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Electron tomography (ET) of biological samples is used to study the organization and the structure of the whole cell and subcellular complexes in great detail. However, projections cannot be acquired over full tilt angle range with biological samples in electron microscopy. ET image reconstruction can be considered an ill-posed problem because of this missing information. This results in artifacts, seen as the loss of three-dimensional (3D) resolution in the reconstructed images. The goal of this study was to achieve isotropic resolution with a statistical reconstruction method, sequential maximum a posteriori expectation maximization (sMAP-EM), using no prior morphological knowledge about the specimen. The missing wedge effects on sMAP-EM were examined with a synthetic cell phantom to assess the effects of noise. An experimental dataset of a multivesicular body was evaluated with a number of gold particles. An ellipsoid fitting based method was developed to realize the quantitative measures elongation and contrast in an automated, objective, and reliable way. The method statistically evaluates the sub-volumes containing gold particles randomly located in various parts of the whole volume, thus giving information about the robustness of the volume reconstruction. The quantitative results were also compared with reconstructions made with widely-used weighted backprojection and simultaneous iterative reconstruction technique methods. The results showed that the proposed sMAP-EM method significantly suppresses the effects of the missing information producing isotropic resolution. Furthermore, this method improves the contrast ratio, enhancing the applicability of further automatic and semi-automatic analysis. These improvements in ET reconstruction by sMAP-EM enable analysis of subcellular structures with higher three-dimensional resolution and contrast than conventional methods. [ABSTRACT FROM AUTHOR]

In discrete tomography, a scanned object is assumed to consist of only a few different materials. This prior knowledge can be effectively exploited by a specialized discrete reconstruction algorithm such as the Discrete Algebraic Reconstruction Technique (DART), which is capable of providing more accurate reconstructions from limited data compared to conventional reconstruction algorithms. However, like most iterative reconstruction algorithms, DART suffers from long computation times. To increase the computational efficiency as well as the reconstruction quality of DART, a multiresolution version of DART (MDART) is proposed, in which the reconstruction starts on a coarse grid with big pixel (voxel) size. The resulting reconstruction is then resampled on a finer grid and used as an initial point for a subsequent DART reconstruction. This process continues until the target pixel size is reached. show that MDART can provide a significant speed-up, reduce missing wedge artefacts and improve feature reconstruction in the object compared with DART within the same time, making its use with large datasets more feasible. [ABSTRACT FROM AUTHOR]

Aim: To evaluate the prevalence, spectrum, and significance of incidental lesions identified on electron beam tomography (EBT) renal angiography performed to investigate renovascular hypertension. Materials and methods: EBT renal angiography images of 148 cases were evaluated in terms of renal artery variations and renal artery stenosis. Extravascular renal findings, abdominal aorta, iliac artery, liver and gallbladder findings, vertebral lesions, and other intraabdominal organ findings were assessed during the examination. Results: No incidental finding was found in 30 cases (20.2%) in total. The most frequent incidental findings were benign ones without any clinical significance. A total of 13 (8.7%) clinically significant findings were identified. Conclusion: When evaluating renal EBT angiography, a detailed review of other systems as well as target organ assessment is of crucial importance as it may affect patient prognosis. [ABSTRACT FROM AUTHOR]

Abstract: Background: Coronary artery calcium (CAC) has emerged as an important prognostic indicator for coronary heart disease risk. The purpose of this study was to assess the impact of increasing CAC burden among those with and without hypertension (HTN). Methods: The study cohort consisted of 44,052 consecutive asymptomatic individuals free of known coronary heart disease referred for electron beam computed tomography (EBT) for the assessment of subclinical atherosclerosis. Patients were followed for a mean of 5.6 ± 2.6 years (range 1–13 years). The primary endpoint for the study cohort was mortality from any cause. Results: About one third (34%) of the subjects were affected by hypertension. There were 901 deaths (2.05%) in the total study population over a mean follow-up of 5.6 ± 2.6 years (range 1–13 years). The lowest event rate was observed in those with no CAC among those without hypertension (1.6 events per 1000 person years), whereas those with CAC ≥400 and hypertension had the highest all fatality rate (9.8 per 1000 person years). Compared to a CAC score of 0, increasing CAC scores (1–99, 100–399, and ≥400) were associated with increases in all-cause mortality. The hazard ratio was 2.19–7.74-fold among those without HTN and 3.00–5.83 fold among those with HTN. Overall likelihood ratio chi square statistics demonstrated that the addition of CAC scores increased mortality prediction beyond traditional risk among those with hypertension. Conclusion: Addition of CAC scores contributed significantly in predicting mortality in addition to just traditional risk factors alone among those with and without hypertension. [Copyright &y& Elsevier]

Abstract: In electron beam tomography a rotating X-ray source is generated by electromagnetic scanning of a high-power electron beam across a spatially fixed circular metal target. The X-rays passing the object of investigation are registered by a circular fast X-ray detector array. A basic problem associated with this scanning principle is the angular overlap of the X-ray focal spot path and the detector, which is required for image reconstruction. Therefore, the X-ray production target and the detector array are commonly arranged with some axial displacement. This displacement may produce image artifacts because X-rays are not longer confined to a transversal plane. We propose a novel transparent X-ray target, which fully solves this problem. The new target concept has been practically tested with respect to thermal behavior and electron beam resistance. Its successful application in an experimental tomography setup is demonstrated. [Copyright &y& Elsevier]

