Magnetic Resonance Imaging for Monitoring of Hepatic Disease Induced by Ebola Virus: a Nonhuman Primate Proof-of-Concept Study.

Severe liver impairment is a well-known hallmark of Ebola virus disease (EVD). However, the role of hepatic involvement in EVD progression is understudied. Medical imaging in established animal models of EVD (e.g., nonhuman primates [NHPs]) can be a strong complement to traditional assays to better investigate this pathophysiological process in vivo and noninvasively. In this proof-of-concept study, we used longitudinal multiparametric magnetic resonance imaging (MRI) to characterize liver morphology and function in nine rhesus monkeys after exposure to Ebola virus (EBOV). Starting 5 days postexposure, MRI assessments of liver appearance, morphology, and size were consistently compatible with the presence of hepatic edema, inflammation, and congestion, leading to significant hepatomegaly at necropsy. MRI performed after injection of a hepatobiliary contrast agent demonstrated decreased liver signal on the day of euthanasia, suggesting progressive hepatocellular dysfunction and hepatic secretory impairment associated with EBOV infection. Importantly, MRI-assessed deterioration of biliary function was acute and progressed faster than changes in serum bilirubin concentrations. These findings suggest that longitudinal quantitative in vivo imaging may be a useful addition to standard biological assays to gain additional knowledge about organ pathophysiology in animal models of EVD. IMPORTANCE Severe liver impairment is a well-known hallmark of Ebola virus disease (EVD), but the contribution of hepatic pathophysiology to EVD progression is not fully understood. Noninvasive medical imaging of liver structure and function in well-established animal models of disease may shed light on this important aspect of EVD. In this proof-of-concept study, we used longitudinal magnetic resonance imaging (MRI) to characterize liver abnormalities and dysfunction in rhesus monkeys exposed to Ebola virus. The results indicate that in vivo MRI may be used as a noninvasive readout of organ pathophysiology in EVD and may be used in future animal studies to further characterize organ-specific damage of this condition, in addition to standard biological assays.

Computed Tomography Imaging for Monitoring of Marburg Virus Disease: a Nonhuman Primate Proof-Of-Concept Study.

Marburg virus (MARV) is a highly virulent zoonotic filovirid that causes Marburg virus disease (MVD) in humans. The pathogenesis of MVD remains poorly understood, partially due to the low number of cases that can be studied, the absence of state-of-the-art medical equipment in areas where cases are reported, and limitations on the number of animals that can be safely used in experimental studies under maximum containment animal biosafety level 4 conditions. Medical imaging modalities, such as whole-body computed tomography (CT), may help to describe disease progression in vivo, potentially replacing ethically contentious and logistically challenging serial euthanasia studies. Towards this vision, we performed a pilot study, during which we acquired whole-body CT images of 6 rhesus monkeys before and 7 to 9 days after intramuscular MARV exposure. We identified imaging abnormalities in the liver, spleen, and axillary lymph nodes that corresponded to clinical, virological, and gross pathological hallmarks of MVD in this animal model. Quantitative image analysis indicated hepatomegaly with a significant reduction in organ density (indicating fatty infiltration of the liver), splenomegaly, and edema that corresponded with gross pathological and histopathological findings. Our results indicated that CT imaging could be used to verify and quantify typical MVD pathogenesis versus altered, diminished, or absent disease severity or progression in the presence of candidate medical countermeasures, thus possibly reducing the number of animals needed and eliminating serial euthanasia. IMPORTANCE Marburg virus (MARV) is a highly virulent zoonotic filovirid that causes Marburg virus disease (MVD) in humans. Much is unknown about disease progression and, thus, prevention and treatment options are limited. Medical imaging modalities, such as whole-body computed tomography (CT), have the potential to improve understanding of MVD pathogenesis. Our study used CT to identify abnormalities in the liver, spleen, and axillary lymph nodes that corresponded to known clinical signs of MVD in this animal model. Our results indicated that CT imaging and analyses could be used to elucidate pathogenesis and possibly assess the efficacy of candidate treatments.

