Radiology Flashcards
Primary signs of fracture on XR
Cortical disruption
Lucency
Impaction sclerosis (esp on weight bearing bones)
Secondary signs of fracture on XR
Lipohaemarthrosis
Haemarthrosis
Soft tissue swelling
Common problems with AP CXR
Mediastinum is widened
Rotation usually in play due to difficult positioning
Poor inspiration esp if flat or intubated
Lateral CXR features
Labelled by side that is closest to cassette
L hemidiphragm has stomach bubble directly under
L oblique fissure more vertical than R
R hemidiaphragm wider than L on L lateral film
R hemidiaphragm complete. L hemidiaphragm incomplete due to cardiac silhouette
Can use lateral decubitus if concern for effusion or PTX and no other imaging modality available. If ?PTX place this side up, if ?effusion, place this side down for best visualisation
CXR assessment of adequacy
Inspiratory effort - 6 anterior ribs on R
Rotation
Angulation - clavicles should overlie posterior 3rd rib
Penetration/Exposure
Poor inspiratory effort CXR - complications
Enlarged mediastinum
Crowding of vessels at lung bases
Rotation on CXR - complications
Hypertranslucecy of ipsilateral lung
Pseudomediastinal mass on R rotation
Aortic arch widened appearance on L rotation
CXR angulation
Craniocaudal beam divergence
Clavicles should project over posterior third rib
CXR penetration
Thoracic vertebrae should be just visible on a PA CXR
Underpenetration common in mobile AP films due to battery power
CXR over penetration complications
Harder to see subtleties
CXR under penetration complications
Pulmonary vessels and interstitium appear more prominent
Detail is lost at the lung bases and the vertebrae
Lung zones
From anterior rib 2 up = upper zone
Ribs 2-4 = midzone
Rib 4 to diaphragm = lower zone
Silhouette signs on CXR
Objects of similar densities will lose their margins when touching each other
RUL forms silhouette with medial pleura of R mediastinum
RML silhouettes to RHB
RLL silhouettes to diaphragm
LUL to LHB and aortic knuckle
LLL to L diaphragm
Silhouette sign CXR pitfalls
Pectus excavatum can cause loss of RHB
Pericardial fat pads
ETT on CXR
Should be 4cm above carina
Can move up and down by 2cm with neck flexion and extension
CVL on CXR
Should be at junction between SVC and RA
Subclavian line may migrate caudally to internal jugular instead of to SVC - increased risk of thrombosis due to decreased size of IJV compared to SVC
If too long can land in RA or RV and cause arrhythmia
Swan-Ganz catheter placement check on CXR
In pulmonary artery - between main pulmonary artery and interlobar artery
Forms a loop on CXR
Should be no more than 2cm from cardiac silhouette
NGT should be at least 10cm past GJ junction at T10
Pacemaker placement check on CXR
Single chamber - RA or RV
Dual chamber - RA and RV
Biventricular or three lead pacemaker - RA, RV and coronary sinus
ICD lead is thicker than pacemaker
RA lead should be anterosuperior on lateral CXR, RV lead should be anteroinferior
Check the leads have a direct course, no fracture and neither taut nor slack
Heart position on CXR
1/3 to the right and 2/3 to the left
RV anterior heart border on lateral CXR
Posterior HB on lateral is LA + LV
Size can vary by 2cm based on insp/exp and systole/diastole
LA enlargement gives subcarinal angle >100’ and a double atria shadow + posterior bulge on lateral
LV or RA enlargement gives prominence of the heart border
RV enlargement appears as filling of the retrosternal space
Signs of pericardial effusion on CXR
Globular heart shape
Straight, well defined heart border
Rapid increase in size
Signs of LHF on CXR
Enlarged mediastinum
Upper lobe diversion
Pleural fluid/increased interstitial markings/Kerley B lines - followed by airspace opacification
Pleural effusion - R precedes L, usually bilateral
L mediastinal borders
LBH:
L subclavian vessels
Aortic knuckle
L pulmonary artery
Auricle
LV
RHB:
R brachiocephalic vessels
R SVC
RA
IVC (not always visible)
How many % of aortic dissections have a normal mediastinal contour?
12%
5 signs of aortic dissection on CXR
Widened mediastinum
Enlarged aortic knuckle (8cm or more is abnormal)
Pericardial effusion
L pleural effusion (16%)
Interval change in size of mediastinal silhouette
Aortic wall calcification displaced from outer margin by >1cm also a sign
Causes of pneumomediastinum
Trauma to airway or oesophagus
Infection
Rupture of alveolus eg diving
Perforated viscous to retroperitoneum
Pneumomediastinum findings on CXR
Lucent halo around heart
“Tubular artery sign” (gas surrounding great vessels)
“Continuous diaphragm” sign (gas at inferior mediastinum)
Subcutaneous emphysema (supraclavicular region)
What is the hilar on CXR?
