Clinical Insight: CXRs

CXR interpretation. The crux of a Post-Call Ward round, and perhaps the bane of one’s existence. No more.

D – Demographics

Before you even begin interpreting a CXR you should have the correct details, including;

• Patient name, age / DOB, sex

• Type of film – PA or AP, erect or supine, correct L/R marker, inspiratory/expiratory series

• Date and time of study

R – RIPE (assessing the image quality)

Next, the technical quality of the film?

• Rotation – medial clavicle ends equidistant from spinous process

• Inspiration – 5-6 anterior ribs in MCL or 8-10 posterior ribs above diaphragm, poor inspiration?, hyperexpanded?

• Position – straight vs oblique, entire lung fields, scapulae outside lung fields, angulation (ie ’tilt’ in vertical plane)

• Exposure – IV disc spaces, spinous processes to ~T4, L) hemidiaphragm visible through cardiac shadow.

S – Soft tissues and bones

In CXR interpretation it is common to leave soft tissues until the end.

• Ribs, sternum, spine, clavicles – symmetry, fractures, dislocations, lytic lesions, density

• Soft tissues – looking for symmetry, swelling, loss of tissue planes, subcutaneous air, masses

• Breast shadows

• Calcification – great vessels, carotids

A – Airway & mediastinum

• Trachea – central or slightly to right lung as crosses aortic arch

• Paratracheal/mediastinal masses or adenopathy

• Carina & RMB/LMB

• Mediastinal width <8cm on PA film

• Aortic knob

• Hilum – T6-7 IV disc level, left hilum is usually higher (2cm) and squarer than the V-shaped right hilum.

• Check vessels, calcification.

B – Breathing

• Lung fields

  • Vascularity – to ~2cm of pleural surface (~3cm in apices), vessels in bases > apices

  • Pneumothorax – don’t forget apices

  • Lung field outlines – abnormal opacity/lucency, atelectasis, collapse, consolidation, bullae

  • Horizontal fissure on Right Lung

  • Pulmonary infiltrates – interstitial vs alveolar pattern

  • Coin lesions

  • Cavitary lesions

• Pleura

  • Pleural reflections

  • Pleural thickening

C – Cardiac

• Heart position –⅔ to left, ⅓ to right

• Heart size – measure cardiothoracic ratio on PA film (normal <0.5)

• Heart borders – R) border is R) atrium, L) border is L) ventricle & atrium

• Heart shape

• Aortic stripe

D – Diaphragm

• Hemidiaphragm levels – Right Lung higher than Left Lung (~2.5cm / 1 intercostal space)

• Diaphragm shape/contour

• Cardiophrenic and costophrenic angles – clear and sharp

• Gastric bubble / colonic air

• Subdiaphragmatic air (pneumoperitoneum)

E – Extras So, putting these to the test. 3 remarkably straight-forward CXRs.

Pro Tip: These arrows are your friends. Trust in them. Not in actual CXRs though, if that needed to be said.Use the paradigm, and post your interpretations below!

Consolidation

Pneumothorax

Effusion