Artefact misinterpretation on CT images of the head

Abstract

In most radiology departments, axial computed tomography (CT) is the standard acquisition mode for routine head examinations. Historically, this practice involved the use of singledetector row machines, and has persisted even with the advent of helical and multidetector row CT systems. Artefacts seen using multidetector row CT systems have been shown to be substantially fewer than a single-detector row machines, and those that were identified were associated with helical scanning. However, artefacts can be seen if the axial scanning mode is used on a multidetector row CT system when one of the detector rows is faulty. It is important for radiologists, CT radiographers, and physicists to be aware of these as they can mimic disease and cause misinterpretation. We report the cases of three patients who underwent emergency head CT examinations that showed artefacts misinterpreted initially as pathological lesions by the radiologist, necessitating further investigations. Although there has been a report of an unknown substance on the collimator assembly causing hypoattenuating artefacts, prior to the present series, there have been no reports of contrast medium spill on the detector and optic assembly causing artefacts.