Relationship between white matter glucose metabolism and fractional anisotropy in healthy and schizophrenia subjects.

Decreased fractional anisotropy and increased glucose utilization in the white matter have been reported in schizophrenia. These findings may be indicative of an inverse relationship between these measures of white matter integrity and metabolism. We used 18F-fluorodeoxyglucose positron emission tomography and diffusion-tensor imaging in 19 healthy and 25 schizophrenia subjects to assess and compare coterritorial correlation patterns between glucose utilization and fractional anisotropy on a voxel-by-voxel basis and across a range of automatically placed representative white matter regions of interest. We found a pattern of predominantly negative correlations between white matter metabolism and fractional anisotropy in both healthy and schizophrenia subjects. The overall strength of the relationship was attenuated in subjects with schizophrenia, who displayed significantly fewer and weaker correlations in all regions assessed with the exception of the corpus callosum. This attenuation was most prominent in the left prefrontal white matter and this region also best predicted the diagnosis of schizophrenia. There exists an inverse relationship between the measures of white matter integrity and metabolism, which may therefore be physiologically linked. In subjects with schizophrenia, hypermetabolism in the white matter may be a function of lower white matter integrity, with lower efficiency and increased energetic cost of task-related computations.

Use of fMRI to predict psychiatric adverse effects of interferon treatment for Hepatitis C - preliminary report.

Interferon alfa2 (IFN-alpha2) is a parenterally administered cytokine used to treat patients with Hepatitis C and B, and malignancy. Interferon (INF) has a relatively high rate of central nervous system (CNS) adverse effects, including agitation, depression, fatigue, cognitive dysfunction, suicidal thought and drug craving. Using functional magnetic resonance imaging (fMRI) we studied patients with Hepatitis C virus (HCV) infection who were not more than mildly clinically depressed at baseline for their CNS reaction to IFN-alpha2. During fMRI, patients underwent visual stimulation with pictures designed to induce feelings of depression. In the two patients who became clinically depressed or markedly anxious while on treatment with interferon, but not in patients who did not experience these effects, there was a significant activation in specific areas of the brain known to be involved with depression, along with an increase above baseline in the Beck Depression Scale for the patient who developed INF-induced depression. The activation pattern differed from that previously observed for endogenous depression, indicating that INF-induced depression may differ in its underlying neuropathology. Functional magnetic resonance imaging can be an important tool in understanding and monitoring for (INF and other) medication-induced CNS effects, and response to treatment.

Functional imaging in Lhermitte-Duclose disease.

PURPOSE: A comprehensive metabolic characterization of a patient with dysplastic gangliocytoma of the cerebellum or Lhermitte-Duclos Disease (LDD) is presented. PROCEDURES: Assessment using 2-deoxy-2-[18F]fluoro-D-glucose (FDG), carbon-11-labeled methionine (11C-MET), carbon-11-labeled choline (11C-Choline) positron emission tomography (PET), and 1H-proton magnetic resonance spectroscopy (MRS) was carried out in a 30-year-old Caucasian woman. RESULTS: FDG-PET revealed hypermetabolism of the tumor. 11C-MET-PET revealed moderate uptake and 11C-Choline showed no uptake. 1H-MRS demonstrated an elevated level of lactate and decreased levels of choline (Cho) and myoinositol. CONCLUSION: Functional imaging in LDD reflects the dual pathological features of neoplasm and hamartoma.