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2.24 Calcium Scoring

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Functionality is available in the Pro edition
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The DICOM Viewer allows you to measure calcium in the coronary arteries using the Calcium scoring tool. The conditions on which the tool is available are listed below:

If a series does not meet these requirements, the Calcium scoring tool will not be available.

The tool selection button will look different depending on the tool that was used last:

PIC Calcium scoring (ellipse) (selected by default)
PIC Calcium scoring (polygon)

To switch between these tools click the arrow on the right side of the tool selection button and select the desired tool.

2.24.1 Selection of measurement areas

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Functionality is available in the Pro edition
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To measure calcium:

  1. Open a CT series suitable for activation of the calcium measurement tool (see Section 2.24). Change the series view projection to axial if necessary (see Section 2.13).

  2. Select the image to measure.

  3. Activate the PIC Calcium scoring (ellipse) tool or PIC Calcium scoring (polygon). These tools are similar to ROI ellipse and ROI polygon (see Section 2.19.6). If the study does not contain information about the age and/or gender of the patient, the dialog shown in Fig. 2.77 appears. Enter missing information and click OK to continue or CANCEL to cancel the measurement. After clicking OK, this dialog no longer appears until the Flat image viewer window is closed. To change the gender and/or age of the patient, close the Flat Images View window and return to step 1.

  4. When the calcium scoring tool is active, a window shown in Fig. 2.78 is displayed on the screen. Move the window if necessary. To do this, move the cursor over the window title (highlighted in red in the figure) and move it, holding the left mouse button. In the upper part of the window there are vessel selection buttons:

    Select the artery for measurement by clicking the corresponding button. The choice of an artery does not affect the measurement result.

  5. Build an ellipse or a polygon around the affected area. For details on how to build one, see Section 2.19.6 (the ROI ellipse and ROI polygon tools). A block with the following data is displayed near the measurement:

PIC

Figure 2.77: Patient data entry dialog

PIC

Figure 2.78: Calcium scoring

PIC When the projection is switched from axial to any other, the tool is deactivated.

To deactivate the tool click the tool selection button PIC Calcium scoring (ellipse) tool or PIC Calcium scoring (polygon) or close the Calcium scoring window. All the changes made are saved until the Flat images view window is closed.

2.24.2 Actions with measurement areas

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Functionality is available in the Pro edition
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For details on how to move measurement areas, see Section 2.19.10, for how to move measurement results, see Section 2.19.11.

To edit the drawing parameters:

  1. Activale the calcium scoring tool.

  2. Locate the cursor on the measurement or the mesurement results to highlight them.

  3. Right-click the mouse and select the Tool options... item from the context menu.

  4. In the dialog box that appears, enter the measurement name.

  5. Set the color by clicking on the color box.

  6. Set the line thickness and the font size.

  7. To connect the block with the measurement results with a dotted line, the Footnote line box must be checked.

  8. To display the block with the measurement results, the Show labels box must be checked.

  9. To use these parameters by default, check the box Set as default.

  10. To apply the settings, click OK. To cancel, click CANCEL.

2.24.3 Measurement results

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Functionality is available in the Pro edition
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The measurement results are displayed in the window shown in Fig. 2.78:

  1. For each vessel separately and in total:

  2. Patient gender

  3. Age group

  4. Percentile

Formula for Agatston index scoring:

( n ) ∑ Tslice Ics = SiFi 3.00 i=1
(2.21)

Ics — Agatston index, n — lesion number, Si — i-lesion area, Fi — i-lesion density factor, Tslice — slice thickness. The Fi value is determined by the maximum pixel density in the lesion area:

Maximum pixel density Fi
130—199 HU 1
200—299 HU 2
300—399 HU 3
≥ 400 HU 4

Formula for calcium scoring:

( n ) ∑ Vcs = Si Tslice i=1
(2.22)

V cs — Agatston index, n — lesion number, Si — i-lesion area, Tslice — slice thickness.

Electron beam tomographic coronary artery calcium score percentiles for men and Women within each age strata

Age
<40 40-44 45-49 50-54 55-59 60-64 65-69 70-74 >74
Man (25251) 3504 4238 4940 4825 3472 2288 1209 540 235
25th percentile 0 0 0 1 4 13 32 64 166
50th percentile 1 1 3 15 48 113 180 310 473
75th percentile 3 9 36 103 215 410 566 892 1071
90th percentile 14 59 154 332 554 994 1299 1774 1982
Woman (9995) 641 1024 1634 2184 1835 1334 731 438 174
25th percentile 0 0 0 0 0 0 1 3 9
50th percentile 0 0 0 0 1 3 24 52 75
75th percentile 1 1 2 4 23 57 145 210 241
90th percentile 3 4 2 55 121 193 410 631 709

The measurement results are exported in the html format can be inserted into report editor (see Chapter 18) or in a text editors that support the html markup, for example, LibreOffice Writer or Microsoft Word. To do this click the EXPORT TO CLIPBOARD button, create a document in a text editor and paste the copied information into it.

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