Name: identifying coronary artery calcification on non-gated computed tomography scans
Uploaded: 2018-08-28T13:30:00
Description: Watch this Scientific Journal Video about Identifying Coronary Artery Calcification on Non-gated Computed Tomography Scans at JoVE.com

This work was supported by the National Institutes of Health [1TL1TR001997-01, 2016-2017].

This protocol follows guidelines set forth by the Institutional Review Board and human subject research protocol of the University of Kentucky.
1. Opening the Image Viewer
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	<li>Open the image viewer used at the institution where the research is being conducted. Double-click on the desktop icon to open the viewer.</li>
	<li>Log in using an institutional username and password.</li>
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2. Identifying the Appropriate Patient
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	<li>Click on the Study ...

<ol>
	<li>Douglas, P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Outcomes+of+anatomical+versus+function+testing+for+coronary+artery+disease.">Outcomes of anatomical versus function testing for coronary artery disease.</a> The New England Journal of Medicine. 372 (14), 1291-1300 (2015).</li><li>Detrano, R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Coronary+calcium+as+a+predictor+of+coronary+events+in+four+racial+or+ethnic+groups.">Coronary calcium as a predictor of coronary events in four racial or ethnic groups.</a> The New England Journal of Medicine. 358, 1336-1345 (2008).</li><li>Sarma, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Radiation+and+chest+CT+scan+examinations:+what+do+we+know.">Radiation and chest CT scan examinations: what do we know.</a> CHEST. 142, 750-760 (2012).</li><li>Winkler, M. 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J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Coronary+artery+and+thoracic+calcium+on+noncontrast+thoracic+CT+scans:+comparison+of+ungated+and+gated+examinations+in+patients+from+the+COPD+Gene+cohort.">Coronary artery and thoracic calcium on noncontrast thoracic CT scans: comparison of ungated and gated examinations in patients from the COPD Gene cohort.</a> Journal of Cardiovascular Computed Tomography. 5, 113-118 (2011).</li><li>Einstein, A. 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American Journal of Roentgenology. 190, 917-922 (2008).</li><li>Kirsch, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Detection+of+coronary+calcium+during+standard+chest+computed+tomography+correlates+with+multi-detector+computed+tomography+coronary+artery+calcium+score.">Detection of coronary calcium during standard chest computed tomography correlates with multi-detector computed tomography coronary artery calcium score.</a> The International Journal of Cardiovascular Imaging. 28, 1249-1256 (2012).</li><li>Wu, M. T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Coronary+arterial+calcification+on+low-dose+ungated+MDCT+for+lung+cancer+screening:+concordance+study+with+dedicated+cardiac+CT.">Coronary arterial calcification on low-dose ungated MDCT for lung cancer screening: concordance study with dedicated cardiac CT.</a> AJR. American Journal of Roentgenology. 190, 923-928 (2008).</li><li>Xie, X., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Validation+and+prognosis+of+coronary+artery+calcium+scoring+in+non-triggered+thoracic+computed+tomography:+systematic+review+and+meta-analysis.">Validation and prognosis of coronary artery calcium scoring in non-triggered thoracic computed tomography: systematic review and meta-analysis.</a> Circulation: Cardiovascular Imaging. 6, 514-521 (2013).</li><li>Itani, Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Coronary+artery+calcification+detected+by+a+mobile+helical+computed+tomography+unit+and+future+cardiovascular+death:+4-year+follow-up+of+6120+asymptomatic+Japanese.">Coronary artery calcification detected by a mobile helical computed tomography unit and future cardiovascular death: 4-year follow-up of 6120 asymptomatic Japanese.</a> Heart and Vessels. 19, 161-163 (2004).</li><li>Hughes-Austin, J. M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Relationship+of+coronary+calcium+on+standard+chest+CT+scans+with+mortality.">Relationship of coronary calcium on standard chest CT scans with mortality.</a> JACC: Cardiovascular Imaging. 9, 152-159 (2016).</li><li>Shemesh, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ordinal+scoring+of+coronary+artery+calcifications+on+low-dose+CT+scans+of+the+chest+is+predictive+of+death+from+cardiovascular+disease.">Ordinal scoring of coronary artery calcifications on low-dose CT scans of the chest is predictive of death from cardiovascular disease.</a> Radiology. 257, 541-548 (2010).</li><li>Sarwar, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Diagnostic+and+prognostic+value+of+absence+of+coronary+artery+calcification.">Diagnostic and prognostic value of absence of coronary artery calcification.</a> JACC: Cardiovascular Imaging. 2, 675-688 (2009).</li><li>Gupta, V. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Coronary+artery+calcification+predicts+cardiovascular+complications+after+sepsis.">Coronary artery calcification predicts cardiovascular complications after sepsis.</a> Journal of Critical Care. 44, 261-266 (2017).</li><li>Takx, R. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Automated+coronary+artery+calcification+scoring+in+non-gated+chest+CT:+agreement+and+reliability.">Automated coronary artery calcification scoring in non-gated chest CT: agreement and reliability.</a> PLoS One. 9 (3), 91239 (2014).</li><li>Hecht, H. S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=2016+SCCT/STR+guidelines+for+coronary+artery+calcium+scoring+of+noncontrast+noncardiac+chest+CT+scans:+A+report+of+the+Society+of+Cardiovascular+Computed+Tomography+and+Society+of+Thoracic+Radiology.">2016 SCCT/STR guidelines for coronary artery calcium scoring of noncontrast noncardiac chest CT scans: A report of the Society of Cardiovascular Computed Tomography and Society of Thoracic Radiology.</a> Journal of Cardiovascular Computed Tomography. 11 (1), 74-84 (2016).</li><li>Erbel, R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Progression+of+coronary+artery+calcification+seems+to+be+inevitable,+but+predictable+-+results+of+the+Heinz+Nixdorf+recall+(HNR)+study.">Progression of coronary artery calcification seems to be inevitable, but predictable - results of the Heinz Nixdorf recall (HNR) study.</a> European Heart Journal. 35 (42), 2960-2971 (2014).</li><li>Blaha, M. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Improving+the+CAC+score+by+addition+of+regional+measures+of+calcium+distribution.">Improving the CAC score by addition of regional measures of calcium distribution.</a> JACC: Cardiovascular Imaging. 9, 1407-1416 (2016).</li></ol>

