Chest Imaging Flashcards
what colour is air on CXR?
black
what colour is fat on CXR?
grey
what colour is soft tissue/ muscle on CXR?
grey/ white
what colour is bone on CXR?
white
what colour is metal on CXR?
bright white
what to check when looking at a CXR?
patients name
CHI
side marker
adequate projection
how do you tell if there is adequate projection on CXR?
PA
ratio of cardiac diameter to horizontal thoracic diameter is <50%
assess scapula
how do you tell if a CXR is adequate inspired?
anterior ends of at least 6 ribs are visible (remember the ribs you can see are posterior)
how do you tell if a CXR if adequately rotated?
medial ends of clavicles equidistant from spinous processes of upper thoracic vertebra
which hila is higher?
left due to the heart
which side of the diaphragm is higher?
right due to the liver
what should the hila look like on CXR?
chevrons ><
if not= bilateral hilar lymphadenopathy
review areas on CXR
- lung apices
- behind the heart
- below the diaphragm
- bone and soft tissues
why do you need to look at the lung apices on CXR?
masses (Pancoast tumour)
pneumothroax
what to look for behind the heart on CXR?
consolidation
masses
hiatus hernia
what to look for below the diaphragm on CXR?
free gas lines tube e.g. NG gastric distension bowel obstruction
what to look for in bones and tissues on a CXR?
fractures masses mastectomy subcutaneous emphysema evidence of previous surgery e.g. axillary clips
how many lobes does each lung have?
left= 2 lobes right= 3 lobes
fissure in the right lung
oblique
horizontal
what causes a lobar collapse?
obstruction of a lobar bronchus
causes of lobar collapse
tumours
aspirated foodstuffs
mucus impacted
why does the lobe collaspe?
air is resorbed, loses volume and collapses
pleural space abnormalities
- pleural effusion
2. pneumothorax
how does a pleural effusion appear on an erect CXR?
pleural fluid collects at lung bases and forms the curved appearance of a meniscus at lung edges blunting the costophrenic angles
what causes a pneumothorax?
rupture of the visceral pleura allows air to rush in from the lungs every time the patient inspires
air accumulates impairing respiratory function
why is tension pneumothorax an emergency?
displaces heart and diaphragm
signs of pulmonary oedema
A (alveolar oedema- batwing opacities) B (kerley B lines) C (cardiomegaly) D (dilated upper lobe vessels) E (pleural effusion)
what is CXR used to confirm the placement of?
endotracheal tubes (ET) nasogastric tubes (NG) central venous lines
where should an endotracheal tube sit?
5cm above carina
malposition of endotracheal tube
past carina
right main bronchus (more vertical at carina)
oesophagus
where should NG tubes sit?
subdiaphragmatic position in the stomach (overlying stomach bubble)
10cm beyond gastro-oesphageal junction
malpositioning of NG tube
remaining in oesophagus
traversing bronchus
intracranial insertion (possible in skull base trauma/ surgery)
where should central venous catheters be placed?
central lines can be inserted via right and left internal jugular or subclavian veins
tip should be at cavoatrial junction
how are peripherally inserted central catheters done?
via cephalic, basilic or brachial veins
malpositioning of central venous catheters
tip to high in proximal SVC (thrombus risk)
tip too low in distal right atrium or ventricle (arrhythmias)
coiled/displaced in vein (IJV/azygous vein)
when is contrast enhanced CT used for pulmonary masses?
assessing tumour size
showing metastases
guided biopsy of peripheral lesion
what is FDG-PET CT used for pulmonary masses?
nodal and distant mets (not brain)
what is a pneumoperitoneum?
perforation of a hollow viscus that results in air in peritoneal cavity
diagnosis of pneumoperitoneum?
erect allowing gas to rise up under the diaphragm(black thin line between diaphragm and subdiaphragmatic structures)
diagnosis of PE
XR
V/Q scan
CTPA
