• Agatston score
• aortic stenosis
• calcium volume
• TAVI

Transcatheter aortic valve implantation (TAVI), is nowdays a worldwide accepted alternative for treating patients at high or intermediate risk for surgery, with recent and ongoing trials even in patients at low surgical risk. The expansion of TAVI indications, as well as the ageing of the population, will lead to an increase of the TAVI procedures performed worldwide in the next decades. A computed cardiac tomography (CCT) is mandatory in all patients before the TAVI procedure. Aortic valve calcium burden assessment, traditionally measured on non-contrast-enhanced (NCE) scans, is important to predict possible complications related to the TAVI procedure, but the Hounsfield Units (HU) threshold chosen to detect calcium on contrast-enhanced (CE) scans has not been yet standardized in literature. The aim of the study is to find the most accurate threshold to evaluate aortic calcium burden in CE scans using the algorithm of 3Mensio software (®Pie Medical Imaging, The Netherlands), comparing different HU thresholds with a gold standard value represented by the Agatston score.
The thresholds for correct calcium identification using the automatic 3Mensio software depend on the contrast enhancement of aortic and cardiac structure, which can be estimated measuring the HU in the LVOT.
This represents the first study where different thresholds are matched with an independent gold standard method, as Agatston score.
In patients with LVOT HU<300, the correct threshold to be set in the software is 450HU, whereas in patients with LVOT HU≥300 the correct threshold is 850HU.
Further studies are warranted in order to establish the clinical impact of these results, their application on other TAVI devices (balloon-expandable or mechanically expandable) and their correlation with clinical outcomes.