Measurement of coronary artery calcium with dual-slice helical CT compared with coronary angiography: evaluation of CT scoring methods, interobserver variations, and reproducibility

Artificial intelligence using a deep learning versus expert computed tomography human reading in calcium score and coronary artery calcium data and reporting system classification

BACKGROUND

Artificial intelligence (AI) applied to cardiac imaging may provide improved processing, reading precision and advantages of automation. Coronary artery calcium (CAC) score testing is a standard stratification tool that is rapid and highly reproducible. We analyzed CAC results of 100 studies in order to determine the accuracy and correlation between the AI software (Coreline AVIEW, Seoul, South Korea) and expert level-3 computed tomography (CT) human CAC interpretation and its performance when coronary artery disease data and reporting system (coronary artery calcium data and reporting system) classification is applied.

METHODS

A total of 100 non-contrast calcium score images were selected by blinded randomization and processed with the AI software versus human level-3 CT reading. The results were compared and the Pearson correlation index was calculated. The CAC-DRS classification system was applied, and the cause of category reclassification was determined using an anatomical qualitative description by the readers.

RESULTS

The mean age was age 64.5 years, with 48% female. The absolute CAC scores between AI versus human reading demonstrated a highly significant correlation (Pearson coefficient R  = 0.996); however, despite these minimal CAC score differences, 14% of the patients had their CAC-DRS category reclassified. The main source of reclassification was observed in CAC-DRS 0-1, where 13 were recategorized, particularly between studies having a CAC Agatston score of 0 versus 1. Qualitative description of the errors showed that the main cause of misclassification was AI underestimation of right coronary calcium, AI overestimation of right ventricle densities and human underestimation of right coronary artery calcium.

CONCLUSION

Correlation between AI and human values is excellent with absolute numbers. When the CAC-DRS classification system was adopted, there was a strong correlation in the respective categories. Misclassified were predominantly in the category of CAC = 0, most often with minimal values of calcium volume. Additional algorithm optimization with enhanced sensitivity and specificity for low values of calcium volume will be required to enhance AI CAC score utilization for minimal disease. Over a broad range of calcium scores, AI software for calcium scoring had an excellent correlation compared to human expert reading and in rare cases determined calcium missed by human interpretation.

Assessing Agreement When Agreement Is Hard to Assess-The Agatston Score for Coronary Calcification

Method comparison studies comprised simple scatterplots of paired measurements, a 45-degree line as benchmark, and correlation coefficients up to the advent of Bland-Altman analysis in the 1980s. The Agatston score for coronary calcification is based on computed tomography of the heart, and it originated in 1990. A peculiarity of the Agatston score is the often-observed skewed distribution in screening populations. As the Agatston score has manifested itself in preventive cardiology, it is of interest to investigate how reproducibility of the Agatston score has been established. This review is based on literature findings indexed in MEDLINE/PubMed before 20 November 2021. Out of 503 identified articles, 49 papers were included in this review. Sample sizes were highly variable (10-9761), the main focus comprised intra- and interrater as well as intra- and interscanner variability assessments. Simple analysis tools such as scatterplots and correlation coefficients were successively supplemented by first difference, later Bland-Altman plots; however, only very few publications were capable of deriving Limits of Agreement that fit the observed data visually in a convincing way. Moreover, several attempts have been made in the recent past to improve the analysis and reporting of method comparison studies. These warrant increased attention in the future.

Predictive Value of Coronary Artery Calcium in Patients Receiving Computed Tomography Pulmonary Angiography for Suspected Pulmonary Embolism in the Emergency Department

PURPOSE

Coronary artery calcium (CAC) is a frequent incidental finding on computed tomography pulmonary angiogram (CTPA) in the evaluation of pulmonary embolism (PE) in the emergency department (ED); however, its prognostic value is unclear. In this study, we interrogate the prognostic value of CAC identified on CTPA in predicting adverse outcomes in the evaluation of PE in the ED.

MATERIALS AND METHODS

In this retrospective cohort study, we identified 610 patients presenting to the ED in 2013 and evaluated with CTPA for suspected PE. Ordinal CAC scores were evaluated as absent (0), mild (1), moderate (2), or severe (3) in each of the 4 main coronary arteries. Composite CAC scores were subsequently compared against adverse clinical outcomes, defined as intensive care unit admission, hospital stay longer than 72 hours, or death during hospital course or at 6-month follow-up, using univariate and multivariate logistic regression analyses. Relevant exclusion criteria included a history of cardiovascular disease.

RESULTS

In all, 365 patients met the inclusion criteria (231 women, mean age 56±16 y) with 132 patients (36%) having some degree of CAC and 16 (4%) having severe CAC. Known malignancy was present in 151 (41%) patients and composite adverse clinical outcomes were observed in 98 patients (32%). Age, presence of acute PE, malignancy, and presence of CAC were significant predictors of adverse outcomes on both univariate and multivariate analyses. CAC was not an independent predictor of short-term adverse outcomes on multivariate analysis ( P =0.06) when all patients were considered. However, when patients with known malignancy were excluded, CAC was an independent predictor of short-term adverse outcomes (odds ratio=2.5, confidence interval=1.1-5.5, P =0.03) independent of age and presence of PE.

CONCLUSION

The presence of CAC on CT PA was predictive of adverse outcomes in patients without known cardiac disease presenting to the ED with suspected PE.

Serum Sortilin Is Associated with Coronary Artery Calcification and Cardiovascular and Cerebrovascular Events in Maintenance Hemodialysis Patients

OBJECTIVE

To analyze the role of serum sortilin in coronary artery calcification (CAC) and cardiovascular and cerebrovascular events (CCE) in maintenance hemodialysis (MHD) patients.

METHODS

One hundred eleven patients with MHD ≥3 months were included in this study. The general data, clinical features, hematological data, and medication history of the patients were recorded. Eighty-five cases were examined by vascular color Doppler ultrasound, cardiac color Doppler ultrasound, lateral lumbar radiography, and coronary artery calcification score. The patients were followed up for a median time of 45 months. The primary endpoint was CCE or death from a vascular event, and the role of sortilin in this process was analyzed.

RESULTS

Among 85 MHD patients, 51 cases (60.00%) had different degrees of CAC. There were significant differences in diabetes, dialysis time, serum phosphorus, calcium-phosphorus product, medical history of phosphate binders, sortilin, and carotid artery plaque between 4 different degrees of calcification groups (p < 0.05). Logistic regression analysis showed that diabetes (OR = 5.475; 95% CI: 1.794-16.71, p = 0.003), calcium-phosphorus product (OR = 2.953; 95% CI: 1.198-7.279, p = 0.019), and sortilin (OR = 1.475 per 100 pg/mL; 95% CI: 1.170-1.858, p = 0.001) were independent risk factors for CAC. During the follow-up, 28 cases of 111 patients (25.23%) suffered from CCE. There were significant differences in CCE between mild, moderate, and severe CAC groups and noncalcification groups (p < 0.05). Cox regression analysis showed that diabetes mellitus (HR 3.424; 95% CI: 1.348-8.701, p = 0.010), CAC (HR 5.210; 95% CI: 1.093-24.83, p = 0.038), and serum sortilin (HR = 8.588; 95% CI: 1.919-38.43, p = 0.005) were independent risk factors for CCE. Besides, we proposed a cutoff value of 418 pg/mL for serum sortilin level, which was able to predict the occurrence of CCE with 75.0% sensitivity and 71.9% specificity. The area under the curve was 0.778 (95% CI: 0.673-0.883).

CONCLUSION

Sortilin is newly found to be independently associated with CAC and CCE in MHD patients.

The relationship between coronary artery calcium density and optical coherence tomography-derived plaque characteristics

BACKGROUND AND AIMS

Although coronary artery calcium (CAC) density has been associated with plaque stability, pathological evidence is lacking. We investigated the relationship between coronary computed tomography (CCT)-derived CAC density and multiple calcified and high-risk plaque (HRP) characteristics using optical coherence tomography (OCT).

METHODS

We analyzed 83 plaques from 33 stable angina patients who underwent both CCT and OCT. CAC density was measured at calcium plaques with ≥90 Hounsfield units (HU) and ≥130 HU using custom CT software. The correlation between median CAC density and OCT-derived calcium size (thickness and area) was assessed. To investigate whether median CAC densities measured at the 90 HU threshold were associated with plaque vulnerability, OCT-derived plaque characteristics and HRP characteristics were compared between the low (90-129 HU), intermediate (130-199 HU) and high (≥200 HU) CAC HU groups.

RESULTS

Median CAC densities at 130 HU were moderately associated with calcium thickness (R = 0.573, p < 0.001) and area (R = 0.560, p < 0.001). Similar results were observed at 90 HU (thickness, R = 0.615, p < 0.001; area, R = 0.612, p < 0.001). Among groups with low, intermediate and high HU levels, calcium thickness (0.42 ± 0.14 mm, 0.60 ± 0.17 mm and 0.77 ± 0.19 mm, respectively; p < 0.001) and area (0.55 ± 0.29 mm², 1.20 ± 0.58 mm² and 1.78 ± 0.87 mm², respectively; p < 0.001) were significantly greater in the high HU group. HRP characteristics, however, did not differ among the three groups.

