Abstract
PURPOSE: To explore the capability of amide proton transfer (APT) imaging in the detection of hemorrhagic and ischemic strokes using preclinical rat models. METHODS: The rat intracerebral hemorrhage (ICH) model (n = 10) was induced by injecting bacterial collagenase VII-S into the caudate nucleus, and the permanent ischemic stroke model (n = 10) was induced by using a 4-0 nylon suture to occlude the origin of the middle cerebral artery. APT-weighted (APTw) MRI was acquired on a 4.7T animal imager and quantified using the magnetization transfer-ratio asymmetry at 3.5 ppm from water. RESULTS: There was a consistently high APTw MRI signal in hyperacute ICH during the initial 12 h after injection of collagenase compared with the contralateral brain tissue. When hemorrhagic and ischemic stroke were compared, hyperacute ICH and cerebral ischemia demonstrated opposite APTw MRI contrasts-namely, hyperintense versus hypointense compared with contralateral brain tissue, respectively. There was a stark contrast in APTw signal intensity between these two lesions. CONCLUSION: APT-MRI could accurately detect hyperacute ICH and distinctly differentiate hyperacute ICH from cerebral ischemia, thus opening up the possibility of introducing to the clinic a single MRI scan for the simultaneous visualization and separation of hemorrhagic and ischemic strokes at the hyperacute stage. Magn Reson Med 74:42-50, 2015. © 2014 Wiley Periodicals, Inc.