Endovascular Coil Embolization of Very Small Intracranial Aneurysms paraclinoid ICA aneurysm) that should be treated. Our study, to date, indicated that the results of the endovascu- lar treatment of very small aneurysms performed under daily practice, and did not rationalize the indications of endovascular treatment for unruptured very small aneurysms. There are various limitations to our study. Namely, untreated aneurysms were not registered and imaging follow-ups after embolization were performed using 3D TOF MRA; although most treatable aneurysm remnants can be visualized with reasonable confidence by using high-resolution TOF-MRA (18). The issue that unruputured very small aneurysms of paraclinoid ICA should be treated remains a matter of debate. In conclusion, endovascular coil embolization of very small aneurysms was technically feasible and showed successful initial angiographic results without procedural morbidity and mortality, although two thromboembolic events occurred during the procedure not resulting neurologic deficits. On clinical and MRA follow-up, a good clinical outcome and no recurrence or bleeding of coiled aneurysms was noted. The long-term efficacy of coil embolization and its potential as a standard treatment strategy in very small aneurysms remains to be seen once randomized large trials are performed. References 1. Molyneux AJ, Kerr RS, Yu LM, Clarke M, Sneade M, Yarnold JA, et al. International subarachnoid aneurysm trial (ISAT) of neurosurgical clipping versus endovascular coiling in 2143 patients with ruptured intracranial aneurysms: a randomised comparison of effects on survival, dependency, seizures, rebleeding, subgroups, and aneurysm occlusion. Lancet 2005;366:809-817 2. Nguyen TN, Raymond J, Guilbert F, Roy D, Be′rube′MD, Mahmoud M, et al. Association of endovascular therapy of very small ruptured aneurysms with higher rates of procedure-related rupture. J Neurosurg 2008;108:1088-1092 3. Sluzewski M, Bosch JA, van Rooij WJ, Nijssen PC, Wijnalda D. Rupture of intracranial aneurysms during treatment with Guglielmi detachable coils: incidence, outcome, and risk factors. J Neurosurg 2001;94:238-240 4. Lim YC, Kim BM, Shin YS, Kim SY, Chung J. Structural limita- tions of currently available microcatheters and coils for endovascular coiling of very small aneurysms. Neuroradiology 2008;50:423-427 5. van Rooij WJ, Keeren GJ, Peluso JP, Sluzewski M. Clinical and angiographic results of coiling of 196 very small (< or = 3 mm) intracranial aneurysms. AJNR Am J Neuroradiol 2009;30:835- 839 6. Suzuki S, Kurata A, Ohmomo T, Sagiuchi T, Niki J, Yamada M, et al. Endovascular surgery for very small ruptured intracranial aneurysms. Technical note. J Neurosurg 2006;105:777-780 7. Pierot L, Spelle L, Vitry F; ATENA Investigators. Immediate clinical outcome of patients harboring unruptured intracranial aneurysms treated by endovascular approach: results of the ATENA study. Stroke 2008;39:2497-2504 8. Brinjikji W, Lanzino G, Cloft HJ, Rabinstein A, Kallmes DF. Endovascular treatment of very small (3 mm or smaller) intracranial aneurysms: report of a consecutive series and a meta-analysis. Stroke 2010;41:116-121 9. Cloft HJ, Kallmes DF. Cerebral aneurysm perforations compli- cating therapy with Guglielmi detachable coils: a meta-analysis. AJNR Am J Neuroradiol 2002;23:1706-1709 10. Moret J, Cognard C, Weill A, Castaings L, Rey A. Reconstruction technic in the treatment of wide-neck intracra- nial aneurysms. Long-term angiographic and clinical results. Apropos of 56 cases. J Neuroradiol 1997;24:30-44 [French] 11. Cognard C, Weill A, Spelle L, Piotin M, Castaings L, Rey A, et al. Long-term angiographic follow-up of 169 intracranial berry aneurysms occluded with detachable coils. Radiology 1999;212:348-356 12. Raymond J, Guilbert F, Weill A, Georganos SA, Juravsky L, Lambert A, et al. Long-term angiographic recurrences after selective endovascular treatment of aneurysms with detachable coils. Stroke 2003;34:1398-1403 13. Gallas S, Pasco A, Cottier JP, Gabrillargues J, Drouineau J, Cognard C, et al. A multicenter study of 705 ruptured intracra- nial aneurysms treated with Guglielmi detachable coils. AJNR Am J Neuroradiol 2005;26:1723-1731 14. Campi A, Ramzi N, Molyneux AJ, Summers PE, Kerr RS, Sneade M, et al. Retreatment of ruptured cerebral aneurysms in patients randomized by coiling or clipping in the International Subarachnoid Aneurysm Trial (ISAT). Stroke 2007;38:1538- 1544 15. Murayama Y, Nien YL, Duckwiler G, Gobin YP, Jahan R, Frazee J, et al. Guglielmi detachable coil embolization of cerebral aneurysms: 11 years’ experience. J Neurosurg 2003;98:959-966 16. Nguyen TN, Hoh BL, Amin-Hanjani S, Pryor JC, Ogilvy CS. Comparison of ruptured vs unruptured aneurysms in recanaliza- tion after coil embolization. Surg Neurol 2007:68:19-23 17. Wiebers DO, Whisnant JP, Huston J 3rd, Meissner I, Brown RD Jr, Piepgras DG, et al. Unruptured intracranial aneurysms: natural history, clinical outcome, and risks of surgical and endovascular treatment. Lancet 2003;362:103-110 18. Wallace RC, Karis JP, Partovi S, Fiorella D. Noninvasive imaging of treated cerebral aneurysms, Part I: MR angiographic follow-up of coiled aneurysms. AJNR Am J Neuroradiol 2007;28:1001-1008 Korean J Radiol 11(5), Sep/Oct 2010 541