{'fraction_non_alphanumeric': 0.0391425908667288, 'fraction_numerical': 0.036346691519105315, 'mean_word_length': 5.509090909090909, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Unruptured Intracranial Aneurysms: Incidence of Rupture and Risk Factors

Backgrounds and Purpose— The authors evaluated the incidence of rupture of unruptured intracranial saccular aneurysm during observation. Methods— Between January 2003 and December 2006, a total of 419 patients with 529 unruptured intracranial saccular aneurysms were observed without treatment. The mean follow-up duration was 905.3 days. Aneurysm size was measured by 3-dimensional CT angiography. Clinical and 3-dimensional CT angiography follow-up were obtained every 6 months. Results— Nineteen aneurysms ruptured during observation resulting in a 1.4% rupture rate per year. A history of subarachnoid hemorrhage (hazard ratio, 7.3; 95% CI, 2.5 to 21.2), posterior circulation aneurysm (hazard ratio, 2.9; 95% CI, 1.1 to 8), and large size were significant independent predictors for aneurysm rupture. Conclusions— Size, history of subarachnoid hemorrhage, and posterior circulation aneurysms were significant risk factors for prediction of rupture of unruptured intracranial saccular aneurysms.