Chest Imaging

Atoll sign	Atoll sign (ring-shaped opacity) COP - Cryptogenic organizing pneumonia (COP)
Bilateral Pulmonary Hypoplasia	Pulmonary hypoplasia in the neonate can be unilateral or bilateral. Bilateral pulmonary hypoplasia is most often the result of compression of the lungs during fetal development. Congenital bone dysplasias and syndromes associated with hort ribs and a small thoracic cage (asphyxiating thoracic dystrophy, thanatophoric dwarfism, Ellis-van Creveld syndrome) compress the lungs and cause hypoplastic lungs. The degree of hypoplasia is often severe and leads to the demise of these infants. Chromosomal abnormalities such as the trisomies are associated with hypoplastic lungs, and in some infants, hypoplasia is “primary” and unexplained.
Black pleura sign	Pulmonary alveolar microlithiasis - Sandlike microcalcifications of lung (black pleura sign)
Cheerio sign	Bronchioloalveolar carcinoma Cavitation may be seen by HRCT (Cheerio sign)
Comet sign	Comet sign: bronchi and vessels curve toward the mass, seen in Round Atelectasis of asbestosis
Comet tail sign of vessel leading to atelectatic lung	bronchioloalveolar carcinoma Cavitation may be seen by HRCT (Cheerio sign)
Continuous diaphragm sign	Continuous diaphragm sign: due to air trapped posterior to pericardium
Deep sulcus sign	Pneumothorax Deep sulcus sign: anterior costophrenic angle sharply delineated
Double bronchial wall sign	Pneumomediastinum - Air outlining bronchial wall: double bronchial wall sign
Early sign of asbestos-related disease	Benign pleural effusion is an early sign of asbestos-related disease
Extrapleural sign	Air between parietal pleura and diaphragm: extrapleural sign
Flattening of hemidiaphragms (reliable sign)	Overinflation • Flattening of hemidiaphragms (reliable sign): highest level of the dome is <1 .5="" a="" above="" and="" between="" cm="" costophrenic="" drawn="" junctions.="" line="" nbsp="" straight="" td="" the="" vertebrophrenic="">
Fleischner sign	Fleischner sign: increased diameter of pulmonary artery (>16 mm) seen in acute PE. It usually disappears within a few days.
Golden inverted “S” sign in RUL, LUL collapse	Secondary Signs of Malignancy (Fig. 1-33) • Atelectasis (Golden inverted “S” sign in RUL, LUL collapse) • Obstructive pneumonia • Pleural effusion • Interstitial patterns: lymphangitic tumor spread • Hilar and mediastinal adenopathy • Metastases to ipsilateral, contralateral lung
Hampton hump	Hampton hump: triangular peripheral cone of infarct = blood in secondary pulmonary lobules (rare); does not grow → should reduce in size on successive radiographs
Monod sign	• Air may surround the aspergilloma (Monod sign), mimicking the appearance of cavitation seen with invasive aspergillosis.
Ring around artery sign	Pneumomediastinum - Air around pulmonary artery and main branches: ring around artery sign
Signet ring sign	Bronchiectasis Thickened walls Signet ring sign: focally thickened bronchial wall adjacent to pulmonary artery branch
Split pleura sign (CT, MRI):	Pulmonary edema - Split pleura sign (CT, MRI): loculated fluid between visceral and parietal pleura with thickening of pleura. Thickened pleura may enhance with IV contrast.
Thymic sail sign	Pneumomediastinum - Elevated thymus: thymic sail sign
Tubular artery sign	Air outlining major aortic branches: tubular artery sign Pneumomediastinum -
Westermark sign: localized pulmonary oligemia (rare)	Pulmonary Embolism Westermark sign: localized pulmonary oligemia (rare)
‘3’ sign.	Chest radiograph in a patient with coarctation. There is rib notching and enlargement of the left subclavian artery, causing a ‘3’ sign.
Approach to diffuse lung disease	?