Objectives The study aimed to compare measurements of coronary artery calcification (CAC) and bone mineral density (BMD) in postmenopausal women. Methods The CAC of the women was measured with electron beam tomography using a GE Imatron C150 XP EBT scanner. Subjects with calcium scores above 0 were classified as CAC(+); those without detectable coronary calcium were classified as CAC(−). BMD was measured by dual-energy X-ray absorptiometry (DEXA). Patients were divided into two groups, depending on the T scores of their lumbar spine, into those with normal bone and those with osteopenia-osteoporosis. Results The proportions of patients classified as CAC(+) were 20% in the normal group and 60% in the osteopenia-osteoporosis group ( p = 0.037). BMD values in L1–4 were 1.13 ± 2.29 and 0.98 ± 2.79 g/cm2 in the normal group and osteopenia-osteoporosis group, respectively and the mean total CAC scores were 1.34 ± 1.2 and 69.0 ± 20.5, respectively. The CAC scores of patients with osteopenia-osteoporosis were significantly higher compared with those of the normal group ( p = 0.014). Conclusion The study shows that postmenopausal women with decreased bone mineral density may have higher risk of subclinical coronary atherosclerosis. [ABSTRACT FROM AUTHOR]

Abstract: Background: The presence of coronary artery calcium (CAC) is an independent marker of increased risk of cardiovascular disease (CVD) events and mortality. However, the predictive value of thoracic aorta calcification (TAC), which can be additionally identified without further scanning during assessment of CAC, is unknown. Methods: We followed a cohort of 8401 asymptomatic individuals (mean age: 53±10 years, 69% men) undergoing cardiac risk factor evaluation and TAC and CAC testing with electron beam computed tomography. Multivariable Cox proportional hazards models were developed to predict all-cause mortality based on the presence of TAC. Results: During a median follow-up period of 5 years, 124 (1.5%) deaths were observed. Overall survival was 96.9% and 98.9% for those with and without detectable TAC, respectively (p <0.0001). Compared to those with no TAC, the hazard ratio for mortality in the presence of TAC was 3.25 (95% CI: 2.28–4.65, p <0.0001) in unadjusted analysis. After adjusting for age, gender, hypertension, dyslipidemia, diabetes mellitus, smoking and family history of premature coronary artery disease, and presence of CAC the relationship remained robust (HR 1.61, 95% CI: 1.10–2.27, p =0.015). Likelihood ratio χ 2 statistics demonstrated that the addition of TAC contributed significantly in predicting mortality to traditional risk factors alone (χ 2 =13.62, p =0.002) as well as risk factors+CAC (χ 2 =5.84, p =0.02) models. Conclusion: In conclusion, the presence of TAC was associated with all-cause mortality in our study; this relationship was independent of conventional CVD risk factors as well as the presence of CAC. [Copyright &y& Elsevier]

Purpose: The objective of this study is to quantify the influence of linear motion, calcification density, and temporal resolution on coronary calcium determination using multidetector computed tomography (MDCT), dual source CT (DSCT), and electron beam tomography (EBT) and to find a quantitative method which corrects for the influences of these parameters using a linear moving cardiac phantom. Methods: On a robotic arm with artificial arteries with four calcifications of increasing density, a linear movement was applied between 0 and 120 mm/s (step of 10 mm/s). The phantom was scanned five times on 64-slice MDCT, DSCT, and EBT using a standard acquisition protocol. The average Agatston, volume, and mass scores were determined for each velocity, calcification, and scanner. Susceptibility to motion was quantified using a cardiac motion susceptibility (CMS) index. Resemblance to EBT and physical volume and mass was quantified using a Δ index. Results: Increasing motion artifacts were observed at increasing velocities on all scanners, with increasing severity from EBT to DSCT to 64-slice MDCT. The calcium score showed a linear dependency on motion from which a correction factor could be derived. This correction factor showed a linear dependency on the mean calcification density with a good fit for all three scoring methods and all three scanners (0.73≤R2≤0.95). The slope and offset of this correction factor showed a linear dependency on temporal resolution with a good fit for all three scoring methods and all three scanners (0.83≤R2≤0.98). CMS was minimal for EBT and increasing values were observed for DSCT and highest values for 64-slice MDCT. CMS was minimal for mass score and increasing values were observed for volume score and highest values for Agatston score. For all densities and scoring methods DSCT showed on average the closest resemblance to EBT calcium scores. When using the correction factor, CMS index decreased on average by 15% and Δ index decreased by 35%. Conclusions: Calcium scores determined on DSCT and 64-slice MDCT are highly susceptible to motion as compared to EBT. The mass score is less susceptible to motion compared to volume and Agatston score. Calcium scores determined on DSCT bear a closer resemblance to EBT obtained calcium scores than 64-slice MDCT. In addition, the calcium score is highly dependent on the average density of individual calcifications and the dependency of the calcium score on motion showed a linear behavior on calcification density. From these relations, a quantitative method could be derived which corrects the measured calcium score for the influence of linear motion, mean calcification density, and temporal resolution. [ABSTRACT FROM AUTHOR]

