The incidence of coronary artery calcification on standard thoracic CT scans

Prevalence and clinical implications of coronary artery calcium scoring on non-gated thoracic computed tomography: a systematic review and meta-analysis

OBJECTIVES

Coronary artery calcifications (CACs) indicate the presence of coronary artery disease. CAC can be found on thoracic computed tomography (CT) conducted for non-cardiac reasons. This systematic review and meta-analysis of non-gated thoracic CT aims to assess the clinical impact and prevalence of CAC.

METHODS

Online databases were searched for articles assessing prevalence, demographic characteristics, accuracy and prognosis of incidental CAC on non-gated thoracic CT. Meta-analysis was performed using a random effects model.

RESULTS

A total of 108 studies (113,406 patients) were included (38% female). Prevalence of CAC ranged from 2.7 to 100% (pooled prevalence 52%, 95% confidence interval [CI] 46-58%). Patients with CAC were older (pooled standardised mean difference 0.88, 95% CI 0.65-1.11, p < 0.001), and more likely to be male (pooled odds ratio [OR] 1.95, 95% CI 1.55-2.45, p < 0.001), with diabetes (pooled OR 2.63, 95% CI 1.95-3.54, p < 0.001), hypercholesterolaemia (pooled OR 2.28, 95% CI 1.33-3.93, p < 0.01) and hypertension (pooled OR 3.89, 95% CI 2.26-6.70, p < 0.001), but not higher body mass index or smoking. Non-gated CT assessment of CAC had excellent agreement with electrocardiogram-gated CT (pooled correlation coefficient 0.96, 95% CI 0.92-0.98, p < 0.001). In 51,582 patients, followed-up for 51.6 ± 27.4 months, patients with CAC had increased all cause mortality (pooled relative risk [RR] 2.13, 95% CI 1.57-2.90, p = 0.004) and major adverse cardiovascular events (pooled RR 2.91, 95% CI 2.26-3.93, p < 0.001). When CAC was present on CT, it was reported in between 18.6% and 93% of reports.

CONCLUSION

CAC is a common, but underreported, finding on non-gated CT with important prognostic implications.

CLINICAL RELEVANCE STATEMENT

Coronary artery calcium is an important prognostic indicator of cardiovascular disease. It can be assessed on non-gated thoracic CT and is a commonly underreported finding. This represents a significant population where there is a potential missed opportunity for lifestyle modification recommendations and preventative therapies. This study aims to highlight the importance of reporting incidental coronary artery calcium on non-gated thoracic CT.

KEY POINTS

• Coronary artery calcification is a common finding on non-gated thoracic CT and can be reliably identified compared to gated-CT. • Coronary artery calcification on thoracic CT is associated with an increased risk of all cause mortality and major adverse cardiovascsular events. • Coronary artery calcification is frequently not reported on non-gated thoracic CT.

Utility of routine non-gated CT chest in detection of subclinical atherosclerotic calcifications of coronary arteries in hospitalised HIV patients

OBJECTIVES

To evaluate coronary artery calcification (CAC) on routine CT chest in hospitalised HIV patients and to assess individual risk factors.

METHODS

Routine CT chests, May 2010-November 2015, of 143 hospitalised HIV-positive patients were reviewed for qualitative assessment of calcification in major coronary arteries by two radiologists. Presence, location and burden of calcification were evaluated on 3 mm axial images of CT chest. Cardiovascular risk factors and HIV lab parameters such as CD4 count, viral load and duration, and status of antiretroviral treatment were collected. Statistical analysis including multivariate logistic regression was performed.

RESULTS

Forty-one patients (28.7%) showed CAC, left anterior descending (n = 38, 92.7%), circumflex (n = 18, 43.9%) and Right Coronary Artery (n = 13, 31.7%); mostly mild CAC burden and mostly proximal left coronary arteries with excellent interobserver and intraobserver agreements (K = 0.9, and 1). Age of CAC+ group (53.9 years) was significantly higher than CAC- group (43.4, p < 0.001, minimum age of CAC+, 27 years). No significant difference between two groups in sex, ethnicity and risk factors and HAART status. CAC+ group showed significantly longer HIV duration (12.3 years vs 8.6, p < 0.0344) and higher CD4 cell counts (mean = 355.9 vs 175.3, p = 0.0053) and significantly lower viral load (76 vs 414K, p = 0.02) than CAC- group. On multivariate logistic regression, age, HIV duration and CD4 were significantly associated with CAC+ (p-values < .05).

CONCLUSIONS

One-third of hospitalised HIV patients showed subclinical CAC on CT chest. HIV duration and age of patients were independent risk factors for developing CAC. Higher CD4 cell count was strongly associated with CAC+.

