Introduction: Identification of ischemic penumbra in acute ischemic stroke is essential to acute therapeutic interventions. Positron emission tomography (PET) is the only technique that provides accurate, quantitative measurement of cerebral blood flow and metabolism in human. However, PET with the conventional 3-step technique requires relatively long time for the examination. Since October 2006, we have been ready to perform PET with a faster technique (a rapid dual autoradiographic method PET, rapid DARG-PET) 1) in patients with acute ischemic stroke within 24 hours after the onset. Total examination time is approximately 25 minutes in the rapid DARG-PET. We examined serial changes in a patient with severe carotid artery stenosis by use of the rapid DARG-PET. Case Presentation A 60-year-old man was admitted for mild dysarthria and right hemiparesis. Diffusion-weighted magnetic resonance imaging (DWI) on admission showed high signals in the territory of the left middle cerebral artery (MCA). A rapid DARG-PET, performed 12 hours after the onset, showed slight reduction in cerebral metabolic rate of oxygen (CMRO2) and cerebral blood flow (CBF) in the area corresponding to the high signal lesion on DWI. It disclosed an increase in cerebral blood volume (CBV) without an increase in oxygen extraction fraction (OEF) in the region surrounding the DWI-high signal area. Angiogram on the second hospital-day revealed pseudo occlusion of the left internal carotid artery (ICA) with a main collateral flow through the anterior communicating artery from the right ICA to the left MCA. The second rapid DARG-PET examination performed two weeks later, revealed normalization of increased CBV. It was hypothesized that, in an acute stroke, blood flow supply associated with the collateral circulation is dynamically changing in the area of ischemia, and thus quantitative assessment of ischemic status is important for the patient care. Conclusions: The rapid DARG-PET is able to identify transient changes in cerebral blood flow and oxidative metabolism in patients with acute ischemic stroke. This technique will be useful for further investigation of pathophysiology and hemodynamic status of stroke in man.
|Journal of Cerebral Blood Flow and Metabolism
|Published - 2007 Nov 13