Longitudinal analyses using 18F-Fluorodeoxyglucose positron emission tomography with computed tomography as a measure of COVID-19 severity in the aged, young, and humanized ACE2 SARS-CoV-2 hamster models.

This study compared disease progression of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) in three different models of golden hamsters: aged (≈60 weeks old) wild-type (WT), young (6 weeks old) WT, and adult (14-22 weeks old) hamsters expressing the human-angiotensin-converting enzyme 2 (hACE2) receptor. After intranasal (IN) exposure to the SARS-CoV-2 Washington isolate (WA01/2020), 2-deoxy-2-[fluorine-18]fluoro-D-glucose positron emission tomography with computed tomography (18F-FDG PET/CT) was used to monitor disease progression in near real time and animals were euthanized at pre-determined time points to directly compare imaging findings with other disease parameters associated with coronavirus disease 2019 (COVID-19). Consistent with histopathology, 18F-FDG-PET/CT demonstrated that aged WT hamsters exposed to 105 plaque forming units (PFU) developed more severe and protracted pneumonia than young WT hamsters exposed to the same (or lower) dose or hACE2 hamsters exposed to a uniformly lethal dose of virus. Specifically, aged WT hamsters presented with a severe interstitial pneumonia through 8 d post-exposure (PE), while pulmonary regeneration was observed in young WT hamsters at that time. hACE2 hamsters exposed to 100 or 10 PFU virus presented with a minimal to mild hemorrhagic pneumonia but succumbed to SARS-CoV-2-related meningoencephalitis by 6 d PE, suggesting that this model might allow assessment of SARS-CoV-2 infection on the central nervous system (CNS). Our group is the first to use (18F-FDG) PET/CT to differentiate respiratory disease severity ranging from mild to severe in three COVID-19 hamster models. The non-invasive, serial measure of disease progression provided by PET/CT makes it a valuable tool for animal model characterization.

Deep-Learning-Based Whole-Lung and Lung-Lesion Quantification Despite Inconsistent Ground Truth: Application to Computerized Tomography in SARS-CoV-2 Nonhuman Primate Models.

RATIONALE AND OBJECTIVES: Animal modeling of infectious diseases such as coronavirus disease 2019 (COVID-19) is important for exploration of natural history, understanding of pathogenesis, and evaluation of countermeasures. Preclinical studies enable rigorous control of experimental conditions as well as pre-exposure baseline and longitudinal measurements, including medical imaging, that are often unavailable in the clinical research setting. Computerized tomography (CT) imaging provides important diagnostic, prognostic, and disease characterization to clinicians and clinical researchers. In that context, automated deep-learning systems for the analysis of CT imaging have been broadly proposed, but their practical utility has been limited. Manual outlining of the ground truth (i.e., lung-lesions) requires accurate distinctions between abnormal and normal tissues that often have vague boundaries and is subject to reader heterogeneity in interpretation. Indeed, this subjectivity is demonstrated as wide inconsistency in manual outlines among experts and from the same expert. The application of deep-learning data-science tools has been less well-evaluated in the preclinical setting, including in nonhuman primate (NHP) models of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection/COVID-19, in which the translation of human-derived deep-learning tools is challenging. The automated segmentation of the whole lung and lung lesions provides a potentially standardized and automated method to detect and quantify disease. MATERIALS AND METHODS: We used deep-learning-based quantification of the whole lung and lung lesions on CT scans of NHPs exposed to SARS-CoV-2. We proposed a novel multi-model ensemble technique to address the inconsistency in the ground truths for deep-learning-based automated segmentation of the whole lung and lung lesions. Multiple models were obtained by training the convolutional neural network (CNN) on different subsets of the training data instead of having a single model using the entire training dataset. Moreover, we employed a feature pyramid network (FPN), a CNN that provides predictions at different resolution levels, enabling the network to predict objects with wide size variations. RESULTS: We achieved an average of 99.4 and 60.2% Dice coefficients for whole-lung and lung-lesion segmentation, respectively. The proposed multi-model FPN outperformed well-accepted methods U-Net (50.5%), V-Net (54.5%), and Inception (53.4%) for the challenging lesion-segmentation task. We show the application of segmentation outputs for longitudinal quantification of lung disease in SARS-CoV-2-exposed and mock-exposed NHPs. CONCLUSION: Deep-learning methods should be optimally characterized for and targeted specifically to preclinical research needs in terms of impact, automation, and dynamic quantification independently from purely clinical applications.

