Background: The aim was to compare digital subtraction angiography (DSA) with magnetic resonance angiography (MRA) in evaluating intracranial aneurysms embolized with Guglielmi Detachable Coils (GDCs) and to assess 3D TOF MRA source data, maximum intensity projection (MIP), and 3D iso-surface reconstruction in the follow-up of patients with cerebral aneurysms treated with GDC.Material and Methods: 3D TOF MRA source data, MIPs, and 3D iso-surface reconstructions of 32 GDC coiled aneurysms were compared with DSA images in the follow-up of 28 patients. Images were assessed for parent and branch artery flow, the presence of neck recurrence, and aneurysm regrowth.Results: In the DSA follow-ups of the 32 aneurysms there was no flow in the embolized aneurysm in 20 (62.5%), flow between the coil loops was found in 11 (34%), and the neck flow was observed in 8 (25%). There was good correlation for all these features when the 3D iso-surface MRA and source data were compared with DSA. The correlation between MIP MRA and DSA was less robust. The correlation was very good in 21 of the 32 aneurysms (65.62%), good in 6 (18.75%), acceptable in 3 (9.37%), and weak and non-diagnostic in 2 (6.25%). Additional information can be obtained by performing plain film x-rays of the skull to demonstrate a change in the coil ball configuration. MRA did not detect any residual aneurysm neck in 2 cases.
Conclusions: MRA is a promising technique to evaluate GDC coiled cerebral aneurysms; however, it cannot substitute DSA.

Keywords: Angiography, Digital Subtraction - methods, Diagnosis, Differential, Embolization, Therapeutic - methods, Intracranial Aneurysm - therapy, Magnetic Resonance Angiography - methods, Regional Blood Flow