Objectives: We sought to quantify the mortality rates associated with absent and low positive (CAC 1 to 10) coronary artery calcium (CAC). Background: There is increasing interest in the absence of CAC as a “negative” cardiovascular risk factor. However, published event rates for individuals with no CAC vary, likely owing to differences in baseline risk, follow-up period, and outcome ascertainment. The prognostic significance of low CAC (CAC 1 to 10) is not well described. Methods: Annualized all-cause mortality rates were assessed in 44,052 consecutive asymptomatic patients referred for CAC testing. Mean follow-up of the cohort was 5.6 ± 2.6 years (range 1 to 13 years). Results: A total of 19,898 patients (45%) had no CAC on screening electron beam tomography, whereas 5,388 (12%) had low levels of CAC (CAC 1 to 10), and 18,766 (43%) had CAC >10. There were 104 deaths in those with no CAC (0.52%), 58 deaths in those with CAC 1 to 10 (1.06%), and 739 deaths in those with CAC >10 (3.96%). Annualized all-cause mortality rates for CAC = 0, CAC 1 to 10, and CAC >10 were 0.87, 1.92, and 7.48 deaths/1,000 person-years, respectively. The hazard ratio (HR) for all-cause mortality among CAC 1 to 10 versus CAC = 0 after adjustment for traditional risk factors was 1.99 (95% confidence interval [CI]: 1.44 to 2.75). Smoking (HR: 3.97, 95% CI: 2.75 to 5.41) and diabetes mellitus (HR: 3.36, 95% CI: 2.09 to 5.41) were associated with few events observed in CAC = 0 group. Conclusions: In appropriately selected asymptomatic patients, the absence of CAC predicts excellent survival with 10-year event rates of approximately 1%. A finding of 0 CAC might be used as a rationale to emphasize lifestyle therapies rather than pharmacotherapy and to forgo repeated imaging studies. Individuals with low CAC score (CAC 1 to 10) are at increased risk above individuals with a 0 score and could be considered a distinct risk group by physicians and investigators. [Copyright &y& Elsevier]

Abstract: We sought to evaluate this “response-to-injury” hypothesis of atherosclerosis by studying the interaction between systolic blood pressure (SBP) and LDL- cholesterol (LDL-C) in predicting the presence of coronary artery calcification (CAC) in asymptomatic men. We studied 526 men (46±7 years of age) referred for electron-beam tomography (EBT) exam. The prevalence of CAC was determined across LDL-C tertiles (low: <115mg/dl; middle: 115–139mg/dl; high: ≥140mg/dl) within tertiles of SBP (low: <121mmHg; middle: 121–130mmHg; high: ≥131mmHg). CAC was found in 220 (42%) men. There was no linear trend in the presence of CAC across LDL-C tertiles in the low (p =0.6 for trend) and middle (p =0.3 for trend) SBP tertile groups, respectively. In contrast, there was a significant trend for increasing CAC with increasing LDL-C (1st: 44%; 2nd: 49%; 3rd: 83%; p <0.0001 for trend) in the high SBP tertile group. In multivariate logistic analyses (adjusting for age, smoking, triglyceride levels, HDL-cholesterol levels, body mass index, and fasting glucose levels), the odds ratio for any CAC associated with increasing LDL-C was significantly higher in those with highest SBP levels, whereas no such relationship was observed among men with SBP in the lower two tertiles. An interaction term (LDL-C×SBP) incorporated in the multivariate analyses was statistically significant (p =0.038). The finding of an interaction between SBP and LDL-C relation to CAC in asymptomatic men support the response-to-injury model of atherogenesis. [Copyright &y& Elsevier]

Rationale and Objectives: In the Calcium Acetate Renagel Evaluation (CARE)-2 study, the effects of calcium acetate plus atorvastatin (Lipitor) on the progression of coronary artery calcifications (CACs) are evaluated versus those of Renagel, monitored using dual electron beam tomography (EBT) scans (two scans at study initiation and two at follow up). The aim of this study is to estimate the interscan variation for the Agatston score and for the volume score determined in patients with end-stage renal disease (ESRD) in the CARE-2 study. Materials and Methods: CAC score and volume were measured at study initiation in 463 ESRD subjects (mean age: 59.4 ± 12.5 years, 48.3% female). All patients underwent dual scanning using an EBT, as first scan of two needed to measure the progression of CAC when treated with sevelamer (Renagel) compared with calcium acetate with or without atorvastatin. All scans in all participants were completed by using an EBT system (GE Imatron, South San Francisco, CA). Interscan variability was defined by the following formula: abs (scan A − scan B) ÷ (0.5 × scan A + 0.5 × scan B) × 100%, where A and B denote the first and second scan, respectively, of the dual scan procedure performed before treatment. We evaluated the reproducibility of the cutpoints commonly used for calcium scores clinically, namely 1–30, 31–100, 101–400, and >400. Results: The CAC interscan variability was 11.8% using the Agatston score and 10.3% using the volume score. The reproducibility was then assessed using cutpoints 1–30, 31–100, 101–400, and >400. Agatston score variability for the four subgroups was 61.3%, 23%, 16.1%, and 8.2%, respectively (mean variability, 11.8%). Volume score variability was 60.0%, 14.4%, 14.6%, and 7.7%, respectively (mean variability, 10.3%). The correlation coefficient for scan A to scan B goes up significantly with increasing calcium scores and reaches 0.99 for scores greater than 400 (P < .0001). Conclusion: Interscan variability was sufficiently small for patients with calcium scores greater than 30. Our study thus demonstrates a sufficient reproducibility of the calcium score using EBT. This score allows for accurate serial assessment of these patients and for comparing different therapies. [Copyright &y& Elsevier]

