Biomedical subjects

T Maeda

Publications and source records attributed to T Maeda.

At least 1,729 records · Page 96Linked to original sources

PubMedDate not supplied

Flow velocity of the cortical vein and its effect on functional brain MRI at 1.5T: preliminary results by cine-MR venography.

The purpose of this study is to demonstrate the effect of altering flow velocity of cerebral cortical veins as the source of the signal change observed in functional magnetic resonance imaging (fMRI) of the brain. 10 healthy volunteers were examined after instructions in self-paced hand grasping. Experiments were performed using a 1.5-Tesla whole body MR scanner with a conventional two-dimensional gradient echo sequence (TR/TE/flip angle 400/60/40, first order flow rephased, reduced band width 8 Hz/pixel). Flow velocity measurements were performed for the cortical veins which corresponded to the activated areas depicted on fMRI. Velocity was estimated from the cine-MR venography (cine-MRV) with a tagging technique. Flow phantom studies were performed to delineate the effect of flow velocity differences upon the subtraction images of fMRI. The cine-MRV revealed increased flow velocity of the cortical veins during activation in seven volunteers, with a mean velocity difference of 15 mm/sec. Flow phantom studies suggested that the increased flow velocity may result in changes of the flow signal profile due to oblique flow displacement. Subtraction of the two images with different flow profiles produces flow signal enhancement. Increased flow velocity of the cortical veins during the activation is an important factor which contributes to the signal of fMRI.

Adult↗

PubMedDate not supplied

Effective segmental chemoembolization of advanced hepatocellular carcinoma with tumor thrombus in the portal vein.

PURPOSE: Evaluate therapeutic results of transcatheter segmental hepatic artery chemo-oily-embolization (segmental TAE) against advanced hepatocellular carcinomas (HCC) accompanied by portal tumor thrombus (PTT). METHODS: Segmental TAE was performed in nine patients with hepatic cirrhosis and advanced HCCs accompanied by PTT. Four subsegmental portal branches were obstructed by PTT in three patients, and two were obstructed in the remaining six patients. TAE was performed into the targeted segmental hepatic artery followed by embolization with gelatin sponge particles. RESULTS: In one patient undergoing subsequent resection, a marked anticancer effect on the PTT was demonstrated histologically. In the eight other patients who did not undergo subsequent resection, the cumulative survival rates were 67% at 6 months, 44% at 1 year, and 22% at 2 years. No serious complications were noted. CONCLUSIONS: This therapeutic approach is thought to be a useful treatment for HCC with PTT, because it reinforces anticancer effects and can be performed more safely than conventional transcatheter arterial embolization.

Aged↗

PubMedDate not supplied

Adrenal nonhyperfunctioning adenoma and nonadenoma: CT attenuation value as discriminative index.

BACKGROUND: When an asymptomatic adrenal mass is incidentally discovered on abdominal CT scans, the distinction between a nonhyperfunctioning adenoma and a nonadenoma would be important. METHODS: We evaluated the CT findings of 36 adrenal masses (14 nonhyperfunctioning adenomas, 22 nonadenomas) in 34 patients with no evidence of hormonal hypersecretion. CT attenuation values of adrenal masses on CT scans were calculated by setting a circular region of interest as large as possible in the center of each adrenal mass. RESULTS: Below 20 HU in CT attenuation values, all adrenal masses, except one case of ganglioneuroma with myxomatous change, were nonhyperfunctioning adenomas. With an arbitrary threshold of 20 HU, the sensitivity of CT attenuation values in distinguishing nonhyperfunctioning adenomas from nonadenomas was 64%, the specificity was 95%, and the accuracy was 83%. When decreasing the threshold to 15 HU, the sensitivity was 64%, the specificity was 100%, and the accuracy was 86%. The CT attenuation value on noncontrast CT was more useful for making this distinction than the size and interior homogeneity. CONCLUSIONS: Our data suggest that an asymptomatic adrenal mass with homogeneous low attenuation (< or = 15 HU) and less than or equal to 4 cm indicates a nonhyperfunctioning adenoma, and no further examinations are necessary. CT attenuation value on non-contrast CT is the most important discriminatory factor.

Adenoma↗

PubMedDate not supplied

Therapeutic embolization of intrahepatic portosystemic shunts by retrograde transcaval catheterization.

A 57-year-old woman presented with hepatic encephalopathy, cirrhosis, and a dual-channel portosystemic venous shunt (PSVS). The shunt was treated successfully by embolization with steel coils via retrograde systemic venous access. Encephalopathy resolved. This new approach is considered safer than the previously reported percutaneous transhepatic route or the mesenteric venous route, requiring a mini-laparotomy.

Catheterization↗

PubMedDate not supplied

Primary carcinoid tumor of the liver: report of two cases with an emphasis on US findings.