ADVANCES IN KNOWLEDGE

Routine CT chest with or without contrast performed for non-cardiac indications is helpful in identification of subclinical CAC in HIV patients and radiologists should be encouraged to report CAC.CAC is seen in younger age group in HIV, and awareness of this finding on routine CT chest would help guiding clinicians to assess risk stratification for primary prevention of ischemic heart disease in this population at an earlier stage when compared to normal population.Duration of HIV infection and age of patients were independent risk factors for developing CAC in our study and CD4 count was strongly associated with presence of CAC.

Mandatory Reporting of Coronary Artery Calcifications Incidentally Noted on Chest Multi-Detector Computed Tomography: A Multicentre Experience

BACKGROUND

Coronary Artery Calcifications (CACs) are associated with coronary atherosclerosis and Cardiovascular (CV) events. In "non-cardiovascular" settings, CACs can be easily detected on chest Multi-Detector Computed Tomography (MDCT). Their evaluation may help to better stratify CV risk in the general population, especially for primary prevention.

AIMS

We retrospectively evaluated the relationship between CAC distribution and CV risk, determined by Framingham Risk Score (FRS), in a cohort of patients who underwent chest MDCT performed for several clinical indications.

METHOD

We retrospectively recruited 305 patients (194 men, 111 women; mean age 70.5 years) from 3 different Italian centres. Patients with coronary stent, pacemaker and/or CV devices were excluded from the study. Circumflex Artery (LCX), Left Main Coronary Artery (LMCA), left Anterior Descending artery (LAD) and right coronary artery (RCA) were analysed.

RESULTS

From a total population of 305 patients, 119 (39%) had low FRS (<10%), 115 (38%) had intermediate FRS (10-20%), and 71 (23%) had high FRS (>20%). The study identified 842 CACs located in decreasing order as follows: RCA (34.5%), LAD (32.3%), LCX (28%) and LMCA (13%). Statistical two-step analysis subdivided patients into two clusters according to FRS (risk threshold = 12.38%): cluster I (mean 9.34) and cluster II (mean 15.09). A significant association between CAC distribution and cluster II was demonstrated. CACs were mostly detected in patients with intermediate FRS. All patients (100%) with the highest CV risk showed intermediate RCA and LMCA involvement.

CONCLUSION

Radiologists can note the distribution of CACs on a chest MDCT and should mandatorily record them in their reports. Depending on CAC presence and location, these findings may have important clinical implications, mostly in asymptomatic patients with intermediate FRS. This information may reclassify a patients' CV risk and improve clinical management.

Using coronary artery calcification combined with pretest clinical risk assessment as a means of determining investigation and treatment in patients presenting with chest pain in a rural setting

462 patients presenting with chest pain to a rural district general hospital underwent calcium scoring and pretest clinical risk assessment in order to stratify subsequent investigations and treatment was retrospectively reviewed. The patients were followed up for two years and further investigations and outcomes recorded. Of the 206 patients with zero calcium score, 132 patients were immediately discharged from cardiac follow-up with no further investigation on the basis of their calcium score, low pretest risk of coronary artery disease, and no significant incidental findings. After further tests, 267 patients were discharged with no further cardiac therapy, 88 patients were discharged with additional medical therapy, and 19 patients underwent coronary artery by-pass grafting or percutaneous intervention. 164 patients with incidental findings on the chest CT (computed tomography) accompanying calcium scoring were reviewed, of which 88 patients underwent further tests and follow-up for noncardiac causes of chest pain. The correlations between all major risk factors and calcium scores were weak except for a combination of diabetes and hypertension in the male gender (P = 0.012), The use of calcium scoring and pretest risk appeared to reduce the number of unnecessary cardiac investigations in our patients: however, the calcium scoring test produced a high number of incidental findings on the associated CT scans.

Common incidental findings on MDCT: survey of radiologist recommendations for patient management

PURPOSE

The aim of this study was to evaluate for agreement with respect to how radiologists report incidental findings encountered on CT.

METHODS

A multiple-choice survey was designed to query radiologists about how they handle 12 incidental findings on body CT, assuming the patient is a 45-year-old woman with no history of malignancy. Included were a 1-cm thyroid nodule, a 5-mm noncalcified lung nodule, coronary artery calcification, a 2-cm adrenal nodule, a 2-cm pancreatic cyst, a 1-cm enhancing liver lesion, a 2-cm high-density renal cyst, short-segment small bowel intussusception, a 1-cm splenic cyst, focal gallbladder wall calcification, and a 3-cm ovarian cyst in both a premenopausal woman and a postmenopausal woman. Choices ranged from "do not report" to advising interventional procedures tailored to the organ. Surveys were administered to body CT attending radiologists at 3 academic institutions.

