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Proximal thoracic aortic diameter measurements at CT: repeatability and reproducibility according to measurement
Leslie E Quint1, Peter S Liu, Anna M Booher
1Department of Radiology, University of Michigan Health System, Ann Arbor, MI 48109, USA. lequint@umich.edu
Insights
Variability in CT measurements of proximal thoracic aorta diameters was assessed. Both double-oblique short axis and semiautomatic centerline analysis showed low variability, but differences up to 5 mm occurred, with neither technique proving superior.
Area of Science:
- Radiology
- Cardiovascular Imaging
- Medical Imaging Analysis
Background:
- Accurate measurement of proximal thoracic aorta diameters is crucial for diagnosing and managing aortic diseases.
- Computed tomography (CT) is a primary imaging modality for evaluating the aorta.
- Standardized measurement techniques are essential for reliable interpretation of CT scans.
Purpose of the Study:
- To compare the variability of proximal thoracic aortic diameter measurements using double-oblique short axis and semiautomatic centerline analysis techniques.
- To assess intraobserver and interobserver variability for each measurement technique.
- To evaluate the agreement between the two measurement techniques.
Main Methods:
- Retrospective analysis of cardiac-gated thoracic aortic CT scans from 25 patients.
- Measurements of aortic diameter at the annulus, sinuses, sinotubular junction, and ascending aorta.
- Application of double-oblique short axis and semiautomatic centerline analysis techniques.
- Statistical assessment using Wilcoxon signed rank test, Spearman's correlation, and Bland-Altman plots.
Main Results:
- Mean intraobserver diameter differences were low for both techniques (double oblique: -0.3 to 0.6 mm; centerline: 0.2 to 2.3 mm).
- Significant interobserver differences were observed for both methods.
- Measurements were strongly correlated (r = 0.81-0.99) but consistently larger with centerline analysis.
- 95% confidence intervals for differences between techniques ranged from ±1.8 to ±3.2 mm.
Conclusions:
- Both double-oblique short axis and semiautomatic centerline analysis demonstrate generally low measurement variability for the proximal thoracic aorta.
- Differences up to approximately 5 mm in diameter can occur within the 95% confidence interval between techniques.
- Neither technique was definitively more reliable than the other, highlighting the need for careful interpretation and potential standardization.
Aim:
To determine the variability in CT measurements of proximal thoracic aortic diameters obtained using double-oblique short axis and semiautomatic centerline analysis techniques. Institutional review board approval, with waiver of informed consent, was obtained for this HIPAA-compliant, retrospective study. Cardiac gated thoracic aortic CT scans were evaluated in 25 patients. Maximum aortic diameter measurements at the annulus, sinuses, sinotubular junction and ascending aorta were generated using double-oblique short axis and semiautomatic centerline analysis techniques. Intraobserver and interobserver variability and variability between techniques were assessed using the Wilcoxon signed rank test, Spearman's correlation coefficients and Bland-Altman plots. Mean intraobserver diameter differences using double oblique views ranged from -0.3 to 0.6 mm. The 95 % confidence interval for difference in diameters was ±2.4 to ±5.1 mm for radiologist #1 and ±2.6 to ±5.2 mm for radiologist #2, depending on location. Mean intraobserver diameter differences using centerline analysis ranged from 0.2 to 2.3 mm, and the 95 % confidence interval for difference in diameters was ±2.0 to ±4.6 mm, depending on location. Significant interobserver differences were seen for both double oblique views and centerline analysis. Measurements obtained using the two methods were strongly correlated (r = 0.81-0.99), although they were consistently larger using centerline analysis (95 % confidence interval, ±1.8 to ±3.2 mm). Although measurement variability of the proximal thoracic aorta was generally low using double oblique and centerline analysis techniques, differences of up to approximately 5 mm in diameter occurred within the 95 % confidence interval. Neither technique was clearly more reliable than the other.
