Normal Right Paratracheal Stripe Width on Chest X-Ray
The right paratracheal stripe is a thin soft-tissue interface visible on frontal chest radiographs, formed by the right tracheal wall, adjacent connective tissue, and the medial pleural reflection. It runs along the right lateral border of the trachea above the azygos arch. Accurate measurement of this stripe is clinically important because widening can be an early sign of significant mediastinal disease.
Normal Reference Values
| Orientation | Measurement |
|---|---|
| Anteroposterior | <4 mm |
Clinical Significance
A right paratracheal stripe measuring 4 mm or more is considered abnormal and warrants further evaluation. Widening typically reflects infiltration or displacement of the paratracheal soft tissues by pathological processes involving adjacent lymph nodes, vascular structures, or the tracheal wall itself.
Because the stripe is composed of multiple tissue layers, even subtle thickening on a routine anteroposterior (AP) chest film should prompt consideration of cross-sectional imaging. Pitfalls include patient rotation, which can artifactually widen the stripe, and the normal variability introduced by respiratory phase.
- Lymphadenopathy — sarcoidosis, lymphoma, metastatic disease
- Mediastinal hematoma — traumatic aortic injury or superior vena cava injury
- Thyroid or parathyroid mass extending into the superior mediastinum
- Tracheal neoplasm or inflammation — primary tracheal tumors, tracheitis
- Vascular abnormality — superior vena cava dilatation, aortic aneurysm
Reference: Savoca CJ, Brasch RC, Gooding CA et al. The right paratracheal stripe in children. Pediatr Radiol. 1978;6(4):203-7.
Imaging Notes
On an anteroposterior chest radiograph, the right paratracheal stripe is measured at its widest point along the right lateral tracheal border, from the outer tracheal wall to the inner mediastinal pleural surface. Measurement should be performed on a well-inspired, non-rotated film; patient rotation toward the right artificially thickens the stripe and may simulate pathology. The stripe is best visualized in the region between the thoracic inlet and the azygos arch.
Although the original threshold was established in a pediatric population, the <4 mm upper limit of normal is widely applied to adult chest radiography as well. When stripe widening is identified, CT of the chest with contrast is the recommended next step to characterize the underlying cause and define mediastinal anatomy precisely.