Contrast Enhancement of Aneurysm Sac Post-Pipeline Treatment Interpreted as Recanalization

Multiple imaging modalities are available to evaluate aneurysms post-flow diverter (FD) placement. Though digital subtraction angiography (DSA) is the gold standard imaging modality post-FD placement, it is not perfect, and neither are other techniques, including contrast-enhanced magnetic resonance angiography (CE-MRA) and magnetic resonance imaging (MRI). We present a case of a 73-year-old woman with a right internal carotid artery (ICA) aneurysm treated with a pipeline embolization device (PED). Initial follow-up post-PED placement by three-dimensional time-of-flight (3D-TOF) MRA demonstrated aneurysm occlusion, which was confirmed by computed tomography angiography (CTA) and CE-MRA in subsequent follow-up appointments. However, repeat CE-MRA two years later suggested recanalization of the aneurysm. After discussion with neuroradiologists and follow-up with a dynamic MRA, this finding was determined to be false. These findings shed light on the potential pitfall of using CE-MRA alone or any single imaging modality in the assessment of aneurysms post-PED placement. Our case report explores various imaging modalities used in the assessment of aneurysms post-PED placement and highlights the need to use multiple techniques for an accurate assessment.