Moonsup Han

Color variation of ZnGa2O4 phosphor by reduction-oxidation processes

The color of the emission of zinc gallate (ZnGa2O4) oscillates between ultraviolet and blue by hydrogen ambient reduction and air ambient oxidation heat treatments. The photoluminescence spectra and electron paramagnetic resonance signals show that ultraviolet emission of reduced ZnGa2O4 always accompanies 680 nm emission originating from single oxygen vacancies (VO*). The increasing difference in binding energy between Ga3+ and O2− in reduced ZnGa2O4 indicates that the configuration of octahedral sites is distorted due to VO* generation and it becomes more ionic which shifts the emission band from 430 to 360 nm. The x-ray diffraction patterns and Raman scattering spectra show that β-Ga2O3 from ZnGa2O4 is formed in both reduction and oxidation processes which suggests the vaporization of Zn ions. We propose a model in which the origin of 360 nm emission is the Ga–O transition at distorted octahedral sites with VO* in ZnGa2O4, whereas 430 nm emission originates from the Ga–O transition of regular octahedra...

Similarity and disparity of obsessive-compulsive disorder and schizophrenia in MR volumetric abnormalities of the hippocampus-amygdala complex

Objectives: Given that obsessive-compulsive disorder (OCD) and schizophrenia may share clinical symptoms as well as functional brain abnormalities, this study was designed to clarify common and different morphological abnormalities in OCD and schizophrenia. Methods: Volumes of the hippocampus, the amygdala, and the thalamus were measured in three age and sex matched groups of 22 patients with OCD, 22 patients with schizophrenia, and 22 normal subjects using three dimensional magnetic resonance imaging. Volume tracing was performed manually on serial coronal slices with the references of sagittal or axial planes using internal landmarks. Results: Hippocampal volume was bilaterally reduced in both OCD and schizophrenic patients versus the normal controls. Left amygdala volume was significantly enlarged in patients with OCD but not in patients with schizophrenia versus the normal controls. The thalamus did not show any volumetric group differences. Conclusions: Non-specific hippocampal reduction in both the OCD and schizophrenic groups is likely to link to a clinical overlap between the two illnesses, whereas the left amygdala enlargement observed only in the OCD patients seems to be suggestive of a unique role for the amygdala in the pathophysiology of OCD.

Marchiafava-Bignami disease: serial changes in corpus callosum on MRI.

SummarySerial MRI findings of changes in corpus callosum lesions in two cases of Marchiafava-Bignami disease are presented. In both, MRI displayed diffuse swelling of the corpus callosum in the acute stage, thought to represent oedema and demyelination. In the chronic stage, in addition to atrophy of the corpus callosum with presumed focal necrosis, previously undescribed focal hypointensity on T2-weighted images, of unknown cause, was observed in the corpus callosum.

Gd-DTPA enhanced MR imaging in intracranial tuberculosis

SummaryTwenty-six patients with intracranial tuberculosis (Tb) (10 with acute meningitis, 5 with chronic meningitis, 5 with meningitic sequelae and 6 with localized tuberculoma(s) were examined with MR before and after Gd-DTPA enhancement (0.1 mmol/kg), using 2.0T superconducting unit, and the images were retrospectively analyzed and compared with CT scans. Without Gd-DTPA enhancement, the MR images were generally insensitive to detection of active meningeal inflammation and granulomas. The signal intensity of granulomas was usually isointense to gray matter on both T1- and T2-weighted images, whether they were associated with diffuse meningitis or presented as localized tuberculoma(s). A few granulomas showed focal hypointensity on T2-weighted images. Calcifications seen on CT of the meningitic sequelae group usually appeared markedly hypointense on all spin-echo sequences. On Gd-DTPA enhanced T1-weighted images, abnormal meningeal enhancement indicating active inflammation was conspicuous, and the granulomas often appeared as conglomerated ring-enhancing nodules, which seems to be characteristic of granulomas. Thin rim enhancement around the suprasellar calcifications were observed in two out of 5 patients with meningitic sequelae. Compared with CT, MR detected a few more ischemic infarcts, hemorrhagic infarcts, meningeal enhancement and granulomas in the acute meningitis group, but missed small calcifications in the basal cisterns well shown on CT in the sequelae group. Otherwise, MR generally matched CT scans. MR imaging appears to be superior to CT in evaluation of active intracranial Tb only if Gd-DTPA is used, while CT is better than MR in evaluating meningitic sequelae with calcification.

