Can Patients with Metal on the Head Undergo CT Examination?
Yes, patients with metal on the head can safely undergo CT examination, but the type of metal and its location may affect image quality due to artifacts. 1, 2
Types of Metal and Their Effects on CT Imaging
- Titanium implants produce significantly less artifact than cobalt-chrome or stainless steel components, allowing for better visualization of surrounding tissues 2
- Metal components can cause streak artifacts that may impair clinical judgment depending on their composition and location 3
- Most modern CT scanners have metal artifact reduction techniques that can improve image quality when scanning patients with metallic objects 1
- The presence of metal does not significantly increase radiation dose during CT scanning in most cases 3, 4
Safety Considerations
- CT scanning is safe with non-ferromagnetic metals (unlike MRI, where metal can be a contraindication) 1
- For patients with suspected metallic foreign bodies, CT is actually preferred over MRI due to safety concerns 1
- If there is suspicion of a ferromagnetic metallic foreign body in the orbit, an MRI is contraindicated, making CT the appropriate choice 1
- Radiographic screening for metallic foreign bodies is recommended before MRI but not necessary before CT 1
Clinical Applications
- CT remains the first-line imaging technique for head trauma assessment even with the presence of metal, as it can effectively demonstrate scalp, bone, extra-axial hematomas, and parenchymal injury 5
- In trauma settings, CT can be performed with immobilization devices in place, including those with metal components, though plastic components are preferred to minimize artifacts 3
- For orbital or head trauma evaluation, non-contrast thin-section CT imaging with multiplanar reconstructions is typically used, regardless of metal presence 1
Potential Limitations and Solutions
- Metal artifacts may obscure certain areas of interest, particularly when using lower-quality CT scanners or with larger metal objects 2
- Increasing the beam energy (kVp) does not necessarily improve image quality around metal implants 2
- Modern CT scanners often include specialized protocols for reducing metal artifacts 1
- In cases where CT image quality is severely compromised by metal artifacts and clinical judgment is impaired, alternative imaging modalities may need to be considered on a case-by-case basis 1, 3
Special Considerations
- For patients with aneurysm clips, CT angiography (CTA) can be used for surveillance but may be limited by metallic streak artifacts 6
- Titanium aneurysm clips produce less artifact than other metals, making them more favorable for post-treatment imaging 6
- For patients with orbital trauma and suspected metal foreign bodies, CT is actually the preferred initial imaging modality 1
In conclusion, the presence of metal on a patient's head is not a contraindication for CT examination. While metal may cause some image artifacts, modern CT technology and proper scanning techniques can minimize these effects in most cases.