Radiology - CHEST Flashcards
How can you distinguish the different densities on a CXR?
Black - air Grey - fat Grey/white - soft tissue/muscle White - bone Bright white - metal
What must you assess to decide whether a CXR is technically adequate?
Projection
Inspiration
Rotation
Penetration
What is the ideal projection for a CXR?
PA radiograph (travels back to front)
Taken with patient standing to have full inspiration and chest flat against detector for minimal rotation
What is the CTR on a PA chest x-ray and what is a normal measurement?
Cardiothoracic Ratio
Ratio of maximal horizontal cardiac diameter to maximal horizontal thoracic diameter (inner edge of ribs/edge of pleura)
Normal = less than 0.5
When should you not measure CTR on a CXR?
AP radiograph
Objects nearer x-ray tube (heart) appear artificially enlarged due to divergence of x-ray beam
Heart appears artificially large on AP radiographs
How can you determine whether there is sufficient inspiration on CXR?
Anterior ends of at least 6 ribs should be visible
How can you determine whether a CXR is correctly centred?
Medial ends of clavicle should be equidistant from spinous processes of upper thoracic vertebrae
What is the Pulmonary Hila?
Hila are junctions between the heart and lungs, and where the pulmonary arteries/veins + bronchi exit/enter the lungs
Which hilum normally lies higher?
The left hilum normally lies higher than the right (left pulmonary artery comes over the bronchus)
On a normal CXR, where does the right diaphragm lie in relation to the left?
Right diaphragm lies about 1.5cm above the left diaphragm
Major deviations from this indicate disease
How are the lungs divided into zones?
Upper, Mid and Lower
Way to compare the right and left if cannot define specific lobes from CXR
Mid = rib 2-5 Upper = above Lower = below
List some common Review Areas?
common areas for missed findings
Lung apices - masses (pancoast tumour), pneumothorax
Behind the Heart - consolidation, masses, hiatus hernia
Below diaphragm - free gas, lines + tubes, gastric distension, bowel obstruction
Bones + soft tissue - fractures, masses, mastectomy, subcutaneous emphysema
Describe the lobes of the lungs
Left - 2 lobes (+ lingula - not separated by fissure, sits next to heart)
Right - 3 lobes
What causes a lobar collapse?
- Occurs when obstruction of lobar bronchus
- Lobe is no longer ventilated and its air gets reabsorbed
- Affected lobe loses volume and begins to collapse
- Density of collapsed lobe increases and adjacent fissures dragged out of position
What are the signs of a Left Lower Lobe Collapse?
- Volume loss on left
- Elevation of hemidiaphragm
- Left hemithorax looks small
- Increased density in left retrocardiac region
- Loss of clarity of medial aspect left hemidiaphragm
- Left hilum displaced upwards
What are the signs of a Left Upper Lobe Collapse?
- Volume loss on left
- Elevation of left hemidiaphragm
- Loss of clarity of heart shadow (can’t make out heart border)
- Diffuse opacification of left hemithorax (veil like opacity)
What are the signs of a Right Upper Lobe Collapse?
- Volume loss on right
- Loss of clarity of upper right mediastinum
- Density in right upper zone, elevation of horizontal fissure
What are the signs of a Right Middle Lobe Collapse?
- Loss of clarity of right heart border
- Density in right lower zone
- Right hemidiaphragm preserved
What are the signs of Right Lower Lobe Collapse?
- Volume loss on the right
- Loss of clarity of the right hemidiaphragm
- Density in right lower zone, depression of horizontal fissure
What are the signs of a combined Right Middle + Lower Collapse?
- Volume loss on right
- Loss of clarity of right hemidiaphragm & right heart border
- Density in right lower zone
- Depression of horizontal + oblique fissure
What pattern does pulmonary consolidation follow?
Consolidation follows same patterns in terms of position/obscuring borders, but without the volume loss
How can infection of the lingula be recognised on CXR?
Causes left heart border to become obscured
What are the signs of Right Middle Lobe Consolidation?
