Hydrogen-1 magnetic resonance (MR) spectroscopic images of patients with intracranial tumors were obtained. Metabolite maps of N-acetyl aspartate, choline, lactate, and creatine concentrations were reconstructed with a nominal spatial resolution of 7 mm and a section thickness of 25 mm. The metabolite maps showed variations in metabolite concentrations across the tumor. In one patient, it was observed that choline concentration was increased in one part of the tumor but decreased in another part. In another patient, the concentration of N-acetyl aspartate was extremely low in one part of the tumor but only slightly increased in another part of the tumor. Lactate was observed in all patients. In one patient, a combined measurement made with positron emission tomography (PET) and MR spectroscopic imaging was performed. This demonstrated that increased lactate concentration measured with H-1 MR spectroscopic imaging corresponded topographically with increased glucose uptake measured with fluorine-18 fluoro-2-deoxyglucose PET. Combined MR spectroscopic and PET measurements provide an opportunity to investigate, in greater detail than before, glucose uptake and catabolism by intracranial tumors.

70 patients with probable Alzheimer''s disease were randomly allocated to four groups: 17 patients received only social support, 18 cognitive training twice a week, in 17 cognitive training was combined with pyritinol 2 x 600 mg/day and in 18 cognitive training was combined with phosphatidylserine 2 x 200 mg/day. Treatment duration was 6 months. Before and after treatment, the patients underwent neuropsychological testing as well as measurement of the regional cerebral metabolic rate for glucose using positron emission tomography and ¹⁸F-2-fluoro-2-deoxy-D-glucose. Before treatment the groups were comparable in respect to resting and activated glucose pattern achieved by a visual recognition task. Electrophysiological changes were assessed as EEG power, globally and in 4 frequency bands. This 6-month study in four groups of patients with Alzheimer''s disease indicated that phosphatidylserine treatment has an effect on different measures of brain function. Since neuropsychological improvements were best documented after 8 and 16 weeks and faded towards the end of the treatment period, it must be concluded that this symptomatic therapy is mainly of short-term benefit and was overcome by the progressive pathological changes at the end of the treatment period.

MR spectroscopic imaging allows visualization of metabolic changes in stroke with a reasonable spatial resolution.

In the first part of the study, a comparison of 19 patients with Alzheimer''s disease (AD) with 19 age-matched controls was performed to establish diagnostic criteria of AD with positron emission tomography and ¹⁸F-2-fluoro-2-deoxygIucose. Patients had a mean age of 60.6 ± 7.1 years, and a mean score of 14.5 ± 7.3 in Mini Mental Status examination, and of 4.9 ± 0.9 on the Global Deterioration Scale. They fulfilled current research criteria (NINCDS-ADRDA) for probable AD and had been screened rigorously to exclude other potentially dementing conditions, in particular cerebrovascular disease. Regional glucose metabolism was always abnormal in temporoparietal association areas, at least unilaterally, and in most patients also in fronto-lateral association areas. Regional metabolism relative to whole-brain metabolism was always normal in cerebellum, brain stem, and lentiform nucleus, and in most patients also in visual and sensorimotor cortex. A metabolic ratio of typically affected to typically unaffected regions was designed to represent this characteristic pattern. It provided a complete separation of AD patients from normals. In the second part of the study, the diagnostic power of this ratio was tested in an independent sample of 56 patients with a mean age of 59.9 ± 11.3 years. Eight of these patients had subjective memory complaints, but were found completely normal at neuropsychological and clinical examination. Twenty-two had cognitive deficits due to diseases other than AD, among them 7 with cerebrovascular disease, and 26 had probable AD. The classification by the metabolic ratio as AD or non-AD was correct in 85%, with a sensitivity of 92, and a specificity of 80%.

In order to compare the effects of high-frequency stimulation of the subthalamic nucleus (STN-DBS) and a levodopa-challenge on cerebral metabolic activity, we conducted PET scans with [(18)F]2-fluoro-2-deoxyglucose (FDG) in the drug- and stimulation- on- and off-condition in a single patient suffering from advanced PD. Our data revealed evidence for improved thalamocortical processing released from inhibition by overactive basal ganglia output nuclei in both on-conditions. While levodopa also led to a reduction of lentiform hyperactivity, effective STN stimulation seemed to interfere with distinct cerebellar and limbic circuits.