Comparison of 3D TOF MR angiographic accuracy in predicting Raymond grade of flow-diverted versus coiled intracranial aneurysms

•Sensitivity of 3D MRA TOF is better for coiled than for flow-diverted aneurysms.•3D TOF MRA is inaccurate in detecting small residual necks or slow residual filling.•Contrast-enhanced studies should be considered for follow-up after flow diversion.

The accuracy of 3D time of Flight Magnetic Resonance Angiography (TOF MRA) has been studied extensively for following coiled intracranial aneurysms. It is used by many clinicians for non-invasive follow-up because of its adequate sensitivity in predicting aneurysmal recanalization compared to diagnostic cerebral angiography. The data on the accuracy of 3D TOF MRA for the Pipeline™ Embolization Device (PED) are sparse. In a retrospective chart review, we compared the accuracy of 3D TOF MRA of PED to coil embolization at our institution. 3D TOF MRA had a lower sensitivity and positive predictive value in detecting aneurysmal filling in PED-treated versus coiled aneurysms (57% versus 87% and 80% versus 100%, respectively). Analysis of discrepancies between conventional diagnostic angiography and 3D TOF MRA revealed that 3D TOF MRA was inaccurate in the setting of small residual necks and slow residual filling of the dome with fluid-fluid layers. Therefore, contrasted studies such as contrast-enhanced MRA may be preferred for non-invasively following PED-treated aneurysms to increase accuracy.