Normal Right Paratracheal Stripe Width on Radiography
The right paratracheal stripe is a thin soft-tissue interface visible on posteroanterior (PA) chest radiographs, formed by the right tracheal wall, paratracheal soft tissues, and the adjacent mediastinal pleura. It appears as a linear opacity along the right lateral border of the trachea, extending from the thoracic inlet to the azygos vein. Accurate assessment of this stripe is a fundamental component of systematic chest radiograph interpretation, as abnormalities may be the earliest sign of significant mediastinal disease.
Normal Reference Values
| Orientation | Measurement |
|---|---|
| Posteroanterior | < 4mm |
Clinical Significance
A right paratracheal stripe measuring 4 mm or less is considered normal on a PA chest radiograph. Widening beyond this threshold indicates pathological thickening of the paratracheal soft tissues and should prompt further investigation, typically with CT of the chest.
The stripe may be obscured or widened by a variety of mediastinal processes. Even subtle asymmetric widening deserves attention, particularly in the appropriate clinical context such as suspected malignancy, trauma, or systemic illness. Bilateral involvement or associated tracheal deviation adds further diagnostic weight.
- Lymphadenopathy — most common cause; seen with lymphoma, sarcoidosis, and metastatic malignancy
- Mediastinal hematoma — following thoracic trauma or aortic injury
- Paratracheal mass — thyroid goiter extending substernally, or primary mediastinal tumors
- Infectious adenitis — tuberculosis or histoplasmosis causing right paratracheal nodal enlargement
- Vascular abnormality — superior vena cava dilation or azygos vein enlargement mimicking stripe widening
Reference: Brant WE, M.D. CA. Fundamentals of Diagnostic Radiology. LWW. (2012).
Imaging Notes
The right paratracheal stripe is evaluated exclusively on the posteroanterior (PA) chest radiograph. Measurement is made at its widest point along the right lateral tracheal wall, from the inner tracheal air column to the mediastinal pleural surface. Optimal assessment requires a well-inspired, adequately penetrated, and non-rotated radiograph; patient rotation can artifactually widen or obscure the stripe. The stripe should be visible as a discrete, uniform linear opacity; irregularity or lobulation increases the suspicion for underlying adenopathy or mass.
When stripe widening is identified on radiography, cross-sectional imaging with contrast-enhanced CT is the standard next step to characterize the nature, extent, and relationship of any paratracheal abnormality to adjacent structures.