CO-55-PET IN STROKE - RELATION TO BLOODFLOW, OXYGEN-METABOLISM AND GADOLINIUM-MRI

BACKGROUND: Several studies have shown the feasibility of Co-isotopes (Co-55 and Co-57) in imaging of neuronal damage in stroke, multiple sc lerosis, cerebral tumors and trauma. These studies indicate that Co-is otopes allow visualization of brain pathology related to inflammatory processes, reactive gliosis and cell death. Until now, it is not clear if Co-55 accumulation occurs in the core of infarction or in the penu mbra. Therefore, in the present study, we compared Co-55-PET with func tional parameter such as cerebral bloodflow (rCBF) using (CO2)-O-15, o xygen metabolism (rCMRO(2)) using O-15(2) and cerebral bloodvolume (CB V) using (CO)-O-15 in PET and with the anatomical parameter Gd-MRI. PA TIENTS AND METHODS: Seventeen patients (11 male; 6 female) age 43 to 8 4 (mean 69) with middle cerebral artery (mca) stroke, as proven by CT or MRI, were examined with Co-55-PET (0.5-1.0 mCi (CoCl2)-Co-55), (CO2 )-O-15-, O-15(2)- and (CO)-O-15-PET in one session 0-30 days after str oke-onset. Regions of infarction were defined by rCMRO(2) being smalle r than 65% or rCBF below 45% of the contralateral value and were subse quently superimposed on the cobalt scan. To compare the Cobalt uptake with the Gd-MRI, a realignment program was used that matches the MRI w ith the blood-flow images. Clinical status was established using the O rgogozo stroke scale at admission and at discharge (at least 6 weeks a fter admission) and the Barthel index. RESULTS: Eight patients showed a positive Co-PET scan and were used for further analysis. It appeared that Co accumulates in areas with a diminished oxygen metabolism and with a preserved bloodflow. We found Co-uptake in only a part of the G d enhanced brain tissue with a tendency to be located peripherally or outside the Gd demarcated brain tissue. CONCLUSION: The results of the present study suggest that Co accumulates into infarcted brain tissue with a rather preserved flow independently of blood-brain barrier bre akdown.