Pulmonary artery and vein chiefly
Small component bronchi + LN + fat
Features of hilar on CXR
Left should be <2cm higher than right. 5% are same height
Left should never be lower than R
Hila to apex distance should be equal to hila to base distance
Enlargement can be LN or vascular
Unilateral enlargement frequently due to artefact eg rotation/scoliosis but can be due to nodes/cancer
CXR bones
Rib fractures occult 20%
Rib fractures in infants usually lateral and posterior in NAI due to squeezing
Distal clavicle erosion can be due to hyperparathyroidism, RA or post-traumatic osteolysis
CXR review areas
Behind the heart
Hila
Apices
Below the diaphragm
Signs of collapse on CXR
Displacement of:
-fissure
-mediastinum (sometimes)
-hila (sometimes)
Narrowing of spacing between ribs
Elevation of hemidiaphragm
Number of C-spine injuries occult on XR
Up to 20%
Signs of fracture on lateral C-spine XR
Loss of vertical alignment
Disruption of Harris ring at C2
Loss of vertebral body height
Facet joint dislocation?
Check disc height
Anterior soft tissue
-should taper at thoracic inlet
-should be <1/2 the width of the the adjacent vertebral body C1-C4 and <the width of the adjacent vertebral body C5-C7
Hangman’s fracture
C2 - both pedicles are fractured
Sign’s of fracture on peg view
Check lateral processes of C1 match with C2
-if C1 is wider than C2 = Jefferson “burst” fracture of C1
Assess atlanto-axial interval and Atlanta-odontoid interval (if this is abnormal check lateral masses line up, if they do it could just be rotation)
Peg fractures
Type 1 = just the tip
Type 2 = across the base
Type 3 = extends into the body of the C2
Thoracolumbar fracture types
Burst fractures - due to compression
Chance - due to flexion/extension eg lap belt and extend through anterior and posterior aspects
Assessing thoracolumbar spine XR
Check spinous process line is congruent
Check interspinous distance
Check interpedicle distance
Check anterior and posterior vertebral lines
Check anterior and posterior vertebral heights
Check vertebrae for primary signs of fracture
Tibial plateau fractures
80% lateral
Use lateral tibial plateau line
Get oblique view if necessary, or CT
Segond fracture off lateral tibial plateau is pathognomonic (means ACL injury 90% of the time)
Shatzker classification of tibial plateau fractures
1 = lateral split fracture
2 = lateral split fracture + depression of lateral tibial plateau
3 = pure depression of lateral plateau
4 = pure depression of medial plateau
5 = bilateral condyle fracture
6 = lateral split fracture + horizontal component
Patella ligament on lateral XR
Patella length should be roughly similar to infra patella tendon length
High riding patella = patella alta (patella tendon rupture)
Low riding patella = patella baja (quads tendon rupture)
What is Böhlers angle?
A line drawn between the highest point of the posterior articular surface of the calcaneus and the highest point of the anterior process intersects with a line drawn between the highest point of the calcaneal tuberosity and the highest point of the posterior articular surface
Normal is 20-40’
Common complication of taller neck fracture
Avascular necrosis of talar dome
Where is the Lis Franc ligament?
Medial cuneiform to the base of the 2nd metatarsal. On normal XR AP foot the medial base of the 2nd metatarsal aligns with the medial aspect of the intermediate cuneiform. On oblique the medial 3rd metatarsal aligns with the medial aspect of the lateral cuneiform
Which metatarsals most affected in March fractures?
2nd and 3rd
Hills-Sachs and Bankart’s lesions
Hills-Sachs is humeral head
Bankarts is glenoid
AC injury classification and ligaments involved
Grade 1 - AC ligament strain. XR may be normal
Grade 2 - AC ligament disruption. Discontinuity +/- widening of ACJ
Grade 3 - 100% superior displacement of clavicle. Both ligaments disrupted
Neer classification of humeral head fractures
1 - head
2 - greater tuberosity
3 - lesser tuberosity
4 - surgical neck/diaphysis
Radio-capitellum line
Line drawn along centre of radius and extending towards humerus should pass through capitellum on all views
Anterior humeral line
Line drawn down anterior humerus on lateral view should pass through capitellum/trochlea. 1/3 should lie anterior, 2/3 should lie posterior to this line. Can indicate supracondylar fracture
What are McGrigor’s lines?
3x lines used to aid in interpretation of skull XR running horizontally across fadein supra-orbital, infra-orbital/zygomatic and maxillary areas
Large bowel vs small bowel on AXR?
Valvular conniventes in SB
Haustra in LB
Signs of SBO on AXR
Dilated loops >3cm
Valvular conniventes/plicae circulates is SB
Multiple air/fluid levels
String of pearls sign
Paucity of gas in large bowel
Signs of LBO on AXR
Haustra
Dilated loops >5-7cm or 9cm for caecum
Volvulus locations by frequency
Sigmoid > caecum > transverse colon
Volvulus signs on AXR
Sigmoid = coffee bean sign
Caecal = dilated loop in upper abdomen, some SBO likely, paucity of distal large bowel gas
Jefferson fracture
C1 burst fracture commonly due to axial loading injury
