Abstract WP62: Delayed Appearance of DWI Lesions in Clinically Suspected DWI-Negative Stroke: DWI-CONVERSION Score

Abstract

Introduction: Our aim was to determine the prevalence and factors associated with delayed appearance of DWI lesion among initially DWI-negative clinically suspected stroke patients in the follow-up DWIs during in-hospital care. Method: Among 5271 patients admitted to stroke unit as clinically suspected stroke/TIA within 7 days from symptom onset in our hospital via ER for 2010~2017, we selected subjects based on the following criteria 1) initial negative DWI (n=827), 2) follow-up DWI within 14 days (n=751). Then, we excluded 57 cases (hemorrhagic cases (n=4), cerebral angiography studies between MRIs (n=53)). Finally-included 694 cases were divided into two cohorts for temporal external validation (2010~2015 (n=488) as derivation; 2016~2017 (n=206) as validation). Results: Of 5271 cases, 827 cases (15.7%) showed initial negative DWI. In 694 finally-included cases, 22.5% (n=156) showed delayed appearance of DWI lesion. In derivation cohort, factors showing significant relationship with positive conversion comprised: medical histories such as atrial fibrillation (aOR 6.17, 3.23-12.01); symptoms including objective hemiparesis (aOR 4.39, 1.90-10.32) (Table 1). These factors were used to construct DWI-CONVERSION score (Table 2a). Its c-statistic was 0.813 in derivation cohort and 0.808 in validation cohort, which is significantly higher than that of ABCD2 score in validation cohort (c-statistic=0.678; P<0.01 for comparison; Table 2b). Conclusion: We identified prevalence and clinical factors significantly associated with delayed appearance of DWI lesions in clinically suspicious stroke patients. DWI-CONVERSION score is a simple tool to predict it.