CT protocol characteristics.

<p>CT protocol characteristics.</p

Histogram of the HU levels of the non-enhanced and contrast-enhanced CT scans of one patient.

<p>The arrows show the selected thresholds. Purple arrow: static threshold (299 HU). Green arrow: patient specific threshold. HU: Hounsfield Units.</p

Results of non-enhanced versus contrast-enhanced CT scans.

<p>Results of non-enhanced versus contrast-enhanced CT scans.</p

Cardiac calcification inserts characteristics.

<p>Cardiac calcification inserts characteristics.</p

The anthropomorphic thorax phantom.

<p>(Reference image provided by QRM GmbH).</p

Percentual differences of the measured volume and mass of the small cylinder, medium-sized and large cylinder with respect to the physical volume and mass in a coronary and abdominal CT protocol.

<p>Percentual differences of the measured volume and mass of the small cylinder, medium-sized and large cylinder with respect to the physical volume and mass in a coronary and abdominal CT protocol.</p

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

<div><p>Objective</p><p>Quantification software for coronary calcification is often used to measure abdominal aortic calcification on computed tomography (CT) images. However, there is no evidence substantiating the reliability and accuracy of these tools in this setting. Differences in coronary and abdominal CT acquisition and presence of intravascular contrast may affect the results of these tools. Therefore, this study investigates the effects of CT acquisition parameters and iodine contrast on automated quantification of aortic calcium on CT.</p><p>Methods</p><p>Calcium scores, provided in volume and mass, were assessed by automated calcium quantification software on CT scans. First, differences in calcium scores between the abdominal and coronary CT scanning protocols were assessed by imaging a thorax phantom containing calcifications of 9 metrical variations. Second, aortic calcification was quantified in 50 unenhanced and contrast-enhanced clinical abdominal CT scans at a calcification threshold of 299 Hounsfield Units (HU). Also, the lowest possible HU threshold for calcifications was calculated per individual patient and compared to a 130 HU threshold between contrast-enhanced and unenhanced CT images, respectively.</p><p>Results</p><p>No significant differences in volume and mass scores between the abdominal and the coronary CT protocol were found. However, volume and mass of all calcifications were overestimated compared to the physical volume and mass (volume range: 0–649%; mass range: 0–2619%). In comparing unenhanced versus contrast-enhanced CT images showed significant volume differences for both thresholds, as well as for mass differences for the 130 vs patient-specific threshold (230 ± 22.6 HU).</p><p>Conclusion</p><p>Calcification scoring on CT angiography tends to grossly overestimate volume and mass suggesting a low accuracy and reliability. These are reduced further by interference of intravascular contrast. Future studies applying calcium quantification tools on CT angiography imaging should acknowledge these issues and apply corrective measures to ensure the validity of their outcomes.</p></div

The cardiac calcification insert.

<p>Frontal (left) and sagittal (right) view. (Reference image provided by QRM GmbH). It contains nine cylindrical calcifications with different masses and volumes, as well as one large water equivalent element and one large calcium hydroxyapatite calibration element.</p