Thoracic Imaging

Thoracic Imaging Chest x-ray Computerised tomography Ultrasound Magnetic resonance imaging New advances MRI not widely used but can show malignancy especially We will look at actual films in the tutorials/practicals

Background Chest X-ray Most common radiological investigation – 40% of all investigations Standard component of a pulmonary examination Systematic review is vital in interpretation of chest x-rays Up to 40% off all radiological investigations are chest x-rays 60% are carried out in the ICU, Sensitivity; 50% of critically ill patients in Icu will have abnormal chest x-ray A systematic review is vital when interpretating x-rays however what order is not critical and you will come across varying orders

Limitations of a chest x-ray 2 dimensional image of a 3 dimensional structure X-ray findings may lag behind other clinical features Normal x-ray does not rule out pathology Dependent on good quality image A chest x-ray forms a piece in the pulmonary examination, should refer to previous x-rays if available and if possible put in context of the other pulmonary findings

Chest x-ray views/types Posteroanterior - PA Anteroposterior - AP Lateral Decubitus

Views PA Standard, radiology dept X-rays posterior to anterior Standing position PA Standard investigation carried out in the x-ray dept Cassette anterior to chest, x-rays shot post-ant from 2 metres away, shoulders abducted to remove scapula Carried out in standing therefore better inspiration

Normal PA

Lung Anatomy (1) aortic arch (2) pulmonary trunk (3) left atrial appendage (4) left ventricle (5) right atrium (6) superior vena cava (7 & 8) diaphragm (9) transverse fissure Transverse fissure – 6th rib laterally Does not estend beyond pulm artery medially Visible in 50%

Views AP Cassette placed behind patient X-rays anterior to posterior Sitting in chair, semi-erect in bed, supine AP marked on film Heart enlarged, poorer inspiration AP Cassette placed behind the patient, portable machine Patient could be sitting in a chair, semi erect in bed, supine in bed. NOTE the patient position will affect the CXR Marked AP on film Heart enlarged often poorer expansion

Normal AP

Views Lateral Localises, shows posterior to heart Side of interest placed against film Decubitus PA on side Small pleural effusions Lateral Helps to localise disease Side of interest placed against film Identifies posterior to the heart and costophrenic recesses Decubitus PA with patient on side Small pleural effusions

vertebrae Heart Norm lateral

Lung Anatomy (1) oblique fissure (2) transverse fissure (3) retrocardiac space (4) retrosternal space Oblique fissure from t4 posteriorly Propeller shaped Differentiation between sides- left is more vertical, has more posterior junction with the diaphragm= does not intersect transverse fissure Left diaphragm is lower and possesses stomach bubble by 2.5cm in 94% population

BASICS Air shows as black solid structures white Too white Too black Too large In the wrong place (Corral et al 1997)

Chest x-ray viewing guide Correct CXR Name Date of birth Date Left and right, marker/stomach How to view Check patient and x-ray details Left or right, markers placed on by radiographer, stomach on left. Heart not always on left

Normal PA Stomach

Patient Position PA, AP, lateral or decubitus view Rotation – Sternal end clavicles equal from vertebral body If AP what position Quality IF AP will have poorer inspiration and larger heart If patient supine will not see pleural effusions very well

Exposure How dark or light a film is Should see vertebral bodies through heart AP will show KV/MAS

Soft Tissues Breast shadows Piercing Air in tissues Tissue folds in obese Medical equipment Breast shadows – mastectomy! Medical equipment, lines (CVP, ICD), endotracheal tube, NG tube, metal implants, pacemakers

Breast shadows

Surgical emphysema

surgical emphysema

Heart valve Pacemaker

ECG ICD ETT

Bony Structures Ribs Scapulae Clavicles Vertebrae Ribs fractures, osteoporosis. Ribs even Scoliosis Scapulae need to be identified so do not confuse when looking at lung fields

#Clavicle

#ribs

Trachea Deviated Carina Artificial airway Trachea – can be pushed or pulled Air filled sacs keep trachea in middle

ETT #Ribs ICD

Mediastinum Deviated Hilar shadows Aortic arch Hilar shadows, pulmonary vasculature and lymph nodes, right side is slightly further out and the left is usually higher by 2 cm, with COPD will get upper lobe diversion Aortic arch may be calcified

Mediastinum - Heart Size No larger than half width of chest Position Two thirds on the left Borders Clear Heart Size, is usually half the width of the chest, is increased with AP picture, and in cardiac disease. Will look smaller if lungs hyperinflated and larger if very poor inspiration Positioned two thirds to the left unless have dextrocardia

Diaphragm Shape Height: right –6rib ant, left – 7 ant Cardiophrenic angle Costophrenic angle Shape Domed, flattened with hyperinflation more domed with poor inspiration or paralysis, gas in stomach Height Right 6 rib ant, left 7 rib anter in 95% of population Left lower because of weigh of heart Bear in mind structures below as stomach can push up occasionally liver can push up, ascites will push up Angles Clear if cardiophrenic poor collapse, if costophrenic blurred pleural effusion

Lung Fields Black with lung markings Other opacity indicated pathology Fissures Zones Air bronchograms Consolidation Lung markings of vessels, absent if a Pneumothorax Pulmonary oedema - bilateral Fissures Right horizontal, present in 80% of PA’s Third thoracic spine, goes down and anteriorly Fluid present? Moved? Oblique on lateral only Zones Upper, above 2nd rib ant Middle, 2-4 rib ant Lower, below forth rib Opacity increased with fluid, consolidation, malignancy

normal

Right upper lobe collapse

Right Lower lobe collapse

Pneumothorax

Pneumothorax

Consolidation

Pleural effusion

Pleural effusion

Right pneumonia

Air bronchogram

Emphysema

Other imaging Computerised tomography Transverse images, cross section Localises masses High radiation dose

Other imaging cont Ultrasound Useful for pleural effusions Good images of heart and valves Loculated pleural effusion

Other imaging cont MRI Malignancy Vascular Congenital abnormalities Tuberculosis May be useful if other imaging not possible

New advances Patient archive communication system Film free radiology Computer use Image enhancement PACS Images stored and generated on computer, allows multiple viewings at once, images can be enhanced, reduces storage and film losses. Useful for teaching as can view radiological reports