Continuous diaphragm’ sign	EXTRAPULMONARY AIR Causes Iatrogenic, blunt or penetrating trauma ▶ barotrauma CXR/CT • Pneumomediastinum: linear air densities streaking within the mediastinum ▶ a visible thymus ▶ air seen anterior to the pericardium ▶ ring-like lucencies due to air surrounding a pulmonary artery § ‘Double bronchial wall’ sign: air on either side of a bronchial wall § ‘Continuous diaphragm’ sign: air over a diaphragmatic surface
CT signs of diaphragmatic rupture dependent viscera sign thick crus sign collar sign	MDCT diagnosis of diaphragmatic rupture is largely based on the fact that abdominal organs are seen in the pleural space outside the diaphragm. The more usual CT signs of diaphragmatic rupture include: discontinuity of the diaphragm with direct visualization of the diaphragmatic injury; herniation of abdominal organs with liver, bowel or stomach in contact with the posterior ribs (‘dependent viscera sign’); thickening of the crus (‘thick crus sign’); constriction of the stomach or bowel (‘collar sign’); active arterial extravasation of contrast material near the diaphragm; and, in the case of a penetrating diaphragmatic injury, depiction of a missile or puncturing instrument trajectory.
Deep sulcus’ sign	‘Deep sulcus’ sign: an unusually deep costophrenic sulcus (as air preferentially accumulates anterior to the lungs and also abuts mediastinal structures in the supine position)
dilatation of the bronchi,	The major sign of bronchiectasis on thin-collimation CT (highresolution CT [HRCT]) is dilatation of the bronchi, with or without bronchial wall thickening. Bronchial dilatation on CT is often manifested by lack of tapering of bronchial lumina (the cardinal sign of bronchiectasis) 16.8), internal bronchial diameter greater than that of the adjacent pulmonary artery (signet ring sign)
Displaced crus sign: Diaphragm sign: Interface sign: Bare area sign:	CT signs which may differentiate pleural effusion and ascites. Scans through lower thorax/upper abdomen in patient with bilateral pleural effusions and ascites. (A) Displaced crus sign: The right pleural effusion collects posterior to the right crus of the diaphragm and displaces it anteriorly. Diaphragm sign: The pleural fluid is over the outer surface of the dome of the diaphragm, whereas the ascitic fluid is within the dome. (B) Interface sign: The interface (arrows) between the liver and ascites is usually sharper than between liver and pleural fluid. Bare area sign: Peritoneal reflections prevent ascitic fluid from extending over the entire posterior surface of the liver in contrast to pleural fluid in the posterior costophrenic recess.
Double bronchial wall’ sign:	EXTRAPULMONARY AIR Causes Iatrogenic, blunt or penetrating trauma ▶ barotrauma CXR/CT • Pneumomediastinum: linear air densities streaking within the mediastinum ▶ a visible thymus ▶ air seen anterior to the pericardium ▶ ring-like lucencies due to air surrounding a pulmonary artery § ‘Double bronchial wall’ sign: air on either side of a bronchial wall § ‘Continuous diaphragm’ sign: air over a diaphragmatic surface
Double diaphragm’ sign	‘Double diaphragm’ sign: visualization of the undersurface of the heart PNEUMOTHORAX
dumb-bell-shaped mass extending through the foramina posterior vertebral body scalloping T2WI: the ‘target’ sign	PERIPHERAL NERVE TUMOURS • These originate from a paravertebral intercostal nerve within the posterior mediastinum • Benign: § Neurofibroma, § Schwannoma (neurilemmoma): • Malignant: § Nerve sheath tumours (neurogenic sarcomas): these are rare RADIOLOGICAL FEATURES Benign tumours CXR A well-defined round or oval posterior mediastinal mass ▶ any pressure deformity causes a smooth, scalloped indentation on the adjacent ribs, vertebral bodies (dural ectasia causes posterior vertebral body scalloping), pedicles or transverse processes ▶ there is preservation of the scalloped cortex (which is often thickened) ▶ the adjacent rib spaces are widened NECT A widened intervertebral foramina in 10% (with an associated dumb-bell-shaped mass extending through the foramina) ▶ homogeneous or heterogeneous appearance (  punctate foci of calcification) ▶ generally < 2 vertebral bodies long CECT Heterogeneous enhancement MRI T1WI: variable SI (similar to the spinal cord) ▶ T2WI: the ‘target’ sign: a characteristic high SI peripherally with low SI centrally ▶ T1WI and Gad: uniform enhancement
Epicardial fat pad ‘sign’	The epicardial fat pad ‘sign’ is positive when, visualized in the lateral projection, an anterior pericardial stripe (bordered by epicardial fat posteriorly and mediastinalfat anteriorly) is thicker than 2 mm. This sign is diagnostic of pericardial thickening or fluid
