycolytic stress. Polychromatic flow cytometry identified pronounced increases in CD45+CD3+NK1.1+NKT1 cells in HFD fed mice when compared to mice fed a normal diet (ND). This observation is further extended to IRI, measuring ex vivo cytokine expression in the HFD and ND. Much higher interferon-gamma (IFN-γ) expression is noted in the HFD mice after IRI. We further tested our hypothesis by performing a lipidomic analysis of hepatic tissue and compared this to Phasor-FLIM imaging using “long lifetime species”, a byproduct of lipid oxidation. There are higher levels of triacylglycerols and phospholipids in HFD mice. Since N-acetylcysteine (NAC) is able to limit hepatic steatosis, we tested how oral NAC supplementation in HFD mice impacted IRI. Interestingly, oral NAC supplementation in HFD mice results in improved hepatic enhancement using contrast-enhanced magnetic resonance imaging (MRI) compared to HFD control mice and normalization of glycolysis demonstrated by Phasor-FLIM imaging. This correlated with improved biochemical serum levels and a decrease in IFN-γ expression at a tissue level and from CD45+CD3+CD1d+ cells. Lipidomic evaluation of tissue in the HFD+NAC mice demonstrated a drastic decrease in triacylglycerol, suggesting downregulation of the PPAR-γ pathway.

National Diagnostic Reference Levels for Nuclear Medicine in Qatar.

Nuclear medicine (NM) started in Qatar in the mid-1980s with a 1-head γ-camera in Hamad General Hospital. However, Qatar is expanding, and now Hamad Medical Corp. has 2 NM departments and 1 PET/CT Center for Diagnosis and Research, with several hybrid SPECT/CT and PET/CT cameras. Furthermore, 2 new NM departments will be established in Qatar in the coming 3 y. Therefore, there is a need to optimize radiation protection in NM imaging and establish diagnostic reference levels (DRLs) for the first time in Qatar. This need is not only for the NM part of the examination but also for the CT part, especially in hybrid SPECT/CT and PET/CT. Methods: Data for adult patients were collected from the 3 SPECT/CT machines in the 2 NM facilities and from the 2 PET/CT machines in the PET/CT center. The 75th percentile values (also known as the third quartile) were considered preliminary DRLs and were consistent with the most commonly administered activities. The results for various general NM protocols were described, especially 99mTc-based radiopharmaceuticals and PET/CT protocols including mainly oncologic applications. Results: The first DRLs for NM imaging in Qatar adults were established. The values agreed with other published DRLs, as was the case, for example, for PET oncology using 18F-FDG, with DRLs of 258, 230, 370, 400, and 461-710 MBq for Qatar, Kuwait, Korea, the United Kingdom, and the United States, respectively. Similarly, for cardiac stress or rest myocardial perfusion imaging using 99mTc-methoxyisobutylisonitrile, the DRLs were 926, 976, 1,110, 800, and 945-1,402 MBq for Qatar, Kuwait, Korea, the United Kingdom, and the United States, respectively. Conclusion: The optimization of administered activity that this study will enable for NM procedures in Qatar will be of great value, especially for new departments that adhere to these DRLs.

Can we obtain the internal information of a surface crack from Rayleigh waves?

In this study, the Rayleigh wave responses of surface cracks with irregular planes are investigated utilizing novel numerical approaches. The effects of the equivalent width, filling situation and geometrical properties of the crack on the wave propagation are analyzed based on the scattered surface wave signals. The scattering process of the source due to an irregular surface crack is implemented by the staggered grid finite difference method (SG-FDM). The complex boundary conditions on the crack surface are classified by a modified stress image method (SIM) with a series of cells. A well comparison result is presented between SG-FDM and the finite element method. Three typical models are designed to analyze the effects of the crack width and filling material on Rayleigh waves. Furthermore, we focus on the influences of the effective width spatial variation characteristics of an irregular crack on Rayleigh wave propagation with different crack depth-wavelength ratios. The energy distribution of the scattered Rayleigh waves depends on the crack average width and the integrity of the filling material after damage repair. Our study reveals the specific wave phenomena (e.g., crack width-dependent and filling condition-dependent scattered waves) influenced by the crack interior structures, and this provides a method for detecting the subsurface structures (e.g., variation of crack width along the depth direction) of a breaking crack and evaluating the repair quality regarding local defects.