Resuscitation 96 (2015) 1–8 Contents lists available at ScienceDirect Resuscitation jou rn al hom ep age : w ww.elsevier.com/locate/resuscitation Clinical paper Repeated diffusion weighted imaging in comatose cardiac arrest patients with therapeutic hypothermia  Chun Song Youn a , Kyu Nam Park a,∗ , Jee Young Kim b , Clifton W. Callaway c , Seung Pill Choi d , Jon C. Rittenberger c , Soo Hyun Kim a , Sang Hoon Oh a , Young Min Kim a a Department of Emergency Medicine, Seoul St. Mary’s Hospital, College of Medicine, The Catholic University of Korea, 222 Banpo-daero, Seocho-gu, Seoul 137-701, Republic of Korea b Department of Radiology, Yeouido St. Mary’s Hospital, College of Medicine, The Catholic University of Korea, 222 Banpo-daero, Seocho-gu, Seoul 137-701, Republic of Korea c Department of Emergency Medicine, University of Pittsburgh School of Medicine, Iroquois Building, Suite 400A, 3600 Forbes Avenue, Pittsburgh, PA 15261, United States d Department of Emergency Medicine, Yeouido St. Mary’s Hospital, College of Medicine, The Catholic University of Korea, 222 Banpo-daero, Seocho-gu, Seoul 137-701, Republic of Korea a r t i c l e i n f o Article history: Received 16 March 2015 Received in revised form 13 June 2015 Accepted 25 June 2015 Keywords: Cardiac arrest Hypothermia, Induced Magnetic resonance imaging Prognosis Coma a b s t r a c t Background: The aim of this study was to evaluate the changing pattern and prognostic values of diffusion-weighted imaging (DWI) at two time points in cardiac arrest patients treated with therapeutic hypothermia. Methods: Twenty two patients with cardiac arrest who underwent two DWI studies were enrolled in the retrospective study. The first DWI was performed after the induction of therapeutic hypothermia (median 6.0 h) and was repeated between 48 h and 168 h (second DWI, median 74 h). Apparent diffusion coefficient (ADC) values were measured in the predefined brain regions, and qualitative analysis was also performed. Good neurologic outcomes were defined as Cerebral Performance Category (CPC) scores of 1 and 2. Results: The ADC value tended to increase over time except the cortical regions of the poor outcome group (N = 10). In the comparisons of receiver operating characteristic (ROC) curve to predict poor outcome using ADC value, postcentral cortex in the second DWI has a better association with neurological outcome (p = 0.001, area under the curve (AUC) = 0.996 for second DWI, AUC = 0.571 for first DWI). In the same analysis using qualitative score, precentral cortex, postcentral cortex, parietal lobe, occipital lobe, caudate and putamen in the second DWI have a better association with neurological outcome. Conclusions: The changing pattern of ADC values after cardiac arrest is different according to anatomic region and neurologic status. The DWI after 48 h has a better association with neurological outcome of cardiac arrest patients in both quantitative and qualitative analysis. © 2015 Elsevier Ireland Ltd. All rights reserved. 1. Introduction Cardiac arrest is a major public health problem and the sur- vival rate of out-of-hospital cardiac arrest (OHCA) is low in both the United States and South Korea. 1,2 Hypoxic brain injury is a major cause of morbidity and mortality after cardiac arrest. 3 Therapeutic hypothermia (TH) or targeted temperature management (TTM) are  A Spanish translated version of the abstract of this article appears as Appendix in the final online version at http://dx.doi.org/10.1016/j.resuscitation.2015.06.029. ∗ Corresponding author. Fax: +82 2 2258 1997. E-mail address: emsky@catholic.ac.kr (K.N. Park). well known to improve survival and neurological outcome after cardiac arrest by improving recovery from ischemic–reperfusion injury. While the optimal target temperature is unknown, TTM at a temperature ≤36 ◦ C is recognized as standard care. 4–6 Diffusion-weighted imaging (DWI) can detect early global ischemic brain injury and can predict neurological outcome. 7–13 DWI provides quantitative assessment of the severity of brain damage through measuring the apparent diffusion coefficient (ADC). 11–13 In ischemic infarction, the apparent diffusion coeffi- cient decreases within minutes to hours after symptom onset; 14,15 however, in global ischemia, ADC reduction is delayed, and the restricted diffusion may not be apparent during the initial hours after the return of spontaneous circulation (ROSC). 8,10,16 http://dx.doi.org/10.1016/j.resuscitation.2015.06.029 0300-9572/© 2015 Elsevier Ireland Ltd. All rights reserved.