Clinical usefulness of multidetector-row CT to evaluate coronary artery calcium score in type 2 diabetes

PURPOSE: According to recent studies, multidetector-row CT (MDCT) with a retrospective ECG-gating reconstruction algorithm shows a high correlation with coronary artery calcium score determined using electron-beam CT. Diabetes leads to many macrovascular complications, including coronary artery disease. The aim of this study was to evaluate risk factors for cardiac macroangiopathy in type 2 diabetes using MDCT. MATERIALS AND METHODS: An observational cross-sectional study was performed in 90 patients with diabetes mellitus. Coronary calcium data was acquired by MDCT (SOMATOM Volume Zoom, Siemens AG, Medical Solutions, Germany). Physical examinations, laboratory data, glycemic control, and control of other risk factors were analyzed. RESULTS: The coronary artery calcium score increased with age. Multivariant analysis revealed that the coronary calcium score was closely correlated with electrocardiogram evaluation and control of hypertension. CONCLUSIONS: Coronary artery calcium score as determined by MDCT can be used as a screening radiological examination for cardiac macroangiopathy in diabetes patients with electrocardiogram abnormality and hypertension.     

Selective use of coronary calcification measurements in an expanded intermediate risk group

Risk assessment is an imperative initial step in the clinical management of cardiovascular risk factors. On the basis of the estimation of the 10-year absolute risk of manifesting coronary heart disease (myocardial infarction or coronary heart disease death), risk categories are conventionally divided into low, intermediate, and high. The most widely used quantitative risk assessment algorithm, the Framingham risk score for hard events, is based on traditional risk factors, but it does not fully account for all available cardiovascular risk factors. Current national guidelines defining coronary heart disease risk categories based on the Framingham risk score may inaccurately assign persons with a high burden of subclinical coronary atherosclerosis to a low-risk group (<10% risk), failing to predict the true risk of a cardiovascular event. Coronary artery calcification as a measure of subclinical atherosclerosis has already established itself as a useful adjunct for refining the broad intermediate risk category of adults, leading to more decisive management strategies. In a point-counterpoint format this article argues for the improved accuracy of coronary calcium scoring in predicting the risk of future cardiac events in persons with a low Framingham risk score (including women and different ethnic groups). To better incorporate recent scientific findings into cardiovascular assessment and to refine stratification in those with a low Framingham risk score, we therefore propose a timely algorithm supporting coronary calcium screening in a selected group of low-risk persons.     

Coronary calcium scanning independently detects coronary artery disease in asymptomatic firefighters: A prospective study

BackgroundSudden cardiac death is the leading cause of death among firefighters in the United States. Fire departments commonly maintain physical examination protocols, often with exercise stress testing, to detect risk of coronary heart disease.ObjectiveWe sought to determine whether coronary calcium detected by electron beam computed tomography (EBCT) adds incremental risk stratification beyond the traditional risk factors in asymptomatic community-based firefighters.MethodsThree hundred ninety nine asymptomatic firefighters underwent a coronary calcium scan on a GE/Imatron C-150 Ultrafast EBCT scanner, using standardized imaging protocols. Framingham risk factor data were obtained on each patient by using a questionnaire. Agatston scores were derived and compared with national database of Agatston scores for asymptomatic populations on the basis of age and sex, allowing determination of a calcium percentile for each score.ResultsCoronary calcium was found only in men >34 years of age. Of the 53% who had positive scans (Agatston score > 0), 87% had higher than average Agatston scores compared with a national database (P < 0.01). Agatston score above the 75th percentile was found in 57% of firefighters. No correlation was observed between traditional risk factors and those with and without coronary calcium.ConclusionsFirefighters have a high burden of calcified coronary atherosclerosis, greater than anticipated on the basis of age and coronary risk factors.     

Estimation of cardiac event risk by MDCT

Coronary calcifications are specific markers for coronary atherosclerosis. The amount of coronary calcium is related to the likelihood of vulnerable plaques. Vulnerable plaques may rupture and may result in sudden coronary thrombus formation, occlusion, ischemia and ventricular fibrillation and finally cardiac death. Therefore, it is reasonable to believe that the risk of cardiac events can be assessed by the quantification of the extent of coronary calcium. However, until now, the predictive value of coronary calcium and the advantage over conventional risk factors has not yet been proven by any prospective cohort study. In practice uncertainty exists in the group of patients with an intermediate risk for cardiac events. In this particular cohort it is likely that the assessment of coronary atherosclerosis may help in the decision to initiate or discard a specific therapy. For this purpose it has been suggested to replace the Framingham age score by a score corrected by the amount of coronary calcium. Follow-up investigations may be helpful in the short term to determine the efficiency of different therapeutical options. To determine a significant progression of the amount of coronary calcium, the absolute mass should be determined in a period of 1 year.     