Primary carcinoid tumor of the liver is rare, and its sonographic (US) findings have rarely been reported. We present two histologically proven cases. Both patients were asymptomatic and huge masses, found incidentally by US, were echogenic with many cystic areas. Lesions were markedly hypervascular on color Doppler US and angiography. Thus, primary carcinoid tumor of the liver should be considered when US detects this type of mass in asymptomatic patients.

Adult↗

PubMedDate not supplied

Hepatocellular carcinoma with sarcomatous change: characteristic findings of two-phased incremental CT.

BACKGROUND: Because of its poor prognosis, the diagnosis of hepatocellular carcinoma with sarcomatous change (HCCSC) is clinically important. The purpose of this study is to elucidate the characteristic CT findings of HCCSC. METHODS: Two-phased dynamic incremental CT images of six histologically proven HCCSC were retrospectively reviewed. RESULTS: All tumors (100%) exhibited peripheral enhancement on delayed CT images. Lymphadenopathy was observed in 100% (six of six patients); intrahepatic metastases, in 83% (five of six). Both metastatic lesions showed findings similar to those of the primary hepatic tumors, such as peripheral enhancement. Histopathological delayed and/or prolonged peripherally enhanced areas consisted of viable cancer cells with sarcomatous changes. CONCLUSIONS: The appearance of HCCSC on CT is that of an irregularly demarcated intrahepatic mass with delayed or prolonged peripheral enhancement, frequently with intrahepatic metastases and lymphadenopathy.

Aged↗

PubMedDate not supplied

CT and MR findings of torsion of greater omentum: a case report.

We report a case of torsion of the greater omentum, which occurred in a 39-year-old man with an adhesive inguinal hernia. Preoperative computed tomography and magnetic resonance (MR) imaging showed a characteristic whirling fatty mass occupying the middle and lower abdomen anteriorly. MR imaging also showed difference of intensities in the twisted omentum, suggesting the presence of the pathological conditions of edema or congestion.

Adult↗

PubMedDate not supplied

MR imaging of hepatocellular carcinomas: effect of Cu and Fe contents on signal intensity.

BACKGROUND: To elucidate the metallic factors contributing to the signal intensities of hepatocellular carcinoma (HCC) on T1-weighted magnetic resonance (MR) images and to determine whether or not changes in signal intensity contribute to the diagnosis of histological grading of HCC. METHODS: In 35 patients immediately after surgery, the quantities of water, lipid, copper (Cu), iron (Fe), and manganese (Mn) were determined in HCCs and the surrounding hepatic parenchyma. The correlations among these findings, the histopathological findings, and the signal intensities of T1-weighted MR images were evaluated. RESULTS: Among the 35 HCCs, 12 (34%) were of high intensity, 14 (40%) were isointense, and 9 (26%) were of low intensity on T1-weighted images versus the surrounding hepatic parenchyma. The paramagnetic ions, which contributed to the signal intensity patterns, were assumed to be Cu in HCCs (30.5 +/- 52.9 microg/g ww), and Fe in the livers (106.2 +/- 86.8 microg/g ww) and HCCs (87.7 +/- 49.1 microg/g ww). In 12 HCCs with high intensity, one was grade I, eight were grade II, and three were grade III according to Edmondson-Steiner's histopathological classification. CONCLUSIONS: Signal intensity and signal intensity patterns alone cannot be signs of low-grade malignancy because of the Fe in livers and in HCCs.

Aged↗

PubMedDate not supplied

Intracerebral hemorrhage after transcatheter thrombolysis of non-occluding superior mesenteric artery thrombosis.

We performed transcatheter thrombolysis on a 64-year-old man with non-occluding superior mesenteric artery (SMA) thrombosis because his severe symptoms could not be controlled with medication. An enhanced computed tomography (CT) scan revealed intramural thrombosis in the SMA. We were concerned that the narrowing of the SMA lumen might progress to complete occlusion, resulting in a high likelihood of mortality. After dissolution of the SMA thrombosis, the original symptoms almost completely disappeared. However, intracranial hemorrhage occurred 8 hr after thrombolysis, requiring surgical intervention. Transcatheter thrombolysis is thought to be a useful treatment for SMA thrombosis, especially in elderly patients with a high operative risk; however, the possibility of intracerebral hemorrhage must be taken into consideration.

Angiography↗

PubMedDate not supplied

Ornithine decarboxylase in developing brain of normal and hydrocephalic rats. Biochemical and immunohistochemical studies.

