Coronary Calcium Scoring
Coronary artery calcium is a biomarker of coronary artery disease – and quantification of coronary calcification is a strong predictor for cardiovascular events such as heart attack or strokes.
Conventional coronary calcium scoring has required dedicated cardiac, ECG gated CT performed with and without contrast. Recently, the reliable derivation of coronary calcium score has been obtained algorithmically from low dose chest CT data (Isgum et al. 2012); the automatically derived score was predictive of cardiovascular events in a large cohort of individuals undergoing CT lung cancer screening.
Zebra has developed an algorithm that automatically calculates Coronary Calcium Scores based on standard, non-contrast Chest CTs. This tool can provide early detection of people at high risk of severe cardiovascular events.
An aneurysm is an abnormal enlargement of an artery due to weakness of the vessel wall. Aneurysms can be caused by abnormal flow within the vessel, disease of the arterial wall and most commonly a combination of the two. Abdominal aortic aneurysms (AAA’s) describe such enlargement in the abdominal portion of the Aorta, most commonly below the level of the renal (kidney) arteries. AAA’s are generally asymptomatic – the aorta being a structure which is surrounded by fat and able to grow in circumference without creating alarm. The greatest risk of AAA’s is of rupture, which results in death almost uniformly (over 90% of the time). The risk of rupture is directly related to the size of the aneurysm: generally the risk of rupture is given as %/yr and increases by 10% with every cm diameter growth. For example, a 3cm diameter Abdominal aorta is considered normal. An aneurysm which measures 6-7cm is associated with a 10-20% risk of rupture per year; a 7-8 cm diameter raises the risk of rupture.
Aortic aneurysms are commonly overlooked in CT imaging, especially when expert radiologists are seeking and diagnosing more urgent conditions. This is especially so for small (<4-5 cm) aneurysms – up to 89% of which go undetected. A recent study found that 9% of “missed” AAA’s, measured 5.5cm or greater – a diameter commonly accepted as the threshold for intervention.
The Zebra AAA detection tool automatically evaluates each contrast enhanced CT study which includes the abdomen. The algorithm measures the greatest dimension of the abdominal aorta and identifies studies in which the aorta measures greater 4cm with an accuracy of over 90%.