Room: Exhibit Hall | Forum 9
Purpose: To develop a low-cost test tool for the quality control and optimization of CT calcium score protocols.
Methods: A test tool was constructed of water equivalent material. The tool is a rod 10 cm long x 1.3 cm diameter. Embedded in this rod are smaller rods 1 cm long x 4 mm diameter having varying densities of calcium hydroxyapatite (0 mg/cc, 100 mg/cc, 200 mg/cc, 300 mg/cc, 400 mg/cc). The absolute Agatston score for this test tool can be calculated knowing the scan parameters of the scanner being tested, as the true number depends on the image thickness due to partial volume effects. For manufacturer 1 (2.5 mm image thickness), the known value is 604; for manufacturer 2 (3 mm image thickness), the known value is 453. The tool was scanned using the clinical protocols on two manufacturers, two models each and varying scan parameters. The scans were analyzed using two different analysis packages.
Results: Scanner manufacturer 1 yielded Agatston score 190.3 Â± 4.6; manufacturer 2 yielded an Agatston score 118.4 Â± 6.7. This large discrepancy is explained largely by partial volume effects, pixelation effects, and quantum mottle. Nonetheless, the results were reproducible over time between scanners and across varying scan protocols. The two FDA-approved analysis packages yielded essentially identical results.
Conclusion: A new test tool has been developed that is inexpensive and useful for quality control of calcium score protocols. While absolute agreement between known and measured Agatston scores is poor, the discrepancies can be largely explained by partial volume effects, pixelation, and quantum mottle. Results were reproducible across time, scan protocol, and analysis package. The new test tool will allow for QC and optimization of CT calcium score protocol and analysis.
Funding Support, Disclosures, and Conflict of Interest: Material support provided by CIRS, Inc.
Quality Control, CT, Test Objects