Diagnostic Imaging, Functional and Laboratory Diagnostics
Imaging modalities
Know the indications, advantages, and limitations of X-ray, ultrasound, CT, MRI, and nuclear medicine. Understand radiation dose principles (ALARA) and when contrast is contraindicated. Recognize classic imaging patterns: pneumonia (consolidation), pneumothorax (absent lung markings), bowel obstruction (air-fluid levels), fracture, and stroke on CT/MRI.
Functional diagnostics
ECG interpretation: rate, rhythm, axis, intervals, ischemia/infarction patterns, arrhythmias. Spirometry: obstructive vs restrictive patterns. Holter monitoring and stress testing indications.
Laboratory diagnostics
Understand reference ranges, preanalytical errors (hemolysis, timing, fasting), and interpretation of common tests: CBC, biochemistry, coagulation, urinalysis, and microbiology. Recognize critical values requiring urgent action.
Traps
- Confusing the best modality for a given clinical question (e.g., MRI for soft tissue, CT for acute hemorrhage).
- Misreading ECG intervals or missing a subtle ischemic change.
- Ignoring preanalytical factors that explain abnormal results.
Rule of thumb
Match the modality to the question: acute bleeding or fracture → CT/X-ray; soft tissue or spinal cord → MRI; gallstones or pregnancy → ultrasound. For labs, always consider preanalytical causes before diagnosing disease.
Worked example
A patient with sudden pleuritic chest pain and absent breath sounds on one side: the correct next step is urgent imaging (chest X-ray or ultrasound) to confirm pneumothorax - not waiting for labs.