Prognostic value of CT-derived left atrial and left ventricular measures in patients with acute chest pain

PurposeTo determine which left atrial (LA) and left ventricular (LV) parameters are associated with future major adverse cardiac event (MACE) and whether these measurements have independent prognostic value beyond risk factors and computed tomography (CT)-derived coronary artery disease measures.Materials and methodsThis retrospective analysis was performed under an IRB waiver and in HIPAA compliance. Subjects underwent coronary CT angiography (CCTA) using a dual-source CT system for acute chest pain evaluation. LV mass, LV ejection fraction (EF), LV end-systolic volume (ESV) and LV end-diastolic volume (EDV), LA ESV and LA diameter, septal wall thickness and cardiac chamber diameters were measured. MACE was defined as cardiac death, non-fatal myocardial infarction, unstable angina, or late revascularization. The association between cardiac CT measures and the occurrence of MACE was quantified using Cox proportional hazard analysis.Results225 subjects (age, 56.2 ± 11.2; 140 males) were analyzed, of whom 42 (18.7%) experienced a MACE during a median follow-up of 13 months. LA diameter (HR:1.07, 95%CI:1.01–1.13 per mm) and LV mass (HR:1.05, 95%CI:1.00–1.10 per g) remained significant prognostic factor of MACE after controlling for Framingham risk score. LA diameter and LV mass were also found to have prognostic value independent of each other. The other morphologic and functional cardiac measures were no significant prognostic factors for MACE.ConclusionCT-derived LA diameter and LV mass are associated with future MACE in patients undergoing evaluation for chest pain, and portend independent prognostic value beyond traditional risk factors, coronary calcium score, and obstructive coronary artery disease.     

High-pitch dual-source CT for coronary artery calcium scoring: A head-to-head comparison of non-triggered chest versus triggered cardiac acquisition

BackgroundTo determine the effect of low-dose, high-pitch non-electrocardiographic (ECG)-triggered chest CT on coronary artery calcium (CAC) detection, quantification and risk stratification, compared to ECG-triggered cardiac CT.MethodsWe selected 1,000 participants from the ImaLife study, 50% with coronary calcification on cardiac CT. All participants underwent non-contrast cardiac CT followed by chest CT using third-generation dual-source technology. Reconstruction settings were equal for both acquisitions. CAC scores were determined by Agatston's method, and divided dichotomously (0, >0), and into risk categories (0, 1–99, 100–399, ≥400). We investigated the influence of heart rate and body mass index (BMI) on risk reclassification.ResultsPositive CAC scores on cardiac CT ranged from 1 to 6926 (median 39). Compared to cardiac CT, chest CT had sensitivity of 0.96 (95%CI 0.94–0.98) and specificity of 0.99 (95%CI 0.97–0.99) for CAC detection (κ = 0.95). In participants with coronary calcification on cardiac CT, CAC score on chest CT was lower than on cardiac CT (median 30 versus 40, p?0.001). Agreement in CAC-based risk strata was excellent (weighted κ = 0.95). Sixty-five cases (6.5%) were reclassified by one risk category in chest CT, with fifty-five (84.6%) shifting downward. Higher BMI resulted in higher reclassification rate (13% for BMI ≥30 versus 5.2% for BMI <30, p = 0.001), but there was no effect of heart rate.ConclusionLow-dose, high-pitch chest CT, using third-generation dual-source technology shows almost perfect agreement with cardiac CT in CAC detection and risk stratification. However, low-dose chest CT mainly underestimates the CAC score as compared to cardiac CT, and results in inaccurate risk categorization in BMI ≥30.     