Polyamines have various roles in cortical development. We examined the ontogenic changes in ornithine decarboxylase (ODC), the rate-limiting enzyme of polyamine biosynthesis, in cerebral cortices of normal and hydrocephalic rats. Both biochemical and immunohistochemical examinations revealed increased ODC protein and enzyme activity during the perinatal period. Apical dendrites of developing neuroblasts migrating from the superficial layer of cortical plate showed intense ODC immunoreactivity. Once they had settled at their final destination, ODC immunoreactivity weakened. Both ODC immunoreactivity and enzyme activity reached very low levels after completion of layer formation of cortex. The enzyme activity of ODC in hydrocephalic cortices exceeded that in normal cortex during the perinatal periods. ODC was rather overexpressed, but no characteristic distribution was observed in the hydrocephalic cortex. These findings indicate the participation of polyamines in the cortical development, especially in the layer formation. The overexpression of ODC in hydrocephalus appears to promote development despite increased hydrostatic pressure.

Animals↗

PubMedDate not supplied

Ornithine decarboxylase in developing brain of hydrocephalic rats. Effects of shunt operation.

We examined the changes in ornithine decarboxylase (ODC) immunoreactivity in the hydrocephalic cerebral cortex of HTX rats after decompression by shunt operation. The ODC immunoreactivity reached a very low level after the completion of cortical layer formation, and only faint staining was found on postnatal day (Pd) 11. The ODC immunoreactivity re-appeared after the shunt operation when the operation was done in the early days of life: the ODC immunoreactivity was first found on day 2 after shunting and persisted until day 8 after shunting. However, this was not apparent when the operation was not performed until Pd 14. The re-expression of ODC in hydrocephalic brain after shunting appears to cause resumption of the developmental process by relieving neurons from increased hydrostatic pressure. The dependence of ODC re-expression on the timing of the operation indicates that there may be a period of neocortical decompression that is critical for effective compensatory development, so that when delayed, decompression fails to re-activate the ODC-dependent development.

Animals↗

PubMedDate not supplied

Immuno-electron microscopic study of tyrosine hydroxylase in the cat urinary bladder and proximal urethra.

The distribution and density of tyrosine hydroxylase (TH)-immunoreactive nerves in the cat urinary bladder and proximal urethra were similar to those of glyoxylic acid fluorescent nerves. Both TH-immunoreactive and fluorescent nerve fibres markedly decreased after 6-hydroxydopamine treatment. Hence, immuno-electron histochemistry of TH was employed to investigate adrenergic termination to the muscle layers of the cat urinary bladder and proximal urethra. A total number of 3728 TH-immunoreactive axon terminals in the lower bladder body, lateral bladder base, trigone, bladder neck and proximal urethra were examined. In the bladder base (the lateral bladder base, trigone and bladder neck) and proximal urethra, most of the TH-immunoreactive axon terminals (57.1-89.2%) lay outside smooth muscle cell fascicles, while most (69.7%) in the bladder body were inside muscle cell fascicles. The proportions of TH-immunoreactive axon terminals accompanying non-TH-immunoreactive axon terminals in the five regions were almost the same (about 70%). The present study demonstrated that the mode of adrenergic termination in the bladder base and proximal urethra notably differed from that in the bladder body, and that approximately 70% of adrenergic axon terminals were associated with non-adrenergic or cholinergic axon terminals in each region.

Animals↗

PubMedDate not supplied

PACS in Kochi Medical School Hospital.

We have evaluated clinically CRT-based diagnosis and the performance of a picture Archiving and Communication System (PACS) in the Department of Radiology, Kochi Medical School. The important requirements of PACS are a good human interface with the diagnostic workstation and a long-term image archiving device. Because the style of image management varies from hospital to hospital, an analysis of the image management policies of each hospital is also important for the configuration of PACS.

Computer Systems↗

PubMedDate not supplied

Aminergic and cholinergic systems in the dorsolateral pontine tegmentum.

Topographic relationship between cholinergic and aminergic neuronal somata has been studied in the dorsolateral pontine tegmentum by using three histochemical techniques, acetylcholinesterase (AchE) histochemistry in rats having received systemic injection of diisopropylfluorophosphate, choline acetyltransferase (CAT) immunohistochemistry and catecholamine fluorescence histochemistry. Based on comparing the data obtained from these different techniques, it seems evident that all noradrenergic neurons contain AchE. The remaining population of AchE-containing somata appears to correspond with CAT-containing, therefore, cholinergic neuronal cell bodies. No AchE-positive perikarya were detected in neuronal structures other than cholinergic and aminergic neurons. In addition, coexistence of noradrenaline and acetylcholine in a single cell seems improbable, at least, in the dorsolateral pontine tegmentum.

Acetylcholine↗

PubMedDate not supplied

Immunocytochemical demonstration of beta 1-subunit of Na+/K(+)-ATPase in the mechanoreceptive Ruffini-like endings of the rat incisor ligament.

