2.23. 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. CT-series with information about the slice thickness are suitable for the measurement. For all other series, the tools are not applicable.

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

	Calcium scoring (ellipse) (selected by default)
	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.

2.23.1 Selection of measurement areas

To measure calcium:

Open a CT series suitable for calcium scoring.

Select the image to measure.

Activate the Calcium scoring (ellipse) tool or Calcium scoring (polygon). These tools are similar to ROI ellipse and ROI polygon (see Section 2.18.5). If the study does not contain information about the age and/or gender of the patient, the dialog shown in Fig. 2.75 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.
When the calcium scoring tool is active, a window shown in Fig. 2.76 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:
- LM — Left main coronary artery
- LAD — Left anterior descending coronary artery
- LCX — Left circumﬂex coronary artery
- RCA — Right coronary artery
Select the artery for measurement by clicking the corresponding button. The choice of an artery does not aﬀect the measurement result.
Build an ellipse or a polygon around the aﬀected area. For detailes on how to build one, see Section 2.18.5 (the ROI ellipse and ROI polygon tools). A block with the following data is displayed near the measurement:
- The name of the artery (corresponds to the button pressed while building);
- Area of calciﬁed lesion. If the measurement area contains several lesions then their total area is displayed;
- Agatston score;
- Volume score.

Figure 2.75: Patient data entry dialog

Figure 2.76: Calcium scoring

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

2.23.2 Actions with measurement areas

For details on how to move measurement areas, see Section 2.18.8, for how to move measurement results, see Section 2.18.9.

To edit the drawing parameters:

Activale the calcium scoring tool.
Locate the cursor on the measurement or the mesurement results to highlight them.
Right-click the mouse and select the Tool options... item from the context menu.
In the dialog box that appears, enter the measurement name.
Set the color by clicking on the color box.
Set the line thickness and the font size.
To connect the block with the measurement results with a dotted line, the Footnote line box must be checked.
To display the block with the measurement results, the Show labels box must be checked.
To use these parameters by default, check the box Set as default.
To apply the settings, click OK. To cancel, click CANCEL.

2.23.3 Measurement results

The measurement results are displayed in the window shown in Fig. 2.76:

For each vessel separately and in total:
- total lesion area (for all lesions);
- lesion numder (N);
- Agatston score (AS);
- Volume score (VS).
Patient gender
Age group
Percentile

Formula for Agatston index scoring:

( n ) ∑ Tslice Ics = SiFi 3.00 i=1

(2.21)

I_cs — Agatston index, n — lesion number, S_i — i-lesion area, F_i — i-lesion density factor, T_slice — slice thickness. The F_i value is determined by the maximum pixel density in the lesion area:

Maximum pixel density	F_i
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, S_i — i-lesion area, T_slice — 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 and can be inserted into 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.