Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2023 Sep 22:(199):10.3791/65458.
doi: 10.3791/65458.

Semi-Automatic Graphical Tool for Measuring Coronary Artery Spatially Weighted Calcium Score from Gated Cardiac Computed Tomography Images

Heli J Patel  1 , Audrey E Kaufman  2 , Marco Pereañez  2 , Georgios Soultanidis  2 , Sarayu Ramachandran  2 , Sonum Naidu  2 , Venkatesh Mani  2 , Zahi A Fayad  2 , Philip M Robson  2
Affiliations

Semi-Automatic Graphical Tool for Measuring Coronary Artery Spatially Weighted Calcium Score from Gated Cardiac Computed Tomography Images

Heli J Patel et al. J Vis Exp. .

Abstract

The current standard for measuring coronary artery calcification to determine the extent of atherosclerosis is by calculating the Agatston score from computed tomography (CT). However, the Agatston score disregards pixel values less than 130 Hounsfield Units (HU) and calcium regions less than 1 mm2. Due to this thresholding, the score is not sensitive to small, weakly attenuating regions of calcium deposition and may not detect nascent micro-calcification. A recently proposed metric called the spatially weighted calcium score (SWCS) also utilizes CT but does not include a threshold for HU and does not require elevated signals in contiguous pixels. Thus, the SWCS is sensitive to weakly attenuating, smaller calcium deposits and may improve the measurement of coronary heart disease risk. Currently, the SWCS is underutilized owing to the added computational complexity. To promote translation of the SWCS into clinical research and reliable, repeatable computation of the score, the aim of this study was to develop a semi-automatic graphical tool that calculates both the SWCS and the Agatston score. The program requires gated cardiac CT scans with a calcium hydroxyapatite phantom in the field of view. The phantom allows for deriving a weighting function, from which each pixel's weight is adjusted, allowing for the mitigation of signal variations and variability between scans. With all three anatomical views visible simultaneously, the user traces the course of the four main coronary arteries by placing points or regions of interest. Features such as scroll-to-zoom, double-click to delete, and brightness/contrast adjustment, along with written guidance at every step, make the program user-friendly and easy to use. Once tracing the arteries is complete, the program generates reports, which include the scores and snapshots of any visible calcium. The SWCS may reveal the presence of subclinical disease, which may be used for early intervention and lifestyle changes.

PubMed Disclaimer

Conflict of interest statement

DISCLOSURES:

The authors declare that they have no conflicts of interest to disclose.

Figures

Figure 1:
Figure 1:. Format of main project folder.
This figure shows how the project’s main folder should be structured and formatted for proper use of the program.
Figure 2:
Figure 2:. Initial program window.
The program, when initially launched, has the buttons laid out along with an art image.
Figure 3:
Figure 3:. Graphical user interface (GUI).
Once images are loaded in, the program’s GUI shows three anatomical views of the images along with crosshairs on each view, representing the cursor.
Figure 4:
Figure 4:. Draw ROI feature.
When the Draw ROI option is chosen, a pop-up of the current axial slice appears. The yellow shows an ROI that was previously drawn on this slice.
Figure 5:
Figure 5:. Contents of results folder.
The metadata folder for a given patient has the shown CSV, PNG, and PDF files if the program is used correctly.
Figure 6:
Figure 6:. LCX report.
This example shows what the first page of a report should look like. The SWCS and Agatston score are displayed in red, along with the extent of calcification—the number of slices included in the Agatston score calculation. The phantom-derived weighting function is also displayed, which shows a given pixel’s weight according to its attenuation level.
Figure 7:
Figure 7:. Various PNGs.
The report for each artery includes A) a graph showing the trajectory of the labeled points/ROIs, B) a snapshot of the phantom, and C) one or more snapshots of noticeable calcium, if any.
Figure 8:
Figure 8:. Validation of program Agatston score.
This Bland-Altman plot shows the percent difference between the Agatston score obtained from the program versus that obtained from the commercial software for 10 cases known to have calcium in one or more coronary arteries.
See this image and copyright information in PMC

References

    1. O’Malley PG, Taylor AJ, Jackson JL, Doherty TM, Detrano RC Prognostic value of coronary electron-bean computed tomography for coronary heart disease events in asymptomatic populations. The American Journal of Cardiology. 85 (8), 945–948 (2000). - PubMed
    1. Budoff MJ et al. Assessment of coronary artery disease by cardiac computed tomography. Circulation. 114 (16), 1761–1791 (2006). - PubMed
    1. Rumberger JA, Simons DB, Fitzpatrick LA, Sheedy PF, Schwartz RS Coronary artery calcium area by electron-beam computed tomography and coronary atherosclerotic plaque area. Circulation. 92 (8), 2157–2162 (1995). - PubMed
    1. Mautner GC et al. Coronary artery calcification: assessment with electron beam CT and histomorphometric correlation. Radiology. 192 (3), 619–623 (1994). - PubMed
    1. Agatston AS et al. Quantification of coronary artery calcium using ultrafast computed tomography. Journal of the American College of Cardiology. 15 (4), 827–832 (1990). - PubMed

Publication types