- Increased density in R lower zone
- Loss of clarity of R heart border BUT preservation of R hemidiaphragm
What are the signs of Left Upper Lobe Consolidation?
- Increased density in left upper + lower zone
- Loss of clarity of L mediastinum
- Volume preserved
- Air bronchograms
What is an Air Bronchogram?
Tubular outline of an airway made visible by filling of surrounding alveoli by fluid or inflammatory exudates
What are some causes of Air Bronchograms?
Lung consolidation Pulmonary oedema Severe interstitial disease Neoplasm Non-obstructive pulmonary atelectasis Normal expiration
When is the pleural cavity visible on CXR?
When space is filled with fluid (pleural effusion) or air (pneumothorax)
On an erect CXR dense pleural fluid collects where?
At the lung bases
Forms curved appearance and can blunt edges of costophrenic angles
True or False:
Pneumothorax follows rupture of visceral pleura, allowing air to rush in from lungs when person inspires
TRUE
What is a Tension Pneumothorax?
If large amounts of air accumulates, the pressure will squash the lungs so patient cannot ventilate them
Can displace mediastinum to the opposite side of pneumothorax
Medical emergency –> NEEDS IMMEDIATE DRAINAGE
What are the radiological signs of pulmonary oedema? (in order of occurrence/severity)
- Dilatation of upper lobe vessels/cardiomegaly
- Interstitial opacities (peribronchovascular cuffing, septal lines)
- Airspace opacification (alveoli filling with fluid)
- When severe + acute shows perihilar or ‘batwing’ distribution - Pleural effusion
What is the useful mneumonic to remember radiological principles of Heart Failure/Pulmonary oedema?
ABCDE A - alveolar oedema (bat wing) B - kerley B lines C - cardiomegaly D - Dilated upper lobe vessels E - pleural Effusion
What are the normal positioning landmarks of Endotracheal tubes?
- Tip 5cm above carina
- Width 2/3 tracheal diameter
- Cuff should not expand trachea
What points may suggest malposition of endotracheal tube?
- Tip extend past carina
- Tip may be seen in right main bronchus (most common)
- May have entered oesophagus
What is the ideal positioning of a nasogastric tube?
Subdiaphragmatic position in stomach
(on CXR - overlying gastric bubble)
Should be at least 10cm beyond gastro-oesophageal junction
What are some possible malpositioning of top position?
- Remaining in oesophagus
- Transversing either bronchus or distally into lung
- Coiled in upper airway
- Intracranial insertion
Where can central venous line catheters be inserted?
Via right and left internal jugular or subclavian veins (CVC)
Where can peripherally inserted central catheters be inserted?
Via Cephalic, basilic or brachial veins
Where should the tip of a central venous line be on a CXR?
Cavoatrial Junction
junction of right lateral border of SVC and superior border of right atrium
What risks are associated with malposition of central venous catheters?
Tip too high (i.e. proximal SVC) - thrombus formation
Tip too low (distal RA or RV) - increased arrhythmia risk
What are the different categories of pulmonary growths according to size?
Miliary nodules - <2mm
Pulmonary micronodule - 2-7mm
Pulmonary nodule - 7-30mm
Pulmonary mass >3mm
What is a Pneumoperitoneum?
Abnormal presence of air or other gas in peritoneal cavity
What causes a pneumoperitoneum?
Perforation of a hollow viscus (stomach, duodenum, small or large bowel) results in gas in peritoneal cavity
What investigation can visualise pneumoperitoneum?
ERECT chest radiograph
(position allows gas to rise up under diaphragm)
Easier to see under right diaphragm than left
What is a classical presentation of Pulmonary Embolism?
- Dyspnoea at rest or exertion
- Pleuritic chest pain
- Cough, orthopnoea, haemoptysis
(Caused by DVT = calf/thigh pain and swelling)
What investigations may be done if suspicion of Pulmonary Embolism?
Determine severity - D-dimers
X-ray - look for alternative causes, usually either normal or nonspecific findings
CTPA - look for clot
V/Q Scan - ventilation perfusion scan to check for defects caused by clots
