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.