Toward the determination of sensitive and reliable whole-lung computed tomography features for robust standard radiomics and delta-radiomics analysis in a nonhuman primate model of coronavirus disease 2019.

Purpose: We propose a method to identify sensitive and reliable whole-lung radiomic features from computed tomography (CT) images in a nonhuman primate model of coronavirus disease 2019 (COVID-19). Criteria used for feature selection in this method may improve the performance and robustness of predictive models. Approach: Fourteen crab-eating macaques were assigned to two experimental groups and exposed to either severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) or a mock inoculum. High-resolution CT scans were acquired before exposure and on several post-exposure days. Lung volumes were segmented using a deep-learning methodology, and radiomic features were extracted from the original image. The reliability of each feature was assessed by the intraclass correlation coefficient (ICC) using the mock-exposed group data. The sensitivity of each feature was assessed using the virus-exposed group data by defining a factor R that estimates the excess of variation above the maximum normal variation computed in the mock-exposed group. R and ICC were used to rank features and identify non-sensitive and unstable features. Results: Out of 111 radiomic features, 43% had excellent reliability ( ICC > 0.90 ), and 55% had either good ( ICC > 0.75 ) or moderate ( ICC > 0.50 ) reliability. Nineteen features were not sensitive to the radiological manifestations of SARS-CoV-2 exposure. The sensitivity of features showed patterns that suggested a correlation with the radiological manifestations. Conclusions: Features were quantified and ranked based on their sensitivity and reliability. Features to be excluded to create more robust models were identified. Applicability to similar viral pneumonia studies is also possible.

Characteristic and quantifiable COVID-19-like abnormalities in CT- and PET/CT-imaged lungs of SARS-CoV-2-infected crab-eating macaques (Macaca fascicularis).

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is causing an exponentially increasing number of coronavirus disease 19 (COVID-19) cases globally. Prioritization of medical countermeasures for evaluation in randomized clinical trials is critically hindered by the lack of COVID-19 animal models that enable accurate, quantifiable, and reproducible measurement of COVID-19 pulmonary disease free from observer bias. We first used serial computed tomography (CT) to demonstrate that bilateral intrabronchial instillation of SARS-CoV-2 into crab-eating macaques (Macaca fascicularis) results in mild-to-moderate lung abnormalities qualitatively characteristic of subclinical or mild-to-moderate COVID-19 (e.g., ground-glass opacities with or without reticulation, paving, or alveolar consolidation, peri-bronchial thickening, linear opacities) at typical locations (peripheral>central, posterior and dependent, bilateral, multi-lobar). We then used positron emission tomography (PET) analysis to demonstrate increased FDG uptake in the CT-defined lung abnormalities and regional lymph nodes. PET/CT imaging findings appeared in all macaques as early as 2 days post-exposure, variably progressed, and subsequently resolved by 6-12 days post-exposure. Finally, we applied operator-independent, semi-automatic quantification of the volume and radiodensity of CT abnormalities as a possible primary endpoint for immediate and objective efficacy testing of candidate medical countermeasures.

Cranial Vena Cava Syndrome in Guinea Pigs with Chronic Jugular Vein Catheters.