The objective of our study was the determination of the influence of the sequential and spiral acquisition modes on the concordance and deviation of the calcium score on 64-slice multi-detector computed tomography (MDCT) scanners in comparison to electron beam tomography (EBT) as the gold standard. Our methods and materials were an anthropomorphic cardio CT phantom with different calcium inserts scanned in sequential and spiral acquisition modes on three identical 64-slice MDCT scanners of manufacturer A and on three identical 64-slice MDCT scanners of manufacturer B and on an EBT system. Every scan was repeated 30 times with and 15 times without a small random variation in the phantom position for both sequential and spiral modes. Significant differences were observed between EBT and 64-slice MDCT data for all inserts, both acquisition modes, and both manufacturers of MDCT systems. High regression coefficients (0.90–0.98) were found between the EBT and 64-slice MDCT data for both scoring methods and both systems with high correlation coefficients (R2>0.94). System A showed more significant differences between spiral and sequential mode than system B. Almost no differences were observed in scanners of the same manufacturer for the Agatston score and no differences for the Volume score. The deviations of the Agatston and Volume scores showed regression dependencies approximately equal to the square root of the absolute score. The Agatston and Volume scores obtained with 64-slice MDCT imaging are highly correlated with EBT-obtained scores but are significantly underestimated (-10% to -2%) for both sequential and spiral acquisition modes. System B is more independent of acquisition mode to calcium score than system A. The Volume score shows no intramanufacturer dependency and its use is advocated versus the Agatston score. Using the same cut points for MDCT-based calcium scores as for EBT-based calcium scores can result in classifying individuals into a too low risk category. System information and scanprotocol is therefore needed for every calcium score procedure to ensure a correct clinical interpretation of the obtained calcium score results. [ABSTRACT FROM AUTHOR]

Abstract: Coronary artery calcium (CAC) scores ≥100 are predictive of CHD events in asymptomatic men. Exercise tolerance of ≥10METs predicts lower event rates in CHD patients; however, its relationship with events in individuals with subclinical atherosclerosis is less known. Participants were 710 asymptomatic men from the Aerobics Center Longitudinal Study whose exercise tolerance (ET) was quantified (<10 or ≥10METs) and whose CAC score was ≥100 as measured by electron beam tomography. During 3.5 years of follow-up 59 CHD events occurred. The age-adjusted hazard ratio (HR) of CHD events was 0.26 (95% CI=0.15–0.45) in men whose ET was ≥10METs compared with men whose ET was <10METs. Adjustment for CHD risk factors and abnormal exercise ECG did not change the association between ET and CHD. The extent of underlying atherosclerosis did not influence the association between ET and CHD; for example, the HR for CHD events in the ≥10MET group among men with CAC scores <400 and ≥400 was 0.16 (95% CI=0.05–0.56) and 0.23 (95% CI=0.11–0.46), respectively. In asymptomatic men with subclinical coronary atherosclerosis, an ET of ≥10METs identifies patients at lower risk for manifest CHD. [Copyright &y& Elsevier]

Abstract: Background: Although cardiovascular risk factor levels are substantially different in Caucasians, African-American, Hispanics, and Asians, the relative rates of coronary heart disease in these groups are not consistent with these differences. The objective of the study is to assess the differences in the prevalence and severity of coronary artery calcification, as a measure of atherosclerosis, in these different ethnic groups. Methods: Electron-beam tomography was performed in 16,560 asymptomatic men and women (Asians=1336, African-Americans=610, Hispanics=1256) aged ≥35 years referred by their physician for cardiovascular risk evaluation. The study population encompassed 70% males, aged 52±8 years. Results: Caucasians were more likely to present with dyslipidemia (p <0.0001), while African-Americans and Hispanics had a higher prevalence of smoking, diabetes, and hypertension (all p <0.001). After adjustment for age, gender, risk factors, and treatment for hypercholesterolemia, compared with Caucasians, the relative risks for men having coronary calcification were 0.64 (95% CI: 0.48–0.86) in African-Americans, 0.88 (95% CI: 0.67–1.15) in Hispanics, and 0.66 (95% CI: 0.55–0.80) in Asians. After similar adjustments, the relative risks for women having coronary calcification, were 1.58 (95% CI: 1.13–2.19) for African-Americans, 0.84 (95% CI: 0.66–1.06) in Hispanics, and 0.71 (95% CI: 0.56–0.89) in Asian women. After adjusting for age and risk factors using multivariable analysis, African-American men were least likely to have any coronary calcium while African-American women had significantly higher OR of any calcification. Asian men and women had significantly lower OR of any calcification. There was no significant difference in prevalence or severity of atherosclerosis between Hispanics and Caucasians, in men or women. Conclusions: Our study results demonstrate significant difference in the presence as well as severity of calcification according to ethnicity, independent of atherosclerotic risk factors. Results from this study (physician referred) closely parallel the results from MESA (population based, measured risk factors). Ethnic specific data on the predictive value of differing coronary calcium scores are needed. [Copyright &y& Elsevier]