CONCLUSIONS

OCT-derived calcium size, but not HRP characteristics, were associated with CAC density, suggesting that CAC density is driven mainly by calcified plaque size but not local plaque vulnerability.

Coronary calcium scoring with partial volume correction in anthropomorphic thorax phantom and screening chest CT images

INTRODUCTION

The amount of coronary artery calcium determined in CT scans is a well established predictor of cardiovascular events. However, high interscan variability of coronary calcium quantification may lead to incorrect cardiovascular risk assignment. Partial volume effect contributes to high interscan variability. Hence, we propose a method for coronary calcium quantification employing partial volume correction.

METHODS

Two phantoms containing artificial coronary artery calcifications and 293 subject chest CT scans were used. The first and second phantom contained nine calcifications and the second phantom contained three artificial arteries with three calcifications of different volumes, shapes and densities. The first phantom was scanned five times with and without extension rings. The second phantom was scanned three times without and with simulated cardiac motion (10 and 30 mm/s). Chest CT scans were acquired without ECG-synchronization and reconstructed using sharp and soft kernels. Coronary calcifications were annotated employing the clinically used intensity value thresholding (130 HU). Thereafter, a threshold separating each calcification from its background was determined using an Expectation-Maximization algorithm. Finally, for each lesion the partial content of calcification in each voxel was determined depending on its intensity and the determined threshold.

RESULTS

Clinical calcium scoring resulted in overestimation of calcium volume for medium and high density calcifications in the first phantom, and overestimation of calcium volume for high density and underestimation for low density calcifications in the second phantom. With induced motion these effects were further emphasized. The proposed quantification resulted in better accuracy and substantially lower over- and underestimation of calcium volume even in presence of motion. In chest CT, the agreement between calcium scores from the two reconstructions improved when proposed method was used.

CONCLUSION

Compared with clinical calcium scoring, proposed quantification provides a better estimate of the true calcium volume in phantoms and better agreement in calcium scores between different subject scan reconstructions.

Accuracy of Calcium Scoring calculated from contrast-enhanced Coronary Computed Tomography Angiography using a dual-layer spectral CT: A comparison of Calcium Scoring from real and virtual non-contrast data

Purpose

Modern non-invasive evaluation of Coronary Artery Disease (CAD) requires non-contrast low dose Computed Tomography (CT) imaging for determination of Calcium Scoring (CACS) and contrast-enhanced imaging for evaluation of vascular stenosis. Several methods for calculation of CACS from contrast-enhanced images have been proposed before. The main principle for that is generation of virtual non-contrast images by iodine subtraction from a contrast-enhanced spectral CT dataset. However, those techniques have some limitations: Dual-Source CT imaging can lead to increased radiation exposure, and switching of the tube voltage (rapid kVp switching) can be associated with slower rotation speed of the gantry and is thus prone to motion artefacts that are especially critical in cardiac imaging. Both techniques cannot simultaneously acquire spectral data. A novel technique to overcome these difficulties is spectral imaging with a dual-layer detector. After absorption of the lower energetic photons in the first layer, the second layer detects a hardened spectrum of the emitted radiation resulting in registration of two different energy spectra at the same time. The objective of the present investigation was to evaluate the accuracy of virtual non-contrast CACS computed from spectral data in comparison to standard non-contrast imaging.

Methods

We consecutively investigated 20 patients referred to Coronary Computed Tomography Angiography (CCTA) with suspicion of CAD using a Dual-Layer spectral CT system (IQon; Philips Healthcare, The Netherlands). CACS was calculated from both, real- and virtual non-contrast images by certified software for medical use. Correlation analyses for real- and virtual non-contrast images and agreement evaluation with Bland-Altman-Plots were performed.

Results

Mean patient age was 57.7 ± 14 years (n = 20). 13 patients (65%) were male. Inter-quartile-range of clinical CACS was 0–448, the mean was 334. Correlation of CACS from real- and virtual non-contrast images was very high (0.94); p < 0.0001. The slope was 2.3 indicating that values from virtual non-contrast images are approximately half of the results obtained from real non-contrast data. Visual analysis of Bland-Altman-Plot shows good accordance of both methods when results from virtual non-contrast data are multiplied by the slope of the logistic regression model (2.3). The acquired power of this results is 0.99.

Conclusion

Determination of Calcium Score from contrast enhanced CCTA using spectral imaging with a dual-layer detector is feasible and shows good agreement with the conventional technique when a proportionality factor is applied. The observed difference between both methods is due to an underestimation of plaque volume, and—to an even greater extend -an underestimation of plaque density with the virtual non-contrast approach. Our data suggest that radiation exposure can be reduced through omitting additional native scans for patients referred to CCTA when using a dual-layer spectral system without the usual limitations of dual energy analysis.

Associations of coronary artery calcified plaque density with mortality in type 2 diabetes: the Diabetes Heart Study

Background

Coronary artery calcified plaque (CAC) is strongly predictive of cardiovascular disease (CVD) events and mortality, both in general populations and individuals with type 2 diabetes at high risk for CVD. CAC is typically reported as an Agatston score, which is weighted for increased plaque density. However, the role of CAC density in CVD risk prediction, independently and with CAC volume, remains unclear.

Methods

We examined the role of CAC density in individuals with type 2 diabetes from the family-based Diabetes Heart Study and the African American-Diabetes Heart Study. CAC density was calculated as mass divided by volume, and associations with incident all-cause and CVD mortality [median follow-up 10.2 years European Americans (n = 902, n = 286 deceased), 5.2 years African Americans (n = 552, n = 93 deceased)] were examined using Cox proportional hazards models, independently and in models adjusted for CAC volume.

Results

In European Americans, CAC density, like Agatston score and volume, was consistently associated with increased risk of all-cause and CVD mortality (p ≤ 0.002) in models adjusted for age, sex, statin use, total cholesterol, HDL, systolic blood pressure, high blood pressure medication use, and current smoking. However, these associations were no longer significant when models were additionally adjusted for CAC volume. CAC density was not significantly associated with mortality, either alone or adjusted for CAC volume, in African Americans.

Conclusions

CAC density is not associated with mortality independent from CAC volume in European Americans and African Americans with type 2 diabetes.

Electronic supplementary material

The online version of this article (10.1186/s12933-018-0714-z) contains supplementary material, which is available to authorized users.

Left Ventricular Hypertrophy Predicts Cardiovascular Events in Hypertensive Patients With Coronary Artery Calcifications

BACKGROUND

Coronary artery calcification (CAC) is associated with increased cardiovascular (CV) risk. Left ventricular hypertrophy (LVH) is an independent risk factor for CV events. Our aim was to estimate the relative CV risk of LVH in the presence of CAC.

METHODS

We included asymptomatic hypertensive patients who were enrolled in the calcification arm of the INSIGHT (International Nifedipine Study Intervention as Goal for Hypertension Therapy). Patients had baseline echocardiography and computed tomography to assess CAC. The primary end-point was the first CV event.

RESULTS

Two hundred and fifty-two subjects (mean age 64.7 ± 5.5 years, 54% men) were followed for a mean of 13.3 ± 2.6 years. 72 patients (28.5%) had LVH and 159 patients (63%) had CAC. During follow up, 89 patients had a first CV event. The rate of CV events was higher in those with than in those without CAC (43.4% vs. 21.5%, P < 0.01) and in those with than in those without LVH (44% vs. 31.6%, P < 0.01). However, LVH had no effect on CV events in the absence of CAC, whereas LVH almost doubled the rate of CV events (61.4% vs. 36.5%, P < 0.01) in the presence of CAC. In comparison to patients without CAC and without LVH the hazard ratio for CV event in those with LVH was 1.46 (95% confidence interval [CI], 0.50-4.21) in those without CAC and 4.4 (95% CI, 2.02-9.56) in those with CAC.

CONCLUSIONS

LVH and CAC independently predict CV events in asymptomatic hypertensive patients. However, the risk of LVH is mainly observed in those with CAC.

Cardiac Calcium Evaluation in Hemodialysis Patients with Multisection Spiral Computed Tomography

Aim

The aim of this study is cardiac calcium content evaluation in hemodialysis patients by a new technique, based on ultrafast multisection CT (MTC).

Methods

The study was carried out on 30 HD patients, 14F and 16 M, average age 57.7±13.9 years, average HD age 57.3±47.4 months. The intact PTH levels were 625.4±571 pg/mL. Serum calcium, phosphate and CaxP product were 9.75±0.84 mg/mL, 6.21±1.01 mg/dL and 60.2±10.7 mg2/dL2, respectively.

Results

The values obtained with the MTC technique were reported in terms of Agatson scores. Score values frankly in the pathologic range (>100) were found in 24 patients (80%). Correlation analysis has shown positive and significant correlation coefficients of the score with patients’ age (p=0.003), serum calcium (p=0.012), CaxP (p=0.015), iPTH (=0.049), and borderline, to HD age (p=0.06).

Conclusion

Risk factors for cardiac calcification are mainly age, degree of hyperparathyroidism, increased CaxP and serum calcium levels. A control of calcium phosphate parameters in hemodialysis patients seems to be mandatory to avoid increased severity of coronary artery disease.