Guinea pigs are a premier small animal model for infectious disease research, and chronic indwelling venous access ports may be used to facilitate various procedures. Here we report catheter-related lesions in 5 uninfected Dunkin-Hartley guinea pigs with chronic jugular vein catheters used for imaging studies. Three guinea pigs were found dead with no premonitory signs. At necropsy, there was severe bilateral pulmonary atelectasis due to 20 to 29 mL of pleural effusion resulting from catheter-related thrombosis and cranial vena cava syndrome. In addition, one of these 3 guinea pigs had a polymicrobial catheter infection with abscessation. A 4th clinically normal guinea pig was euthanized at the end of the study, having spontaneously lost its catheter 7 mo prior, and had 17 mL of pleural effusion. The 5th guinea pig was euthanized following pooling of contrast material around the distal catheter in the cranial vena cava on CT. By histology, affected animals had recent and remote thrombosis or fibrosis (or both) of the cranial vena cava and right atrial wall, with osseous and cartilaginous metaplasia. Cranial vena cava syndrome should be considered as a differential for dyspnea or death in chronically catheterized laboratory animals.

Acute transient tachypnea following gadoxetate administration in a rhesus macaque during contrast-enhanced magnetic resonance imaging.

During an infectious disease modeling study, a rhesus macaque (Macaca mulatta), experienced acute transient tachypnea including transient severe motion during the 70-second phases of serial contrast-enhanced magnetic resonance imaging of the abdomen. This same animal experienced transient severe motion during all but 2 of the 8 scans of the year-long study. This animal was the only animal in the study (1 of 12) to have this reaction to gadoxetate; the animal also vomited after the contrast injection once on day 146 of the study. On day 86, a different contrast agent (gadobutrol) was used, and the reaction did not occur. No treatment was required for any conditions relating to the reaction due to the self-limited nature. This type of reaction has not yet been reported in veterinary subjects before and is likely to be idiosyncratic after first exposure. However, this reaction should not be life threatening, and other contrast agents can be used if acute transient tachypnea does occur.

Working Together to Address Women's Health in Research and Drug Development: Summary of the 2017 Women's Health Congress Preconference Symposium.

Historically, women have been underrepresented in clinical research, requiring physicians to extrapolate medical recommendations for women from clinical research done in cohorts consisting predominantly of male participants. While government-funded clinical research has achieved gender parity in phase-3 clinical trials across many biomedical disciplines, improvements are still needed in several facets of women's health research, such as the inclusion of women in early-phase clinical trials, the inclusion of pregnant women and women with physical and intellectual disabilities, the consideration of sex as a biological variable in preclinical research, and the analysis and reporting of sex and gender differences across the full biomedical research continuum. The National Institutes of Health (NIH) Office of Research on Women's Health and the Office of Women's Health of the U.S. Food and Drug Administration (FDA) cosponsored a preconference symposium at the 25th Annual Women's Health Congress, held in Arlington, VA in April, 2017, to highlight gains made and remaining needs regarding the representation of women in clinical research, to introduce innovative procedures and technologies, and to outline revised policy for future studies. Six speakers presented information on a range of subjects related to the representation of women in clinical research and federal initiatives to advance precision medicine. Topics included the following: the return on investment from the NIH-funded Women's Health Initiative; progress in including women in clinical trials for FDA-approved drugs and products; the importance of clinical trials in pregnant women; FDA initiatives to report drug safety during pregnancy; the NIH-funded All of Us Research Program; and efforts to enhance FDA transparency and communications, including the introduction of Drug Trials Snapshots. This article summarizes the major points of the presentations and the discussions that followed.

The perimenopausal atherosclerosis transition: relationships between calcified and noncalcified coronary, aortic, and carotid atherosclerosis and risk factors and hormone levels.

