False-positive Intracranial Aneurysms on MR Angiography: Incidence and Causes

ABSTRACT

PURPOSE: The purpose of this study is to analyze the incidence and causes of false-positive intracranial aneurysms on MR angiography (MRA). MATERIALS AND METHODS: We retrospectively evaluated 210 cases that were incidentally diagnosed as intracranial aneurysms on MRA. All the cases were confirmed by CT angiography (CTA) or digital subtraction angiography (DSA). We investigated the incidence, location, size, and causes of the false-positive aneurysms on MRA. RESULTS: Of 210 cases, 28 cases were confirmed as false-positive aneurysms. Most of the lesions were located on the middle cerebral artery (n = 9, 7 lesions located in the bifurcation and 2 lesions located in the trunk) and the anterior communicating artery (n = 5). The diameters of most of the lesions (78.6%) were smaller than 3 mm. Causes were junctional dilatation (n = 14), vascular tortuosity (n = 6), normal variation (n = 3) and unknown causes (n = 3). CONCLUSION: Understanding the risks and pitfalls of false-positive intracranial aneurysms determined on MRA would be helpful for improving the diagnostic accuracy of screening MRA and for reducing the number of unnecessary invasive examinations.