The pipeline embolization device for the intracranial treatment of aneurysms trial

Abstract

Background and purpose: Endoluminal reconstruction with flow diverting devices represents a novel constructive technique for the treatment of cerebral aneurysms. We present the results of the first prospective multicenter trial of a flow-diverting construct for the treatment of intracranial aneurysms.

Materials and methods: Patients with unruptured aneurysms that were wide-necked (> 4 mm), had unfavorable dome/neck ratios (<1.5), or had failed previous therapy were enrolled in the PITA trial between January and May 2007 at 4 (3 European and 1 South American) centers. Aneurysms were treated with the PED with or without adjunctive coil embolization. All patients underwent clinical evaluation at 30 and 180 days and conventional angiography 180 days after treatment. Angiographic results were adjudicated by an experienced neuroradiologist at a nonparticipating site.

Results: Thirty-one patients with 31 intracranial aneurysms (6 men; 42-76 years of age; average age, 54.6 years) were treated during the study period. Twenty-eight aneurysms arose from the ICA (5 cavernous, 15 parophthalmic, 4 superior hypophyseal, and 4 posterior communicating segments), 1 from the MCA, 1 from the vertebral artery, and 1 from the vertebrobasilar junction. Mean aneurysm size was 11.5 mm, and mean neck size was 5.8 mm. Twelve (38.7%) aneurysms had failed (or recurred after) a previous endovascular treatment. PED placement was technically successful in 30 of 31 patients (96.8%). Most aneurysms were treated with either 1 (n = 18) or 2 (n = 11) PEDs. Fifteen aneurysms (48.4%) were treated with a PED alone, while 16 were treated with both PED and embolization coils. Two patients experienced major periprocedural stroke. Follow-up angiography demonstrated complete aneurysm occlusion in 28 (93.3%) of the 30 patients who underwent angiographic follow-up. No significant in-construct stenosis (≥ 50%) was identified at follow-up angiography.

Conclusions: Intracranial aneurysm treatment with the PED is technically feasible and can be achieved with a safety profile analogous to that reported for stent-supported coil embolization. PED treatment elicited a very high rate (93%) of complete angiographic occlusion at 6 months in a population of the most challenging anatomic subtypes of cerebral aneurysms.

Fig 1.

Laterally projecting left carotid aneurysm with residual filling after prior coiling. A, Subtracted carotid angiography in the frontal-projection working angle demonstrates residual filling of the aneurysm neck extending into the proximal fundus. B, Unsubtracted frontal projection in the working angle demonstrates a PED in position across the aneurysm neck. No additional embolization coils were added. The gap between the coil mass and PED construct (arrow) indicates the region of residual aneurysm filling. C, Follow-up angiogram in the frontal projection 6 months after treatment shows complete occlusion of the aneurysm. D, A native image in the frontal projection shows that the gap between the coil mass and PED construct has resolved (arrow). This finding indicates that the aneurysm has not only undergone complete thrombosis, but that the thrombus mass has been resorbed in the interim with contraction of the intra-aneurysmal thrombus-coil mass complex around the outside of the construct.

Fig 2.

Dysplastic wide-neck partially thrombosed aneurysm arising from the proximal cavernous segment of the internal carotid artery. A and B, 3D images reconstructed from rotational angiographic source data demonstrate that the neck of the aneurysm incorporates >180° of the vessel circumference over a 10-mm segment of the carotid artery. C, Conventional angiography in the lateral working projection depicts the partially thrombosed wide-neck aneurysm arising from the circumferentially diseased segment. Just proximal to the aneurysmal segment is a mild focal stenosis (arrow). D, Native image in the lateral working-angle projection after treatment demonstrates the Pipeline construct in place across the aneurysm neck, with a loose packing of the aneurysm with embolization coils. E, Follow-up angiography at 180 days in the lateral working projection shows total occlusion of the aneurysm as well as complete anatomic remodeling of the diseased parent artery. The dysplastic aneurysmal vascular segment now has a smooth tubular configuration. The proximal stenosis has also completely remodeled and now is normal in caliber.

Fig 3.

Left ICA parophthamalic-segment aneurysm in a patient with progressive ipsilateral vision loss. A and B, 3D reconstructed images from rotational source data show a very large wide-neck aneurysm arising from the parophthalmic segment of the left ICA. C, Initial angiogram in the frontal working projection demonstrates a very large aneurysm arising from the left ICA. D, Following reconstruction with a PED, filling of the aneurysm with contrast is diminished because flow has been redirected along the normal course of the ICA and into the left anterior circulation. The patient emerged from general anesthesia with an improvement in left-eye vision. E, A native image depicts the PED construct in position across the aneurysmal segment. F, Subtracted image from the 6-month follow-up angiogram shows anatomic reconstruction of the parent artery with complete aneurysm occlusion. G, Axial CT image at the level of the optic chiasm before treatment demonstrates the peripherally calcified fundus of the very large left ICA aneurysm projecting into the suprasellar cistern. H, Six-month follow-up axial CT image depicts a PED in place within the parent ICA with complete resolution of the aneurysm-thrombus mass. The suprasellar cistern, which was formerly effaced by the aneurysm, now appears normally filled with CSF. These serial images depict the physiologic progression that is possible in some cases after PED reconstruction—starting with mechanical flow diversion, progressing to physiologic aneurysm thrombosis and complete occlusion, followed by endoluminal parent artery reconstruction and, ultimately, anatomical restoration with resolution of the aneurysm-thrombus mass and dissipation of the regional mass effect.