Risk stratification of non-contrast CT beyond the coronary calcium scan

Coronary artery calcification (CAC) is a well-known marker for coronary artery disease and has important prognostic implications. CAC is able to provide clinicians with a reliable source of information related to cardiovascular atherosclerosis, which carries incremental information beyond Framingham risk. However, non-contrast scans of the heart provide additional information beyond the Agatston score. These studies are also able to measure various sources of fat, including intrathoracic (eg, pericardial or epicardial) and hepatic, both of which are thought to be metabolically active and linked to increased incidence of subclinical atherosclerosis as well as increased prevalence of type 2  diabetes. Testing for CAC is also useful in identifying extracoronary sources of calcification. Specifically, aortic valve calcification, mitral annular calcification, and thoracic aortic calcium (TAC) provide additional risk stratification information for cardiovascular events. Finally, scanning for CAC is able to evaluate myocardial scaring due to myocardial infarcts, which may also add incremental prognostic information. To ensure the benefits outweigh the risks of a scanning for CAC for an appropriately selected asymptomatic patient, the full utility of the scan should be realized. This review describes the current state of the art interpretation of non-contrast cardiac CT, which clinically should go well beyond coronary artery Agatston scoring alone.     

Assessment of cardiovascular risk status at CT colonography

PURPOSE: To retrospectively determine whether calcium scores of the abdominal aorta obtained during computed tomographic (CT) colonography relate to Framingham risk factors and clinical cardiac events. MATERIALS AND METHODS: The institutional review board approved the current HIPAA-compliant retrospective study and waived informed consent. Between 1995 and 1998, 480 patients underwent CT colonography; 467 patients were available for assessment. Calcium scores with a threshold attenuation value of 130 HU or greater were recorded for abdominal aorta (suprarenal, infrarenal, and aortic bifurcation regions and total). Patient histories were abstracted for established cardiac risk factors and subsequent cardiac events. Associations between calcium measurements and binary risk factors were assessed with Wilcoxon rank sum test; those with continuous risk factors, with Spearman rank correlation coefficient; and those with combined end points, with Cox proportional hazards model. RESULTS: Follow-up data were available for 467 patients with median age of 65 years (range, 34-83 years); 59% (275 of 467) were men. Nine patients had cardiac events subsequent to CT colonography. Results of proportional hazards regression analysis revealed a significant association between myocardial infarction or cardiac event-related death and calcium scores of the aortic bifurcation that exceeded 895, the value for the 75th percentile for this calcium variable (P < .01). Associations with established cardiac risk factors for all four calcium scores were significant (P < .05). Spearman rank correlation coefficients for associations between total calcium score and patient characteristics of age, number of pack-years of smoking, and systolic blood pressure were 0.51, 0.43, and 0.29, respectively (P < .001 for all). CONCLUSION: Aortic calcification scores at CT colonography are significantly associated with established cardiac risk factors and cardiac-related events. This screening information can be obtained without additional scanning or risk to the patient.     

Fully Automatic Coronary Calcium Score Software Empowered by Artificial Intelligence Technology: Validation Study Using Three CT Cohorts

ObjectiveThis study aimed to validate a deep learning-based fully automatic calcium scoring (coronary artery calcium [CAC]_auto) system using previously published cardiac computed tomography (CT) cohort data with the manually segmented coronary calcium scoring (CAC_hand) system as the reference standard.Materials and MethodsWe developed the CAC_auto system using 100 co-registered, non-enhanced and contrast-enhanced CT scans. For the validation of the CAC_auto system, three previously published CT cohorts (n = 2985) were chosen to represent different clinical scenarios (i.e., 2647 asymptomatic, 220 symptomatic, 118 valve disease) and four CT models. The performance of the CAC_auto system in detecting coronary calcium was determined. The reliability of the system in measuring the Agatston score as compared with CAC_hand was also evaluated per vessel and per patient using intraclass correlation coefficients (ICCs) and Bland-Altman analysis. The agreement between CAC_auto and CAC_hand based on the cardiovascular risk stratification categories (Agatston score: 0, 1–10, 11–100, 101–400, > 400) was evaluated.ResultsIn 2985 patients, 6218 coronary calcium lesions were identified using CAC_hand. The per-lesion sensitivity and false-positive rate of the CAC_auto system in detecting coronary calcium were 93.3% (5800 of 6218) and 0.11 false-positive lesions per patient, respectively. The CAC_auto system, in measuring the Agatston score, yielded ICCs of 0.99 for all the vessels (left main 0.91, left anterior descending 0.99, left circumflex 0.96, right coronary 0.99). The limits of agreement between CAC_auto and CAC_hand were 1.6 ± 52.2. The linearly weighted kappa value for the Agatston score categorization was 0.94. The main causes of false-positive results were image noise (29.1%, 97/333 lesions), aortic wall calcification (25.5%, 85/333 lesions), and pericardial calcification (24.3%, 81/333 lesions).ConclusionThe atlas-based CAC_auto empowered by deep learning provided accurate calcium score measurement as compared with manual method and risk category classification, which could potentially streamline CAC imaging workflows.     