Coronary Computed Tomography Angiography in Combination with Coronary Artery Calcium Scoring for the Preoperative Cardiac Evaluation of Liver Transplant Recipients

Liver transplantation is the best treatment option for early-stage hepatocellular carcinoma, liver cirrhosis, fulminant liver failure, and end-stage liver diseases. Even though advances in surgical techniques and perioperative care have improved postoperative outcomes, perioperative cardiovascular complications are a leading cause of postoperative morbidity and mortality following liver transplantation. Ischemic coronary artery disease (CAD) and cardiomyopathy are the most common cardiovascular diseases and could be negative predictors of postoperative outcomes in liver transplant recipients. Therefore, comprehensive cardiovascular evaluations are required to assess perioperative risks and prevent concomitant cardiovascular complications that would preclude good outcomes in liver transplant recipients. The two major types of cardiac computed tomography are the coronary artery calcium score (CACS) and coronary computed tomography angiography (CCTA). CCTA in combination with the CACS is a validated noninvasive alternative to coronary angiography for diagnosing and grading the severity of CAD. A CACS > 400 is associated with significant CAD and a known important predictor of posttransplant cardiovascular complications in liver transplant recipients. In this review article, we discuss the usefulness, advantages, and disadvantages of CCTA combined with CACS as a noninvasive diagnostic tool for preoperative cardiac evaluation and for maximizing the perioperative outcomes of liver transplant recipients.

Coronary artery calcification in clinical practice: what we have learned and why should it routinely be reported on chest CT?

The recent acceptance of low dose chest computed tomography (LDCT) as a screening modality for early lung cancer detection will significantly increase the number of LDCT among high risk population. The target subjects are at the same time at high risk to develop cardiovascular (CV) events. The routine report on coronary artery calcification (CAC) will therefore, enhances the screening benefit by providing the clinicians with an additive powerful risk stratification tool for the management or primary prevention of CV events. This review will provide the radiologists with helpful information for the daily practice regarding on what is CAC, its clinical applications and how to diagnose, quantify and report on CAC while reading the LDCT.

CT attenuation values of blood and myocardium: rationale for accurate coronary artery calcifications detection with multi-detector CT

Objectives

To determine inter-session and intra/inter-individual variations of the attenuations of aortic blood/myocardium with MDCT in the context of calcium scoring. To evaluate whether these variations are dependent on patients’ characteristics.

Methods

Fifty-four volunteers were evaluated with calcium scoring non-enhanced CT. We measured attenuations (inter-individual variation) and standard deviations (SD, intra-individual variation) of the blood in the ascending aorta and of the myocardium of left ventricle. Every volunteer was examined twice to study the inter-session variation. The fat pad thickness at the sternum and noise (SD of air) were measured too. These values were correlated with the measured aortic/ventricular attenuations and their SDs (Pearson). Historically fixed thresholds (90 and 130 HU) were tested against different models based on attenuations of blood/ventricle.

Results

The mean attenuation was 46HU (range, 17-84HU) with mean SD 23HU for the blood, and 39HU (10-82HU) with mean SD 18 HU for the myocardium. The attenuation/SD of the blood were significantly higher than those of the myocardium (p<0.01). The inter-session variation was not significant. There was a poor correlation between SD of aortic blood/ventricle with fat thickness/noise. Based on existing models, 90 HU threshold offers a confidence interval of approximately 95% and 130 HU more than 99%.

Conclusions

Historical thresholds offer high confidence intervals for exclusion of aortic blood/myocardium and by the way for detecting calcifications. Nevertheless, considering the large variations of blood/myocardium CT values and the influence of patient’s characteristics, a better approach might be an adaptive threshold.

Scoring of coronary artery calcium scans: history, assumptions, current limitations, and future directions

Coronary artery calcium (CAC) scanning is a reliable, noninvasive technique for estimating overall coronary plaque burden and for identifying risk for future cardiac events. Arthur Agatston and Warren Janowitz published the first technique for scoring CAC scans in 1990. Given the lack of available data correlating CAC with burden of coronary atherosclerosis at that time, their scoring algorithm was remarkable, but somewhat arbitrary. Since then, a few other scoring techniques have been proposed for the measurement of CAC including the Volume score and Mass score. Yet despite new data, little in this field has changed in the last 15 years. The main focus of our paper is to review the implications of the current approach to scoring CAC scans in terms of correlation with the central disease - coronary atherosclerosis. We first discuss the methodology of each available scoring system, describing how each of these scores make important indirect assumptions in the way they account (or do not account) for calcium density, location of calcium, spatial distribution of calcium, and microcalcification/emerging calcium that might limit their predictive power. These assumptions require further study in well-designed, large event-driven studies. In general, all of these scores are adequate and are highly correlated with each other. Despite its age, the Agatston score remains the most extensively studied and widely accepted technique in both the clinical and research settings. After discussing CAC scoring in the era of contrast enhanced coronary CT angiography, we discuss suggested potential modifications to current CAC scanning protocols with respect to tube voltage, tube current, and slice thickness which may further improve the value of CAC scoring. We close with a focused discussion of the most important future directions in the field of CAC scoring.

Serum uric acid is associated with coronary artery calcification

Uric acid (UA) is associated with atherosclerosis, and coronary artery calcium (CAC) is a marker of atherosclerosis. The authors studied the association between UA and CAC. A total of 663 asymptomatic patients (564 men; mean age, 55±7 years) were evaluated for the presence of CAC. The study population was divided into three tertiles according to their UA levels, and the prevalence of CAC was compared between the tertiles. CAC was detected in 349 (53%) patients. Levels of UA were significantly higher in those with CAC than in those without CAC (5.6+1.2 vs 5.3+1.3; P=.003). The odds ratio for the presence of CAC in the highest vs lowest UA tertile was 1.72 (95% confidence interval, 1.17-2.51). The highest UA tertile remained associated with the presence of CAC after adjustment for known cardiovascular risk factors. The results show that high serum UA levels are associated with the presence of CAC.

Coronary calcium in patients with and without diabetes: first manifestation of acute or chronic coronary events is characterized by different calcification patterns

BACKGROUND

Coronary artery calcification (CAC) is closely related to coronary atherosclerosis. However, less is known about the clinical significance of extensive CAC (ECAC) in regard to types of first coronary events (acute vs. chronic). Diabetes mellitus (DM) represents a strong risk factor for CAD although its association with CAC is controversial. Aiming to elucidate these controversies we investigated the long-term outcome of coronary artery disease (CAD) in relation to degree of CAC in patients with and without DM from our annual cheek-up outpatient clinic.

METHODS

Coronary artery computed tomography (CT) was performed in 667 patients who were yearly evaluated during a mean follow-up period of 6.3 ±3.4 year. The following 4 CAC categories were established: calcium absence; total calcium score (TCS): 1-100 AU; TCS: 101-600 AU and ECAC: TCS above 600 AU. Acute event was defined as first acute myocardial infarction (MI) or a new unstable angina. First chronic event was defined as a positive stress test with a consequent elective percutaneous coronary intervention or coronary artery bypass grafting.

RESULTS

628 subjects (94%) were free from any cardiac events, 39 (6%) experienced first cardiac event: 18 of them suffered acute and 21 chronic events. There were 67 patients with and 600 patients without DM: 78% of patients with DM presented CAC vs. 50% of patients without DM (p < 0.001).The mean TCS was 17 times higher in the chronic than in the acute events group: 914 vs. 55 AU, p < 0.001. In 95% of the patients with chronic events more than one calcified vessel was found, compared to 67% of the patients with acute events and only 30% of those without events (p < 0.001). Incidence of CAD events (all types pooled together) rose consequently from 2% in subjects without CAC to 34% in subjects with ECAC (p < 0.001). However, among the 32 subjects with ECAC, 11 (34%) developed chronic event while none of them had acute event. In contrast, none of subjects with TCS =0 or TCS 1-100 AU presented with chronic events. Subjects with TCS 101-600 AU presented 10 (9%) chronic and 5 (4.5%) acute events (p < 0.001).

CONCLUSIONS

Asymptomatic subjects with ECAC are not firstly manifested as acute coronary events but presented a high level of chronic CAD-related events during the 6.3 ±3.4 year follow-up. In contrast, first acute CAD-related events occurred mostly in subjects with mild and moderate CAC score.

Calcification at orifices of aortic arch branches is a reliable and significant marker of stenosis at carotid bifurcation and intracranial arteries

PURPOSE

Simple rating scale for calcification in the cervical arteries and the aortic arch on multi-detector computed tomography angiography (MDCTA) was evaluated its reliability and validity. Additionally, we investigated where is the most representative location for evaluating the calcification risk of carotid bifurcation stenosis and atherosclerotic infarction in the overall cervical arteries covering from the aortic arch to the carotid bifurcation.

METHOD

The aortic arch and cervical arteries among 518 patients (292 men, 226 women) were evaluated the extent of calcification using a 4-point grading scale for MDCTA. Reliability, validity and the concomitant risk with vascular stenosis and atherosclerotic infarction were assessed.

