Streak artefact due to leads - anthropomorphic phantom (CT head)
Phantom with no metal around
Here we have the desired head scan with no metal around the patient's head. The phantom has been placed as such.
No obvious streak artefacts from external sources, taking into account the limitations of an anthropomorphic phantom.
Leads next to head
Here the patient has thin monitoring leads next to the head (common in an inpatient situation).
Note: obvious streaking artefacts due to beam hardening.
Here the patient has more monitoring leads next to the head (common in a trauma situation)
Note: worsening streaking artefacts secondary to beam hardening.
Case Discussion
This is an experimental case using an anthropomorphic phantom to replicate differing scenarios in which leads may be placed next to a patient's head. Even small, thin metallic leads result in artefacts that can compromise image quality. The brain has such a small difference in Hounsfield units between grey and white matter, so these artefacts can significantly degrade the scan.
It is best practice to move the leads away from the head; this often involves placing all monitoring at the 'foot' of the table.
This can be tricky in a trauma situation as the opposite needs to occur for the chest and abdomen. So, most often, some adjusting needs to happen between scans.
In extreme scenarios where the patient's arms would not be moved, a trauma scan can be done "head first" with all equipment at the base of the bed; however, this does mean the airway can be harder to reach as the patient is in the scanner.
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