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Reproducibility of thoracic aortic diameter measurement using computed tomographic scans
I Shimada1, S J Rooney, P A Farneti
1Cardiothoracic Surgical Unit, Queen Elizabeth Hospital, Edgbaston, Birmingham, UK.
Summary
Measurement error in thoracic aortic aneurysm (TAA) diameter can impact clinical decisions. While calliper measurements are acceptable, accuracy is best with a single observer, and standardization is crucial for multiple observers to minimize errors.
Area of Science:
- Medical Imaging
- Cardiovascular Surgery
- Radiology
Background:
- Decisions for thoracic aortic aneurysm (TAA) surgical repair rely on size and expansion rate, indices of rupture risk.
- Measurement error in TAA diameter can influence clinical decision-making regarding surgical intervention.
Purpose of the Study:
- To evaluate the reproducibility of thoracic aortic aneurysm diameter measurements.
- To assess inter- and intra-observer variability in measuring TAA using computed tomography (CT) scans.
Main Methods:
- Four observers measured minimum aortic diameter on 50 pre-selected CT scans.
- Measurements were taken using a calliper method and an in-scan tool.
- Statistical analysis included Wilcoxon's signed ranks test and Bland-Altman repeatability assessment.
Main Results:
- No significant intra-observer differences were found.
- Three observers showed no significant inter-observer differences, but one observer differed significantly from two others (P < 0.05).
- Worst inter-observer repeatability was 4.37 mm; mean difference was +/-0.88 mm, maximum +/-8.0 mm. Measurement variability increased with aortic diameter.
Conclusions:
- Calliper measurement is acceptable for TAA surveillance, particularly with a single observer.
- Increasing measurement error with larger diameters may affect expansion rate estimation.
- Standardization of technique and quality assurance protocols are recommended for multiple observers and units.