Retrospective Study
Copyright ©The Author(s) 2016. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Radiol. Jun 28, 2016; 8(6): 594-599
Published online Jun 28, 2016. doi: 10.4329/wjr.v8.i6.594
Does computed tomography permeability predict hemorrhagic transformation after ischemic stroke?
Peggy Yen, Allison Cobb, Jai Jai Shiva Shankar
Peggy Yen, Allison Cobb, Jai Jai Shiva Shankar, Department of Diagnostic Radiology, Queen Elizabeth II Health Sciences Centre, Halifax, Nova Scotia B3K 6A3, Canada
Author contributions: Yen P, Cobb A and Shankar JJS performed the research; Yen P and Cobb A collected the data; Yen P and Shankar JJS designed the research and wrote the manuscript.
Institutional review board statement: This study was reviewed and approved by the Nova Scotia Health Authority Research Ethics Board (CDHA-RS/2013-233).
Informed consent statement: The Nova Scotia Health Authority Research Ethics Board approved a waiver of consent form for this retrospective review. Participants were not required to give informed consent for the use of their data.
Conflict-of-interest statement: The authors have no competing interests.
Data sharing statement: No additional data are available.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Correspondence to: Jai Jai Shiva Shankar, MD, Associate Professor of Medicine, Department of Diagnostic Radiology, Queen Elizabeth II Health Sciences Centre, P.O. Box 9000, Halifax, Nova Scotia B3K 6A3, Canada. shivajai1@gmail.com
Telephone: +1-902-4890577 Fax: +1-902-4732018
Received: October 24, 2015
Peer-review started: October 27, 2015
First decision: February 2, 2016
Revised: February 13, 2016
Accepted: March 22, 2016
Article in press: March 23, 2016
Published online: June 28, 2016
Processing time: 238 Days and 15.9 Hours
Abstract

AIM: To use perfusion-derived permeability-surface area product maps to predict hemorrhagic transformation following thrombolytic treatment for acute ischemic stroke.

METHODS: We retrospectively analyzed our prospectively kept acute stroke database over five consecutive months for patients with symptoms of acute ischemic stroke (AIS) who had computed tomography (CT) perfusion (CTP) done at arrival. Patients included in the analyses also had to have a follow-up CT. The permeability-surface area product maps (PS) was calculated for the side of the ischemia and/or infarction and for the contralateral unaffected side at the same level. The cerebral blood flow map was used to delineate the ischemic territory. Next, a region of interest was drawn at the centre of this territory on the PS parametric map. Finally, a mirror region of interest was created on the contralateral side at the same level. The relative permeability-surface area product maps (rPS) provided an internal control and was calculated as the ratio of the PS on the side of the AIS to the PS on the contralateral side. A student t-test was performed after log conversion of rPS between patients with and without hemorrhagic transformation. Log conversion was used to convert the data into normal distribution to use t-test. For the group of patients who experienced intracranial bleed, a student t-test was performed between those with only petechial hemorrhage and those with more severe parenchymal hematoma with subarachnoid haemorrhage.

RESULTS: Of 84 patients with AIS and CTP at admission, only 42 patients had a follow-up CT. The rPS derived using the normal side as the internal control was significantly higher (P = 0.003) for the 15 cases of hemorrhagic transformation (1.71 + 1.64) compared to 27 cases that did not have any (1.07 + 1.30). Patients with values above the overall mean rPS of 1.3 had an increased likelihood of subsequent hemorrhagic transformation. The sensitivity of using this score to predict hemorrhagic transformation was 71.4, the specificity was 78.6, with a positive predictive value of 62.5 and negative predictive value of 84.6. The accuracy was 76.2. The odds ratio of an event occurring with such an rPS was 9.2. Of the 15 cases of hemorrhagic transformation, there was no difference (P = 0.35) in the rPS between the eight cases of petechial and the seven cases of more severe hemorrhagic events.

CONCLUSION: Pretreatment PS can predict the occurrence of hemorrhagic transformation on follow-up of AIS patients with relatively high sensitivity, specificity, positive and negative predictive value.

Keywords: Stroke; Mechanical thrombolysis; Cerebral hemorrhage; Capillary permeability; Thrombolytic therapy

Core tip: Hemorrhagic transformation is one of the most important complications following thrombolytic treatment of acute ischemic stroke (AIS). Predicting hemorrhagic complication at presentation can be useful to clinicians. Perfusion-derived permeability-surface area product maps (PS) may help in predicting hemorrhagic transformation. We investigated whether PS can predict hemorrhagic transformation on follow-up. We found that pretreatment PS can predict the occurrence of hemorrhagic transformation on follow-up of AIS patients with relatively high sensitivity, specificity, positive and negative predictive value. However, it cannot predict the degree of severity, which is critical in the decision to treat.