An Introduction to Chest X-rays

1
An Introduction to Chest X-rays

• Dr Sam Carvey
• FY2 N.M.G.H.

2
Why request a CXR?

• SOB
• Chest pain
• Chronic cough
• Trauma
• Line insertion
• NG/NJ tube

3
Normal CXR
11
1
3
7
7
6
2
5
4
9
8
12
10
4

• Trachea
• Right Atrium
• Aortic knuckle
• Left ventricle
• Lung fields
• Horizontal fissure
• Hilum
• Diaphragm
• Cardiophrenic angle
• Costophrenic angle
• Apex
• Anterior rib

5
Lateral CXR

• Used to localise lesions/pathology seen on
  frontal XR. In practice never requested!
• In theory good to have basic understanding as
  helps to understand lobes.
• Might come up in an exam to throw you

6

• Trachea
• Right ventricle
• Left ventricle
• Left atrium
• Hilum
• Aorta

1
4
5
6
2
Horizontal fissure
3
Right oblique
Left oblique
7
Lobes
8
What makes a good CXR?

• 1. PA vs AP
• PA is the most accurate. This stands for
  posterior to anterior. X-ray beams are aimed from
  behind patient to cassette in front from a
  distance of approx 180cm. This results in
  minimally divergent beams.
• Requires patient to stand in front of cassette
  therefore can be difficult for some patients.
• AP (anterior to posterior) films are taken when
  patient is too unwell/frail to stand for PA.
• On AP films the mediastinum in magnified (as
  heart is further away from the cassette and
  closer to the beams)
• Portable/bedside XRs are always AP. The are also
  compromised as patient often cannot take full
  inspiration or may be rotated. The beam is never
  going to be 180cm away!

9

• 2. Inspiration
• XRs should be take during inspiration
• General rule is 6 anterior ribs above the
  diaphragm.
• Shallow inspiration
• Causes
• Pain
• frail/elderly
• unconscious
• Problems
• transverse cardiac diameter may appear
  artificially large
• Vessels can appear crowded at lung bases giving a
  false appearance of infection/collapse

10

• 3.Exposure
• Vertebral bodies should just be visible through
  lower part of cardiac shadow.
• If you cannot see them the film is
  underpenetrated. Lung fields will appear falsely
  white.
• If they are too clearly visible the film is
  overpenetrated.
• 4. Rotation
• Medial end of each clavicle should be equal
  distance from centre of vertebrae.
• Rotation can make manubrium/aorta/vessels appear
  more prominent. This could simulate a
  mass/mediastinal widening.
• 5. Scapula
• Arms should be abducted to remove scapula from
  picture.

11
Method to interpreting a CXR

• Be systematic.
• Sometimes best to comment on a blatantly obvious
  abnormality first if you are confident then start
  with your system.
• Dont forget the boring bits name, type,
  quality of the film especially in the exams!

12
Descriptive terms

• Upper, middle, lower zone
• Zones if youre sure you know which one but often
  impossible from PA alone
• Shadowing
• dense, fluffy, diffuse, nodular, reticular,
  linear
• Lucency - black
• Opaque - white
• Consolidation
• Means a pathological process that fills the
  alveoli with pus/blood/fluid/cells etc
• Most commonly infection
• Pneumonia and consolidation are often used
  synonymously but not strictly true.
• Probably best to say an area of consolidation
  most likely to represent infection
• Silhouette sign
• An intrathoracic lesion touching a border of the
  heart/aorta/diaphragm will obliterate that border
  on CXR.
• Air bronchogram
• Tubular outline of bronchus.
• Usually pneumonia

13

• System Example
• Introduction
• Trachea
• Lungs
• Hilum
• Heart and mediastinum
• Diaphragm
• Bones and soft tissues
• Forgotten areas

14

• Introduction
• Name (if you know it / it is on the film)
• Age
• Male or female? - In the exam you might not
  actually have this info but watch out for breast
  shadows as the examiner might want you to comment
  on this.
• Date
• Type of film (AP, PA, Supine, Portable, Erect)
• Quality (penetration, inspiration, rotation,
  scapula withdrawn)
• So a good opening statement is
• This is a PA chest radiograph of Jane Bloggs,
  taken on the 8/03/11. The penetration is
  adequate, the patient has taken a good
  inspiration and does not appear rotated

15

• 2. Trachea
• Should be central. Deviation can indicate lung
  pathology
• Towards affected side collapse
• Away from affected side mass, pneumothorax,
  pleural effusion
• 3. Lung fields
• Should be equal transradiancy.
• Look for shadows (discrete, generalised,
  consolidation, collapse, effusion)
• Increased translucency? (think pneumothorax,
  bulla, hyperinflation, pulmonary embolism,
  caviating mass)
• Increased opacity? ( think collapse,
  consolidation, effusion, lesion)
• Check cardiophrenic and costophrenic angles and
  apex.
• Horizontal fissure
• Fissure between upper and lower lobe on right.
  Should run from hilum to axilla, approx 6th rib.
  Not always seen. Change in position can indicate
  pathology (eg. collapse)
• Pleura - Check lung markings run to costal edge
  -?pneumothorax

16

• 4. Hilum
• Composed of pulmonary arteries, veins, lymph
  nodes and airways
• Position
• Left is slightly higher than right in majority.
  Occasionally equal. Right should not be higher
  than left. Is the hilum in an abnormal place?
  (eg.pulled up/down by collapse
• Shape and density
• Should be concave and similar appearance
  bilaterally. Enlarged ?HF Bulky ?mass
• 5. Mediastinum
• Check for clear edge
• Should be 30 or less intrathoracic diameter.
• Enlarged? Think aortic dissection, lymph nodes,
  thymus, thyroid, tumour

17

• Heart
• Cardiothoracic ratio should be less than 50.
• ?enlarged think heart failure, cardiomyopathy,
  pericardial effusion
• Is the shape normal?
• Ventricular aneursym? Dilated/hypertrophied
  atrium/ventricle?
• 6. Diaphragms
• Position.
• Right diaphragm should be higher than left by
  approx 3cm although this is very variable.
• Elevated or depressed? Why? Is something pushing
  it down or pulling it up?
• Check for free air under the diaphragm
• Are they clearly defined? If not why? mass?
  Pneumonia?

18

• 7. Bones
• Fractures
• - Fractures in clavicle/ribs could cause
  pneumo/haemothorax!
• Unusual looking bone
• - ?metastases
• Soft tissues
• Breast shadows
• Subcutaneous fat
• Surgical emphysema
• 8. Frequently forgotten areas!
• Apex
• - TB? Pancoasts tumour?
• Behind the heart
• - Malignancy?
• Under the diaphragm
• - Free air!!

19
Practice
20
(No Transcript)
21
(No Transcript)