RESULTS

Calcification was most frequently observed in the aortic arch itself, the orifices from the aortic arch, and the carotid bifurcation. Compared with the bilateral carotid bifurcations, the aortic arch itself had a stronger inter-observer agreement for the calcification score (Fleiss' kappa coefficients; 0.77), but weaker associations with stenosis and atherosclerotic infarction. Calcification at the orifices of the aortic arch branches had a stronger inter-observer agreement (0.74) and enough associations with carotid bifurcation stenosis and intracranial stenosis. In addition, the extensive calcification at the orifices from the aortic arch was significantly associated with atherosclerotic infarction, similar to the calcification at the bilateral carotid bifurcations.

CONCLUSIONS

The orifices of the aortic arch branches were the novel representative location of the aortic arch and overall cervical arteries for evaluating the calcification extent. Thus, calcification at the aortic arch should be evaluated with focus on the orifices of 3 main branches.

Coronary artery calcification is associated with the development of hypertension

BACKGROUND

Hypertension (HTN) is associated with coronary artery calcification (CAC). We hypothesized that preexisting CAC is associated with the development of HTN.

METHODS

This study included 483 normotensive subjects (mean age 54 years, 83% males) who underwent a baseline evaluation of their CAC score with ungated dual-section computed tomography during 2001-2002 and returned for at least the first annual follow-up. All subjects underwent an annual examination and were followed for a mean period of 6.6 ± 3.2 years to identify newly developed HTN. Data on the patient's medical history, physical examination and laboratory evaluations were collected.

RESULTS

During the follow-up, 104 subjects developed HTN. The rate of newly developed HTN was significantly higher among those with CAC (60 of 223 subjects; 27%) than among those without CAC (44 of 260; 17%) (P < 0.01). The presence of CAC predicted the development of HTN with a hazard ratio of 1.73 (95% confidence interval, 1.17-2.56; P < 0.01). After adjustment for age, sex, body mass index, smoking, baseline systolic blood pressure, and levels of glucose, triglycerides, and low-density lipoprotein cholesterol, the presence of CAC still predicted the development of HTN with a hazard ratio of 1.63 (95% confidence interval, 1.02-2.60; P = 0.04).

CONCLUSIONS

Preexisting CAC is associated with the development of HTN.

An alternative method for quantifying coronary artery calcification: the multi-ethnic study of atherosclerosis (MESA)

Background

Extent of atherosclerosis measured by amount of coronary artery calcium (CAC) in computed tomography (CT) has been traditionally assessed using thresholded scoring methods, such as the Agatston score (AS). These thresholded scores have value in clinical prediction, but important information might exist below the threshold, which would have important advantages for understanding genetic, environmental, and other risk factors in atherosclerosis. We developed a semi-automated threshold-free scoring method, the spatially weighted calcium score (SWCS) for CAC in the Multi-Ethnic Study of Atherosclerosis (MESA).

Methods

Chest CT scans were obtained from 6814 participants in the Multi-Ethnic Study of Atherosclerosis (MESA). The SWCS and the AS were calculated for each of the scans. Cox proportional hazards models and linear regression models were used to evaluate the associations of the scores with CHD events and CHD risk factors. CHD risk factors were summarized using a linear predictor.

Results

Among all participants and participants with AS > 0, the SWCS and AS both showed similar strongly significant associations with CHD events (hazard ratios, 1.23 and 1.19 per doubling of SWCS and AS; 95% CI, 1.16 to 1.30 and 1.14 to 1.26) and CHD risk factors (slopes, 0.178 and 0.164; 95% CI, 0.162 to 0.195 and 0.149 to 0.179). Even among participants with AS = 0, an increase in the SWCS was still significantly associated with established CHD risk factors (slope, 0.181; 95% CI, 0.138 to 0.224). The SWCS appeared to be predictive of CHD events even in participants with AS = 0, though those events were rare as expected.

Conclusions

The SWCS provides a valid, continuous measure of CAC suitable for quantifying the extent of atherosclerosis without a threshold, which will be useful for examining novel genetic and environmental risk factors for atherosclerosis.

Relation of coronary artery calcium to cardiovascular risk in patients with combined diabetes mellitus and systemic hypertension

Certain patients with type 2 diabetes mellitus (DM) do not have increased cardiovascular (CV) risk. The aim of the present study was to stratify hypertensive adults with DM into those with low or high CV risk according to the absence or presence of coronary artery calcium (CAC). The study group included 423 patients, a subgroup of the 544 participants in the calcification side arm of the International Nifedipine Study: Intervention as Goal for Hypertension Therapy. All underwent a baseline computed tomography scan with an unenhanced dual-detector spiral computed tomography scan for CAC measurements. All were free of CV disease and completed 3 years (short-term) of follow-up. A total of 268 patients were included in the 15-year (long-term) follow-up period. The study group was divided into 4 subgroups according to the presence or absence of DM and CAC and was analyzed for a first CV event. Of the 423 patients, 164 (39%) had DM. Cardiovascular events occurred in 41 patients during the first 3 years and in 111 of 268 patients during the long-term follow-up. The rate of CV events was greater in the patients with DM with CAC than in those without (15% vs 7% after 3 years and 52% vs 32% after 15 years). Compared to those without DM without CAC, the short-term adjusted hazard ratio for CV event in those with DM with and without CAC was 6.6 (95% confidence interval 1.4 to 30.5) and 3.9 (95% confidence interval 0.7 to 22.6), respectively. A similar trend was seen in the long-term follow-up study. In conclusion, patients with hypertension and DM can be stratified into a lower CV risk in the absence of CAC.

Comparison of dual-source and electron-beam CT for the assessment of coronary artery calcium scoring

OBJECTIVE

Cardiac CT allows the detection and quantification of coronary artery calcification (CAC). Electron-beam CT (EBCT) has been widely replaced by high-end CT generations in the assessment of CAC. The aim of this study was to compare the CAC scores derived from an EBCT with those from a dual-source CT (DSCT).

METHODS

We retrospectively selected 92 patients (61 males; mean age, 60.7 ± 12 years) from our database, who underwent both EBCT and DSCT. CAC was assessed using the Agatston score by two independent readers (replicates: 1, 2; 3=mean of reading 1 and 2).

RESULTS

EBCT scores were on average slightly higher than DSCT scores (281 ± 569 vs 241 ± 502; p<0.05). In regression analysis R(2)-values vary from 0.956 (1) to 0.966 (3). We calculated a correction factor as EBCT=(DSCT+1)(1.026)-1. When stratifying into CAC categories (0, 1-99, 100-399, 400-999 and ≥1000), 79 (86%) were correctly classified. From those with positive CAC scores, 7 out of 61 cases (11%, κ=0.81) were classified in different categories. Using the corrected DSCT CAC score, linear regression analysis for the comparison to the EBCT results were r=0.971 (p<0.001), with a mean difference of 6.4 ± 147.8. Five subjects (5.4%) were still classified in different categories (κ=0.84).

CONCLUSION

CAC obtained from DSCT is highly correlated with the EBCT measures. Using the calculated correction factor, agreement only marginally improved the clinical interpretation of results. Overall, for clinical purposes, face value use of DSCT-derived values appears as useful as EBCT for CAC scoring.

Correlation between carotid bifurcation calcium burden on non-enhanced CT and percentage stenosis, as confirmed by digital subtraction angiography

OBJECTIVES

Previous evidence supports a direct relationship between the calcium burden (volume) on post-contrast CT with the percent internal carotid artery (ICA) stenosis at the carotid bifurcation. We sought to further investigate this relationship by comparing non-enhanced CT (NECT) and digital subtraction angiography (DSA).

METHODS

50 patients (aged 41-82 years) were retrospectively identified who had undergone cervical NECT and DSA. A 64-multidetector array CT (MDCT) scanner was utilised and the images reviewed using preset window widths/levels (30/300) optimised to calcium, with the volumes measured via three-dimensional reconstructive software. Stenosis measurements were performed on DSA and luminal diameter stenoses >40% were considered "significant". Volume thresholds of 0.01, 0.03, 0.06, 0.09 and 0.12 cm(3) were utilised and Pearson'S correlation coefficient (r) was calculated to correlate the calcium volume with percent stenosis.

RESULTS

Of 100 carotid bifurcations, 88 were available and of these 7 were significantly stenotic. The NECT calcium volume moderately correlated with percent stenosis on DSA r=0.53 (p<0.01). A moderate-strong correlation was found between the square root of calcium volume on NECT with percent stenosis on DSA (r=0.60, p<0.01). Via a receiver operating characteristic curve, 0.06 cm(3) was determined to be the best threshold (sensitivity 100%, specificity 90.1%, negative predictive value 100% and positive predictive value 46.7%) for detecting significant stenoses.

CONCLUSION

This preliminary investigation confirms a correlation between carotid bifurcation calcium volume and percent ICA stenosis and is promising for the optimal threshold for stenosis detection. Future studies could utilise calcium volumes to create a "score" that could predict high grade stenosis.

The relation of carotid calcium volume with carotid artery stenosis in symptomatic patients

BACKGROUND AND PURPOSE

Recent research showed a strong correlation of calcium volume scores with degree of stenosis, suggesting that calcium volume could be used in the diagnosis of carotid artery stenosis. We investigated the accuracy of the use of calcium volume scores to diagnose carotid artery stenosis in our target population of recently symptomatic patients.

