Indications for CT Scanning
CT scanning is indicated primarily for major blunt trauma in hemodynamically stable patients, detection of coronary artery disease in symptomatic patients with low-to-intermediate pretest probability, and evaluation of cardiac structure/function when other modalities are inadequate or contraindicated. 1, 2
Major Blunt Trauma
CT plays a critical role in acute trauma management, particularly for patients who are hemodynamically stable 1:
Whole Body CT (WBCT) Indications
Consider WBCT for high-mechanism injuries including 1:
- High-velocity motor vehicle collision (>35 mph)
- MVC with rollover or passenger ejection
- Motorcycle trauma
- MVC-pedestrian collision
- Falls from height >15 feet
Additional factors influencing WBCT decision: patient age, functional status, hemodynamic stability, neurological status, and initial portable radiograph/FAST results 1.
Chest CT Specifics
- Contrast-enhanced CT chest is preferred over noncontrast for suspected chest trauma 1
- More sensitive and specific than conventional radiographs for detecting rib fractures, pneumothorax, hemothorax, and pulmonary contusion 1
- Arterial phase CT warranted when concern exists for aortic or major vessel injury 1
Important caveat: While some studies show survival benefit with WBCT versus selective CT, meta-analyses show conflicting mortality results 1. Clinical judgment remains essential for selective versus whole-body approach.
Abdominal/Pelvic CT
Use IV contrast unless absolutely contraindicated - contrast-enhanced CT has greater sensitivity for detecting visceral organ and vascular injury compared to noncontrast 1.
Cardiac CT Applications
Coronary Artery Disease Detection
CT angiography is appropriate for 2:
- Symptomatic patients with low-to-intermediate pretest probability of obstructive CAD (Class 1 recommendation from ESC guidelines)
- Intermediate CHD risk patients (10-20% 10-year risk) for calcium scoring
- Low-risk patients with family history of premature CHD for calcium scoring
Inappropriate uses: Screening asymptomatic patients with coronary CT angiography, repeat coronary calcium testing, or repeat CT angiography in stable asymptomatic patients 2.
Structural Heart Disease
Appropriate indications include 2:
- Preprocedural planning for heart valve interventions (now established standard)
- Evaluation of coronary anomalies
- Congenital heart disease assessment
- Right ventricular function evaluation
- Left ventricular ejection fraction when other imaging inadequate
- Prosthetic heart valve evaluation
- Myocardial viability assessment when other modalities inadequate/contraindicated
Preoperative Evaluation
- Appropriate for patients undergoing noncoronary cardiac surgery (valve replacement, ASD closure) with intermediate pretest CAD risk 2
- No appropriate indications for noncardiac surgery preoperative evaluation 2
Common Pitfalls to Avoid
- Do not order CT brain for simple headache - less than 2% find abnormalities explaining headache 3
- Avoid screening asymptomatic patients with coronary CT angiography 2
- Do not skip contrast administration in trauma unless absolute contraindication exists 1
- FAST ultrasound is for triage only - positive FAST with hemodynamic instability may lead directly to surgery, but negative FAST does not exclude injury and CT remains necessary 1
Radiation Risk Justification
The benefits of CT outweigh radiation risks in septic patients (90.5% physician consensus), and this principle extends to major trauma where CT is essential for detecting life-threatening injuries 4, 1.