Influence of a small field-of-view size on the detection of coronary artery calcifications with MSCT: in vitro and in vivo study

The purpose of this study is to asses the impact of small field-of-view (FOV) sizes on the detection of coronary artery calcifications using multislice-spiral computed tomography (MSCT). First, a static chest phantom containing calcium inserts was scanned 10 times using a standardized scan protocol. Secondly, 50 patients (28 male, 63.6±10.6 years) underwent cardiac MSCT using the same protocol. Images were reconstructed with three different FOV sizes (180×180, 220×220, 380×380 mm²). Coronary calcium scoring and risk stratification were performed for each image series. In the phantom study, the Agatston score calculated with a FOV size of 180×180 mm² was 657.80±20.05. At a FOV of 220×220 mm² and 380×380 mm², the corresponding values were 657.04±21.36 and 655.04±20.74, respectively. The corresponding values in the patient study were 541.65±869.87, 541.91±872.57 and 536.61±867.81. No statistically significant differences in the calcium score were found comparing different FOV sizes. Significantly more lesions (p=0.00149) were detected in the patient study. Comparing the different FOV sizes of 180×180 mm² and 220×220 mm² (380×380 mm²), four (six) patients had to be assigned to different risk groups. The use of small FOV sizes resulted in an improved detection of coronary calcifications influencing the risk stratification for further cardiac events in MSCT coronary calcium scoring.     

CT低剂量技术在冠状动脉钙化积分检查中的应用现状与新进展

冠状动脉钙化积分(CACS)是无创性评估心血管风险分层及冠心病发生、发展和预后的一项重要指标,可以辅助临床治疗策略的选择制定。遵从辐射防护最优化原则(ALARA),可以采用直接方法(降低管电流、管电压,自动管电流调制技术)、间接方法(大螺距、迭代重建技术),以及直接在冠状动脉CT血管成像、双能CT虚拟平扫和非心电门控胸部CT平扫影像上测量CACS,从而降低该检查辐射剂量,并可准确、可重复地测量CACS,进行心血管风险分层。     

Coronary calcium score as gatekeeper for 64-slice computed tomography coronary angiography in patients with chest pain: per-segment and per-patient analysis

We sought to investigate the performance of 64-slice CT in symptomatic patients with different coronary calcium scores. Two hundred patients undergoing 64-slice CT coronary angiography for suspected coronary artery disease were enrolled into five groups based on Agatston calcium score using the Mayo Clinic risk stratification: group 1: score 0, group 2: score 1–10, group 3: score 11–100, group 4: score 101–400, and group 5: score > 401. Diagnostic accuracy for the detection of significant (≥50% lumen reduction) coronary artery stenosis was assessed on a per-segment and per-patient base using quantitative coronary angiography as the gold standard. For groups 1 through 5, sensitivity was 97, 96, 91, 90, 92%, and specificity was 99, 98, 96, 88, 90%, respectively, on a per-segment basis. On a per-patient basis, the best diagnostic performance was obtained in group 1 (sensitivity 100% and specificity 100%) and group 5 (sensitivity 95% and specificity 100%). Progressively higher coronary calcium levels affect diagnostic accuracy of CT coronary angiography, decreasing sensitivity and specificity on a per-segment base. On a per-patient base, the best results in terms of diagnostic accuracy were obtained in the populations with very low and very high cardiovascular risk. Authors have no financial conflict of interest. Neither this paper nor any of its content has not been submitted to other journals.     

Association of pericardial fat volume with coronary atherosclerotic disease assessed by CT angiography

Objective:

To investigate the association of pericardial fat volume (PFV) with coronary artery disease (CAD) in patients with intermediate pre-test probability of ischaemic heart disease assessed by coronary CT angiography.

Methods:

From a total of 115 consecutive Iraqi patients who underwent 64-multislice multidetector CT angiography examinations, only 74 patients (females, 38% and males, 68%) with a mean age of 54 ± 8 years were found to be eligible for statistical analysis. The patients were divided into two groups according to the median value of PFV (above and below 100 ml).