OBJECTIVE: Women of perimenopause age experience an upward transition of cardiovascular risk possibly in association with changing hormonal status. We examined the cross-sectional relationships between the atherosclerotic plaque within the coronary and carotid arteries and aorta and the menopausal hormone levels among asymptomatic perimenopausal women. METHODS: The Assessment of the Transition of Hormonal Evaluation with Noninvasive Imaging of Atherosclerosis was a prospective substudy of the Prospective Army Coronary Calcium project. We screened 126 asymptomatic perimenopausal women (mean age, 50 y) using contrast-enhanced CT angiography (multidetector CT) and carotid ultrasound. Women had coronary calcium data from 5 to 10 years earlier. The measures included cardiovascular risk factors, serum hormone levels, 64-slice multidetector CT, and carotid ultrasound. RESULTS: The prevalence of any coronary plaque was 35.5%. The prevalence of noncalcified plaque was 30.2%, and noncalcified plaque was the only manifestation of coronary artery disease in 10.7%. Markers of androgenicity (increased free testosterone and reduced sex hormone-binding globulin) were associated with an increased extent of calcified and noncalcified coronary artery plaque and aortic plaque. However, these relationships were not independent of cardiovascular risk factors. Follicle-stimulating hormone was directly associated with the number of aortic plaques. The levels of estrogen hormones were unrelated to plaque presence or extent. CONCLUSIONS: Coronary, aortic, and carotid arterial plaque is prevalent in perimenopausal women without cardiac symptoms. The assessment of perimenopausal hormone status was not independently associated with subclinical atherosclerosis beyond standard cardiovascular risk factors.

Cardiac CT angiography compared with myocardial perfusion stress testing on downstream resource utilization.

BACKGROUND: Nuclear myocardial perfusion stress (MPS) testing and cardiac computed tomographic angiography (CCTA) are commonly used noninvasive tests. Limited studies exist comparing their clinical and cost outcomes. OBJECTIVES: We compared the clinical and cost outcomes of MPS with CCTA in a symptomatic cohort. METHODS: We retrospectively identified 241 symptomatic patients without known coronary artery disease (CAD) who underwent MPS between May 2006 and April 2008. A comparison group of 252 age- and sex-matched symptomatic patients without known CAD underwent 64-slice CCTA during the same period. The primary outcome was the per-patient rate of posttest clinical evaluations and cardiac testing for the presenting symptom. Total direct costs were also compared. RESULTS: The group consisted of 44% women of mean age 53 ± 10 years. There were no differences in risk factors or pretest probability of obstructive CAD (83% intermediate risk) between groups. During mean follow-up of 30 ± 7 months, we found no difference between CCTA and MPS in per-patient rates of any posttest evaluation or testing, 24.6% versus 27.7% (P = 0.44), respectively. CCTA patients had lower utilization of invasive angiography (3.3% vs 8.1%; P = 0.02) and a nonsignificant trend toward reduced downstream cardiac testing (11.5% vs 17.0%; P = 0.08). Including the evaluation of significant incidental findings (7.1% in CCTA), mean direct costs were significantly lower using CCTA ($808; 95% CI, $611-$1005) compared with MPS ($1315; 95% CI, $1105-$1525; P <0.001). CONCLUSIONS: Low-intermediate risk patients without known CAD who underwent CCTA, compared with MPS, had similar rates of posttest evaluations, fewer invasive catheterizations, and lower overall evaluation costs.

Relation between the Framingham Risk Score, coronary calcium, and incident coronary heart disease among low-risk men.