Rationale and Objectives: Although the use of gadolinium (Gd)-based contrast agents for angiographic studies of abdominal aorta, renal vasculature, and digital subtraction angiography has been reported, no studies have shown their diagnostic efficacy and image quality in coronary computed tomography angiography (CTA). The aim of this study is to evaluate the image quality of Gd-based contrast agents during coronary CTA. Materials and Methods: A phantom study was done to evaluate the attenuation of serial dilutions of Gd and iodinated agents. This study was done on a 64-slice multirow detector CT (MDCT) scanner and e-speed scanner and CT attenuation Hounsfield units (CTHU) were compared. We evaluated 35 consecutive patients who underwent Gd-enhanced CTA. CTHU of aorta was measured at first, mid, and lowest slice levels with and without contrast administration. The image quality was graded on the basis of visualization of the coronary arteries (scale I-III; III demonstrating diagnostic image quality of the distal-most vessels). In a substudy, four patients with borderline renal insufficiency underwent CTA using Gd and iodinated contrast agents admixed in a 50:50 ratio. Results: The phantom study showed that enhancement of various dilutions of Gd and iodine resulted in near identical CTHU with both e-speed and 64-slice scanners (r(2) > or = 0.997). Mean CTHU with contrast at the top slice was 116 HU, at middle slice was 125 HU, and at the lower slice was 93 (111.14 +/- 22). Quality evaluation showed 2 grade III, 9 grade II, and 24 grade I images (average quality of images 1.35). Mean CTHU was 222. Conclusion: Gd-enhanced contrast medium provides adequate enhancement of coronary vasculature, allowing for diagnostic evaluation of coronary arteries with new CT systems. Use of newer generations of multirow detector CT scanners should further enhance the quality of images. [ABSTRACT FROM AUTHOR]

Conventional coronary angiography is the gold standard for the diagnosis of coronary artery anomalies. Coronary anomalies are relatively rare findings in patients undergoing conventional coronary angiography for suspected obstructive coronary artery disease. Recently, the increasing performance of diagnostic techniques, such as electron beam tomography (EBT), magnetic resonance (MR) and, more recently, multislice computed tomography (MSCT), has enabled their application to cardiac imaging. MSCT, in particular, has a prominent role in coronary imaging due to its spatial and temporal resolution and threedimensional capabilities. We report the incidence and pathophysiology of coronary artery anomalies based on the capabilities of recent diagnostic tools with the aim of improving an accurate and noninvasive diagnostic approach. [ABSTRACT FROM AUTHOR]

Background and objective: Coronary heart disease (CHD) is the leading cause of death worldwide including Brazil. Improved precision in detecting early coronary disease may aid in more targeted preventive therapy. The National Cholesterol Education Program (NCEP) provides guidelines for determining the aggressiveness of primary prevention strategies including lipid lowering based on Framingham risk equation. Identification of subclinical atherosclerosis and coronary plaque burden is a step towards identifying high-risk individuals. This investigation was designed to determine how the updated NCEP guidelines classify asymptomatic individuals with presence of any as well as advanced CACS (coronary artery calcium score), a powerful intermediary for CHD events, in asymptomatic Brazilian men. Methods and results: Five hundred forty-six asymptomatic Brazilian men (mean age: 46±7 years) presented to a single electron beam tomography (EBT) facility in Sao Paulo. The study population was categorized into low risk (0–1 risk factors, n =166, 30%), intermediate risk (≥2 risk factors but <10% risk of CHD over 10 years, n =150, 27%), moderately high risk (2 risk factors and 10–20% risk of hard CHD events in 10 years, n =147, 28%) and high-risk (≥2 risk factors and >20% risk of hard CHD events in 10 years, n =83, 15%), respectively. In our study population, overall no CACS, mild CACS (1–99.9), moderate–severe CACS (≥100) were observed in 317 (58%), 160 (29%) and 69 (13%) men, respectively. Advanced calcification (CACS≥75th percentile for age) was present in 19% (n =104) men. Based on the LDL-C cutoffs recommended by the NCEP guidelines for initiation of lipid lowering, overall only 55% with CACS≥100 and 42% men with CACS≥75th percentile qualified for pharmacotherapy. As a result nearly half of individuals with CACS≥100 (45%) and CACS≥75th percentile (48%) missed eligibility for drug therapy. Conclusion: Our findings reveal the potential limitation of NCEP guidelines in identifying asymptomatic Brazilian men with significant coronary atherosclerosis who are potential candidates for aggressive primary prevention. Assessment of CACS may provide incremental value to global risk assessment in high-risk Brazilian men. [Copyright &y& Elsevier]

