Nobuyuki Kato

Aging in the CNS: Comparison of gray/white matter volume and diffusion tensor data

This study investigated the global and regional effects of aging on brain volume, mean diffusivity (MD), and fractional anisotropy (FA) in 73 normal female subjects using voxel-based analysis. On a global scale, gray matter volume and FA were negatively correlated, whereas MD was positively correlated with age. Voxel-wise analyses showed brain volume and FA were negatively correlated predominantly in anterior structures, whereas MD was positively correlated in the cortical gray matter and periventricular white matter. Volume preservation was observed in the cingulate gyrus and subjacent white matter. FA increase was observed in the putamen. Voxel-based direct comparisons of volume and diffusion properties showed FA was more strongly negatively correlated in the fronto-temporal white matter, compared with volume and MD. Stronger positive correlation of MD was observed in the thalamus, caudate nucleus, and midbrain and stronger negative correlation of brain volume was observed in the frontal lobe and basal ganglia, compared with the other. These results indicate that diffusion properties and brain volume are complementary markers to the effects of aging.

Spectrum of Epstein-Barr virus-related diseases: a pictorial review

Epstein-Barr virus (EBV) prevails among more than 90% of the adult population worldwide. Most primary infections occur during young childhood and cause no or only nonspecific symptoms; then the virus becomes latent and resides in lymphocytes in the peripheral blood. Inactive latent EBV usually causes no serious consequences, but once it becomes active it can cause a wide spectrum of malignancies: epithelial tumors such as nasopharyngeal and gastric carcinomas; mesenchymal tumors such as follicular dendritic cell tumor/sarcoma; and lymphoid malignancies such as Burkitt lymphoma, lymphomatoid granulomatosis, pyothorax-associated lymphoma, immunodeficiency-associated lymphoproliferative disorders, extranodal natural killer (NK) cell/T-cell lymphoma, and Hodgkin’s lymphoma. The purpose of this article is to describe the spectrum of EBV-related diseases and their key imaging findings. EBV-related lymphoproliferative disorders and lymphomas are especially common in immunocompromised patients. Awareness of their clinical settings and imaging spectrum contributes to early detection and early treatment of possibly life-threatening disorders.

1H-MR spectroscopy and gray matter volume of the anterior cingulate cortex in schizophrenia.

Schizophrenic and normal control subjects were examined using both 1H-magnetic resonance spectroscopy (MRS) and structural MR imaging, in order to accurately assess the partial volume within the spectroscopic volume of interest (VOI) in the anterior cingulate cortex. The gray matter volume within VOI correlated positively with the N-acetyl-aspartate (NAA) to choline (Cho) ratio in schizophrenics only, not in controls. Schizophrenic patients had a reduced NAA/Cho ratio and an elevated Cho/creatine ratio compared to controls after the partial volume effect was eliminated. There was a significant negative correlation between the NAA/Cho ratio and the severity of blunted affect symptom in schizophrenics. These results provide further support to the idea that the measures of 1H-MRS indicate not only neuronal loss but also neuronal dysfunction in schizophrenia.

Multiple generators in the auditory automatic discrimination process in humans

To reveal the spatiotemporal characteristics of the auditory automatic discrimination process, mismatch negativity (MMN) generators were assessed with a high-resolution EEG system (128ch) and scalp current density (SCD) analysis. Ten normal volunteers participated in the study. Event-related potentials were recorded during a selective attention task. Sequential SCD mappings revealed that a current sink/source combination in the left temporal regions and a current sink in the right frontotemporal regions appeared around 200 msec irrespective of the ear of stimulation. Moreover, a parietal sink/source combination was demonstrated on the right hemisphere around 240 ms irrespective of the ear of stimulation. These findings demonstrate that the auditory automatic change detection process is, both spatially and temporally, a multiple-generated system.