The Prospective Army Coronary Calcium Project is evaluating the predictive value of coronary artery calcium (CAC) in unselected, healthy, lower-risk, 40- to 50-year-old men. Although this study has found that coronary calcium is predictive of future coronary heart disease (CHD), criteria are needed to narrow the screening population to those in whom CAC measurement is most efficient (vs unselected screening of low-risk men). In 1,634 unselected volunteer men (mean age 42 years, mean 10-year CHD Framingham risk score [FRS] 4.6%, CAC prevalence 22.4%), we evaluated the independent relation between CAC and incident CHD over 5.6 years including hard events (hospitalized unstable angina, myocardial infarction, and CHD death) and coronary revascularization. The cohort was analyzed in tertiles of FRS for the relation between CAC and CHD outcomes. FRS tertile cutpoints were 0% to 3% (n = 547), >3% to 5% (n = 547), and >5% (n = 540) 10-year CHD risk. Over a mean follow-up of 5.6 +/- 1.5 years (range 1.0 to 8.3), there were 22 total CHD events, including 14 hard events and 8 revascularizations. Most events occurred in the highest FRS tertile (n = 14) versus the middle (n = 6) and lowest (n = 2) risk tertiles (p = 0.005). CAC and CHD events increased across FRS tertiles. Only in the highest FRS tertile was there a significant relation between CAC and CHD outcomes (hazard ratio 9.3). In conclusion, CAC screening could be of benefit in refining risk assessment of low-risk men, but only when the FRS exceeds approximately 5%.

Sixty-four-slice CT angiography to determine the three dimensional relationships of vascular and soft tissue wounds in lower extremity war time injuries.

This article analyzes the use and benefits of the 64-slice CT scanner in determining the 3D relationships of vascular and soft tissue wounds in lower extremity war time injuries. A brief overview of CT scanning is given as well as the techniques used to produce the images needed for diagnosis. The series follows two similar cases of war time injury patients at the Walter Reed Army Medical Center. The first case is a 30-year-old active duty male, who presented with multiple trauma from a motor vehicle accident because of an improvised explosive device (IED) blast, sustaining substantial lower extremity injuries. The second case is a 34-year-old active duty male, who presented with multiple trauma blast injuries. Both cases were of interest because the vasculature was found to be very close to the surface of the wound, which put the arteries at risk for rupture and for iatrogenic injury during repeated debridements.

Does prolonged warfarin exposure potentiate coronary calcification in humans? Results of the warfarin and coronary calcification study.

Warfarin has been shown to accelerate vascular calcification in experimental animals, and possibly humans, through inhibition of the vitamin K-dependent protein matrix gla protein, a potent inhibitor of tissue calcification. We performed a cross-sectional analysis of the extent of coronary artery calcification (CAC) in patients without coronary heart disease, currently taking or referred for warfarin therapy. The primary end point was severity of CAC measured by electron beam computed tomography attributed to duration of warfarin use, after adjustment for cardiovascular risk factors. Seventy patients (46 men, mean age 68 +/- 13 years) were enrolled from three groups of warfarin use duration: (1) <6 months (n = 31, mean duration 1 +/- 1 months), (2) 6-24 months (n = 11), and (3) >24 months (n = 28, mean 67 +/- 40 months). Overall, the mean total CAC score (Agatston) was 293 +/- 560: group 1 (175 +/- 285), group 2 (289 +/- 382), and group 3 (426 +/- 789). In univariate analysis, there was a nonsignificant trend to increased CAC with increasing warfarin exposure (P = 0.18). Bivariate analysis revealed no correlation between warfarin duration and CAC score (r = 0.075, P = 0.537). Linear regression for the independent variable coronary calcium score controlling for warfarin treatment duration and intensity (duration of warfarin use months x mean INR), Framingham risk score, and creatinine clearance showed that only the Framingham risk score was associated with CAC (P = 0.001). Among patients without known coronary heart disease, duration of warfarin exposure was not associated with extent of coronary calcification.

Sixty-four-multislice computed tomography in a patient with arrhythmogenic right ventricular dysplasia.

