Systematic review of CT and MR perfusion imaging for assessment of acute cerebrovascular disease

BACKGROUND AND PURPOSE: Perfusion imaging sequences are an important part of imaging studies designed to provide information to guide therapy for treatment of cerebrovascular disease. The purpose of this study was to perform a meta-analysis of the medical literature on perfusion imaging to determine its role in clinical decision making for patients with acute cerebral ischemia.MATERIALS AND METHODS: We searched MEDLINE by using a strategy that combined terms related to perfusion imaging with terms related to acute cerebral ischemia and brain tumors. We identified 658 perfusion imaging articles and classified them according to the clinical usefulness criteria of Thornbury and Fryback. We found 59 articles with promise of indicating usefulness in clinical decision making. We devised and implemented a clinical decision making scoring scale more appropriate to the topic of acute cerebral ischemia.RESULTS: Several articles provided important insights into the physiologic processes underlying acute cerebral ischemia by correlation of initial perfusion imaging deficits with clinical outcome or ultimate size of the infarct. However, most articles showed relatively low relevance to influencing decisions in implementing treatment.CONCLUSION: Most perfusion imaging articles are oriented toward important topics such as optimization of imaging parameters, determination of ischemia penumbra, and prediction of outcome. However, information as to the role of perfusion imaging in clinical decision making is lacking. Studies are needed to demonstrate that use of perfusion imaging changes outcome of patients with acute cerebral ischemia.

This study is the culmination of work performed in response to a request for applications submitted by the Neuroradiology Education and Research Fund of the American Society of Neuroradiology (ASNR) for a systematic review of the medical literature regarding the usefulness of perfusion imaging in neuroradiology. The authors were charged with the task of examining the evidence for a substantive role for perfusion imaging in evaluation of the brain with a focus on understanding the place of perfusion imaging in medical decision making. We found that most published work has focused on 2 subjects, cerebrovascular disease and brain neoplasms, and 2 techniques, CT perfusion imaging and MR perfusion imaging. This study presents the results of our meta-analysis solely with regard to cerebrovascular disease. The results of the meta-analysis of perfusion imaging in imaging of brain tumors will be provided in a separate report.The goal of the meta-analysis was to determine the extent to which perfusion imaging figures affect clinical decision making and influence patient outcomes. It is important to note that the goal was not to establish whether perfusion imaging yields important information that advances our understanding of the physiologic processes of cerebral infarction or whether perfusion imaging might provide data that could determine likelihood of success of stroke therapy.