The identification of CAC is an extremely powerful prognostic tool with an ever-growing body of literature supporting its use in many different clinical scenarios. The majority of the literature is focused on gated cardiac CT scans for the identification of CAC, but there is robust evidence of both the correlation of CAC on non-gated CT scans, as well as the prognostic ability of this finding. Given the CT scan utilization in the United States, as well as the ever-growing concerns about radiation exposure, the ability to...

Coronary artery disease is a predictor of major adverse cardiovascular events. CAC on CT scans provides objective evidence of coronary artery disease and may identify previously undiagnosed patients. In addition, CAC has a significant prognostic value. Specifically, the absence of CAC on gated cardiac CT scans identifies a patient population that has a low risk for subsequent cardiovascular events in many different subsets of patients, including patients presenting with cardiac symptoms, as well as asymptomatic patients1,2. With ~70 million CT scans performed in the United States and the usage rising, and approximately 11 - 12 million of those scans being CT scans of the chest, the potential for identification of CAC in a large number of patients remains high3. However, the majority of the CT scans of the chest performed in that analysis are not dedicated cardiac CT scans. Dedicated cardiac CT scans have standardized slice thickness, acquisition protocols, electrocardiographic (ECG) gating to minimize cardiac motion, and reconstruction protocols. There is also a standardized quantitation for gated cardiac CT scans using the Agatston score. The Agatston scoring system has been well validated and associated with clinical outcomes1,2.
CAC can be readily identified on these non-gated CT scans but is often overlooked4. Good correlation has been demonstrated between CAC identified on non-gated CT scans and Agatston scores obtained from gated CT scans (&#62; 90% in pooled analysis)5,6,7,8,9,10. In non-gated CT scans, the presence of CAC has been associated with worse clinical outcomes; whereas, the absence is linked to morbidity and mortality benefits10,11,12,13,14,15.
While different studies have looked at the prognosis of CAC on non-gated studies, there has been limited published data on how best to identify CAC. There have been attempts to identify an automated approach to the identification of CAC in low-dose CT chests scans done for lung cancer screening purposes; however, the translation of this to other study protocols is extremely limited16. The introduction of differential CT scanners, protocols, and contrast (both timing and amount) limits the application of this automated approach. Attempts by the Society of Cardiovascular Computed Tomography and the Society of Thoracic Radiology to promote the standard reporting of CAC on all CT chests have been met with mixed results17. While offering a general framework in this guideline document, the specifics of the identification of coronary calcification, especially for providers who do not routinely visualize coronary anatomy, are limited. Also, strategies specific to abdominal CT scans, contrasted studies, and adjudicating challenging cases are not addressed. Many studies publish their own inter- and intra-observer reproducibility for the protocol they used; however, there is not a standard approach used across different studies.
The ability to consistently and reliably identify CAC on these non-gated CT scans allows for the retrospective and prospective observational investigation of CAC in predicting cardiovascular outcomes in many different conditions. However, there needs to be a standard approach taken to identifying CAC on non-gated CT scans to ensure the reproducibility of the results, as well as a consistency in training to help in clinical practice.