Arrhythmogenic right ventricular dysplasia (ARVD) is an inheritable cardiomyopathy that is characterized by fibrofatty infiltration of the RV myocardium, often resulting in arrhythmias and sudden cardiac death. The diagnosis often requires imaging of the right ventricle, typically by magnetic resonance imaging. We describe a case of AVRD in which cardiac computed tomography was used as the imaging method for the right ventricle. The CT images showed changes consistent with ARVD to include RV enlargement, excessive trabeculations, fatty infiltration, and marked RV hypokinesia. We believe these images show a novel use for multislice CT in the diagnostic evaluation of patients with suspected ARVD.

Real-world application of coronary computed tomography angiography and its potential effect on downstream resource utilization in evaluating angina.

BACKGROUND: Evaluating low-risk outpatients with chest pain is a common clinical problem and poses significant demand on clinical resource utilization. Despite the impressive performance characteristics of coronary multislice computed tomography (MSCT) angiography, its implementation in the diagnostic evaluation of outpatient chest pain and its effect on downstream resource utilization remains undefined. OBJECTIVE: We compared the effect of a strategy that used MSCT with a traditional strategy (pre-MSCT strategy) in which MSCT was not available on clinical downstream resource utilization, defined as the need for further stress testing or cardiac catheterization. METHODS: We retrospectively identified 75 patients without known disease who had undergone MSCT angiography for the primary indication of possible angina. The review of clinical vignettes of these 75 patients and completion of surveys assessing diagnostic strategy by two general cardiologists represented the pre-MSCT diagnostic strategy. Survey responses were compared with the number of cardiac catheterizations and stress tests that actually resulted after MSCT angiography (MSCT strategy). RESULTS: A strategy that used MSCT angiography in the evaluation of patients with possible angina would have significantly reduced the need for further stress testing and cardiac catheterizations (58 vs 11; P < 0.005). Furthermore, this strategy would have resulted in significantly fewer unnecessary cardiac catheterizations (6 vs 23; P < 0.005). CONCLUSIONS: Coronary MSCT angiography can potentially reduce the need for further stress tests or cardiac catheterizations in the evaluation of low- to intermediate-risk patients with possible angina. Prospective studies are needed to validate these findings and to assess the overall cost effectiveness of implementing MSCT early in the outpatient evaluation of angina.

The relationship between subclinical atherosclerosis and electrocardiographic abnormalities as biomarkers of cardiovascular risk.

Electrocardiographic findings indicating myocardial disease, such as left ventricular hypertrophy or ST-T wave abnormalities, or the presence of coronary artery calcium, indicating atherosclerotic coronary artery disease, are both biomarkers of future cardiovascular (CV) risk. Although the risk factors for myocardial and coronary artery disease are similar, their concomitant expression has implications for CV disease screening and prevention programmes. The relationship between the resting 12-lead ECG and subclinical atherosclerosis measured as coronary artery calcium (CAC) with electron beam tomography was examined in 937 healthy participants (aged 40-50 years) enrolled in a CV risk screening study. Electrocardiograms and CAC were interpreted in blinded fashion, using standard criteria. An abnormal ECG was coded in 268 (28.6%) participants, most commonly left ventricular hypertrophy (3.1%), delayed precordial R wave transition (5.7%), T-wave abnormalities (10.0%) and intraventricular conduction delay (10.4%). Although abnormal ECG findings were associated with CV risk variables, the prevalence of any CAC was similar in subjects with any ECG finding (43 of 268, 16.0%) compared with those with normal ECGs (125 of 669, 18.7%, p =NS). In a logistic model controlling for CV risk factors including systolic blood pressure, low-density lipoprotein cholesterol (LDL-C), body mass index (BMI), glycosylated haemoglobin, race, age and gender, significant associations with CAC were found for LDL-C, race and BMI. There was no significant relationship between CAC and ECG abnormalities (odds ratio 0.80, 95% confidence interval 0.54-1.20). In conclusion, electrocardiographic abnormalities and subclinical calcified atherosclerosis were not significantly associated with each other in this middle-aged screening population. This suggests these two biomarkers may be complementary towards broader detection of latent CV risk.