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Inter- and intra- observer variability is a problem often faced when an expert or observer is tasked with assessing
the severity of a disease. This issue is keenly felt in coronary calcium scoring of patients suffering from atherosclerosis
where in clinical practice, the observer must identify firstly the presence, followed by the location of candidate calcified
plaques found within the coronary arteries that may prevent oxygenated blood flow to the heart muscle. This can
be challenging for a human observer as it is difficult to differentiate calcified plaques that are located in the coronary
arteries from those found in surrounding anatomy such as the mitral valve or pericardium. The inclusion or exclusion
of false positive or true positive calcified plaques respectively will alter the patient calcium score incorrectly, thus
leading to the possibility of incorrect treatment prescription.
In addition to the benefits to scoring accuracy, the use of fast, low dose multi-slice CT imaging to perform the
cardiac scan is capable of acquiring the entire heart within a single breath hold. Thus exposing the patient to
lower radiation dose, which for a progressive disease such as atherosclerosis where multiple scans may be required,
is beneficial to their health.
Presented here is a fully automated method for calcium scoring using both the traditional Agatston method, as
well as the Volume scoring method. Elimination of the unwanted regions of the cardiac image slices such as lungs,
ribs, and vertebrae is carried out using adaptive heart isolation. Such regions cannot contain calcified plaques but
can be of a similar intensity and their removal will aid detection. Removal of both the ascending and descending
aortas, as they contain clinical insignificant plaques, is necessary before the final calcium scores are calculated and
examined against ground truth scores of three averaged expert observer results. The results presented here are
intended to show the requirement and feasibility for an automated scoring method that reduces the subjectivity and
reproducibility error inherent with manual clinical calcium scoring.
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