Prospective epidemiologic studies have identified several risk factors for heart disease, and most can be the target of risk reduction interventions. The most widely recognized risk factors for atherosclerotic cardiovascular disease (ASCVD) include age, gender, cigarette smoking, sedentary lifestyle, elevated LDL, reduced HDL, hypertension, and diabetes. The consistency of associations between these factors and ASCVD risk across populations is substantial. Our understanding of the pathogenesis and etiology of coronary ASCVD, as well as its clinical implications, has grown tremendously over the past 20 y. The role garlic might play in treating ASCVD has been postulated for many years, but until recently no studies on garlic's ability to inhibit the atherosclerotic process have been reported. A pilot study evaluating coronary artery calcification and the effect of garlic therapy in a group of patients who were also on statin therapy suggested incremental benefits. The implications of this study must be put in context of the potential importance of early atherosclerosis detection and prevention. [ABSTRACT FROM AUTHOR]

Abstract: Background: Arterial stiffness has recently been proposed as a powerful independent predictor of cardiovascular disease. However, the influence of arterial stiffening on the interaction between the heart and large vessels and atherosclerosis is not well defined. The arterial stiffness index (ASI) has recently been determined with a new device (VitalVision) that calculates ASI in the upper arm using computerized oscillometry. Coronary artery calcification (CAC) is a useful surrogate marker of coronary artery disease detected non-invasively by electron beam tomography (EBT). We investigated the correlation between ASI and CAC in a group of patients. Methods: CAC and ASI measurements were determined with EBT and a VitalVision device, respectively, on the same day in 97 asymptomatic patients. Patients with calcium scores above 0 were classified as CAC+ and those with calcium scores equal to 0 were classified as CAC−. The ASI index was divided into three groups – mild, moderate, and high – according to the H-value, provided by the VitalVision device. Results: In patients below 51 years of age, no correlation between the ASI and CAC was found. In patients over 50 years of age, a moderate positive and significant correlation was found between the CAC score and ASI measurements (r =0.40, p =0.001). Conclusions: The presence of a correlation between the CAC and ASI in patients over 50 shows that the ASI can be used to investigate atherosclerotic risk. [Copyright &y& Elsevier]

X‐ray computed tomography (CT) is widely available in the world and has the ability to provide high definition, thin section imaging of any body part. In particular, CT over the past decade has been shown in numerous publications to allow for quantitation of coronary calcification, a proven surrogate for coronary artery atheromatous plaque. Electron beam tomography (EBT) and multi‐detector CT (MDCT) have been studied for these purposes; although the majority of the data has been derived from EBT studies. This chapter details the patho‐biology of atherosclerotic disease, the basis of using EBT (and/or CT in general) to define atherosclerotic plaque including the technical and engineering pitfalls and promises, and details issues of clinical application. [ABSTRACT FROM AUTHOR]

The osteo-odonto-keratoprosthesis (OOKP), although described over 40 years ago, remains the keratoprosthesis of choice for end-stage corneal blindness not amenable to penetrating keratoplasty. It is particularly resilient to a hostile environment such as the dry keratinized eye resulting from severe Stevens-Johnson syndrome, ocular cicatricial pemphigoid, trachoma, and chemical injury. Its rigid optical cylinder gives excellent image resolution and quality. The desirable properties of the theoretical ideal keratoprosthesis is described. The indications, contraindications, and patient assessment (eye, tooth, buccal mucosa, psychology) for OOKP surgery are described. The surgical and anaesthetic techniques are described. Follow-up is life-long in order to detect and treat complications, which include oral, oculoplastic, glaucoma, vitreo-retinal complications and extrusion of the device. Resorption of the osteo-odonto-lamina is responsible for extrusion, and this is more pronounced in tooth allografts. Regular imaging with spiral-CT or electron beam tomography can help detect bone and dentine loss. The optical cylinder design is discussed. Preliminary work towards the development of a synthetic OOKP analogue is described. Finally, we describe how to set up an OOKP national referral center. [ABSTRACT FROM AUTHOR]

Rationale and Objectives: It has been demonstrated that aortic valve calcification (AVC) shares many similarities with coronary atherosclerosis, including risk factors and pathologic characteristics. We sought to examine the relationship of AVC to coronary artery calcification (CC), to assess whether similar risk factors affect the process in a similar way. Materials and Methods: The study included 620 asymptomatic persons (513 men and 107 women, mean age 59 years range [30-82]) who underwent two consecutive electron beam tomography (EBT) scans at least 1 year apart (mean 3.3 years). Calcification scores were obtained by summation of Agatston and volumetric scores. Stabilization of calcium was defined as no increase in score per year or positive percent change in score 1%/year. Of 106 with AVC, 105 (99%) had CC. Sixty-five patients had an AVC >10 on initial scan, and 50 (77%) demonstrated progression on the follow-up scan. Of 394 participants with CC >10 on initial scan, follow-up scans showed CC stabilization in 64 (16.2%) and CC progression in 330 (83.8%). Patients with AVC were significantly older than those with only CC (64.5 versus 56.5 years, P < .0001). The average age of the patient with AVC was 7 years older than the average age with CC. AVC (by volumetric score) progressed more rapidly in patients with diabetes (P = .036) and smoking (P = .042) than those without. Results: We found no difference in the degree of change in the CC scores (by Agatston or volumetric methods) over time between men and women, or in any baseline cardiac risk factor (P > .05 for all measures). In 65 patients with both AVC and CC >10, there was a significant association between progression of AVC and CC (P = .047); the absolute rate of change of AVC was 24.5 +/- 43.2 %/year, and CC was 28.0 +/- 49.1 %/year. Conclusion: Virtually all patients with AVC had CC, potentially explaining the coronary risk associated with AVC. There is substantially parallel development between rates of progression of EBT-assessed AVC and CC. [ABSTRACT FROM AUTHOR]

