Interpretation of X-ray chest is of immense importance in pediatric practice. Although, sophisticated gadgets are very much used in the day to day practice yet role of conventional radiographic examination cannot be ignored rather still remains the corner stone of basic investigation. Plain and fluoroscopy chest X-ray constitute 80–85% of pediatric study. Other investigations like ultrasonography (USG) (8–12%), computed tomography (CT) (3–5%), magnetic resonance imaging (2–4%), nuclear medicine (2–4%), and vascular and interventional procedure (0.5–1%) contribute the rest. Among plain X-rays, chest X-ray takes its share of 65–70%. So one must know how to read chest X-rays properly and methodically.
ABCS OF INTERPRETING CHEST X-RAY
- A: Abdomen
- B: Bones
- C: Chest
- S: Soft tissues.
Everybody must learn a methodical approach, so that it becomes a routine practice and thus missing findings may be minimized.2
Reading Chest X-ray
- Have a structured method!
- Be consistent with that method
- Please don't take short cuts
- Look at all your patient's X-rays yourself
- Practice…Practice… Practice.
CHEST X-RAY
- Views
- Posterior-Anterior (PA),
- Lateral
- Anterior-Posterior (AP)
- Lateral decubitus.
- Steps of interpretation
- Soft tissue shadows
- Bones
- Domes of diaphragm
- Trachea
- Cardiac silhouette
- Superior mediastinal and hilar shadows
- Costophrenic sulci
- Lung fields.
This approach of reading chest X-ray will be very helpful as missing even subtle findings would be narrow.
Adequacy of a Skiagram
One should be able to count 10 posterior and 6 anterior ribs in supine AP view.
Three main factors determine the technical quality of the radiograph:
- Inspiration
- Penetration
- Rotation.
Inspiration
The chest radiograph should be obtained with the patient in full inspiration to help assess intrapulmonary abnormalities.
At full inspiration, the diaphragm should be observed at about the level of the 8th–10th rib posteriorly, or the 5th–6th rib anteriorly (Fig. 1).
Expiratory film is required to diagnose (Fig. 2):
- Pneumothorax
Penetration
In a properly exposed chest radiograph:
- The lower thoracic vertebrae should be visible through the heart
- The bronchovascular structures behind the heart (trachea, aortic arch, pulmonary arteries, etc.) should be seen.
Prerequisites for Proper Chest X-ray
- Frontal film: Both pedicles of spine and broncho-vascular markings should be visible through cardiac shadow (Fig. 3)
- Lateral film: More caudal thoracic vertebral bodies should appear darker than the cranial ones (Fig. 4).6
Underexposure
In an underexposed chest radiograph, the cardiac shadow is opaque, with little or no visibility of the thoracic vertebrae.
The lungs may appear much denser and whiter, much as they might appear with infiltrates present (Fig. 5).
Overexposure
With greater exposure of the chest radiograph, the heart becomes more radiolucent and the lungs become proportionately darker. In an overexposed chest radiograph, the air-filled lung periphery becomes extremely radiolucent, and often gives the appearance of lacking lung tissue, as would be seen in a condition such as emphysema (Fig. 6).
Rotation
Patient rotation can be assessed by observing the clavicular medial heads and determining whether they are equal distance from the spinous processes of the thoracic vertebral bodies (Fig. 7).8
NORMAL CHEST X-RAY
Now you must learn how to read out a normal chest X-ray. It should be methodical and structured (Fig. 8).9
X-ray chest PA view shows normal soft tissues, visualized bones, and the diaphragm. Trachea is central in position. Cardiac silhouette appears normal. Superior mediastinal and hilar shadows appear normal. Costrophrenic angles are clear. Lung fields are clear. No other significant finding.
Impression: Normal appearance.