strategies of treatment according to the angiographic characteris- tics of PcomA and Posterior cerebral artery (PCA). Materials and methods Clinical and radiological records of 166 cases of coil embolization treated for a PcomA aneurysm during 11 years were retrospectively reviewed. Twenty one patients with PcomA aneurysm who had initially undergone endovascular treatment and had been identified the occlusion of PcomA on immediate or follow-up angiography were enrolled. We classified PcomA aneurysm according to the characteristics PcomA and PCA (P1) in baseline angiography as followed; Type I was defined as PcomA aneurysm with an absent PcomA and a normal sized P1. Type II was defined as a hypoplastic PcomA and a nor- mal sized P1. Type III was defined as a normal sized PcomA and an absent P1. Type IV was defined as a normal sized PcomA and a hypoplastic P1. Type V was a normal sized PcomA and a nor- mal sized P1. Results Among all cases of PcomA obstruction, 15 cases (71.4%) were type II PcomA aneurysm, 4 cases were type IV, one case was type III and one case was type V. The ischemic events related PcomA obstruction occurred in 3 cases (type II, type III and type IV), which were included in 2 tuberothalamic infarc- tions (type III and type IV) and one cortical infarction in PCA territories (type II). Conclusion In cases of PcomA aneurysm with normal sized PcomA and hypoplastic or absent P1, the surgeon should pay special attention to the obstruction of PcomA and we believe that the size of ipsilateral P1 in baseline angiography might be important factor of ischemic complication related to the obstruc- tion of PcomA. Disclosures J. Ko: None. Y. Kim: None. E-125 MICROEMBOLISM AFTER ENDOVASCULAR COILING OF UNRUPTURED CEREBRAL ANEURYSMS: INCIDENCE AND RISK FACTORS 1 J Park*, 2 D Lee, 1 J Ahn, 1 B Kwun. 1 Neurosurgery, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea, Republic Of Korea; 2 Radiology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea, Republic Of Korea 10.1136/neurintsurg-2015-011917.199 Object To analyze the incidence and risk factors of microembolic lesions on MR diffusion-weighted imaging (DWI) after endovas- cular coiling of unruptured intracranial aneurysms (UIA). Methods We analyzed data obtained from 271 consecutive patients (70 men and 201 women; median age 57 years, range 23–79 years) who presented with UIA for coil embolization between July 2011 and June 2013. Two independent reviewers examined DWI and apparent diffusion coefficient (ADC) maps obtained the following day for the presence of restrictive diffu- sion spots and counted the number of spots. A multivariate anal- ysis was then performed to identify independent risk factors for developing microembolism following coiling of an aneurysm. Results Microembolic lesions were noted in 101/271 patients (37.3%). Results of a multivariate analysis showed that the fol- lowing factors significantly influenced the risk for a microembo- lism: age, diabetes, previous history of ischemic stroke, white matter FLAIR high signal lesions, multiple aneurysms, and inser- tion of an Enterprise stent (all ORs > 1.0 and all P-values < 0.05). Previously known risk factors such as prolonged proce- dure duration, aneurysm size, and decreased antiplatelet function did not show any significant influence. Conclusion The incidence of microembolism after endovascular coiling of UIA was not low. Lesions occurred more frequently in patients with vascular status associated with old age, diabetes and previous stroke. The multiplicity of aneurysms and the type of stent used for treatment also influenced lesion occurrence. Disclosures J. Park: None. D. Lee: None. J. Ahn: None. B. Kwun: None. E-126 FAVORABLE BASELINE CT ASPECTS AND DWI BRAINSTEM IMAGING IN ACUTE BASILAR ARTERY OCCLUSIONS ARE POOR PREDICTORS OF GOOD FUNCTIONAL OUTCOME F Syed*, A Honarmand, D Ban, A Elmokadem, V Daruwalla, M Hurley, A Shaibani, S Ansari. Radiology, Northwestern University, Chicago, IL, USA 10.1136/neurintsurg-2015-011917.200 Introduction Basilar artery occlusions (BAO) are associated with very high morbidity and mortality owing to the eloquent supply of the brainstem and midbrain. Despite the positive endovascular trials for anterior circulation acute ischemic stroke, there remains a clear lack of consensus regarding the optimal method of patient selection for IA treatment especially in the posterior cir- culation (PC). We evaluated the baseline NCCT PC-ASPECTS as well as DWI brainstem scores in acute ischemic stroke patients with BAO prior to IA treatment and their association with final func- tional outcomes. Methods A retrospective study was performed on consecutive cases of basilar stroke patients presenting in the acute setting (<12 h). The inclusion criteria included: presentation <12 h from symptom onset, CTA/MRA verified BAO, and pre-treat- ment imaging with NCCT and MR DWI. Patient demographics, medical comorbidities, time from symptom onset to recanaliza- tion, final recanalization (TICI scale), and clinical outcomes (90 day mRS score) were obtained, accordingly. Two neuroradiolo- gists conducted blinded scoring of PC-ASPECTS for all baseline NCCT based on previously published method. 1 One observer evaluated these baseline MR-DWI studies for brainstem infarcts based on previously published scoring system. 2 PC-ASPECTS were dichotomized into ‡8 (favorable) and <8 (unfavorable) 1 and brainstem DWI was dichotomized to <3 (favorable) and ‡3 unfavorable for primary analysis. 2 Chi-square, Mann-Whitney U, student t test, and Pearson correlation coefficient (r) were used for univariate analyzes as appropriate. For evaluation of inter- rater reliability, Intraclass Correlation Coefficient (ICC) was used. A P value of 0.05). Results Thirty four patients (12 F/22 M; mean age of 63.36 ± 15.48 years) were studied. Among 34 cases, 27 were selected based on CT and MR DWI. Interobserver agreement for baseline PC-ASPECTS assigned to the baseline CT studies was excellent (ICC = 0.93). The median PC-ASPECTS and DWI brainstem scores were 8 and 1.5, respectively. Eighteen out of 34 patients (53%) had baseline favorable PC-ASPECTS. Among 27 cases baseline MR studies, 18 (66%) cases had favorable DWI brain- stem scores. A significant fair inverse correlation was observed between PC-ASPECTS and DWI brainstem scores (r = - 0.43, P = 0.02). Both favorable and unfavorable PC-ASPECTS and DWI brainstem score groups were comparable in baseline characteris- tics, medical history, time from symptom onset to recanalization (P > 0.05). Thirteen patients (38%) achieved final good func- tional outcome. Successful recanalization (TICI 2b, 3) rate was 88% (n = 30); however it was not associated with good func- tional outcomes (P < 0.68). Neither PC-ASPECTS nor DWI Electronic poster abstracts A98 J NeuroIntervent Surg 2015;7(Suppl 1):A1–114