SIGNS OF

RADIOLOGICAL IMPORTANCE

IN THE

THORAX

THORACOABDOMINAL SIGN

• •Posterior costophrenic sulcus extends more caudally than anterior basilar lung

• •Lesion extending below the dome of diaphragm must be in the posterior chest whereas lesion terminating at the dome must be in the anterior region

• •Cervicothoracic and thoracoabdominal signs were described by Felson

CERVICOTHORACIC SIGN

• Used to determine location of mediastinal lesion in the upper chest

• •Based on the principle that an intrathoracic lesion in direct contact with soft tissues of the neck will not be outlined by air

• •Uppermost border of the anterior mediastinum ends at level of the clavicles

• •Middle and posterior mediastinum extends above the clavicles

• •Mediastinal mass projected superior to the level of clavicles must be located either within the middle or posterior mediastinum

• •More cephalad the mass extends the more posterior the location will be

HILUM OVERLAY SIGN

• •Described by R .B. Felson

• •If hilar vessels are sharply delineated it can be assumed that the overlying mass is anterior or posterior.

• •If mass inseparable, pulmonary arteries and other structures are adjacent to one another.

HILUM CONVERGENCE SIGN

• •Described by R.B. Felson

• •Used to distinguish between a prominent hilum and an enlarged pulmonary artery

• •If branches of PA converge towards centre then mass is an enlarged PA

• •If branches of PA converge towards heart than mass is a mediastinal tumor

INCOMPLETE BORDER SIGN

• The incomplete border sign is useful to depict an extrapulmonary mass on chest radiograph.

• An extrapulmonary mass will often have a inner well defined border and an ill-defined outer margin . This can be attributed to the inner margin being tangential to the x-ray beam and having good inherent contrast with the adjacent lung. On the other hand, the outer margin is enface or partially enface with the x-ray beam and merges with the pleural or chest wall. Thus the border is obscured.

Differential diagnosis of Extrapulmonary Mass:

• Differential diagnosis for extrapulmonary mass can be further  divided into pleural or extrapleural.

• Common pleural masses include:

• loculated pleural collection

• haematoma

• pleural plaques

• fibrous tumour of pleura

• Extrapleural causes can arise from component of chest wall, bone/cartilage, nerve, vascular, fat, muscle and skin. If there is sign of rib/bone involvement on chest radiograph the lesion is most likely to be extrapleural. In adults, skeletal metastases are the most common malignant chest wall neoplasm while chondrosarcoma  is the most common primary malignant tumor.

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