Quantification of abdominal aortic calcification: Inherent measurement errors in current computed tomography imaging

Area of Science:

• Radiology
• Medical Imaging Analysis
• Cardiovascular Imaging

Background:

• Coronary calcification quantification software is frequently applied to abdominal aortic calcification on computed tomography (CT) images.
• The reliability and accuracy of these tools for abdominal calcification are not well-established.
• Differences in CT acquisition parameters and the presence of intravascular contrast may influence quantification results.

Purpose of the Study:

• To investigate the impact of CT acquisition parameters and iodine contrast on automated quantification of aortic calcium.
• To assess the accuracy and reliability of existing quantification software in a clinical setting.

Main Methods:

• Automated calcium quantification software assessed calcium scores (volume and mass) on CT scans.
• A thorax phantom with calcifications was imaged using both abdominal and coronary CT protocols.
• Fifty unenhanced and contrast-enhanced clinical abdominal CT scans were analyzed, comparing different Hounsfield Unit (HU) thresholds.

Main Results:

• No significant differences in volume and mass scores were found between abdominal and coronary CT protocols.
• All calcifications were overestimated in volume (0-649%) and mass (0-2619%) compared to physical measurements.
• Significant volume differences were observed between unenhanced and contrast-enhanced CT images, with further mass differences noted at specific thresholds.

Conclusions:

• Calcium scoring on CT angiography tends to significantly overestimate calcification volume and mass, indicating low accuracy and reliability.
• Intravascular contrast further compromises the accuracy of these automated tools.
• Future research using calcium quantification on CT angiography should address these limitations and implement corrective measures for valid outcomes.