Abstract: We measured the main pole field using electron beam tomography to analyze the GHz response of a single-pole-type (SPT) write head. The response of the head to a current was measured up to 1.3GHz using a head without a recording medium. The magnetic field profiles around the main pole were obtained with 25-nm spacing from the head surface. The head response followed the current switching with a rise time of 0.3ns, and the frequency response performance did not show any critical degradation up to 1.3GHz. There was no difference in the head responses between the SPT head and a longitudinal recording head. [Copyright &y& Elsevier]

Background: Electron beam tomography coronary calcium imaging is an evolving technique for the early detection of coronary atherosclerosis, and recent studies have established its prognostic value in asymptomatic individuals. The relationship of coronary artery calcium scores (CAC) to obstructive coronary artery disease (CAD) has been poorly studied but is clinically relevant because it determines which individuals are likely to benefit from revascularization procedures. Hence, we prospectively evaluated the prevalence of myocardial ischemia in asymptomatic patients with cardiovascular risk factors and subclinical atherosclerosis.Methods and Results: We studied 864 asymptomatic patients with no previous CAD but with cardiovascular risk factors, referred for electron beam tomography coronary calcium imaging to our institution over an 18-month period. From this group, 220 consecutive patients (85% men; mean age, 61 +/- 9 years; age range, 31-84 years) with moderate to severe atherosclerotic disease (coronary calcium score > or =100 Agatston units) were prospectively evaluated by technetium 99m sestamibi single photon emission computed tomography (SPECT). Patients were followed up (mean follow-up, 14 months) and data regarding their subsequent clinical management recorded. Of the 220 patients, 119 had moderate atherosclerosis (CAC score of 100-400 Agatston units) and 101 had severe atherosclerosis (CAC score > or =400 Agatston units). Abnormal SPECT findings were seen in 18% of patients with moderate atherosclerosis (n = 21) and 45% of patients with severe atherosclerosis (n = 45). Increasing severity of atherosclerosis was related to increasing ischemic burden (summed difference score = 1 +/- 0.2 for CAC score of 100-400 Agatston units and 3.2 +/- 0.5 for CAC score > or =400 Agatston units). In a multivariate linear regression model incorporating risk factors, CAC was the only predictor of silent ischemia.Conclusion: In comparison to previously published data, we detected a higher prevalence of silent ischemia even in patients with moderate coronary atherosclerosis (18%). This may reflect the differing risk factor profile of our patient population. When coronary calcium screening is used to preselect asymptomatic patients with cardiovascular risk factors for myocardial perfusion imaging, the optimum coronary calcium score threshold will depend on the population prevalence of risk factors and asymptomatic obstructive CAD. [ABSTRACT FROM AUTHOR]

Coronary artery calcification (CAC) may help identify novel risk factors for coronary atherosclerosis. However, analysis of CAC is challenging because of the distribution of CAC in the population. This has resulted in difficulty in interpreting and comparing results across studies. We applied several analytic approaches to CAC data in order to determine the impact of analytic methods on the association with established cardiovascular risk factors in 914 asymptomatic subjects in the Study of Inherited Risk Factors for Coronary Atherosclerosis. Multivariable analyses included: (1) linear regression of different transformations of CAC scores; (2) tobit regression of the log of (CAC+1); (3) logistic regression using CAC zero as a cut-point; and (4) ordinal logistic regression using CAC categories. Linear regression of the log CAC scores and logistic regression of CAC zero cut-point failed to detect associations with some risk factors. In contrast, linear and tobit regression of the log (CAC+1) and ordinal regression of CAC categories identified more associations and provided consistent results. Commonly applied methods of CAC analysis may fail to detect associations with cardiovascular risk factors. We present analytic approaches that are likely to provide consistent results and recommend the use of at least two distinct multivariable methods. [Copyright &y& Elsevier]

