Three-dimensional time-of-flight MR angiography at 3 T compared to digital subtraction angiography in the follow-up of ruptured and coiled intracranial aneurysms: a prospective study.

INTRODUCTION: Since digital subtraction angiography (DSA) carries a low risk of morbidity, and is associated with patient discomfort and higher cost, our objective was to determine whether high-resolution 3-D time-of-flight MR angiography (TOF-MRA) at 3 T may replace DSA in the follow-up of patients after coiling of an intracranial aneurysm.
METHODS: This prospective study included 50 consecutive patients with a ruptured and subsequently coiled intracranial aneurysm. All patients were followed up at a mean of 14 months after coiling with DSA and high-resolution 3-D TOF-MRA at 3 T generating 0.02 mm3 isotropic voxels. One examiner used DSA and TOF-MR angiograms to assess the need for and risk of retreatment; these data were used to calculate intermodality agreement. Another two examiners independently assessed aneurysm occlusion by DSA and TOF-MRA according to the Raymond scale; these data were used to calculate interobserver agreement.
RESULTS: Discrepancies between DSA and TOF-MRA were found in three patients (intermodality agreement kappa=0.86). While DSA indicated complete aneurysm occlusion, TOF-MRA showed small neck remnants in the three patients. Coils on all DSA projections obscured these three neck remnants. Interobserver agreement was higher for DSA (kappa=0.82) than for TOF-MRA (kappa=0.68), which was in part due to the complexity of the information provided by TOF source images and reconstructions.
CONCLUSION: 3-D TOF-MRA at 3 T is not only an adjunctive tool but is ready to replace DSA in the follow-up of patients with previously coiled intracranial aneurysms. Additional DSA may only be performed in complex and not clearly laid out aneurysms.