Garland’s triad (‘1-2-3’ sign)	Sarcoidosis Symmetrical hilar lymphadenopathy (in almost all cases) ▶ this is the most common cause of intrathoracic lymphadenopathy ▶ the anterior nodes occasionally increase in size (posterior nodal enlargement is very unusual) • Garland’s triad (‘1-2-3’ sign): symmetrical hilar adenopathy and right paratracheal adenopathy
Hampton’s hump’	• ‘Hampton’s hump’: a peripheral area of wedge-shaped consolidation secondary to infarction • Westermark sign: regional oligaemia with a sharp cutoff due to a pulmonary embolism
Hilar Convergence Sign	? Less then a cm of the pulmonary artery is seen, meaning that the mass is in the hilum (cuan)
hilar overlay’ sign	PERICARDITIS
Increased radiolucency of the ipsilateral hemithorax	Pneumothorax: this is often under tension with contralateral mediastinal shift ▶ frequently the pleural air lies anterior and medial to the lung and is more difficult to diagnose (with the only sign being an increased radiolucency of the ipsilateral hemithorax) ▶ often there is increased sharpness of the mediastinal border which, unlike with a pneumomediastinum, extends from the superior extent of the lung to the diaphragm ▶ a pneumothorax compresses the thymus (rather than being elevated as seen with a pneumomediastinum)
Inferior rib notching	Arterial: Coarctation of the aorta, aortic thrombosis, subclavian obstruction, any cause of pulmonary oligaemia Venous: Superior vena cava obstruction Arteriovenous: Pulmonary arteriovenous malformation, chest wall arterial malformation Neurogenic: Neurofibromatosis (ribbon ribs)
Luftsichel” sign	“Luftsichel”: radiolucency in upper lung zone that results from upward migration of superior segment of the left lower lobe (LLL)
Pressure erosion of a rib due to a neurofibroma.	Neurofibromatosis type 1 (NF-1): skeletal findings. Pressure erosion of a rib due to a neurofibroma. (Most rib deformities in NF-1 are due to the skeletal dysplasia, not pressure erosion.)
Signs that suggest a pneumothorax	Signs that suggest a pneumothorax • ipsilateral transradiancy, either generalized or hypochondrial • a deep, finger-like costophrenic sulcus laterally • a visible anterior costophrenic recess seen as an oblique line or interface in the hypochondrium; when the recess is manifest as an interface it mimics the adjacent diaphragm (‘double diaphragm sign’) • a transradiant band parallel to the diaphragm and/or mediastinum with undue clarity of the mediastinal border • visualization of the undersurface of the heart, and of the cardiac fat pads as rounded opacities suggesting masses • diaphragm depression.
Superior rib notching	Connective tissue diseases: Rheumatoid arthritis, SLE, Sjo¨gren’s, scleroderma Metabolic: Hyperparathyroidism Miscellaneous: Neurofibromatosis, restrictive lung disease, poliomyelitis, Marfans syndrome, osteogenesis imperfecta, progeria
Tension Pneumothorax	Moderate or gross mediastinal shift, should be taken as indicating tension, particularly if the ipsilateral hemidiaphragm is depressed (reliable).
the anterior and posterior junction lines	Since both junction lines are inconsistently seen, however, the lack of visualization of one or both is not a reliable sign of disease.
tree-in-bud sign	Small centrilobular nodular and linear branching opacities (tree-in-bud sign) express inflammatory and infectious bronchiolitis
Upper lobe blood diversion:	Upper lobe blood diversion: this is a normal finding on supine XRs – therefore it is not a useful sign in an ITU patient PULMONARY OEDEMA
water lily sign, camalote sign rising sun sign, serpent sign empty cyst sign ‘air bubble’ sign	Hydatid Cysts an air–fluid level, A floating membrane (water lily sign, camalote sign), a double wall, an essentially dry cyst with crumpled membranes lying at its bottom (rising sun sign, serpent sign), a cyst with all its contents expectorated (empty cyst sign) High specificity of CT for the diagnosis of perforated pulmonary hydatid cyst (‘air bubble’ sign) has been reported. Rupture into the pleural space causes an effusion or, if there is additional airway communication, a hydropneumothorax. The diagnosis may be established by serological testing, or examination of the sputum if there is rupture into airways.
Westermark sign	• ‘Hampton’s hump’: a peripheral area of wedge-shaped consolidation secondary to infarction • Westermark sign: regional oligaemia with a sharp cutoff due to a pulmonary embolism