The basal ganglia represents a key component of the pathophysiological model for obsessive-compulsive disorder (OCD). This brain region is part of several neural circuits, including the orbitofronto-striatal circuit and dorsolateral prefronto-striatal circuit. There are, however, no published studies investigating those circuits at a network level in non-medicated patients with OCD. Resting state functional magnetic resonance imaging scans were obtained from 20 non-medicated patients with OCD and 23 matched healthy volunteers. Voxelwise statistical parametric maps testing strength of functional connectivity of three striatal seed regions of interest (ROIs) with remaining brain regions were calculated and compared between groups. We performed additional correlation analyses between strength of connectivity and the severity scores for obsessive-compulsive symptoms, depression, and anxiety in the OCD group. Positive functional connectivity with the ventral striatum was significantly increased (P(corrected) < .05) in the orbitofrontal cortex, ventral medial prefrontal cortex and dorsal lateral prefrontal cortex of subjects with OCD. There was no significant correlation between measures of symptom severity and the strength of connectivity (P(uncorrected) < .001). This is the first study to investigate the corticostriatal connectivity in non-medicated patients with OCD. These findings provide the first direct evidence supporting a pathophysiological model involving basal ganglia circuitry in OCD.

Cerebral amyloid angiopathy (CAA) is one of the cardinal pathological features in the vascular components of Alzheimer’s disease (AD). CAA itself results in disrupted microvasculature, mainly in the cerebral cortex, eventually leading to a brain cortical or subcortical hemorrhage in a population of elderly people, but clinically overt brain hemorrhages are not so frequent in AD patients. Here we assessed 50 AD patients and 26 controls to detect latent brain hemorrhages with gradient-echo T₂*-weighted images, a sensitive magnetic resonance imaging technique to detect hemosiderin components in the brain. Microbleeds, demarcated as low-intensity spots in T₂*-weighted images, were detected in 16.7% of AD patients without cerebrovascular disease (CVD) and in 12.5% of those with CVD, while no microbleeding was detected in the control subjects. No significant difference was observed between the microbleed-positive group and the microbleed-negative counterpart in their clinical background, such as hypertension, the use of antiplatelet drugs and smoking. In addition, white matter high intensities in the T₂-weighted image were significantly more confluent in the microbleed-positive AD group than its negative counterpart. In conclusion, our evaluation of AD brains revealed that latent microbleeds in AD patients are more frequent than in normal controls. Microbleeds not being related to common hemorrhagic risk factors, but being significantly related to white matter pathologies suggested that microbleeds in AD may be associated with CAA, but not with hypertension or CVD.

The areas showing decreased tissue anisotropy in DTI corresponded well with pathologically vulnerable areas in MSA. In addition, the local tissue anisotropy of MCP decreased in accordance with functional disability. These observations implied that DTI is a feasible method for in vivo evaluation of the white matter pathology in MSA.

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We present a case of cerebral aspergillosis in an immunocompetent patient. The MRI signal characteristics were compared with the histologic findings. Irregular low-signal zones were demonstrated between the wall of the abscess and the central necrosis on T2-weighted images; the pathology specimen revealed concentrated iron in these transitional zones but no hemosiderin. Iron is an essential element for the growth of fungal hyphae. The low-signal zones may represent the areas where there was active proliferation of aspergillus, and the unique location of the low signal may be a helpful imaging characteristic for the diagnosis of an aspergillus abscess.