Results:

The median value of PFV in our study was 100 ml (range, 17–319 ml). A significant association was observed between high PFV and significant coronary artery stenosis (p = 0.005), between high PFV and significant left circumflex stenosis (p = 0.021) and between high PFV and the presence of coronary plaque (p = 0.005). Whereas there was no significant correlation between high PFV and coronary calcium score (p = 0.188), between high PFV and number of diseased coronary vessels (p > 0.3), and between high PFV and body weight and body mass index.

Conclusion:

Increased PFV is strongly associated with the presence and severity of CAD.

Advances in knowledge:

Our study highlights the role of pericardial fat as an emerging biomarker in cardiovascular risk assessment and supports its association with the magnitude of CAD.Pericardial fat is an adipose tissue surrounding the heart, with anatomic proximity to the epicardial coronary arteries. Several studies^1–5 show growing evidence that pericardial adipose tissue may be associated with increased left ventricular mass, metabolic syndrome, endothelial dysfunction, insulin resistance and the presence of coronary artery disease (CAD) via local secretion of numerous pro-inflammatory hormones and cytokines.Coronary CT angiography is a non-invasive method that has been used for cardiovascular risk stratification based on the presence and severity of coronary calcium and atherosclerotic plaque with a reported sensitivity of 94–95% and specificity of 82%. Pericardial fat volume (PFV) can be assessed by direct measurement that depends on the detection of the thin pericardium or as a component of heart-level thoracic fat volume.^6,7Pericardial fat has been found to have a higher lipolysis and lipogenesis activity than that of other fat tissues with a strong correlation between PFV and triglyceride concentration in the myocardium.⁸Furthermore, recent data have shown that PFV assessed by CT angiography is significantly associated with severe coronary stenosis, plaque burden even in asymptomatic individuals, high-risk plaque features and an increased risk of future cardiac events.^9–11The aim of this study was to investigate the association of PFV with CAD, cardiac risk factors and calcium scoring index in patients with an intermediate pre-test probability of ischaemic heart disease assessed by coronary CT angiography.     

CT of coronary artery disease

The socioeconomic importance of heart disease provides considerable motivation for development of radiologic tools for noninvasive imaging of the coronary arteries. Current computed tomographic (CT) techniques combine high speed and spatial resolution with sophisticated electrocardiographic synchronization and robustness of use. Application of these modalities for evaluation of coronary artery disease is a topic of active current research. Coronary artery calcium measurements with different CT techniques have been used for determining the risk of coronary events, but the exact role of this marker for cardiac risk stratification remains unclear pending results of population-based studies. Contrast material-enhanced CT coronary angiography has become an established clinical indication for some scenarios (eg, coronary artery anomalies, bypass patency, surgical planning). With current technology, the accuracy of CT coronary angiography for detection of coronary artery stenoses appears promising enough to warrant pursuit of this application, but sensitivity is still not high enough for routine diagnostic needs. The high negative predictive value of a normal CT coronary angiogram, however, may be useful for reliable exclusion of coronary artery stenosis. The cross-sectional nature of CT may allow noninvasive assessment of the coronary artery wall. Use of contrast-enhanced CT coronary angiography for detection, characterization, and quantification of atherosclerotic changes and total disease burden in coronary arteries as a potential tool for cardiac risk stratification is currently being investigated.     

Prognostic outcome of routine clinical noninvasive multidetector-row computed tomography coronary angiography in patients with suspected coronary artery disease: a 2-year follow-up study

Purpose

The aim of the study was to assess the prognostic value of multidetector-row CT coronary angiography (MDCT-CA) in patients with suspected coronary artery disease (CAD) in a routine clinical context.

Materials and methods

A total of 125 patients (82 men, age 57.4±10.3 years) with suspected CAD underwent MDCT-CA. All patients were assessed for cardiovascular risk factors, symptoms and coronary calcium score. A 2-year follow-up study for the occurrence of major adverse cardiac events was performed.

Results

According to the Morise pretest score, 76 patients (60.8%) were at intermediate risk. Patients with suspected CAD presented the following prognostic outcome (p<0.0001): in 41 patients with normal coronary arteries at MDCT-CA, the event rate was 0%; five of 49 patients with nonobstructive CAD had major cardiac events; two of 35 patients with obstructive CAD suffered cardiac death and 19 underwent revascularisation. At multivariate analysis, the presence of obstructive CAD is the only significant independent prognostic variable (hazard ratio, 10.1393; 95% confidence interval 3.2189?C31.9379; p<0.0001).

Conclusions

Routine clinical MDCT-CA provides an excellent prognostic value at 2-year follow-up in patients with normal coronary arteries. The cardiac event rate increases with CAD severity.     

