A 61-year-old man underwent simultaneous PET/MRI 5.5 hours after sudden onset of aphasia (NIH Stroke Scale 4), which revealed a diffusion/perfusion mismatch of different extents as measured with pulsed arterial spin-labeling MRI (59 mL), perfusion-weighted MRI (27 mL), and [15O]H2O-PET (36 mL) (figure). Due to spontaneous recanalization, the penumbra tissue did not progress towards infarction. This demonstrates that the outcome of critically hypoperfused stroke brain tissue may be favorable even without sufficient collateral flow and without therapeutic intervention.1 Here, PET/MRI offers the chance to cross-evaluate MRI-based blood flow estimates against simultaneous PET in acute stroke, which may improve the understanding of stroke pathophysiology.2
Acute middle cerebral artery occlusion. Diffusion disturbance (A) is surrounded by a perfusion deficit of different extents depending on the modality (B–D). Spontaneous vessel recanalization (E, F) prevents infarct growth as detected on follow-up imaging (G). DWI = diffusion-weighted MRI; FLAIR = fluid-attenuated inversion recovery; MRA = magnetic resonance angiography; pASL = pulsed arterial spin-labeling; PW = perfusion-weighted (Tmax >6 seconds).
Footnotes
↵* These authors contributed equally to this work.
Author contributions: Dr. Werner and Dr. Saur: patient treatment/data collection, PET data processing. Dr. Mildner and Dr. Möller: MRI data processing. Dr. Classen, Dr. Sabri, and Dr. Hoffmann: contributed to the revised manuscript. Dr. Barthel: study concept, drafted the manuscript.
Study funding: Supported by the German Research Foundation, which funded the PET/MRI system (grant code: SA 669/9-1). The Max Planck Society co-funded the system.
Disclosure: P. Werner, D. Saur, T. Mildner, H. Möller, and J. Classen report no disclosures relevant to the manuscript. O. Sabri served as primary investigator for Siemens Healthcare. Dr. Sabri received speaker honoraria from Siemens Healthcare. K. Hoffmann reports no disclosures relevant to the manuscript. H. Barthel received speaker honoraria from Siemens Healthcare. Go to Neurology.org for full disclosures.
- © 2016 American Academy of Neurology
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