Tool and TechniquesUnusual enhancement patterns from inadvertent arterial contrast injection during CT angiography
Introduction
A comprehensive imaging protocol for cerebrovascular incidents typically includes non-contrast computed tomography (CT), CT angiography (CTA) from aortic arch to vertex with or without CT perfusion. Although uncommon, inadvertent arterial cannulation (typically brachial artery in the antecubital fossa) may occur and contrast thereafter injected at a high flow rate into the arterial circulation. When this occurs the normal forward flow of blood can be overcome and undiluted contrast retrogradely fills the arterial tree and may, eventually, flow antegradely to vessels that supply the brain. This, in turn, results in unexpected contrast distribution, density and timing resulting in non-diagnostic studies [1], [2]. More importantly, if undetected, this may be misinterpreted as pathology leading to further unnecessary investigations [3], [4], [5].
To our knowledge, there have only been two case reports describing arterial cannulation in cerebral CT perfusion or CTA [3], [4]. We describe two further cases involving inadvertent arterial contrast injection.
Section snippets
Case 1
A 93-year-old woman presented with headache, left retro-orbital pain and reduced vision in the left eye. The following day, she became confused and developed left-sided facial droop. She underwent comprehensive stroke imaging (Fig. 1). During the perfusion study with 40 mL Omnipaque 350 iodinated contrast at 8 mL/s followed by a saline flush of similar volume and rate, she reported left antecubital fossa cannula site pain during injection. Assuming contrast extravasation, the cannula was
Discussion
Recognition of the enhancement patterns in normal and variant anatomy following inadvertent arterial injection is crucial as they can mimic pathology and lead to delayed or inappropriate treatment [4], [5].
The pattern of enhancement varies depending on the rate of injection, arterial anatomy, the type and timing of the scan. Anatomical variants such as vertebral artery dominance, PICA continuation of vertebral artery, fetal PCOM and bovine aortic arch may result in variation in enhancement
Conclusion
Being aware of the potential for arterial cannulation with subsequent intraarterial contrast administration in CT perfusion and CTA studies as well as the imaging appearance of such studies can avoid delays in appropriate diagnosis and treatment.
Funding
This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.
Declaration of Competing Interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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