Radiographic signs and differentials of conditions

presenting with hypertransradiant hemithorax

Prepared by; Joyce F. Mwatonoka MD5

April 2017

Objectives

• Introduction• Differentials and their radiological signs

Introduction

• Transradiancy or Radiolucency indicates greater transparency to X-ray photons ie ability of material of relatively low atomic number to allow most x-rays to pass through them producing dark images on x-ray film

Cont…

• Hypertransradiant means increase in transradiancy of the lung field

• Unilateral hyperlucent hemithorax - when one side of the chest is more lucent (black) than the other on a frontal chest radiograph

Normal Vs Unilateral Hypertransradiant CXR

Cont…

• It is a common pediatric chest radiographic finding

• When evaluating a patient with this finding it is important to note whether the apparent unilateral hyperlucent hemithorax is truly too lucent or if the contralateral hemithorax is too opaque

Cont…

• Unilateral hypertranslucent hemithorax has many potential causes; but it may be a result of rotation away from an optimal position (technical problem) or because of a pathology

1. Rotation

• The side towards which the patient turns/rotates is hyperlucent due to shorter distance of tissues from x ray source and hence increased x ray transmission;

• Irrespective of whether the CXR has been taken AP/PA

Unilateral hypertranslucent hemithorax due to patient rotation

Cont…

• One can assess patient’s rotation by observing the clavicular heads (sternoclavicular joints) and determine whether they are equidistance from the spinous process of the thorasic vertebrae bodies

2.Pathology

• There are many different conditions which may present with unilateral hypertransradiant hemithorax

• Two mnemonics;a) SAFE POEM b) CRAWLS

a) SAFE POEM

• S: Swyer-James syndrome• A: agenesis (pulmonary)• F: fibrosis (mediastinal)• E: effusion (pleural effusion on the contralateral

side)• P: pneumonectomy/pneumothorax• O: obstruction• E: embolus (pulmonary)• M: mucous plug

b) CRAWLS

• C: contralateral lung increased density, e.g. supine unilateral pleural effusion, unilateral diffused pleural thickening

• R: rotation• A: air, e.g. pneumothorax• W: wall, e.g. chest wall mass

mastectomy, polio, Poland syndrome

Cont…

• L: lungs e.g.airway obstruction; foreign body,

endobronchial tumor, extrinsic masses such as an enlarged nodes/heart

emphysemaunilateral lung transplantation for pulmonary

emphysema Swyer-James syndrome

Cont…

unilateral large bullae large pulmonary embolus Pulmonary agenesis• S: Scoliosis

Contralateral lung increased density

• Here the lucent side is normal and the opposite side is abnormally radiopaque

• Commonest cause is supine radiograph in pleural effusion

Supine radiograph in pleural effusion

• A minimal volume of 175 mL is required to produce notable change on the supine radiograph

• The opacity first projects over the lower lung zones, then the entire hemithorax as the fluid increases

AP supine view of the chest in a 60-year-old man with right-sided effusion. There is asymmetric density with increased haziness in the lower Rt

hemithorax (blue arrow). Note that the pulmonary vascular structures are not obscured or silhouetted by the vague density but, rather, are still visible

through it (open arrow)

Pneumothorax • Visible visceral pleural edge seen as a very thin, sharp

white line• No lung markings are seen peripheral to this line• The peripheral space is radiolucent compared to

adjacent lung• The lung may completely collapse• Mediastinal shift in a tension pneumothorax• Subcutaneous emphysema and pneumomediastinum

(retrosternal space >2.5cm) may also be present

Types

Visible visceral pleura in pneumothorax

Upright CXR demonstrating right pneumothorax. Note the clear visceral pleural line (white arrows) and the lucency in the right chest

White arrows indicate the visceral pleural margin in this expiration view of a patient with

bilateral pneumothoraces

Lateral CXR of pneumomediastinum

Pneumomediastinum

Pneumomediastinum and subcutaneous emphysema associated with pandemic (H1N1) influenza

Tension pneumothorax

Tension pneumothorax

Emphysema

• Pulmonary hyperlucency• Low set flat diaphragm• Increased anterior posterior diameter (barrel

chest)• Vertical heart

PA chest x-ray showing lung hyperinflation in a patient with COPD (emphysema)

Increased AP diameter

Giant Bullous

• Bullae is an air-filled space in the lung parenchyma due to destruction of alveolar tissue, distal to terminal bronchiole

• Giant bulla = bulla >1/3 of the hemithorax size and compression of adjacent lung parenchyma

• Bullae + emphysema = bullous emphysema (can be congenital or complication of COPD)

• Their rupture cause pneumothorax and atelectasis

Cont…

• VLS (vanishing lung syndrome)/Idiopathic giant bullous emphysema

• Characterized by giant emphysematous bullae, which commonly develop in the upper lobes and occupy at least one-third of a hemithorax

• Most affected patients smoke cigarettes

Radiographic features

• Can be non-specific• Bullae occupy > 1/3 of the affected

hemithorax (vary in size 1-20 cm) • May have compress effect to adjacent

structures (lung parenchyma atelectasis, invert the ipsilateral diaphragm or contralateral displacement of the mediastinum)

CXR shows a large lucent area in the right upper zone extending to the middle zone

Cont…

Swyer James Syndrome

• Swyer-James-MacLeod syndrome /Bret syndrome, is a rare lung condition that manifests as unilateral hemithorax lucency as a result of postinfectious obliterative bronchiolitis

• It typically follows a viral respiratory infection such as adenoviruses or Mycoplasma pneumoniae infection in infancy or childhood, and post-transplant patients

Radiographic features

• Hyperlucency of the involved lung or lobe• Decreased vascularity• Small hilum• Decreased volume of the involved lung or lobe• Air trapping on the expiratory radiographs

Inspiratory and expiratory CXR

Foreign body aspiration

• Foreign body radiopaque in 6-20%• Obstructive emphysema/induced

hyperinflation (check valve effect) - expiratory CXRs are more sensitive

• Atelectasis • Pneumonia

X-ray chest shows a radio-opaque foreign body (piece of sharpener blade) inhaled accidentally

by a 3-year-old child

Increased Lt lung volume and hyperlucency, and mediastinum shift to the right on expiratory CXR

Cont…

Cont…

Large pulmonary embolus

• Dyspnoea, chest pain, and haemoptysis have been described as a classic triad in PE

• Westermark's sign: regional oligaemia• Fleishner sign: enlarged pulmonary artery (20%)• Hampton hump: peripheral wedge of airspace

opacity• Pleural effusion (35%)• Knuckle sign

Cont…

Cont…

Other radiological features of PE

Cont…

MastectomyHyperlucent left lung compared to right because of the reduced soft tissue

Mastectomy

Poland syndrome

• It’s a rare birth defect characterized by underdevelopment or absence of the chest muscle (pectoralis) on one side of the body, and usually also webbing of the fingers (cutaneous syndactyly) of the ipsilateral hand

Poland syndrome

Cont…

References;

• Chest Radiology the Essentials 2nd Edition • A-Z of Chest Radiology 2007• Radiopaedia• Medscape• Google images

Thank you for your attention!