Time of Flight Magnetic Resonance Angiography: A Trap for the Unwary☆

Introduction: Magnetic resonance imaging is now frequently used to image blood vessels. This case illustrates a pitfall of this mode of imaging.

Report: A 6-year-old girl sustained a severe neck injury and subsequently developed a Horner's syndrome. A time-of-flight magnetic resonance scan could be interpreted by the inexperienced as showing an extensive dissection. However, a contrast-enhanced scan confirmed the presence of a localised carotid injury only.

Discussion: Time-of-flight magnetic resonance scanning produces flow voids which can mimic dissection, particularly in high velocity vessels such as the carotid artery. This case is a reminder that whatever imaging modality is used, correct interpretation is essential.