MR Appearance of Central Neurocytoma

To provide a detailed description of the MR appearances of central neurocytoma, MR images of 13 patients with central neurocytoma were retrospectively reviewed and compared with CT examinations. The histology was confirmed by ultrastructural and immunohistochemical studies. In 12 patients the tumors were histologically benign and located in the anterior part of the lateral ventricle, 6 of which extended to the 3rd ventricle. There was one case of a histologically malignant variant involving the thalamus and lateral ventricle. The tumors were primarily solid, but contained cysts (85%, 11/13), calcifications (69%, 9/13), and signal void from tumor vessels (62%, 8/13), frequently producing heterogeneous signal intensity on both T1- and T2-weighted images. Most of the solid portion appeared isointense or slightly hyperintense relative to the cerebral cortex on all MR pulse sequences. Calcifications were iso- or hypointense on MR, making them difficult to characterize with MR alone. Intratumoral hemorrhage was seen in 2 patients on MR but not on CT. Contrast enhancement was variable in degree and pattern. Coronal and sagittal MR images were valuable in evaluating the tumor extent and origin site, and in planning the surgical approach. It is concluded that MR imaging appears to be more useful than CT in the overall evaluation of central neurocytoma, even though calcification is better characterized with CT.

Endovascular Coil Embolization of 435 Small Asymptomatic Unruptured Intracranial Aneurysms: Procedural Morbidity and Patient Outcome

BACKGROUND AND PURPOSE: Whether treatment of small asymptomatic aneurysms is appropriate or not remains controversial. We performed a retrospective study on the procedural morbidity and mortality of coil embolization of small asymptomatic unruptured intracranial aneurysms (UIAs) to obtain a more generalized estimate of procedural risk. MATERIALS AND METHODS: A total of 435 small (maximum diameter ≤7 mm) asymptomatic UIAs in 370 patients were treated by coil embolization. Aneurysm sizes were determined by using 3D angiograms. We assessed procedure-related morbidity and mortality, immediate postprocedural angiographic results, short-term imaging follow-up results, and clinical outcomes. RESULTS: Initial aneurysm occlusion was complete in 334 aneurysms, near complete in 78, and incomplete in 22. One internal carotid artery (ICA) aneurysm that ruptured during the procedure was treated with parent artery occlusion. Two hundred wide-neck aneurysms were coiled with the aid of various neck-remodeling techniques. The 44 procedure-related complications were the following: 24 thromboembolisms, 11 coil protrusions or prolapses into the parent vessel, 4 intraprocedural ruptures, 3 device-related complications, and 2 femoral-access complications. We had a total of 44 (10.1%) procedure-related complications with only 1 leading to persistent neurologic deficit. Procedure-related permanent morbidity and mortality were 0.27% (1/370) and 0%, respectively. CONCLUSIONS: In this series of small unruptured asymptomatic aneurysms, endovascular treatment was achieved with good short-term angiographic outcome and low permanent neurologic impairment. The goal of this study was not to provide a conclusion about treatment guidelines for small UIA but rather to help guide future recommendations by presenting a more generalized estimate of endovascular treatment risk than is currently available.

Preinterventional Clopidogrel Response Variability for Coil Embolization of Intracranial Aneurysms: Clinical Implications

BACKGROUND AND PURPOSE: Thromboembolism is one of the most serious complications in coil embolization for intracranial aneurysms, and antiplatelet premedication may reduce this complication. However, interindividual variation exists in the efficacy of CPG. This study sought to elucidate the clinical implications of preinterventional CPG response variability in patients who undergo coil embolization for intracranial aneurysms. MATERIALS AND METHODS: CPG premedication was given to 186 consecutive patients with 209 aneurysms who underwent elective coil embolization, and the response to the premedication was measured by a point-of-care antiplatelet function test (VerifyNow assay). Patients were stratified into 4 quartiles according the test results, and their correlation with the occurrence of periprocedural complications was analyzed. The contribution of a variety of variables to the high PRU was also tested. RESULTS: In this cohort, rates of thromboembolic events and all adverse events were 7.5% and 9.1%, respectively. The quartiles of the P2Y12 reaction unit of the ADP channel (PRU) showed a significant tendency toward thromboembolic events (P = .013) and all procedure-related adverse events (P = .009), while those of the BASE and percentage inhibition did not. Thromboembolic events occurred in 17.0% and procedure-related adverse events, in 21.3% of the patients in the fourth quartile. Female sex was the only significant factor related to the fourth quartile of PRU in the multiple logistic regression analysis (P = .014). CONCLUSIONS: Procedure-related thromboembolic events occurred more frequently in patients in the upper quartile with higher PRU, especially in the fourth quartile. Further study including a large number of patients is expected to confirm this finding.