RESULTS

Twenty-seven radiologists completed the survey. The mean experience level was 15.7 years after training. Seventy percent or greater agreement on interpretation was identified for only 6 findings: recommend ultrasound for a 1-cm thyroid nodule, recommend ultrasound for a 3-cm cyst in postmenopausal woman, follow Fleischner Society recommendations for a 5-mm lung nodule, describe only coronary calcification, and describe as likely benign both short-segment small bowel intussusception and a 1-cm splenic cyst.

CONCLUSIONS

Agreement is lacking, both across institutions and within departments, for the management of 6 commonly encountered incidental findings on body CT. Individual departments should develop internal guidelines to ensure consistent recommendations based on existing evidence.

Arterial calcifications

Arterial calcifications as found with various imaging techniques, like plain X-ray, computed tomography or ultrasound are associated with increased cardiovascular risk. The prevalence of arterial calcification increases with age and is stimulated by several common cardiovascular risk factors. In this review, the clinical importance of arterial calcification and the currently known proteins involved are discussed. Arterial calcification is the result of a complex interplay between stimulating (bone morphogenetic protein type 2 [BMP-2], RANKL) and inhibitory (matrix Gla protein, BMP-7, osteoprotegerin, fetuin-A, osteopontin) proteins. Vascular calcification is especially prevalent and related to adverse outcome in patients with renal insufficiency and diabetes mellitus. We address the special circumstances and mechanisms in these patient groups. Treatment and prevention of arterial calcification is possible by the use of specific drugs. However, it remains to be proven that reduction of vascular calcification in itself leads to a reduced cardiovascular risk.

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.

Incidental internal carotid artery calcifications on temporal bone CT in children

BACKGROUND

Incidental internal carotid artery (ICA) calcifications are occasionally noted on CT images of the brain and temporal bone. In adults, incidental calcifications have been correlated with increased incidence of hypercholesterolemia, cardiac disease, diabetes and carotid stenosis.

OBJECTIVE

To determine the incidence of incidental calcifications of the carotid siphon on temporal bone CT in children.

MATERIALS AND METHODS

We retrospectively reviewed 24 months of consecutive temporal bone CT examinations in children aged 18 years and younger. CT examinations on 663 patients were reviewed and the presence or absence of ICA calcifications was ranked as absent, questionable or definitive. In patients in whom definitive calcifications were identified, hospital charts were reviewed for evidence of diabetes mellitus, hypercholesterolemia, hypertriglyceridemia, hyperlipidemia and chronic renal disease as potential causes of early atherosclerosis.

RESULTS

Of the 663 patients, 25% had definitive calcifications within the wall of the ICA: 6% of children younger than 2 years and 28% of children 12-19 years of age.

CONCLUSIONS

Incidentally noted ICA calcifications are a common finding on temporal bone CT in children, most likely a physiologic response to turbulent flow at natural bends in the artery rather than secondary to underlying disease predisposing to early atherosclerotic calcification.

Incidental findings computed tomography of the thorax

Numerous findings incidental to the stated indication for obtaining a computed tomogram (CT) of the chest are encountered. While some findings are life threatening (eg, pulmonary embolism), others are clearly benign (pulmonary hamartoma, vertebral hemangioma). This article discusses management issues related to the detection of unexpected findings in different compartments of the thorax. In the future, more detailed outcome data will be available to better guide medical decision-making.

Impact of genetic defects on coronary atherosclerosis in patients suspected of having familial hypercholesterolaemia

BACKGROUND

In the present study we assessed whether the presence of genetic mutations typical of familial hypercholesterolaemia (FH) was associated with greater atherosclerosis in the coronary vessels in patients with severe hypercholesterolaemia and a family history of early cardiovascular disease.

MATERIALS AND METHODS

Two hundred and thirty-five patients selected for having severe hypercholesterolaemia and a family history of cardiovascular disease were classified as FH (57 men and 38 women) or non-FH (84 men and 56 women) according to a genetic analysis of the LDL-R or ApoB genes. Coronary atherosclerosis was evaluated by performing a thoracic CT scan and exercise stress testing.

RESULTS

Familial hypercholesterolaemia individuals had a significantly higher prevalence of coronary calcification than the non-FH patients from among both the men (OR = 3.90; 95% CI 1.86-8.19; P < 0.001) and the women (OR = 2.34; 95% CI 1.01-5.48; P = 0.05). In exercise stress testing, ECG abnormalities suggestive of cardiac ischaemia were found with a higher prevalence in the FH patients than the non-FH patients from among both the men (OR 6.15; 95% CI 2.16-17.5; P < 0.001) and the women (OR 4.76; 95% CI 0.91-24.6; P = 0.06). All differences were statistically significant after adjusting for age and cholesterol and for most classical risk factors that differed between the FH and non-FH groups.

CONCLUSION

Among patients with severe hypercholesterolaemia and a family history of early cardiovascular disease, the presence of a genetically ascertained FH is associated with a higher prevalence of coronary artery calcifications and a positive exercise stress test. These results suggest that despite a similar phenotype, patients carrying mutations suggestive of FH may have a greater cardiovascular risk than patients without these mutations.