Multidetector-row CT of the heart

Despite worldwide efforts aimed at primary and secondary prevention, heart disease is still the leading cause of death in the western world. There is great interest in developing tools for noninvasive assessment of the presence and degree of coronary artery disease. The advent of multidetector-row CT allows high-resolution volume coverage of the entire thorax and motion-free imaging of the heart and adjacent vessels within one breathhold. An exciting application with significant potential for cardiac risk stratification, which may overcome the obvious limitations of coronary calcium imaging in the future, is the use of the cross-sectional nature of contrast-enhanced multidetector-row CT coronary angiography for assessment of total coronary artery plaque burden.     

Current Roles and Future Applications of Cardiac CT: Risk Stratification of Coronary Artery Disease

Cardiac computed tomography (CT) has emerged as a noninvasive modality for the assessment of coronary artery disease (CAD), and has been rapidly integrated into clinical cares. CT has changed the traditional risk stratification based on clinical risk to image-based identification of patient risk. Cardiac CT, including coronary artery calcium score and coronary CT angiography, can provide prognostic information and is expected to improve risk stratification of CAD. Currently used conventional cardiac CT, provides accurate anatomic information but not functional significance of CAD, and it may not be sufficient to guide treatments such as revascularization. Recently, myocardial CT perfusion imaging, intracoronary luminal attenuation gradient, and CT-derived computed fractional flow reserve were developed to combine anatomical and functional data. Although at present, the diagnostic and prognostic value of these novel technologies needs to be evaluated further, it is expected that all-in-one cardiac CT can guide treatment and improve patient outcomes in the near future.     

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.     

Practical tips and tricks in cardiovascular computed tomography: Non-contrast “heartscans”—beyond the calcium score

The Agatston total coronary artery calcium (CAC) score, derived from a non-contrast CT scan of the heart (also known as the “heartscan”) in asymptomatic and symptomatic patients, has been shown to provide incremental and independent assessment to conventional risk factors based upon literally hundreds of studies published from around the world. However, recent data have emerged to indicate that there is additional information which can be derived from a “heartscan” beyond the calcium score. These include recent data on the applicability across ethnic sub-groups, prognostication in the elderly, defining “heart age” versus chronological age for individual risk stratification, evaluating CAC distribution in addition to total CAC score, and looking beyond the coronary arteries regarding left ventricular size, arotic root/thoracic aorta diameter, and epicardial fat.     

Coronary artery calcium score on low-dose computed tomography for lung cancer screening

AIM: To evaluate the feasibility of coronary artery calcium score (CACS) on low-dose non-gated chest CT (ngCCT).METHODS: Sixty consecutive individuals (30 males; 73 ± 7 years) scheduled for risk stratification by means of unenhanced ECG-triggered cardiac computed tomography (gCCT) underwent additional unenhanced ngCCT. All CT scans were performed on a 64-slice CT scanner (Somatom Sensation 64 Cardiac, Siemens, Germany). CACS was calculated using conventional methods/scores (Volume, Mass, Agatston) as previously described in literature. The CACS value obtained were compared. The Mayo Clinic classification was used to stratify cardiovascular risk based on Agatston CACS. Differences and correlations between the two methods were compared. A P-value < 0.05 was considered significant.RESULTS: Mean CACS values were significantly higher for gCCT as compared to ngCCT (Volume: 418 ± 747 vs 332 ± 597; Mass: 89 ± 151 vs 78 ± 141; Agatston: 481 ± 854 vs 428 ± 776; P < 0.05). The correlation between the two values was always very high (Volume: r = 0.95; Mass: r = 0.97; Agatston: r = 0.98). Of the 6 patients with 0 Agatston score on gCCT, 2 (33%) showed an Agatston score > 0 in the ngCCT. Of the 3 patients with 1-10 Agatston score on gCCT, 1 (33%) showed an Agatston score of 0 in the ngCCT. Overall, 23 (38%) patients were reclassified in a different cardiovascular risk category, mostly (18/23; 78%) shifting to a lower risk in the ngCCT. The estimated radiation dose was significantly higher for gCCT (DLP 115.8 ± 50.7 vs 83.8 ± 16.3; Effective dose 1.6 ± 0.7 mSv vs 1.2 ± 0.2 mSv; P < 0.01).CONCLUSION: CACS assessment is feasible on ngCCT; the variability of CACS values and the associated re-stratification of patients in cardiovascular risk groups should be taken into account.