Ge nitride formation in N-doped amorphous Ge2Sb2Te5

The chemical state of N in N-doped amorphous Ge2Sb2Te5 (a-GST) samples with 0–14.3Nat.% doping concentrations was investigated by high-resolution x-ray photoelectron spectroscopy (HRXPS) and Ge K-edge x-ray absorption spectroscopy (XAS). HRXPS showed negligible change in the Te 4d and Sb 4d core-level spectra. In the Ge 3d core-level spectra, a Ge nitride (GeNx) peak developed at the binding energy of 30.2eV and increased in intensity as the N-doping concentration increased. Generation of GeNx was confirmed by the Ge K-edge absorption spectra. These results indicate that the N atoms bonded with the Ge atoms to form GeNx, rather than bonding with the Te or Sb atoms. It has been suggested that the formation of Ge nitride results in increased resistance and phase-change temperature.

Cerebral sparganosis : analysis of 34 cases with emphasis on CT features

SummaryCerebral sparganosis is a rare parasitic CNS disease, producing chronic active granulomatous inflammation. We retrospectively reviewed the clinical data, CT scans and histopathologic specimens in 34 patients with cerebral sparganosis. The majority of the patients (89%) were rural inhabitants; 75% had a history of ingestion of frogs and/or snakes. The major presenting symptoms were seizure (84%), hemiparesis (59%) and headache (56%) of chronic course. On CT scans, the disease most frequently involved the cerebral hemispheres, particularly frontoparietal lobes, with occasional extension to the external and internal capsules and basal ganglia. The cerebellum was rarely involved. Bilateral involvement was seen in 26%. The main CT findings consisted of white matter hypodensity with adjacent ventricular dilatation (88%), irregular or nodular enhancing lesion (88%), and small punctate calcifications (76%). In combination, the CT triad above appears to be specific for this disease, and was noted in 62% of cases. Of 16 follow-up CT scans, 5 (38%) showed a change in the location of the enhancing nodule. With a single CT scan, it does not appear to be possible to determine whether the worm is alive or dead, information important for deciding whether to intervene surgically. Change in the location of the enhancing nodule and/or worsening of the other CT findings on sequential CT scans would suggest that the worm is alive and that the patient is a candidate for surgery.

Embolization of wide-necked aneurysms with using three or more microcatheters

SummaryBackground. A new and relatively simple endovascular technique, in which more than three microcatheters are used for endovascular treatment of cerebral aneurysms for the first time, is described. Method. Eight patients with wide necked aneurysms were successfully treated with detachable coils using the multiple microcatheter technique. Three patients presented with subarachnoid haemorrhage and five were unruptured. The aneurysm locations were superior hypophyseal artery (2), posterior communicating artery (2), middle cerebral artery bifurcation (1), distal anterior cerebral artery (1), basilar artery (1) and vertebral artery (1). The average neck size was 7.4 ± 2.8 mm (3.5–12 mm), average width of the aneurysms was 10.6 ± 5.7 mm (6.2–23 mm) and depth was 8.9 ± 5.8 mm (3–22 mm). Three microcatheters (7 patients) and four microcatheters (1 patient) were introduced and used for coil delivery. Three or four coils were deployed and intermingled to stabilize the whole coil mass as well as to occupy the aneurysmal sac. When a relatively stable coil frame was formed, one coil was detached and subsequent coils were inserted. After the coil mass became more stable, other coils were also detached and all microcatheters were used for subsequent coil deployment. Findings. All aneurysms were successfully treated without complications. Postemboilzation angiograms showed no contrast filling in 5 cases (100% occlusion) and a very small residual neck in 3 cases. There was no procedure related complication. Conclusion. The multiple microcatheter technique can be one technical option for the endovascular treatment of wide necked aneurysms.