Common and uncommon intracranial arterial anatomic variations in multi-detector computed tomography angiography (MDCTA). What radiologists should be aware of

OBJECTIVES: The aim of this retrospective study was twofold: (1) to show the role of multi-detector computed tomography angiography (MDCTA) in the evaluation of intracranial arterial anatomic variations; (2) to highlight their clinical importance with illustrated example cases. MATERIALS AND METHODS: One thousand seven hundred thirty-nine patients who underwent carotid and/or cerebral CTA using a 16-row multi-detector CT over the last 9 years were retrospectively analysed with attention to the presence of persistent carotid-basilar anastomosis and other intracranial arterial variations. RESULTS: All kinds of persistent carotid-basilar anastomosis were present in our series. The most common was the presence of fetal pCom (23 %). From the other studied anatomic variants, the most common was the presence of a hypoplastic A1 segment. In all cases CTA was an excellent diagnostic tool, providing not only high-resolution angiographic images, but also details of the surrounding structures. CONCLUSIONS: The knowledge of intracranial anatomic variations could be very important for the treatment planning of patients who need neurointervention or to explain uncommon and unexpected clinical findings. CTA can reliably provide this kind of information by depicting intracranial anatomic variations. TEACHING POINTS: • Knowledge of intracranial anatomic variations is important. • Radiologist should be aware of the intracranial anatomic variations. • Computed tomography angiography can reliably depict intracranial anatomic variations.