The localization of one of the isoforms of Na+/K(+)-ATPase, the beta 1-subunit, was investigated in the periodontal Ruffini endings of rat incisors by light- and electron-microscopic immunocytochemistry. Immunoreactivity for the rat beta 1-subunit followed the pattern of dendritic terminal arborization in the alveolar half of the lingual periodontal ligament. Ultrastructurally, the reaction products were localized in dilatations of axons, possibly the terminals of Ruffini-like endings in the periodontal ligament. No immunoreactivity was seen in Schwann cells. The immunostaining results support the view that the beta 1-subunit of Na+/K(+)-ATPase is the predominant isoform in sensory neurones, and that this protein is a useful marker for periodontal Ruffini-like endings.

Alveolar Process↗

PubMedDate not supplied

Calbindin D28K-like immunoreactive nerve fibres in the predentine of rat molar teeth.

Immunoelectron-microscopy was applied to reveal the existence of nerve fibres and terminals showing calbindin D28k (CB)-like immunoreactivity (IR) in the rat molar tooth pulp. In the root pulp, thick, smooth-surfaced CB-IR nerve fibres were in bundles accompanying the blood vessels. In the coronal pulp, the fibres arborized repeatedly and extensively. CB-IR nerve fibres had a predominantly thick, smooth-surfaced appearance, though parts appeared thin and beaded. Occasionally some thin, varicose CB-IR nerve fibres ran along the odontoblasts, penetrating into the predentine alongside the dentinal tubules. They could be traced for approx. 10-20 microns into the predentine from the pulp-predentine border. Immunoelectron-microscopy revealed that only some of the nerve terminals in the predentine showed CB-IR, and that predentinal CB-IR nerve terminals were located close to the odontoblast processes. No synaptic structures were observed between them. The presence of CB-IR nerve terminals in the predentine suggests that many, if not all, CB-IR nerve fibres could be nociceptors. The CB could be involved in Ca2+ homeostasis during the activation of nociceptors.

Animals↗

PubMedDate not supplied

Evaluation of extraocular muscle enlargement in dysthyroid ophthalmopathy.

PURPOSE: To evaluate extraocular muscle enlargement (EME) in dysthyroid ophthalmopathy. METHODS: EME was assessed by orbital computed tomography (CT) in 573 patients with dysthyroid ophthalmopathy in order to investigate the frequency and exact location of EME and the clinical features of related ocular symptoms in patients with dysthyroid ophthalmopathy. RESULTS: Of the 573 patients examined, 187 patients (38%) showed evidence of EME on CT images. This disorder was more frequent in male patients than in female patients. EME was also more frequently seen in older patients than in younger patients. Enlargement of a single muscle was found in 55% of the 187 patients, with the most frequently affected muscle being the inferior rectus muscle. When multiple muscles were enlarged, the inferior rectus muscle was the most frequently affected, followed by the medial rectus muscle. CONCLUSIONS: Of the clinical findings specific to dysthyroid ophthalmopathy examined in the present study, the incidence of exophthalmos, upper lid swelling, superior limbic keratoconjunctivitis, keratitis, diplopia, and dysthyroid optic neuropathy was significantly increased in patients with dysthyroid ophthalmopathy, indicating a close relationship between these findings and the underlying disease, but the incidence of upper lid retraction was not significantly increased.

Adolescent↗

PubMedDate not supplied

Scanning laser tomography to evaluate optic discs of normal eyes.

PURPOSE: To investigate the effects of age, eye refraction, and disc area on topographic parameters of the optic nerve head in normal volunteers, using the Heidelberg Retina Tomograph. METHODS: Seventy-seven eyes of 77 normal volunteers were examined by scanning laser tomography. The topographic parameters analyzed were disc area, cup area, cup/disc area ratio, rim area, cup volume, rim volume, mean cup depth, maximum cup depth, cup shape measure, height variation contour, mean retinal nerve fiber layer thickness (MnRNFLT), and retinal nerve fiber layer (RNFL) cross-section area. The effect of age, refraction, and disc area on each parameter was analyzed by the multiple linear regression model. RESULTS: Significant declines in MnRNFLT and RNFL cross-section area were found with increasing age (P < .05). The mean cup depth and maximum cup depth were significantly deeper in myopic subjects (P < .05). Large discs had large cup area, cup/disc area ratio, rim area, cup volume, mean cup depth, cup shape measure (P < .01), and maximum cup depth (P < .05). The MnRNFLT was smaller in large discs (P < .01). Rim volume was unaffected by age, refraction, or disc area. CONCLUSIONS: The age, refraction, and disc area were related to several optic disc parameters obtained by the Heidelberg Retina Tomograph. Because of these relationships, care should be taken to analyze the appearance of the optic disc on the basis of these parameters in patients with glaucoma or other diseases. Rim volume appears to be a good parameter for evaluating the optic disc without considering age, refraction, or disc area.

Adult↗