2014/2015 Hassan Al-Balas, MD

 Imaging modalities in chest evaluation.  Chest pathology:  Lung parenchymal pathology  Mediastinal pathology.  Pleural pathology.  Specific Entities:  Pulmonary edema.  TB.  Airway disease.  Pneumothorax.

 Chest X-Ray:  PA and Lateral views:  PA view is obtained with patient in standing position and in full inspiration.  Lateral chest view is obtained with left side against the cassette to minimize cardiac magnification.  AP view:  Portable view is obtained with patient in supine or sitting patient.  Because of decreased X Ray source patient distance, there is significant magnification factor.  Usually obtained in sick patients in ICU and is less useful than PA view.

 Evaluate PA CXR for adequate and proper technique:  Penetration:  Faint visualization of the thoracic disc spaces behind the cardiac shadow.  Rotation:  Thoracic spine process is midway between medial ends of the clavicles.  Inspiration:  Adequate inspiratory film should show the dome of the diaphragm below the 10 th rib posteriorly.

 Chest X-Ray:  Special views:  Decubitus view:  Obtained with patient on his lateral side.  Is used to evaluate:  Size and possible loculation of the pleural effusion.  Small pneumothorax in patient an upright CXR is not possible.  Air trapping.  Lordiotic view:  Obtained with patient leaning backward.  Useful for evaluation of lung apices.

 CT Scan:  Non-contrast CT:  Is used to evaluate lung parenchyma, e.g. metastasis.  Contrast enhanced CT:  Essential for evaluation of mediastinal and hilar structures.  High Resolution CT:  Non contrast thin section images.  For evaluation of interstitial lung disease.  MRI:  Very limited value for chest evaluation.  Nuclear Ventilation/ perfusion scans:  To evaluate for pulmonary embolism.  Angiography:  Evaluate vascular pathology.

12 Individual alveoli are too small to resolve, but together they appear radiolucent.

 Air space disease.  Interstitial lung disease.  Focal lung masses/ Nodules.

14 Filling of alveoli by: water, blood, pus, proteinaceous fluid or cells - Ground glass - Consolidation

 Also known alveolar lung disease.  Features of Airspace disease:  Air bronchogram.  Respects lobar anatomy.  Ill-defined borders except at fissures.  Airspace disease could be:  Partial: Ground glass opacity.  Complete: Consolidation.

 Causes of ALD:  Acute:  Pulmonary edema.  Pneumonias.  Pulmonary hemorrhage.  Chronic:  Broncho-alveolar carcinoma.  Lymphoma.  Alveolar proteinosis.

19 -Diffuse and bilateral. -May have regional distribution.

 Normal interstitium is not seen on CXR unless is diseased.  Four patterns of interstitial lung disease:  Linear.  Reticular.  Nodular  Reticulo-nodular  End stage pattern of interstitial lung disease = honeycombing.  Small sub-pleural cystic changes of the lung parenchyma.  Most prominent in the lower lung lobes.  Nonspecific finding represent end stage ILD secondary to several underlying pathology.

 Linear pattern:  Thickened interlobular septa.  Called kerley A and B lines:  kerley A lines:  Long lines(2-6cm).  Centrally located radiating from hila.  More common in upper and mid lung fields.  Kerley B lines:  Short (1-2cm).  Peripheral sub-pleural location.  More common in lower lung fields.  Common etiology:  Pulmonary edema: most common etiology.  Interstitial pneumonia-viral or mycoplasma.  Lymphangitis carcinomatosis.

 Reticular pattern:  Result from summation of irregular linear opacities.  Usually associated with low lung volumes.  Classic example:  Idiopathic pulmonary fibrosis.  Asbestosis.  Scleroderma.

UIP

 Nodular pattern:  Numerous small nodules (1mm-10mm in diameter).  Miliary pattern: small nodules 1-2mm in diameter.  Classic examples:  Miliary TB.  Sarcoidosis.  Silicosis.  Metastasis from thyroid, kidney, …

 Characterization of focal lung pathology:  Size:  Nodule( 3cm).  Number:  Single vs. multiple.  Cavitation:  Presence and thickness of the cavity.  Calcifications:  Presence and pattern of calcifications.  Margins:  Rounded vs speculated.

 Bronchogenic carcinoma:  Adenocarcinoma:  Most common.  Peripherally located.  Broncho-alveolar carcinoma is a subtype.  Squamous cell carcinoma:  Second most common type.  Strong smoking association.  Centrally located.  Most likely to cavitate.  Large cell carcinoma:  Rare type, peripherally located tumor.  Small cell carcinoma:  Strong smoking association.  Centrally located.  Very poor prognosis.

Hamartoma

 Pleural effusion:  Accumulation of transudate or exudate fluid in the pleural cavity.  Signs of pleural effusion:  Blunted costo-phrenic angle.  Meniscus sign.  Opacification of hemithorax.  Loculated effusion:  Usually seen in empyema or malignant effusion.  Failure of layering on decubitus film.  CT may show split pleural sign.

When cc of fluid accumulate in pleural space, the usually acute costo-phrenic angle becomes blunted Normal R costophrenic angleBlunted L costophrenic angle

Meniscus Sign l Pleural fluid tends to rise higher along its edge producing a meniscus shape medially and laterally l Usually only lateral meniscus can be seen l The meniscus is a good indicator of the presence of a pleural effusion

 DDX:  Total lung collapse/ atelectasis.  Entire lung consolidation.  Large pleural effusion.  Post pneumonectomy.

