Chest Imaging and Interpretation

Agenda

  • Administrative updates

  • Discussion on US waivers

  • Review of prior material

  • Systematic reading of chest X-ray (CXR)

  • Introduction of new material on chest imaging

Chest Imaging Objectives

  • Consolidation and pneumonia appearance on CXR

  • Identification and reasoning for pleural effusions

  • Appropriateness of CT scans and IV contrast

  • Common findings in pneumothorax

  • Pathophysiology of tension pneumothorax

  • Contraindications and side effects of IV contrast

  • Radiological findings of pulmonary embolism

  • Recognition of lung abscess and cavitation

  • Findings associated with atelectasis

  • Familiarity with nuclear medicine and ultrasound imaging

  • Understanding cardiac imaging modalities

  • Imaging techniques in chest trauma evaluation

Indications for CXR

  • Age 18-50: Cough with fever, pneumonia history, hemoptysis, dyspnea, trauma, chest pain

  • Smokers >50: Similar indications as above, plus weakness and dizziness

Anatomic Variants

  • Dextroposition: Heart points more to right

  • Dextrocardia: Heart on right side with situs inversus

  • Situs inversus totalis: Organs mirrored from normal configuration

Cardiac Anatomy on CXR

  • Cardiothoracic ratio <50% in normal adults

  • Important cardiac contours visible on frontal CXR

Cardiac Contours and Imaging Modalities

  • Ascending aorta, aortic knob, main pulmonary artery definitions

  • CT for coronary evaluation, wall motion analysis, and myocardial perfusion assessment

  • MRI for anatomical and functional heart imaging

Congestive Heart Failure (CHF) CXR Patterns

  • Interstitial edema: Thickened interlobular septa, peribronchial cuffing, fluid in fissures

  • Alveolar edema: Patchy airspace densities, pleural effusions

  • Cephalization of vessels: Increased vascular prominence in upper lobes

Aortic Aneurysms & Dissections

  • Aneurysms: Defined as vessel enlargement >50% size

  • Aortic dissection: Intimal tear; type A (ascending) and type B (descending)

Pulmonary Embolism

  • Most arise from leg thrombi, Virchow’s triad: hypercoagulability, stasis, trauma

  • High false-negative in CXR; look for Hampton's hump, Westermark's sign

Classification of Parenchymal Lung Disease

  • Airspace disease: Results in opacities, seen commonly with pneumonia

  • Interstitial lung disease: Reticular or nodular patterns without air bronchograms

  • Atelectasis: Volume loss leading to opacity and displacement of fissures,

    • Types: Subsegmental, compressive, obstructive

Chest Trauma Overview

  • Commonly caused by blunt or penetrating trauma

  • Rib fractures indicate potential severe injuries, flail chest as a sign of multiple fractures

Pneumothorax Types

  • Simple PTX: Spontaneous or traumatic; signs include visceral pleural line

  • Tension PTX: Progressive air accumulation, leading to mediastinal shift

Pleural Effusions

  • Normal fluid: 2-5 mL; can be exudates (inflammation, malignancy) or transudates (CHF)

  • CXR findings: Blunted costophrenic angles, meniscus sign

  • Ultrasound can identify pleural fluid and effusion types.