PubMed · 11661218
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Thomas D Jordan. 1973. Euthanasia.. https://pubmed.ncbi.nlm.nih.gov/11661218/
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BACKGROUND: Learning deficits are prominent among patients with chronic schizophrenia and are associated with poor everyday functioning. Little is known, however, about the brain physiology underlying these difficulties with encoding new information. PURPOSE: The purpose of the current study was to compare the brain response during novel picture encoding between patients with chronic schizophrenia and healthy individuals using functional magnetic resonance imaging (fMRI). METHODS: Nine middle-aged patients with DSM-III-R or DSM-IV schizophrenia and 10 age- and education-comparable healthy individuals were studied. Using fMRI, the blood oxygenation level dependent (BOLD) signal was measured during novel picture encoding (experimental condition) and during presentation of a repeated picture (control condition). Encoding-related brain response was examined in both groups and compared between the patient and comparison groups in each voxel within four bilateral search regions (fusiform gyrus, parahippocampal gyrus, hippocampus, and inferior frontal gyrus). RESULTS: Despite comparable subsequent ability to recognize the presented pictures, patients with schizophrenia showed abnormal encoding-related brain response in regions of the hippocampus and parahippocampal and fusiform gyrii compared to healthy individuals. In medial temporal regions, patients showed greater BOLD response during the control condition (repeated picture) than during the experimental condition (novel pictures). CONCLUSION: Abnormalities of the medial temporal brain systems examined in this study may underlie learning deficits in schizophrenia. Further research is needed to illuminate the role of these brain dysfunctions in poor everyday functioning and their amenability to treatment.
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BACKGROUND: The reproducibility of contrast-enhanced MRI has not been established. We compared MRI reproducibility for infarct size determination with that of (99m)Tc-sestamibi (MIBI) single photon emission computed tomography (SPECT). METHODS AND RESULTS: Patients with chronic myocardial infarction defined by enzymes (peak creatine kinase-MB 173+/-119 U/L) were scanned twice by MRI (MRI I and MRI II, n=20) and twice by SPECT (SPECT I and SPECT II, n=15) on the same day. The MRI contrast agent was injected during MRI I but not MRI II to test the effect of imaging time after contrast. Resting Tc-MIBI SPECT images were acquired and infarct size was determined with commercial software. Infarct size in patients scanned by MRI and SPECT was 14+/-6% of left ventricular mass (%LV) by MRI (range 4%LV to 27%LV) and 14+/-7%LV by SPECT (range 4%LV to 26%LV). MRI I and II scans were performed 10+/-2 and 27+/-3 minutes after contrast, respectively. For MRI, the difference in infarct size between scans I and II (bias) was -0.1%LV, and the coefficient of repeatability was +/-2.4%LV. For SPECT, bias was -1.3%LV, and the coefficient of repeatability was +/-4.0%LV. Within individual patients, no systematic differences in infarct size were detected when the 2 MRI scans were compared, the 2 SPECT scans were compared, or MRI was compared to SPECT. CONCLUSION: The size of healed infarcts measured by contrast-enhanced MRI does not change between 10 and 30 minutes after contrast. The clinical reproducibility of contrast-enhanced MRI for infarct size determination compares favorably with that of routine clinical SPECT.