Chest X-Ray as a Screening Tool for Aortic Arch Dilation: CT-Based Evaluation of Reliability

Area of Science:

• Radiology
• Cardiovascular Imaging
• Thoracic Imaging

Background:

• Chest radiography (CXR) is the primary imaging modality for thoracic abnormalities.
• Aortic knob width on CXR may indicate aortic dilation, but lacks standardized clinical thresholds.
• No established CXR criteria exist for reliably assessing aortic dilation.

Purpose of the Study:

• To evaluate the utility of aortic knob width measurements on CXR for detecting aortic dilation.
• To establish quantitative CXR thresholds for identifying thoracic abnormalities.
• To assess the correlation between CXR and CT angiography measurements of the aorta.

Main Methods:

• Retrospective analysis of 240 emergency department patients with PA CXR and CTA.
• Measurement of three aortic knob dimensions (horizontal, oblique, vertical) on CXR.
• Comparison of CXR measurements with CTA at proximal and distal aortic levels.

Main Results:

• Horizontal aortic knob width showed the strongest correlation with CTA measurements.
• A regression model using horizontal knob diameter, age, and sex achieved an AUC of 0.884 for detecting aortic dilation (>40 mm).
• A conservative threshold yielded 100% sensitivity and 1.00 negative predictive value for excluding dilation.

Conclusions:

• Quantitative CXR aortic knob width, age, and sex can aid in excluding aortic arch dilation.
• This approach demonstrates high negative predictive value, potentially serving as a screening tool.
• Further validation in diverse populations is needed to confirm its role in guiding advanced imaging decisions.