Cobalt-55 positron emission tomography in recurrent ischaemic stroke

The present study investigates if Cobalt-55 (Co-55) positron emission tomography (PET) allows us to distinguish and detect recent, recurrent strokes in patients who had already suffered a previous infarct in the same vascular territory. Fourteen patients with recurrent strokes underwent a Co-55 PET scan of the brain. Recently infarcted areas, less than 2 months old, had a high Co-55 uptake ratio, whereas infarcts of 6 months to 1 year had an uptake ratio comparable to normal brain tissue. In infarcts older than 2 years the Co-55 uptake ratio was decreased compared to the control values. The evolution in Co-55 uptake ratios with time can be explained by the dynamics of the inflammatory response within the infarct core. Co-55 PET allows to demonstrate stroke recurrence and suggests that single photon emission tomography, using Co-57 as the tracer, could be a more easy alternative to be used in routine neurological practice. (C) 1999 Elsevier Science B.V. All rights reserved.