Comparison of spiral and electron beam tomography in the evaluation of coronary calcification in asymptomatic persons

Recently, investigators have begun evaluating the ability of spiral computed tomography (sequence scan mode-SEQ) to measure coronary calcium. Electron Beam Tomography (EBT) and SEQ studies were performed in 10 women and 23 men, with a mean age of 54+/-9 years. The EBT study was performed within 4 weeks (mean 11+/-4 days) of the SEQ with no clinical interval event (MI, revascularization). The mean EBT calcium score (Agatston method) was 52.1+/-58.6, with a range of 0 to 175. The SEQ mean score was 60.1+/-71.1 (range 0 to 253). There were 7 persons with scores of 0 on both scans, and 9 persons with scores of zero on either EBT or spiral CT, but not both. Three persons had negative EBT studies where SEQ detected calcium, and 6 persons had EBT detected calcium and negative SEQ studies. The six patients with negative SEQ and positive EBT studies had a mean score of 47+/-25.7 (range 9 to 99). The remaining sixteen persons had coronary calcium detected on both studies. As compared to EBT, spiral CT had a sensitivity of 74% and a specificity of 70%, for an overall diagnostic accuracy of 73%. The positive and negative predictive values were 85 and 54%, respectively for SEQ in this study. The absolute difference in scores between the two tests was 29.1+/-28.5 (mean+/-S.D.). The inter-test variability, defined as the mean values of the differences between the calcium scores in the two scans on the same subjects divided by the mean of the two scores (Absolute Difference between tests/mean), was 84.5% in this study. In asymptomatic persons, spiral CT (using SEQ) provides a limited sensitivity (74%) and specificity (70%) for coronary calcium when compared to EBT. Caution should be used when evaluating the results of spiral CT coronary calcium especially in patients with relatively low calcium scores (<200).

Preview method for electron-beam CT scanning of the coronary arteries

RATIONALE AND OBJECTIVES

The purpose of this study was to evaluate a method that uses electron-beam computed tomography to obtain the most appropriate starting level for complete imaging of the coronary tree and to compare it with the existing method. A second aim was to evaluate the spatial location of the coronary arteries relative to different anatomic cardiac and chest landmarks.

MATERIALS AND METHODS

Two hundred forty consecutive patients were randomly assigned to imaging with either a six-level preview (new) method or the traditional preview method. The accuracy of each preview method to encompass the coronary anatomy was compared.

RESULTS

All coronary arteries were included in 3-mm scans obtained starting three levels above the origin of the left main coronary artery. The left anterior descending coronary artery extended 3-9 mm above the left main artery in 33 patients (14%). The coronary arteries were encompassed by scans depicting 72-105 mm; thus, with 3-mm sections, up to 35 scans are necessary to cover the entire coronary tree. No stable relationship between the coronary arteries and the pulmonary artery or carina could be found.

CONCLUSION

The six-level preview method that identifies the left main coronary artery and begins 9 mm above this level is the most accurate method for depicting the coronary anatomy. No anatomic landmarks in the heart or chest can be used reliably to identify the position of the coronary arteries in individual patients.

Helical and single-slice conventional CT versus electron beam CT for the quantification of coronary artery calcification

OBJECTIVE

We compared electron beam CT with conventional CT to determine the best method for the assessment of the coronary calcium score. We used conventional CT to examine symptomatic and asymptomatic patients suspected of having coronary artery disease.

SUBJECTS AND METHODS

One hundred sixty male patients underwent electron beam CT and helical CT with a pitch of 1 (n = 30) and 2 (n = 30) and using a single-slice mode with (n = 50) and without (n = 50) prospective ECG triggering. In another 50 patients, we determined reproducibility for repeated scanning using electron beam CT. For all images, we derived the calcium score according to the Agatston method. We performed regression analysis and determined mean variability. Mean variability was calculated as the ratio of the absolute difference to the mean of the corresponding calcium scores.

RESULTS

The correlation coefficients for electron beam CT and all conventional CT modes were very high (range, 0.93-0.98). The mean variability was highest in the helical mode with a pitch of 2 (61.4%) and lowest for the single-slice mode with prospective ECG triggering (25.4%). For repeated electron beam CT, the correlation coefficient and mean variability were 0.99 and 22.1%, respectively.

CONCLUSION

ECG-triggered single-slice conventional CT had the best agreement with electron beam CT calcium scores.

Imaging of coronary artery calcification. Its importance in assessing atherosclerotic disease

Coronary artery calcification is a marker for atherosclerotic disease. The calcifications frequently occur early in the disease process and often before the development of luminal narrowing or cardiac events. Electron beam CT has a high accuracy in detecting calcifications, and thus has prognostic value in predicting luminal narrowing and future cardiac events.