MATERIALS AND METHODS

Ninety symptomatic patients suspected of having carotid artery stenosis underwent CTA, resulting in images of 159 evaluable arteries. The correlation between calcium volume and degree of stenosis was calculated by using the Pearson correlation coefficient. With thresholds of 0.03 and 0.09 mL, we assessed the diagnostic performance of a calcium volume-based evaluation of stenosis for a previously reported stenosis cutoff of 40% and for the clinically important cutoffs of 50% and 70%.

RESULTS

In our patients series, the calcium volume score was not related to the stenosis degree on the symptomatic side (R = 0.04, P = .7) and was weakly related on the asymptomatic side (R = 0.29, P = .005). The diagnostic accuracy of the calcium volume score to estimate 40% stenosis was relatively low: a sensitivity of 47% or 64% and a specificity of 52% or 82%, for the 0.09 and 0.03 mL thresholds, respectively. The diagnostic accuracy decreased with increasing degree of stenosis.

CONCLUSIONS

We could not confirm the previously reported strong correlation of calcium volume with stenosis degree in our population of patients with recent neurologic symptoms. We conclude that in this particular domain, calcium volume cannot be used to estimate the degree of stenosis.

Coronary artery calcification predicts long-term mortality in hypertensive adults

BACKGROUND

Coronary artery calcification (CAC) predicts mortality in normotensive individuals. We hypothesized that CAC has an impact on long-term mortality in hypertensive patients.

METHODS

We followed 423 participants of the INSIGHT (International Nifedipine Study Intervention as Goal for Hypertension Therapy) calcification substudy, for the incidence of mortality as a function of CAC. All patients were hypertensive (mean age 64 ± 6 years, 48% male), without coronary artery or peripheral vascular disease, aged >55 years and with at least one more major cardiovascular (CV) risk factor. All underwent a baseline computed tomography (CT) (Dual slice) to determine the calcification score and were followed for a mean period of 14 ± 0.5 years. Mortality and the cause of death were derived from the registry of the Ministry-of-Interior Affairs.

RESULTS

During the follow-up, 94 patients died; 27 from CV causes, 54 from non-CV causes and 13 of undefined causes. The prevalence of calcification at baseline was 59% (195/329) among the survivors compared to 82% (77/94) in participants who died and 96.7% (26/27) among those who died of CV causes. The incidence of CV death was 14 times higher among those with than those without CAC (9.6% (26/272) vs. 0.7% (1/151); P < 0.01). After adjusting for age, gender, left ventricular hypertrophy, proteinuria, duration of hypertension, and renal function the presence of calcification predicted all cause mortality with a hazard ratio (HR) of 1.8 (95% confidence interval (CI) 1.04-3.07).

CONCLUSIONS

CAC is associated with long-term mortality in asymptomatic hypertensive adults.

Ordinal scoring of coronary artery calcifications on low-dose CT scans of the chest is predictive of death from cardiovascular disease

PURPOSE

To assess the usefulness of ordinal scoring of the visual assessment of coronary artery calcification (CAC) on low-dose computed tomographic (CT) scans of the chest in the prediction of cardiovascular death.

MATERIALS AND METHODS

All participants consented to low-dose CT screening according to an institutional review board-approved protocol. The amount of CAC was assessed on ungated low-dose CT scans of the chest obtained between June 2000 and December 2005 in a cohort of 8782 smokers aged 40-85 years. The four main coronary arteries were visually scored, and each participant received a CAC score of 0-12. The date and cause of death was obtained by using the National Death Index. Follow-up time (median, 72.3 months; range, 0.3-91.9 months) was calculated as the time between CT and death, loss to follow-up, or December 31, 2007, whichever came first. Logistic regression analysis was used to determine the risk of mortality according to CAC category adjusted for age, pack-years of cigarette smoking, and sex. The same analysis to determine the hazard ratio for survival from cardiac death was performed by using Cox regression analysis.

RESULTS

The rate of cardiovascular deaths increased with an increasing CAC score and was 1.2% (43 of 3573 subjects) for a score of 0, 1.8% (66 of 3569 subjects) for a score of 1-3, 5.0% (51 of 1015 subjects) for a score of 4-6, and 5.3% (33 of 625 subjects) for a score of 7-12. With use of subjects with a CAC score of 0 as the reference group, a CAC score of at least 4 was a significant predictor of cardiovascular death (odds ratio [OR], 4.7; 95% confidence interval: 3.3, 6.8; P < .0001); when adjusted for sex, age, and pack-years of smoking, the CAC score remained significant (OR, 2.1; 95% confidence interval: 1.4, 3.1; P = .0002).

CONCLUSION

Visual assessment of CAC on low-dose CT scans provides clinically relevant quantitative information as to cardiovascular death.

Significant coronary calcification detected using contrast-enhanced computed tomography: is it an indication for further investigation?

BACKGROUND

Evaluate the significance of coronary arteries calcifications detected using contrast-enhanced chest computed tomography (CECCT) scans.

METHODS

A total of 145 patients who underwent both CECCT and gated stress myocardial perfusion imaging (MPI) within 2 weeks were included. The chest CT scans were reviewed for the presence of coronary artery calcium (CAC) by 2 experienced blinded readers. The degree of calcifications seen in any visualized area of the major coronary arteries was graded on a scale of 1 to 3 (1 when 0 to 4 small scattered plaques were seen, 2 when 5 or more scattered plaques were seen, and 3 when diffuse contiguous calcification were seen). The grade of CAC was correlated with the presence of MPI abnormalities. Additionally, the locations of the MPI abnormality was correlated with the CAC grade in the culprit coronary artery.

RESULTS

Of 580 major coronary arteries evaluated, 79% had grade 1 CAC, 10% had grade 2, 11% had grade 3, and 1% were inevaluable. Of the 145 patients, 33 (23%) had abnormal MPI results. Twenty-three of the patients with abnormal MPI results (70%) had more than 4 calcified plaques (CAC grade of 2 or 3) in one or more of their coronary arteries, whereas 41 of 122 patients with normal MPI results (37%) had similar CAC grades (P=0.001). Seventeen of the 33 patients (52%) who had MPI defects also had significant CAC in the culprit coronary artery, 7 patients (21%) had significant CAC in a different coronary artery from the MPI defect territory, 8 patients (24%) had no significant CAC visualized, and in 1 patient a pacemaker wire interfered with CAC grading in the culprit coronary artery (RCA). The sensitivity, specificity, the positive, and negative predictive values of grade 2 or 3 CAC for an abnormal MPI results were 70%, 63%, 36%, and 88%, respectively. When a subgroup of patients above 60 years old with grade 3 CAC was reanalyzed, the sensitivity, specificity, the positive, and negative predictive values for an abnormal MPI results were 69%, 73%, 41%, and 90%, respectively.

CONCLUSION

Multiple diffuse CAC as detected during the interpretation of CECCT scans in combination with advanced age is a significant finding that warrants further investigation for functionally significant CAD.

Long-term changes in serum cholesterol level does not influence the progression of coronary calcification

BACKGROUND

A number of reports controversially describe the influence of cholesterol level and lipid-lowering treatment (LLT) on the progression of coronary calcium (CC). We tested the hypothesis that long-term changes in serum cholesterol (CL) would affect the progression of CC.

METHODS

The study population comprised 510 patients with stable angina pectoris, mean age of 63 ± 9 years. At baseline 372 patients received statin and/or fibrate (LLT group) while 138 patients did not (No-LLT at baseline group). Spiral CT every 24 months was used to track the progression of CC over a median 5.6 year follow-up.

RESULTS

CL decreased during follow-up in both groups, but more pronouncedly in patients with LLT. The changes in total calcium score (TCS) were similar in both groups (p=0.3). Changes in CL during follow-up were not associated with CC: TCS increased by 501 ± 63 from baseline in the 1st (upper) quartile, and by 350 ± 44, 403 ± 41 and 480 ± 56 in the 2nd, 3rd, and 4th quartiles of CL longitudinal changes (p = 0.2), respectively. Baseline TCS and its changes were not correlated with baseline CL and its changes. New calcified lesions were diagnosed in 132 (28.2%) out of the 467 patients available for this analysis, without significant difference between groups (p=0.4). Multivariate analysis demonstrated that only baseline TCS (p < 0.001), body mass index (p = 0.007) and age (p = 0.006) were independent predictors for the TCS changes.

CONCLUSIONS

Longitudinal CL changes do not seem to have a measurable effect on the rate of progression of CC.

Coronary calcium screening using low-dose lung cancer screening: effectiveness of MDCT with retrospective reconstruction

OBJECTIVE

The purpose of our study was to show the usefulness of nongated low-dose chest CT for coronary screening by comparing the results of coronary artery calcium measurement with that of dedicated calcium-scoring CT.

MATERIALS AND METHODS

One hundred twenty-eight consecutive participants (all men; mean age, 52 +/- 7 years) underwent low-dose chest CT and calcium-scoring CT with prospective ECG gating using 40-MDCT. Low-dose chest CT volume data were reconstructed as 25-cm field of view and three slice thicknesses: 1, 2.5, and 5 mm. For each examination, the lesion area, Agatston calcium score, and calcium mass were measured at 90- and 130-H thresholds. All measurements (130-H threshold) from the calcium-scoring CT were used as reference standards. Spearman's correlation test was used to compare the results.