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identifying coronary artery calcification on non-gated computed tomography scans

Coronary artery calcification (CAC) provides an objective measure of coronary artery disease and can readily be identified on non-gated computed tomography (CT) scans with a high correlation with gated cardiac CT scans. This standardized protocol takes a step-wise approach to not only optimizing an image for the identification of calcification but also to distinguishing CAC from other common causes of calcification in the cardiac silhouette. Recognition of CAC on non-gated CT scans helps to identify a very powerful prognostic factor that can influence therapeutic interventions or downstream diagnostic testing without requiring a gated cardiac scan. These non-gated CT scans are often acquired as part of the routine care of the patient, and this data is readily available without another dose of&#160;ionizing radiation. This protocol allows for the precise and accurate extraction of this data for the purposes of retrospective data analysis in clinical research studies, but also in the clinical evaluation and management of patients.

Coronary anatomy is relatively predictable in most patients as described above. The typical locations to evaluate these vessels are also easily identified in most patients (Figure 1). Using the described methodology, the presence or absence of CAC could be reliably identified in 84% of the patients in a single cohort (267 of 317 possible patients)15. The vast majority of patients excluded did not have a CT scan in the designated time f...

Watch this Scientific Journal Video about Identifying Coronary Artery Calcification on Non-gated Computed Tomography Scans at JoVE.com

Identifying Coronary Artery Calcification on Non-gated Computed Tomography Scans

Here, we present a protocol to reliably and systematically identify coronary artery calcification (CAC) on non-gated computed tomography (CT) scans of the chest or abdomen. CAC provides an objective measure of coronary artery disease for both research and clinical purposes.

Coronary artery calcification (CAC) provides an objective measure of coronary artery disease and can readily be identified on non-gated computed ...

This method can help answer key questions about the clinical interpretation of radiographic images, specifically, how to reliably interpret coronary calcification on non-gated computed tomography, or CT scans. The main advantage of this technique is that it's applicable in a wide range of studies and provides a consistent approach to the identification of a powerful prognostic tool. Begin by opening the image viewer and using an institutional username and password to log in to the program.Click on the Study List icon, select With Patient ID Equal To in the dropdown menu, and enter the patient's hospital identification number. Under Modalities, click All Modalities to unselect all of the imaging modalities, and select the Computed Tomography modality. Under Body Regions, leave the default set to All Body Regions.Then, click Find. Click Performed On to organize the list by the date of study, and select the study of interest. Use the tile tool to highlight a single tile, and click to make the screen a single pane.Hover the mouse over the series icon to identify the series that has an about three millimeter slice thickness, and drag this icon to the center of the viewing screen. Scroll through the images to ensure an adequate visualization of the coronary tree until an image with one of the coronary arteries is visualized. Right-click to select the Window/Level option, and click on Interactive Window/Level.As a starting point, type 500 in the Window field and 150 in the Level field. Manually adjust the window and level sizes until the fat, including the epicardial fat, appears dark gray to black, the myocardium is a slightly lighter gray, and the calcium and metal are white. Then close the window and level boxes to begin viewing the images.To identify the coronary artery calcification, scroll through the image, looking at one coronary artery at a time and recording whether coronary artery calcification is present or absent in each of the four major epicardial coronary arteries. To determine whether a questionable area is coronary artery calcification, right-click to open the menu and select Annotate. Click Elliptical Region Of Interest, and draw an outline around the potential calcification, as well as some epicardial fat, without including any other chambers.After adjusting the outline size and location as necessary, create a region of interest over the sternum and over the ascending aorta. Then compare the maximum Hounsfield unit in the area of potential calcification to the maximum Hounsfield units in the selected ascending aorta and sternum regions. The typical locations for evaluating the coronary vessels are easily identified in most patients.In these representative gated and non-gated scans, calcification within the right coronary artery can be visualized. In these non-gated and gated CT chest scans of a different patient, cardiac motion obscured the mild coronary calcification in the proximal left circumflex artery. General considerations for identifying the severity of the calcification include the number of vessels involved, the number of plaques in each vessel, and the density of calcification in each plaque.While attempting this protocol, it is important to remember to be consistent in applying each of these steps. Following this procedure, other methods such as coronary artery calcium quantification can be performed to answer additional questions about the severity of coronary artery disease. This technique has allowed researchers to retrospectively review CT scans to incorporate this important imaging finding in large data sets without the need for expensive prospective studies.Although the image processing itself is very safe, it is important to take the necessary precautions to ensure patient confidentiality when viewing the images for research purposes.

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