Opacified hemithorax l In atelectasis, there is s shift toward the side of the opacification. l In pleural effusion, there is a shift away from the side of the opacification. l In pneumonia, there is no shift. l In pneumonectomy, the 5 th rib is usually absent.

 Mediastinal masses can be differentiated from lung parenchymal lesions by their smooth contour since they are covered by parietal pleura.  The mediastinum is divided anatomically into four compartments:  Superior.  Anterior.  Middle.  Posterior.

 Superior mediastinum:  Located between the thoracic inlet and a line connecting sterno-manubrial joint with T4 body.  DDX of superior mediastinal mass:  Lesion extending from the neck e.g. thyroid mass, cystic hygroma.  Lymphadenopathy.  Vascular abnormalities e.g. aneurysm.

 Anterior mediastinum:  Also known pre-vascular space.  Located between the stenum anteriorly and pericardium and great vessels posteriorly.  It contains lymph nodes and thymus.  DDX of anterior mediastinal mass are:  4 T’s  Thymoma  Teratoma  Thyroid  Terrible lymphoma.

Lymphadenopathy

Thymoma

 Middle mediastinum:  Also known vascular space.  Located between the anterior and posterior mediastnum.  Contains the heart, pericardium, trachea and major arteries and veins.  DDX of middle mediastinal masses:  3 A’s.  Vascular/ aneurysm.  Lymphadenopathy.  Congenital lesions.

 Posterior mediastinum:  Post vascular space.  Located posterior to the heart and anterior to the spine.  Content: descending aorta, esophagus, sympathetic chains and lymph nodes.  DDX of posterior mediastinal masses:  Neurogenic tumors-most common.  Others e.g. lymphoma, descending aortic aneurysm, esophageal varices, hiatal hernia,..

 Usually results from congestive heart failure.  It may/ may not be associated with cardiomegaly.  Other causes of pulmonary edema includes:  Renal failure.  fluid overload.  Two types of pulmonary edema:  Interstitial pulmonary edema.  Alveolar pulmonary edema.

Congestive Heart Failure Four Signs of Pulmonary interstitial edema l Thickening of the interlobular septa: n Kerley B lines l Peribronchial cuffing: n Wall is normally hairline thin l Thickening of the fissures l Pleural effusions

Peribronchial Cuffing l Bronchial wall is usually not visible l Interstitial fluid accumulates around bronchi l Causes thickening of bronchial wall l When seen on end, looks like little “doughnuts” l Meaningful when seen distal to hilar area

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Fluid in The Fissures l Fluid collects in the subpleural space n Between visceral pleura and lung parenchyma l Normal fissure is thickness of a sharpened pencil line l Fluid may collect in any fissure n Major, minor, accessory fissures, azygous fissure

Fluid in the minor fissure

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Congestive Heart Failure Pulmonary alveolar edema l Fluffy, indistinct patchy densities l Outer third of lung frequently spared n Bat-wing or butterfly configuration l Lower lung zones more affected than upper

75154 slides 75 Pulmonary Edema Minor fissure

 Normal cardiothoracic ratio is less than 50%.  Several entities may cause apparent cardiomegaly:  Portable AP view.  Obesity.  Ascites.  Pectus excavatum.

Cardio-thoracic Ratio <50%

 Two forms of TB:  Primary:  Usually is a disease of childhood.  Usually resolves without trace or may leave Ghon complex.  Usually mild consolidation associated with unilateral hilar and mediastinal lymphadenopathy.  Reactivation TB:  Ill-defined opacity associated with cavitation and satellite lesions.  Affects mostly posterior segment of the upper lobes or superior segment of the lower lobes.

TB

 Includes:  COPD.  Emphysema.  Chronic bronchitis.  Bronchiactasis.  Cystic vs. cylindrical.  Focal vs. diffuse

l There are two layers of pleura- parietal and visceral-the pleural space between them. l Normally there is no air in the pleural space.  The visceral pleura is inseparable from the lung parenchyma and moves with the lung. l When air enters the pleural space, the parietal and visceral pleura separate making the visceral pleura visible l The thin white line of the visceral pleura is called the visceral pleural white line l You must see the visceral pleural white line to make diagnosis of pneumothorax

A pneumothorax will be visible as a thin white line - the visceral pleural white line

89154 slides Enlarged Retrosternal Air Space Flattened Diaphragms Bullous Emphysema 89

Skin fold vs. Pneumothorax l A fold of the patient’s skin may become trapped between the patient and cassette l Skin folds are common n Especially in patient’s who have lost a great deal of weight l This skin fold can mimic a pneumothorax

The key difference is that a skin fold is an edge consisting of a density (light) and then a lucency (dark) Skin Fold Dense Lucent This is an edge

Whereas the visceral pleural line is a thin white line with a lucency (darker) on both sides of it Pneumothorax Lucent Dense Lucent This is a line

Skin Fold Pneumothorax

Types of Pneumothoraces l Two major types of pneumothorax n Simple: n In a simple pneumothorax, there is no shift of the heart or mediastinal structures (trachea). n Air in left hemithorax balances the air in the right hemithorax. n Tension: l Progressive loss of air into pleural space causing a shift of the heart and mediastinal structures away from side of pneumothorax l Opposite lung is compressed l Respiratory function severely compromised

Tension pneumothorax