Intraluminal thrombosis and growth-mechanism of giant intracranial aneurysms

12 giant intracranial aneurysms were studied by MRI. Intraluminal thrombosis was observed in 9 aneurysms. Thrombosis was found more frequently in larger aneurysms. Thrombi were formed posteriorly or inferiorly in the lumen of 4 among 5 IC-cavernous aneurysms. Location of the neck of the aneurysms and stagnation of blood flow influenced by gravity may be causative factors determining the location of thrombi. In 6 aneurysms intraluminal thrombi were inhomogeneous on MRI, suggesting that the thrombi had been formed at different times. New thrombi were formed between the aneurysmal wall and the old thrombus in 3 cases. Dissection of the aneurysmal wall by residual blood flow in the lumen or hemorrhage in the aneurysmal wall may be one of the growth mechanisms of giant intracranial aneurysms.     

Glucose consumption and rate constants for 18F-fluorodeoxyglucose in human gliomas.

To investigate the value of direct measurement of the rate constants by performing 18F-labeled fluorodeoxyglucose (FDG) studies of glucose consumption in human gliomas in vivo, a kinetic method with 3- and 4-parameter rate constant models for FDG uptake was used to analyze data from dynamic scans obtained by positron emission tomography after injection of FDG into 14 patients with glioma. The results were compared with those obtained by the autoradiographic method using 3- and 4-parameter rate constant models. There were no significant differences in the glucose consumption calculated by the four different methods both in the gliomas and in the contralateral intact cortex. It was found that the rate constant k4* could be neglected in calculation of glucose consumption in gliomas as well as in the contralateral intact cortex. The rate constant k3*, an index of hexokinase function, was higher in malignant gliomas than in benign gliomas and was close to that in the contralateral cortex. This study indicates that the 3-parameter autoradiographic method, which is the most common one used in clinical practice, is reliable for the calculation of glucose consumption in human gliomas. Furthermore, direct measurement of the regional rate constants for FDG by the kinetic method was found to be useful for evaluation of the biochemical and physiological characteristics of human gliomas in vivo.     

In Vivo Proton Spectroscopy of Intracranial Infections and Neoplasms

The chemical characteristics of 10 neoplastic and 11 infectious brain masses were studied by in vivo ¹H magnetic resonance spectroscopy. In tumors, peak height ratios of n-acetyl-L-aspartate to choline were decreased compared to those in normal brain tissue and infectious masses (p < 0.02), but the ratios in normal brains and those with infections did not differ. N-acetyl-L-aspartate—to-creatine/phosphocreatine ratios were significantly lower in infectious masses and tumors compared to normal brain tissue (p = 0.003). However, in progressive multifocal leukoencephalopathy, N-acetyl-L-aspartate appeared relatively unchanged. Lactate was greater than choline in 9 of 11 brains with infection, 0 of 14 control brains, and 1 of 10 tumors. Lactate-to-choline ratios were significantly elevated in infectious masses compared with tumors (p < 0.01). ¹H magnetic resonance spectroscopy is promising for the noninvasive diagnosis of focal brain masses.     

A case of posterior choroidal artery infarction]

The posterior choroidal artery supplies the lateral geniculate body, the posterior thalamus and the caudate body. Currently, a few cases of infarction in this arterial territory have been reported. This is a case of 59-year-old male, exhibiting left homonymous hemianopsia and left hemiparesis. Clinically it was impossible to make a diagnosis of infarction in this area. We were able to determine that it was a posterolateral choroidal artery infarction rather than an anterior choroidal artery infarction using 1.5 T-magnetic resonance imaging (MRI). The MRI scan clearly disclosed the areas of infarction, which included the lateral geniculate body, the posterior thalamus and the caudate nucleus body. Additionally, cerebral angiography revealed an occluded proximal portion of the right posterior cerebral artery (P2) and a patent right anterior choroidal artery. Anatomically, the areas surrounding the lateral geniculate body are supplied by both the anterior and the posterolateral choroidal arteries. However, the posterolateral choroidal artery infarctions are believed to be rare due to usual dominance of the anterior choroidal artery. Presently, with the use of MRI scanning, these areas can be easily visualized. Therefore, the posterolateral choroidal artery infarction can be diagnosed more easily. It is conceivable that more cases will be accurately diagnosed using this tool.     

Significance of deposits and abnormalities of the glomerular basement membrane in tissue injury accompanying IgA nephropathy.

The glomerular injuries in 129 cases of IgA nephropathy (IgA-N) were examined ultrastructurally with special reference to the glomerular basement membrane (GBM) deposits and capillary loop abnormalities, and the correlation between these findings and the clinicopathological data was analyzed. The following results were obtained. 1) The degree of daily excretion of urine protein (UP) and creatinine clearance (Ccr) revealed a significant correlation with the degree of mesangial hypercellularities and the frequency of segmental lesions. 2) All sites of GBM deposits, and discontinuity and/or splitting among the GBM abnormalities showed a significant relation to the severity of proliferation and segmental lesions. 3) The GBM deposits, discontinuity and splitting showed a significant relation to the degree of UP and Ccr. We speculate therefore that capillary loop deposits and/or capillary loop discontinuity and splitting could represent histological prognostic factors for an unfavorable outcome in IgA nephropathy.