Need for Standardized Methods to Measure the Aorta
What is the variability in aortic measurements with multiple imaging modalities in clinical centers?
The investigators characterize the diversity of methods utilized in clinical practice by comparing aortic measurements performed by echocardiography (echo), computed tomography (CT), and magnetic resonance imaging (MRI) at the six GenTAC (National Registry of Genetically Triggered Thoracic Aortic Aneurysms and Cardiovascular Conditions) clinical centers to those performed at the imaging core lab in 965 studies. Each center acquired and analyzed their images according to local protocols. The same images were subsequently analyzed blindly by the core lab, based on a standardized protocol for all imaging modalities. Paired measurements from clinical centers and core lab were compared by mean of differences and intraclass correlation coefficient (ICC).
For all segments of the ascending aorta, echo showed a higher ICC (0.84-0.93) than CT (0.84) and MRI (0.82-0.9), with smaller mean of differences. MRI showed higher ICC for the arch and descending aorta (0.91 and 0.93). In a mixed adjusted model, the different imaging modalities and clinical centers were identified as sources of variability between clinical and core lab measurements, while age groups or diagnosis at enrollment were not.
The authors concluded that by comparing core lab to clinical center’s measurements, this study identified important sources of variability in aortic measurements.
This study sought to understand how the different techniques used for aortic measurements in clinical practice affect the variability of aortic measurements reported, and how the implementation of a standardized method by a centralized core lab might address this variability. The study reports that transthoracic echocardiography (TTE) has a higher reproducibility between iCORE and clinical centers in measures of the proximal aortic segments, while CT and MRI are more reproducible at the arch and descending segments. Furthermore, there was significant variability among the enrolling centers and the imaging modalities (better consistency of TTE measurements), but not among age groups or diagnoses. These findings highlight the importance of utilizing a unified protocol for analysis of aortic measurements, and its implementation by a centralized core laboratory.
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