Purpose: To estimate the variation of left ventricular (LV) mass and volume measurement with cine and angiography by electron beam tomography (EBT). Method and materials: Sixty-three consecutive patients (41 men, 22 women; age range 46–91) referred for cardiac imaging for clinical indications underwent cine and coronary artery electron beam angiography (EBA) studies on the same day. The cine images consisted of 144 images (12 slices/level × 12 levels), taken 12 frames/s for a full cardiac cycle. The EBA images consisted of 50–70 slices triggered at end-systole, with an acquisition time of 100 ms/slice. Slice thickness was 8 mm for the cine images and 1.5 mm for the EBA images. A total volume of 120–180 ml of nonionic contrast was used for each subject. The LV mass (myocardial tissue volume), LV cavity volume and total LV volume (tissue + cavity) measurements were completed using the software from the EBT computer console (G.E., S. San Francisco, CA). Results: The LV mass, cavity volume and total LV volumes at end-systole were 124.11 g, 45.66 and 163.86 ml when derived from the cine images and 130.74 g, 41.31 and 165.82 ml when derived from the EBA images. There were no significant differences between the cine and EBA-derived measurements, however the EBA-derived measurements showed slightly larger LV mass (mean 6.63 g), smaller cavity volume (mean −4.35 ml) and larger total LV volume (mean 1.96 ml, all p > 0.05) than did the cine-derived measurements. Based on case-by-case observations, these differences appear to be related to the higher spatial resolution of the thinner EBA images which allows better discrimination between papillary and trabecular muscle and LV. This leads to slightly smaller cavity size estimations and greater LV mass measurements. There was significant correlation between cine and EBA-derived measurements. Formulas were developed for relating the measurements made from the two modalities as follows: For LV mass: EBA value = 0.91 × cine value + 17.09, R = 0.95, p < 0.001; For LV cavity volume: EBA value = 1.06 × cine value − 6.91, R = 0.96, p < 0.001; For total LV volume: EBA value = 0.98 × cine value + 5.09 in ml, p < 0.001. The mean differences in measurements using the two modalities were 8.1, 18.2 and 6.5% for LV mass, LV cavity volume and total LV volume, respectively. Conclusion: Both cine and EBA images were useful for measuring LV mass and volume with good inter-test agreement. Cardiac volume and mass measurements derived from cine EBT studies probably slightly underestimate LV mass and overestimate LV volume. [ABSTRACT FROM AUTHOR]

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: ObjectivesThe study was done to evaluate whether ethnic differences exist in the prevalence of coronary artery calcification (CAC), and to determine whether differences in calcification correlate with the degree of coronary obstruction.: BackgroundElectron beam tomography (EBT) can be used to quantitate the amount of CAC and assist in prognostication of future cardiac events. It is unclear whether ethnic differences in coronary mortality are related to differences in the prevalence of coronary obstruction and CAC.: MethodsA total of 782 symptomatic subjects underwent both EBT and angiography. A 50% luminal narrowing defined an angiographic obstruction.: ResultsWe observed substantial ethnic differences in prevalence of both CAC and angiographic stenosis. In whites (n = 453), prevalence of CAC (score >0) was 84%, and significant obstruction on angiogram was 71%. Compared with whites, blacks (n = 108) had a significantly lower prevalence of CAC (62%, p < 0.001) and angiographic disease (49%, p < 0.01). Hispanics (n = 177) also had a lower prevalence of CAC (71%, p < 0.001) and angiographic obstruction (58%, p < 0.01). Asians (n = 44) were not significantly different in regard to CAC (73%, p = 0.06) or angiographic stenosis (64%, p = 0.30). These ethnic differences remained after simultaneously controlling (by use of multiple logistic regression) for age, gender and cardiac risk factors.: ConclusionsAs compared with whites, blacks and Hispanics had significantly lower prevalence of CAC and obstructive coronary disease. Ethnic differences in risk-factor profiles do not explain these differences. This study demonstrated that whites have a higher atherosclerotic burden than blacks and Hispanics, independent of risk-factor differences among symptomatic patients referred for angiography. [Copyright &y& Elsevier]

: ObjectivesWe sought to assess the natural history of a cohort of asymptomatic individuals with very high (≥1,000) calcium scores (CSs) on a screening electron beam tomography (EBT) not submitted to further testing after the initial scan. We also compared the outcome of our prospective cohort with that of historical controls with severe abnormalities on myocardial perfusion imaging (MPI).: BackgroundCoronary calcium detected on EBT imaging has been shown to correlate with the total plaque burden. However, there is still controversy as to the prognostic significance of calcium, as some investigators believe that the presence of coronary calcification may stabilize the atherosclerotic plaque.: MethodsNinety-eight asymptomatic subjects (mean age: 62 ± 10) were followed for an average of 17 ± 11 months (range: 4 to 36 months) after undergoing EBT screening for the occurrence of hard coronary events (HCEs), defined as myocardial infarction or coronary death. All patients had an initial CS ≥1,000, and in none did the results of the EBT screening lead to further invasive or non-invasive testing.: ResultsDuring the follow-up period, 35 patients (36%) suffered an HCE. All events were recorded in the first 28 months of follow-up. Subjects with HCEs had higher initial CSs than subjects not suffering HCEs (1,561 ± 270 vs. 1,199 ± 200, p < 0.001). The annualized event rate in subjects with a CS ≥1,000 was significantly greater than that of historical controls with severe perfusion abnormalities on MPI (25% vs. 7.4%, respectively; p < 0.0001).: ConclusionsA high CS (≥1,000) on a screening EBT in an asymptomatic person portends a very high risk of an HCE in the short term. This risk appears to be greater than the risk associated with a severe perfusion abnormality on MPI. [Copyright &y& Elsevier]

We report for the first time upon a case of myxoma that involved both atrial and ventricular sides of the anterior mitral valve leaflet. Electron beam tomography (EBT) showed that the tumor was attached to both the atrial and ventricular sides of the mitral valve, while echocardiography did not. EBT also diagnosed dynamic obstruction of left ventricular outflow tract caused by the tumor. [ABSTRACT FROM AUTHOR]