chest radiology

1. Chest Imaging

2. Densities
•
•
•
•
•
Four densities on XR
Black – air/gas
Dark grey – fat
Light grey – fluid/solid organ
White – bone/calcium
Increasing
opacification

3. CXR
• Rule No 1! – always check name of patient
and date
• Check orientation (L & R labeled correctly)
• Projection (PA or AP, lateral, decubitus,
supine)
• Accurate assessment of heart size and
mediastinum on PA views
• All supine/portable - AP

4. CXR - systematic
• ABCDE for both frontal & lateral projection
• A – airways
– Trachea/central bronchi midline or just to right, no narrowing, carinal
angle <90°
• B – breathing/lungs
– Parenchyma – too white or too black?
• Look at the fissures
– Bones – ribs, vertebrae, humeri clavicles, scapulae – for fractures,
lytic(black), sclerotic (white) lesions, vertebral body heights
• C – cardiac/vessels
– Cardiac silhouette & Mediastinum contours & width
– Hilum – normal hilar shadow made up of vessels, Lt is higher than right
by 0-2.5 cm. Must have concave shape
– Pulmonary vessels – upper zone vessels vessels smaller than lower

5. CXR - systematic
• D – look under the diaphragm
– free gas – perforated viscus
– Costophrenic angle for pleural effusion
• E – extremities
– The corners of the film
• Line position
• Hidden areas: lung apices, behind the heart,
breast shadows, paravertebral, thyroid

6. Normal CXR
Trachea
Aortic Arch
Rt Mainstem
bronchus
Pulm artery
RA
Pulm artery
Atrial
appendage
LV
Diaphragm
stomach

7. Normal CXR
Trachea
Pulmonary
artery
Aortic arch
LA
RV
LV
Costophrenic
angle

8. Anatomy
RUL
LUL
ML
RLL
LLL

9. Heart
• Cardiothoracic ratio (CTR)
– <50% adults
– PA film – AP magnifies heart
– Causes of increased CTR
• Obesity, pectus, portable film, cardiomegaly,
pericardial effusion
• Shape
• Valve calcification

10. Lungs
• Too black
• Too white
– Opacity, density, infiltrate, mass/nodule
• Alveolar air cells
– Normally contain air (black)
– Cells eg infection/inflam pus, tumour, eosinophils
– Fluid eg aspiration, drowning, oedema, haemorrhage
• Interstitial
• Collapse V consolidation
– Volume loss: mediastinal shift, fissures, diaphragm,
hilum, rib crowding
– Air bronchograms

11. Silhouette sign
• When air in alveoli replaced with fluid/cells
contrast between the lung and the
neighbouring structure (heart, diaphragm) is
lost and borders become indistinct.
• Use the silhouette sign to determine which
lobe of the lung consolidation is in.

12. 14 y M

13. Hx: 61 y M SOB

14. 10 y F bilateral crackles. No response to ventolin

15. Hx 60 y M, chronic cough, haemoptysis

16. Hx 12 Y F fever & cough

17. Hx: 5Y M reduced air sounds left chest, decrease O2 sat

18. Hx 23 F confusion

19. 66 Y F SOB

20. FHx: 54 y M SOB

21. Hx 41 Y F

22. Hx 16 Y M known malignancy

23. Hx: 88 Y M fever weight loss

24. Hx 78 Y F previous rectal cancer

25. The Black Lung
• First consider Rotation:
– (look at the clavicles)
– The lung closer to the film plate will absorb
more of the x-rays and so be whiter, whilst the
lung further away allows distance for scattered
rays to get through, and so will be blacker

26. 9 y M Wheeze

27. 23 y M

28. 21 y M chest pain

29. 20 Y M

30. 87 y M SOB
pseudopneumothorax

31. Pulmonary embolism
• Abnormalities seen on CXR in PE
–
–
–
–
–
–
–
–
MORE OFTEN NORMAL – never forget this!!
Segments/subsegments of linear atelectasis
Raised hemidiaphragm
Focal region of hyperlucency (oligaemia)
“Westermark’s sign” – black area of lung seen in
only 2%
Peripheral foci of consolidation (infarction) e.g.
Hampton’s Hump. <10% show infarction.
Dilated central arteries due to arterial hypertension.
Abrupt cut-off of a vessel – only if in the central
arteries
Pleural effusion

32. 38 y M

34. Pleural Plaques
• Associated with asbestos exposure
• Thickening of the parietal pleura which
calcifies, especially seen over the
diaphragmatic surface as dense linear
bands.
• Does NOT equal asbestosis, which is
pulmonary parenchymal disease related to
asbestos exposure
– can occur together.

35. 77 y M

36. • Hilar Enlargement
– unilateral or bilateral
– Look for the convex contour
• Neoplasm:
– central bronchogenic tumour itself, or lymphadenopathy. e.g. Ca
Bronchus, lymphoma, Lymphangitis carcinomatosis
•
•
•
•
•
Infective e.g. TB (usually unilateral), Mycoplasma, Viral in children
Sarcoidosis rarely unilateral, very symmetrical
Post-stenotic dilatation of pulmonary artery
Pulmonary artery aneurysm (very rare)
All causes of pulmonary arterial hypertension: primary (idiopathic) or
secondary e.g. COAD, long- term PE, chronic left to right cardiac
shunt.

37. Mediastinum
•
•
•
•
•
•
•
When reviewing CXR, don’t forget this
region, which contains the oesophagus,
the trachea, the aorta, the thymus
Differential Diagnosis of an anterior
Mediastinal mass: “The 4 Ts”
Thymoma
Thyroid goitre
Teratoma
Terrible Lymphoma
Assessing the mediastinal width after
severe road trauma is important to assess
for
–
•
aortic rupture. However, these films are
always supine (so AP) so very variable!!
In practice, if the widest part of the upper
mediastinum is >30% of the total thorax
diameter at that level, suspect aortic
injury if clinically possible. However,
NEVER ignore high clinical suspicion
even if the xray seems normal.

38. 14 y M