RESULTS

Among the low-dose chest CT examinations, sensitivity was best determined with a 1-mm slice thickness at 130 H and 2.5-mm slice thickness at 90 H. Specificity was best determined with a 5-mm slice thickness at 130 H. Accuracy (90%) was best determined with a 2.5-mm slice thickness at 130 H. Of all protocols, calcium area, score, and mass from a 2.5-mm slice thickness at 130 H correlated best with the reference results (r = 0.89 for all three criteria).

CONCLUSION

Using a low radiation dose and nongated MDCT, we can detect coronary artery calcium and obtain results comparable to those obtained with dedicated calcium-scoring CT that uses a higher dose and ECG gating.

Coronary calcification: effect of small variation of scan starting position on Agatston, volume, and mass scores

PURPOSE

To retrospectively evaluate the effect of a small variation of scan starting position on coronary artery calcium scores based on nonoverlapping 3-mm multidetector computed tomographic (CT) data sets.

MATERIALS AND METHODS

Informed consent and institutional review board approval were obtained. A retrospective study was performed by using prospective unenhanced electrocardiographically triggered cardiac multidetector CT scans in 228 women (mean age, 67 years +/- 5 [standard deviation]). From the original 1.5-mm data set, two sets of adjacent images with a section thickness of 3 mm and a variation in starting point of 1.5 mm were obtained. Calcium scoring was performed to acquire Agatston, volume, and mass scores. Subjects were assigned to one of five risk categories (I-V) according to the Agatston score of each 3-mm data set and the average score. Kappa value was calculated to assess agreement in risk category assignment. Differences and relative differences between scores obtained for both 3-mm data sets were calculated overall and according to risk category. The effect of scoring algorithm on the relative differences between scores was analyzed with the Wilcoxon signed rank test.

RESULTS

Categories I-V contained 102, 35, 48, 31, and 12 subjects, respectively. For all scoring algorithms, median relative differences decreased from more than 130% in category II to less than 10% in category V. In the three highest categories, relative differences were significantly smaller for volume and mass scores than for Agatston scores (P < .05). Twenty-one subjects were assigned to different risk categories between the two data sets (kappa = 0.87). Eleven patients were assigned a nonzero score in one and a zero score in the other data set.

CONCLUSION

A small variation in scan starting position can substantially influence calcium measurements and poses an inherent limit to calcium scoring with contiguous 3-mm sections. Mass and volume scores are slightly less affected than are Agatston scores.

Frequency of coronary artery calcification on low-dose computed tomography screening for lung cancer

PURPOSE

The purpose of this study was to determine the frequency of coronary artery calcification (CAC) in high-risk people undergoing computed tomography (CT) screening for lung cancer.

METHODS

Between 1999 and 2004, we performed CT screening for lung cancer on 4250 participants, all without documented prior cardiovascular disease, using multidetector-row (MD) CT. Of the patients, 1102 underwent imaging with a four-detector-row CT at 120 kVp and 40 mA, with pitch 1.5 and collimation of 2.5 mm in a single breath hold of 15-20 seconds, and 3148 did with an eight-detector-row CT at the same kVp, mA, and pitch settings but with collimation of 1.25 mm. Visualized CACs in each coronary artery (main, left anterior descending, circumflex, and right) were scored separately as 0 (absent), 1 (mild), 2 (moderate), or 3 (severe), yielding a possible score of 0-12 for each person. Frequency distributions by gender, age, and pack-years of smoking were determined. Odds ratios (ORs) were calculated using logistic regression analysis of the prevalence of CAC as a joint function of gender, age, pack-years of smoking, and presence of diabetes.

RESULTS

Among the subjects younger than 50 years, positive CAC scores were three times more frequent for men than for women (22% vs. 7%); among those older than 50 years, the frequency increased for both men and women but the increase for women was greater than that for men. The frequency of positive CAC scores increased with increasing pack-years of smoking; it was always higher for men than for women. The ORs were 2.6 for male gender (P<.0001), 3.7 and 9.6 for ages 60-69 years and 70 years or older, respectively, for increasing age (P<.0001 for both), 1.6 and 2.3 for 30-59 pack-years and 60 pack-years or longer, respectively, for increasing pack-years of smoking (P<.0001 for both), and 1.6 for having diabetes (P=.016).

CONCLUSION

The CAC score can be derived from ungated low-dose MDCT images. This information can contribute to risk stratification and management of coronary artery disease.

Relationship Between Aortic Calcification and Stroke in a Mass Screening Program Using a Mobile Helical Computed Tomography Unit

BACKGROUND

It is reported that there is a significant relationship between the calcification of the aortic arch detected by chest X-ray examination and stroke. However, the relationship between stroke and aortic calcification (AoC) detected during a mass screening using a mobile helical computed tomography (CT) unit remains unknown.

METHODS AND RESULTS

The study population consisted of 2,618 subjects (1,345 men, and 1,273 women; mean age, 52.9+/-13.8 years) who participated in a mass CT screening for lung cancer and tuberculosis. In the present study, 28 subjects (18 men, and 10 women; mean age, 65.9+/-13.5 years) had a past history of cerebral infarction. There were no subjects with a past history of intracerebral or subarachnoid hemorrhage. The frequency of AoC was significantly higher in the infarction group who were older than 50 years of age. In logistic regression analysis, the AoC was a stronger contributor of infarction than sex, age, and risk factors. Furthermore, the odds ratio of AoC for subjects with a past history of infarction increased as the number of calcified segments increased, and these values were 1.82 (95% confidence interval (CI) 1.06-3.15) in men, and 2.53 (95% CI 1.12-5.75) in women.

CONCLUSIONS

These results suggest that detection of AoC during mass chest screening using a mobile helical CT unit is an effective way to evaluate the risk of cerebral infarction.

Usefulness of helical computed tomography in detection of mitral annular calcification as a marker of coronary artery disease

BACKGROUND

Mitral annulus calcification (MAC) may be a form of atherosclerosis. The goal of the present work was to investigate whether helical CT can determine the presence of MAC and to clarify its possible association with coronary artery disease (CAD) in elderly patients.

DESIGN AND METHODS

Three hundred and twenty-nine consecutive elderly patients (165 men and 164 women, age range 60-79 years) underwent double helical CT of the heart to determine MAC and coronary calcifications (CC) according to a previously described protocol.

RESULTS

MAC was documented in 60 patients (25 men, 35 women; mean age 69 +/- 4.5 years, range 60-78 years). The non-MAC group (control) included 269 patients (140 men, 129 women; mean age 67 +/- 4.6 years, range 60-79 years). Age was the only risk factor which had significant association with MAC (p = 0.01). A significant difference was found between MAC and control group for mean total CC score and advanced CC (total CC > 300) (323 +/- 565 vs. 184 +/- 429, p = 0.033 and 30% vs. 16%, p = 0.017, respectively). A significant difference was also found between groups for the prevalent proven CAD (30% vs. 16%, p = 0.008). Stepwise logistic regression analysis identified age [odds ratio (OR) 3.3, 95% confidence interval (CI) 1.7-6.4, p < 0.001)], gender (male) (OR 3.1, 95% CI 1.6-6.0, p = 0.001), and MAC (OR 2.4, 95% CI 1.2-5.0, p = 0.016) as the independent variables significantly associated with CAD. The independent variables significantly associated with advanced CC (TCS > 300) were MAC (OR 2.6, 95% CI 1.3-5.2, p = 0.005), gender (male) (OR 2.3, 95% CI 1.2-4.2, p = 0.012) and age (OR 1.9, 95% CI 1.0-3.7, p = 0.052).

CONCLUSIONS

Our study demonstrated the usefulness of helical computed tomography in the detection of mitral annular calcification as an additional marker of prevalent CAD. However, the diagnostic significance of the MAC detection is relatively minor and should not be considered as a direct proof for coronary atherosclerosis.

Update on using coronary calcium screening by computed tomography to measure risk for coronary heart disease

Coronary artery disease (CAD) is the number one killer of adults in the United States, claiming one-half million deaths annually. Early detection and prevention strategies clearly remain a top priority for health care providers in order to reduce the high mortality rate of heart disease. As an unequivocal reflection of arteriosclerosis, coronary arterial calcium (CAC) may provide a means to qualitatively assess the overall disease severity and likewise serve as a means to assess risk for CHD. It is known that patients with heavy calcium burdens have more advanced CAD, a concomitantly a higher likelihood of coronary stenoses, and a concomitant higher risk for acute cardiac events. Computed tomography has been shown to be an accurate, non-invasive method to quantify coronary calcification burden in patients. Evidence shows that calcium measurements by CT correlate well with histological plaque analyses, and that CAC measurements accurately reflect disease severity and can be useful to assess individual risk for CHD. The purpose of this article is to summarize the currently available evidence that has attempted to validate CAC screening as a screening exam and risk predictor for coronary heart disease.

Coronary Artery Stenoses: Detection with Calcium Scoring, CT Angiography, and Both Methods Combined

PURPOSE

To investigate prospectively the relative accuracy of computed tomographic (CT) angiography, calcium scoring (CS), and both methods combined in demonstrating coronary artery stenoses by using conventional angiography as the reference standard.

