Abstract
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Objectives To evaluate the feasibility of 18F-Misonidazole (FMISO) PET/CT and 3T MRI early after ischemic stroke. To detect and to locate hypoxic tissues in acute stroke patients with a specific hypoxic cells PET tracer and to compare FMISO PET/CT with 3T diffusion sequence MRI (DWI).
Methods From October 2009 to June 2010, consecutive patients aged > 18 years presenting a first symptomatic hemispheric stroke with NIHSS 5-20/42, were enrolled after signed informed consent. PET were acquired 2 hours after intravenous administration of 3.7 MBq/Kg of FMISO on a Siemens Truepoint 6 PET/CT system. MRI were performed 2 hours after PET on a 3T Philips MRI. FMISO PET were coregistered on DWI MRI. A quantitative analysis was performed. Mean uptake in the normal hemisphere was used as a reference (SUVref). A statistical thresholding method was applied on the infarcted hemisphere. According to literature, hypoxic tissues were defined as all areas with a FMISO PET uptake > SUVref + 3DS.
Results Ten patients were included (6M-4F, mean age 66.5 years, 2 subcortical and 8 large cortical infarcts). FMISO PET/CT were performed in a mean delay of 24 hours after stroke onset (6.5-30.00 h) followed by MRI 120 minutes later (77-300 min). A significant retention of FMISO was observed in 9/10 patients (large areas encompassing all stroke volume in 3, peripheric areas in 6). Areas of increased uptake were mainly included in DWI positive lesions (8/9). In 3/9, these hypoxic areas were associated in the infarct with regions of absent uptake, corresponding to necrosis. No uptake (ie constituted infarct without residual hypoxia) was observed in the infarct for 1 patient.
Conclusions Complementary dual acquisition of FMISO PET/CT and 3T MRI within the first 30 hours after stroke onset appeared feasible. Hypoxic tissues were detected by FMISO in 90% of patients, mainly in DWI positive lesions