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Azygos arch valves at computed tomography angiography and pitfalls related to its variety in appearance and function
Karin Steinke1, Arash Moghaddam
1Royal Brisbane and Women's Hospital, Herston, 4029 Queensland, Australia.
Insights
Azygos arch valves are common on computed tomography angiography (CTA) scans, with many showing signs of insufficiency. This study evaluated their prevalence and assessed insufficiency using high-rate contrast material injection during CTA.
Area of Science:
- Radiology
- Vascular Anatomy
Background:
- The azygos vein is a major venous channel in the thorax.
- Azygos arch valves are venous valves located at the junction of the azygos vein and the superior vena cava.
- Their prevalence and functional significance, particularly insufficiency, are not well-established in computed tomography angiography (CTA) imaging.
Purpose of the Study:
- To determine the prevalence of azygos arch valves.
- To evaluate the rate of azygos valve insufficiency.
- To assess these findings using chest or body computed tomography angiography (CTA) with high-rate contrast material injection.
Main Methods:
- Retrospective analysis of 321 CTAs performed with high intravenous injection rates (3-5 mL/second) of contrast material.
- Evaluation for contrast material reflux from the superior vena cava into the azygos vein.
- Identification of azygos valves and assessment of insufficiency based on contrast material presence posterior to the valve.
Main Results:
- Contrast reflux into the azygos vein was observed in 191 (59.5%) of 321 CTAs.
- Azygos valves were identified in 124 (64.9%) of these 191 examinations.
- Azygos valve insufficiency was present in 66 (53.2%) of the 124 examinations where valves were identified.
Conclusions:
- Azygos arch valves are frequently encountered during CTA.
- These valves exhibit considerable variation in size and shape.
- A significant proportion of identified azygos valves demonstrate features indicative of insufficiency.
Objective:
To evaluate the prevalence of azygos arch valves and assess azygos valve insufficiency at computed tomography angiography (CTA) of the chest or body with high rate contrast material injection.
Methods:
Three hundred twenty-one CTAs using high intravenous injection rates (3-5 mL/second) of 300 mgI/mL contrast material were retrospectively evaluated for the presence of contrast material reflux from the superior vena cava into the azygos vein. Among the patients with contrast material reflux, azygos valves were identified within the azygos arch. Age, sex, and site of contrast material injection were analyzed. Azygos valve insufficiency was considered to be present if there was contrast material within the azygos vein posterior to the azygos valve.
Results:
Of the 321 examinations, 191 (59.5%) showed reflux into the azygos vein. There was no significant difference in frequency of reflux into the azygos vein between right and left arm injection site (56.4% vs 63.5%, P = 0.20) or male and female patients (63.4% vs 55.0%, P = 0.12). No difference in mean age was noted between patients with reflux and those without it (P = 0.97). Azygos valves were identified in 124 (64.9%) of 191 CTA examinations with contrast reflux and pitfalls related to their appearance variety are discussed. No significant difference was found in valve frequency between male and female patients (66.0% vs 63.4%, P = 0.70). Contrast material posterior to the visible azygos valve was present in 66 (53.2%) of 124 examinations.
Conclusions:
Azygos arch valves are a common finding on CTA. They come in various sizes and shapes, and many of them show features of insufficiency.
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