MATERIALS AND METHODS

The study was approved by the institutional review board Human Research Ethics Committee, and all patients completed written informed consent. Fifty patients (40 men, 10 women) aged 62 years +/- 11 (+/- standard deviation) who were suspected of having coronary artery disease underwent both conventional coronary angiography and multisection coronary CT angiography with CS. Sensitivity and specificity of CS, CT angiography, and both methods combined in demonstrating luminal stenosis greater than or equal to 50% were determined for each arterial segment, coronary vessel, and patient. Receiver operating characteristic (ROC) curves were generated for CS prediction of significant stenosis, and the Mann-Whitney U test was used for comparison of CS between groups.

RESULTS

When used with segment-specific electrocardiographic phase reconstructions, CT angiography demonstrated stenosed segments with 79% sensitivity and 95% specificity. Mean calcium score was greater in segments, vessels, and patients with stenoses than in segments, vessels, and patients without stenoses (P < .001 for all); nine (16%) of 56 stenosed segments, however, had a calcium score of 0. The patient calcium score correlated strongly with the number of stenosed arteries (Spearman rho = 0.75, P < .001). CS was more accurate in demonstrating stenosis in patients than in segments (areas under ROC curve were 0.88 and 0.74, respectively). CT angiography, however, was more accurate than CS in demonstrating stenosis in patients, vessels, and segments. The sensitivity and specificity of CS varied according to the threshold used, but when the calcium score cutoff (ie, >150) matched the specificity of CT angiography (95%), the sensitivity of CS in demonstrating stenosed segments was 29% (compared with 79% for CT angiography). Combining CT angiography with CS (at threshold of 400) improved the sensitivity of CT angiography (from 93% to 100%) in demonstrating significant coronary disease in patients, without a loss of specificity (85%); this finding, however, was not statistically significant.

CONCLUSION

CT angiography is more accurate than CS in demonstrating coronary stenoses. A patient calcium score of greater than or equal to 400, however, can be used to potentially identify patients with significant coronary stenoses not detected at CT angiography.

Carotid bifurcation calcium and correlation with percent stenosis of the internal carotid artery on CT angiography

The aim of this paper was to determine the correlation between calcium burden (expressed as a volume) and extent of stenosis of the origin of the internal carotid artery (ICA) by CT angiography (CTA). Previous studies have shown that calcification in the coronary arteries correlates with significant vessel stenosis, and severe calcification (measured by CT) in the carotid siphon correlates with significant (greater than 50% stenosis) as determined angiographically. Sixty-one patients (age range 50-85 years) underwent CT of the neck with intravenous administration of iodinated contrast for a variety of conditions. Images were obtained with a helical multidetector array CT scanner and reviewed on a three-dimensional workstation. A single observer manipulated window and level to segment calcified plaque from vascular enhancement in order to quantify vascular calcium volume (cc) in the region of the bifurcation of the common carotid artery/ICA origin, and to measure the extent of ICA stenosis near the origin. A total of 117 common carotid artery bifurcations were reviewed. A "significant" stenosis was defined arbitrarily as >40% (to detect lesions before they become hemodynamically significant) of luminal diameter on CTA using NASCET-like criteria. All "significant" stenoses (21 out of 117 carotid bifurcations) had measurable calcium. We found a relatively strong correlation between percent stenosis and the calcium volume (Pearson's r = 0.65, P<0.0001). We also found that there was an even stronger correlation between the square root of the calcium volume and the percent stenosis as measured by CTA (r= 0.77, P<0.0001). Calcium volumes of 0.01, 0.03, 0.06, 0.09 and 0.12 cc were used as thresholds to evaluate for a "significant" stenosis. A receiver operating characteristic (ROC) curve demonstrated that thresholds of 0.06 cc (sensitivity 88%, specificity 87%) and 0.03 cc (sensitivity 94%, specificity 76%) generated the best combinations of sensitivity and specificity. Hence, this preliminary study demonstrates a relatively strong relationship between volume of calcium at the carotid bifurcation in the neck (measured by CT) and percent stenosis of the ICA below the skull base (as measured by CTA). Use of calcium volume measurements as a threshold may be both sensitive and specific for the detection of significant ICA stenosis. The significance of the correlation between calcium volume and ICA stenosis is that potentially a "score" can be obtained that will identify those at risk for high grade carotid stenosis.

Spiral computed tomography evidence of close correlation between coronary and thoracic aorta calcifications

Coronary calcium (CC) is invariably associated with coronary atherosclerosis and can be diagnosed noninvasively by fast spiral computed tomography (dual slice mode) (CT). Calcium is often deposited in the aorta as well, but the pathogenesis, correlates and clinical implications of calcification of the aorta are not yet elucidated. A possible association between the presence of CC and thoracic aorta calcification, as detected by spiral CT, has not been investigated yet. The goal of the present work was to examine by spiral CT whether an association exists between the presence of CC and thoracic aorta calcification in patients with high risk for atherosclerotic development. Four hundred and five patients with at least two risk factors for atherosclerosis were included (212 men and 193 women, age ranged 52-79 years). All underwent chest CT for CC and aortic calcification scoring. Calcifications' thickness of > or =5 mm was considered advanced. CC was documented in 294 patients (170 men, 124 women; mean age 66 +/- 6 years, range 55-78 years). The non-CC group (control) included 111 patients (42 men, 69 women; mean age 64 +/- 6 years, range 52-79 years). Significant differences were found between CC group and control for the presence of ascending aorta calcification (69% versus 36%, P < 0.001), and advanced calcification of > or =5mm (17% versus 4%, P < 0.001). Significant differences were also found between groups regarding the presence of descending aorta calcification (60% versus 38%, P < 0.001), and number of consecutive slices with calcification (18.8 +/- 12.4 versus 10.7 +/- 8.7, P < 0.01). We identified age (in decades) (OR 1.9, 95% CI 1. 2-3.0, P < 0.001), gender (female) (OR 0.4, 95% CI 0.2-0.6, P < 0.001), and thoracic aorta calcification (OR 2.9, 95% CI 1.7-5.0, P < 0.001) as the independent variables significantly associated with CC. Only age [odds ratio (OR) 3.05, 95% confidence interval (CI) 1.86-5.01, P < 0.001] and CC (OR 2.53, 95% CI 1.26-5.08, P = 0.006) were identified as independent variables for the prediction of thoracic aorta calcification.

CONCLUSIONS

Our study demonstrated a strong association of CC and calcification of the thoracic aorta on spiral CT.

Coronary calcium by spiral computed tomography predicts cardiovascular events in high-risk hypertensive patients

OBJECTIVE

The ability of coronary artery calcium (CAC) to predict coronary events has been shown in several studies. We aimed to investigate the hypothesis that CAC as assessed by dual slice spiral computed tomography (DSCT), is an independent risk factor for cardiovascular events in hypertensive patients.

METHODS

We followed 446 participants of INSIGHT (International Nifedipine Study Intervention as Goal for Hypertension Therapy) calcification study, for the incidence of cardiovascular events as a function of CAC and other factors. All were hypertensive, without coronary artery disease (CAD), ages > 55 years and with at least one more major cardiovascular risk factor. All underwent a baseline DSCT and were followed for a mean period of 3.8 +/- 0.4 years. All events were documented while the scheduled visits and confirmed by the INSIGHT critical event committee.

RESULTS

Follow-up was conducted on all participants. 294 patients (66%) had CAC at baseline. Forty-seven patients experienced a first cardiovascular event: acute myocardial infarction (MI), 16; sudden cardiac death, two; unstable angina resulting in revascularization, 14; stroke, 15. The incidence of first cardiovascular events was 3.7 times higher among those who had CAC at baseline than among those who had no CAC (14.5% (41 of 294) versus 3.9% (6 of 152)). Patients who experienced an event were more likely to be males, had had higher prevalence of peripheral vascular disease, longer duration of hypertension, and had higher levels of systolic blood pressure (SBP), glucose, creatinine and uric acid. Adjusting for these covariates, CAC (total coronary calcium score (TCS) > 0) independently predicted cardiovascular events with an odds ratio (OR) of 2.76 [95% confidence interval (CI) 1.09-6.99, P = 0.032].

CONCLUSION

The presence of CAC predicts cardiovascular events in high-risk asymptomatic hypertensive patients.

Accelerated Progression of Coronary Calcification: Four-year Follow-up in Patients with Stable Coronary Artery Disease

PURPOSE

To prospectively assess the 4-year progression rate of coronary artery calcium (CAC) in patients with clinically stable coronary artery disease (CAD) with multi-detector row computed tomography (CT).

MATERIALS AND METHODS

The study group consisted of 382 consecutive patients. All underwent baseline dual-sector spiral CT, and CT was repeated at 2 and 4 years later. Progression of CAC was assessed with measurement of the increase in total calcium score (TCS) and with repeated-measures analysis and multivariate linear regression models. Logistic regression model was used to predict incidence of new lesions.

