The blood-brain barrier (BBB) is the border between the brain tissue and the blood and consists of a pre- and post-capillary and a capillary segment. At capillaries protein transport is possible via receptor-mediated endocytosis through endothelial cells. At the arteries and veins the BBB is thicker and there is, under physiological conditions, no direct transport from the brain tissue to the b...

OBJECTIVE To determine the feasibility of creating a perivascular space adjacent to the central retinal vein at the level of the lamina cribrosa as a potential method of reestablishing perfusion in central retinal vein occlusion. METHODS Various designs for a puncture instrument, or lamina puncture lancet, were investigated in cadavers, pigs that had undergone enucleation, and in vivo rabbit ...

BACKGROUND AND PURPOSE Although MR spectroscopy and functional MR imaging of the brain have been successful at 4 T, conventional fast spin-echo imaging of the brain at 4 T has not been adequately evaluated. The purpose of this study was to compare the detection of white matter abnormalities in multiple sclerosis (MS) at 1.5 T and 4 T. METHODS Fifteen patients with clinically definite MS were ...

We describe 2 patients with unusual white matter cystic dilations, which could correspond to widening of the perivascular spaces. They underwent morphologic MR imaging with tractography, functional MR imaging (fMRI), and neuropsychological evaluation. fMRI examination showed no functional reorganization of cortical areas. Tractography showed an apparent decrease of white matter tract vectors in...

Perivascular epithelioid cell tumor (PEComa) is an extremely rare neoplasm that appears to arise most commonly at visceral (especially gastrointestinal and uterine), retroperitoneal, and abdominopelvic sites. Malignant PEComas exist but are very rare. These tumors represent a family of mesenchymal neoplasms, mechanistically linked through activation of the mTOR signaling pathway. Metastatic PEC...

The thymus is one of the subjects that have received the most intensive investigation in recent years, and it has become clear that the thymus plays an important role in development of the immune system. The present state of the knowledge of the thymus studies is surveyed repeatedly and no repetition is needed (see, for instance: GOOD and GABRIELSEN 1964; DEFENDI and METCALF 1964). A remarkable...

We describe a case of Rocky Mountain spotted fever encephalitis and present the associated findings of an MR examination of the brain, which showed increased signal intensity in the distribution of perivascular spaces. Resolution of the MR abnormalities coincided with clinical improvement.

PEComas are a collection of generally rare tumors, defined by the World Health Organization as 'mesenchymal tumors composed of histologically and immunohistochemically distinctive perivascular epitheloid cells'. We describe the case of retroperitoneal PEComa with a liposarcoma-like appearance on cross-sectional imaging, but distinctive immunohistochemistry revealing the correct diagnosis.

We describe a patient who showed cystic lesions in the midbrain and obstructive hydrocephalus. MR imaging features corresponded to abnormal dilatation of perivascular spaces. Similar clinical and MR imaging findings were described in previous reports of patients presenting with mesencephalo-thalamic expanding lacunae; the diagnosis of some of those cases was confirmed at postmortem examination ...

Spontaneous thymoma was found in the left lobe of the thymus of a male 10-week-old Sprague-Dawley (SD) rat. Microscopically, the thymic mass showed a sheet of dark area with multiple pale foci. The dark area mainly consisted of densely compacted small lymphoid cells with sporadic large epithelioid cells and mitotic figures. The epithelioid cells and mitotic figures were more frequent than those...