CT appearance of Epstein-Barr virus-associated gastric carcinoma

Epstein-Barr virus (EBV) is associated with pathogenesis of several epithelial neoplasms and lymphoproliferative disorders. A certain percentage of gastric carcinomas are associated with EBV. EBV-associated gastric carcinoma is a distinct entity associated with good prognosis. Multiple carcinomas are highly prevalent in EBV-associated gastric carcinomas, and this warrants thorough endoscopic investigation before determining the extent of surgical resection. Therefore, it is important to consider the presence of Epstein-Barr virus in the preoperative CT evaluation of gastric carcinomas. The purpose of this article is to illustrate the CT features of Epstein-Barr virus-associated gastric carcinoma. The surgically resected gastric carcinomas at our institution from 1998 to 2004 were reviewed and were examined for the presence of EBV, and 13 EBV-associated gastric carcinoma lesions were found in 10 patients. The preoperative CT scans were reviewed in these patients. Radiologic features that may suggest the presence of Epstein-Barr virus in gastric carcinoma includes location in the upper part of the stomach, a large thickness-to-width ratio, and a bulky portion projecting from the gastric wall.

Magnetic resonance findings of bile duct adenoma with calcification

Computed tomographic (CT) and magnetic resonance (MR) appearances of bile duct adenoma (BDA in a patient who underwent partial hepatectomy of segment 8 are presented. BDA showed a ring-shaped hyperdense area suggesting calcification and ring enhancement on CT. It appeared hypointense on both T1- and T2-weighted MR images. Preoperatively, the diagnoses considered included metastatic carcinoma, cholangiocarcinoma, tuberculosis, and rare tumors such as epithelioid hemangioendothelioma. The radiological findings were confirmed by pathological investigation.

Electrophysiological evidence for sequential activation of multiple brain regions during the auditory selective attention process in humans.

In an attempt to examine dynamic involvement of multiple brain regions in the auditory selective attention process, negative difference wave (Nd) generators were assessed using a high-resolution EEG system (128ch) and scalp current density (SCD) analysis. Ten normal volunteers participated in the study. Event-related potentials were recorded during a selective attention task. Sequential SCD mappings revealed that current sinks were located in the bilateral temporal regions at 160 ms subsequent to the onset of stimuli, shifting the dipole orientation more tangentially to the scalp at around 220 ms. Moreover, a current sink was demonstrated in the midfrontal region at around 320 ms. These findings confirm that different cortical regions are sequentially involved in the auditory selective attention process.

Assessment of major aortopulmonary collateral arteries with multidetector-row computed tomography

Multidetector-row computed tomography (MDCT) studies were performed in three adult patients with pulmonary atresia with a ventricular septal defect. In all patients, the native pulmonary arteries were absent, and the pulmonary circulation was totally supplied by major aortopulmonary collateral arteries (MAPCAs). MDCT studies with 1-mm collimation provided detailed information on MAPCAs and bronchial collaterals, such as the numbers and sites of origin, their varying diameters, their courses, and the areas of the lungs they supply. MDCT studies may provide an efficient road map for safe and successful selective catheterization and may substitute for conventional angiography in patients with considerable risks.

Transarterial embolization of a nonpuerperal traumatic vulvar hematoma

Nonpuerperal traumatic vulvar hematomas are relatively uncommon. Conservative and surgical management are the usual treatment options for traumatic vulvar hematomas. There is no report of transarterial embolization of nonpuerperal traumatic vulvar hematoma. We report a 35-year-old woman who presented with a vulvar hematoma caused by an accidental fall on a toy of her child. The hematoma was expanding and was refractory to conservative treatment. A computed tomography (CT) scan revealed active extravasation of contrast material from the left internal pudendal artery. We performed transarterial embolization of the left internal pudendal artery. The left external pudendal artery, which had an anastomosis with the left internal pudendal artery, was also embolized. Postembolization angiography demonstrated no further extravasation of contrast material. We believe that transarterial embolization can be an effective treatment of nonpuerperal traumatic vulvar hematomas when conservative treatment fails.