CT Without Contrast for Pelvic or Hip Fracture
Yes, CT without contrast is acceptable for evaluating suspected pelvic or hip fractures, though it is not the first-line imaging modality and is less sensitive than MRI for detecting occult fractures.
Initial Imaging Approach
Plain radiographs should always be obtained first for suspected pelvic or hip fractures, as they detect at least 90% of proximal femoral fractures and remain the standard initial imaging 1. The American College of Radiology recommends an anteroposterior (AP) view of the pelvis with a cross-table lateral view of the symptomatic hip 2, 3.
Role of CT Without Contrast
When CT is Appropriate
CT without contrast is reserved as a problem-solving modality following negative radiographs when clinical suspicion for fracture remains 1.
For hemodynamically stable trauma patients, CT with IV contrast of the thoraco-abdomino-pelvis is preferred as it provides a complete inventory of injuries and identifies active bleeding sources 3.
CT without contrast receives an appropriateness rating of 7 out of 9 (usually appropriate) for suspected insufficiency fractures of the pelvis or hip with negative radiographs, though it is explicitly noted as "not as sensitive as MRI but remains a reasonable alternative" 1.
Clinical Utility
CT detects occult hip fractures in approximately 24% of cases when radiographs are negative, with the majority being subcapital (54%) or intertrochanteric (36%) fractures 4.
CT imaging changes patient management in 20% of occult hip fracture cases, with 82% of detected fractures managed operatively 4.
CT with multiplanar and 3D reformations provides precise diagnosis and aids surgical planning for complex pelvic and acetabular fractures 5.
MRI Remains Superior for Occult Fractures
MRI without IV contrast is the preferred second-line imaging modality when radiographs are negative but clinical suspicion persists 1.
MRI demonstrates 99-100% sensitivity for proximal femoral fractures, compared to CT's lower sensitivity 1.
MRI receives an appropriateness rating of 9 out of 9 (usually appropriate) for suspected hip fractures with negative radiographs, while CT receives only 7 out of 9 1.
MRI detects not only fractures but also soft tissue injuries and bone marrow edema, providing comprehensive evaluation 1, 6.
When to Choose CT Over MRI
Practical Considerations
CT is preferable when MRI is contraindicated (pacemakers, certain implants, severe claustrophobia) or unavailable 6, 4.
CT has shorter acquisition times, which is advantageous in the emergency department setting, particularly for elderly patients who may have difficulty remaining still 6.
CT is the gold standard for initial diagnosis in trauma settings and should not be replaced by MRI in acute high-energy injuries 6.
Specific Clinical Scenarios
For stress or insufficiency fractures with negative radiographs, CT without contrast is rated as "may be appropriate" (rating 5-7), but MRI remains strongly preferred 1.
In pregnant patients, MRI without contrast should be performed instead of CT due to radiation concerns (pelvis CT delivers approximately 25 mGy fetal absorbed dose) 1.
Critical Pitfalls to Avoid
Never rely on CT with IV contrast for fracture detection alone—there is no literature supporting contrast-enhanced CT for acute hip fracture diagnosis 1.
Do not skip radiographs and proceed directly to CT unless the patient is hemodynamically unstable from trauma 3.
Recognize that CT may miss subtle fractures that MRI would detect—if clinical suspicion remains high despite negative CT, proceed to MRI 1, 6.
Be aware that increasing the number of X-ray views does not decrease reliance on CT for occult fracture detection 4.
Algorithmic Approach
- Obtain AP pelvis and cross-table lateral hip radiographs first 2, 3
- If radiographs are positive, no further imaging needed for fracture diagnosis (though CT may help with surgical planning) 1
- If radiographs are negative but clinical suspicion high:
- In trauma with hemodynamic instability: immediate pelvic X-ray, then CT with IV contrast if stabilized 3