RESULTS

Eighty-seven percent (333 of 382) of the study group were men, with mean age of 65 years +/- 11, and 13% (49 of 382) were women, with mean age of 68 years +/- 11. The average TCS increased after 4 years by sixfold from baseline in the 1st quartile, and by four-, two- and 1.5-fold in the 2nd, 3rd, and 4th quartiles of baseline TCS (P <.01), respectively. Multiple linear regression analysis included age; sex; natural logarithm of baseline TCS; history of hypertension, diabetes mellitus, current smoking, hypercholesterolemia, and lipid-lowering therapy with cholesterol synthesis enzyme inhibitor (statin); and family history of premature CAD. Results demonstrated that natural logarithm of baseline TCS and history of current smoking were independent predictors of the 4th-year natural logarithm of TCS levels (R(2) = 0.85, P <.001). New lesions were diagnosed in 56 (15%) patients. History of statin therapy (odds ratio = 0.35; 95% confidence interval [CI]: 0.16, 0.77; P <.01), age with an increment of 5 years (odds ratio = 0.76; 95% CI: 0.64, 0.90; P =.01), and natural logarithm of baseline TCS (odds ratio = 0.73; 95% CI: 0.62, 0.86; P <.01) were independent predictors for new calcific lesions during 4 years.

CONCLUSION

Accelerated progression of CAC during 4 years was found in clinically stable patients with CAD.

Coronary Artery Calcium Scoring Using 16-MDCT and a Retrospective ECG-Gating Reconstruction Algorithm

OBJECTIVE

Our aim was to compare detection, quantification, and cardiovascular risk stratification of coronary artery calcium (CAC) between electron beam CT and 16-MDCT with retrospective reconstruction. SUBJECTS AND METHODS. One hundred patients underwent both electron beam CT and 16-MDCT, and coronary artery calcium score, volume, and mass were obtained.

RESULTS

Correlation between the two CT scanners was high for both calcium score (r(2) = 0.955), volume (r(2) = 0.952), and mass (r(2) = 0.977). Although electron beam CT is viewed as the gold standard, the sensitivity and specificity in the detection of CAC using 16-MDCT with a threshold of 130 H were 98.7% and 100%, respectively. The variability of calcium scores between the two CT scanners (26.5%) was comparable with two electron beam CT scanners reported previously. The variability of calcium volume (20.7%) and mass (20.3%) was lower than that of the score (Student's t test, r = 0.05, 0.01). In clinical cardiovascular risk stratification based on two CT calcium scores, the Cohen's kappa value was 0.929. There was no significant difference between the two scanners using Wilcoxon's signed rank test (p = 0.157).

CONCLUSION

The 16-MDCT scanner with retrospective reconstruction, showing high agreement for detection and quantification of CAC with electron beam CT, holds promise in the detection of coronary artery atherosclerosis.

Coronary artery calcium quantification at multi-detector row helical CT versus electron-beam CT

PURPOSE

To compare coronary artery calcium scores from a multi-detector row helical computed tomographic (CT) scanner with those from an electron-beam CT scanner, with emphasis on subjects with calcium scores less than 400.

MATERIALS AND METHODS

Seventy-eight asymptomatic subjects (37 women, 41 men; age range, 39-78 years; mean age, 54.2 years) underwent multi-detector row CT and electron-beam CT. Volume and Agatston scores were calculated with a workstation. Statistical analyses included assessment of association between calcium scores from two scanners, calculation of percent absolute difference to assess score variability between scanners, equivalence analysis, construction of Bland-Altman plots to assess agreement between scores, and assessment of changes in score grouping and risk criteria based on score differences between scanners.

RESULTS

Electron-beam CT calcium scores were higher than multi-detector row CT scores. Linear association between calcium scores obtained from paired scans was significant (r = 0.96-0.99, P <.001). Mean percent absolute differences were 67.9% and 65.0% for volume and Agatston scores, respectively (48.6% and 46.3% for corresponding natural log-transformed scores). In subjects with a score of 11 or greater, mean percent absolute differences between electron-beam CT and multi-detector row CT scores ranged from 15% to 30% (<10% for natural log-transformed calcium scores). With a 20% equivalence limit, calcium scores from the two scanners were statistically equivalent (P <.05). Score grouping would have been subject to change in 12 (11 increased and one decreased; six with scores of 11 or greater), and possible risk management decisions would have been subject to change in eight (16%) of 51 subjects who underwent electron-beam CT versus multi-detector row CT scanning.

CONCLUSION

Multi-detector row CT appears to be comparable to electron-beam CT for coronary calcification screening, except in subjects with a calcium score less than 11.

Coronary Artery Calcification Scoring by Prospectively Triggered Multidetector-Row Computed Tomography

The objective of this study was to measure the interobserver and interscan variation of coronary artery calcium scores using multidetector-row computed tomography (MDCT). Seventy-five patients underwent 2 sequential MDCT scans for coronary artery calcification. Each patient's score was separately measured by 3-blinded radiologists. Scores were treated as discrete and continuous data, and independent statistical analysis was performed on all results. There was a high proportion of interscan and inter-reader concordance for the presence of coronary calcium (range, 0.893-0.973) and for its quantity (range, 0.936-0.988). Overall, prospectively triggered multidetector-row calcium scoring is reproducible though there is more variation in those patients with already high scores. There is no need to scan patients twice at the same sitting.

Imaging of coronary calcification by computed tomography

As an unequivocal biomarker for arteriosclerosis, the presence of coronary calcium serves as a qualitative reflection of the severity of coronary artery disease (CAD). Greater calcium burdens correlate with more advanced disease, a higher likelihood of coronary stenoses, and a higher risk for coronary heart disease (CHD). Empirically, the quantification of coronary calcium not only provides an accurate reflection of disease severity, but also has great potential as a screening tool for CHD. Computed tomography (CT) has been shown to be capable of providing accurate, noninvasive measurements of coronary calcification. Evidence shows that calcium measurements by CT correlate well with histological plaque analyses, and that calcium burdens accurately reflect disease severity and can be used to assess individual risk for CHD. The purpose of this review article is to examine the accumulated evidence that has attempted to validate CT as a diagnostic tool for CAD and as a screening exam for CHD.

Assessment of Coronary Artery Calcification in Hemodialysis Patients Using Multi-Detector Spiral CT Scan

Cardiovascular disease in association with coronary artery calcification (CAC) is the leading cause of death in patients with end-stage renal disease (ESRD). The evaluation of CAC has been performed by electron beam CT scan. The purpose of the present study was to assess CAC using multi-detector spiral CT (MDCT) and to evaluate contributors to CAC in these patients. Fifty-three patients on chronic hemodialysis participated in this study. Their mean age was 61.0+/-9.6 years, and the mean duration of dialysis therapy was 6.7+/-5.4 years. We used an automatic device to measure arterial pulse wave velocity (PWV) as an index of arterial wall stiffness. The aortic calcification index (ACI) was quantified morphometrically by CT scan. The CAC score correlated positively with ACI score (r =0.863, p <0.0001). Linear regression analysis indicated that the CAC scores correlated positively with age (r =0.406, p =0.0023), C-reactive protein (r =0.38, p =0.0047) and PWV (r =0.303, p =0.0271). Stepwise regression analysis indicated that ACI (beta-coefficient=0.862, p <0.0001) and arterial PWV (beta-coefficient=0.303, p <0.0001) were independently associated with CAC score. The mean CAC score of patients with cardiac events (2,568.5+/-2,575.1 mm3) was significantly higher than that (258.0+/-409.2 mm3) of patients without cardiac events. In conclusion, our results showed clearly that assessment of CAC score using MDCT may be predictive for detecting the presence of coronary artery disease. CAC is indirectly associated with increased arterial stiffness and the extent of aortic calcification in hemodialysis patients. We did not find a significant correlation between CAC score and parameters of mineral metabolism, including serum levels of calcium, phosphorus and parathyroid hormone. A longitudinal prospective study is required to assess the predictive value of this technique in determining cardiac events in large numbers of hemodialysis patients.

Accelerated coronary artery calcification in mildly reduced renal function of high-risk hypertensives

OBJECTIVE

To examine the effect of mild renal dysfunction on coronary artery calcifications.

METHODS

We examined the progression of coronary atherosclerosis, as measured by dual-section spiral computed tomography, using the total coronary artery calcium score as a quantitative measure of the burden of atherosclerosis. Of 547 high-risk Israeli hypertensive patients, who were participants of the prospective calcification study (a side-arm of the international INSIGHT study), 313 patients completed the 3-year follow-up. Subjects were studied upon entry (on placebo) and again after 3 years of treatment (nifedipine or thiazide). Patients were divided into two groups depending on their creatinine clearance: (i) </= 60 ml/min, renal dysfunction (RD) (n = 53) and (ii) > 60 ml/min, normal renal function group (n = 263).

RESULTS

Blood pressure, hypercholesterolemia, and smoking did not differ between the groups. After 3 years of treatment, blood pressure control was similar, whereas the total coronary artery calcium score progression was two-fold greater in the RD than the normal group (156 +/- 32 versus 64 +/- 8, respectively) (P = 0.006). In a multiple logistic regression analysis, the odds ratio (OR) for total coronary artery calcium score progression was higher for the RD group (2.1) [95% confidence interval (CI) 1.2-3.7]. Gender, body mass index, smoking, cholesterol, family history of ischaemic heart disease and diabetes were not significant predictors. Thiazide-based antihypertensive therapy predicted a faster progression compared to nifedipine (OR 1.66, 95% CI 1.09-2.51).

CONCLUSIONS

Mild renal dysfunction accelerates coronary artery calcifications, above and beyond conventional risk factors.