Biomedical subjects

T Masui

Publications and source records attributed to T Masui.

196 records · Page 11Linked to original sources

PubMedDate not supplied

Clinical evaluation of pulmonary 3D time-of-flight MRA with breath holding using contrast media.

OBJECTIVE: Our goal was to evaluate the clinical utility of pulmonary 3D TOF MRA using a contrast medium and breath holding. MATERIALS AND METHODS: To determine an optimal imaging time in a pilot study, 30 sequential axial images were obtained for each of 18 patients by using a turbo fast low angle shot sequence immediately after a bolus injection of 5 ml Gd-DTPA. MRA consisted of five sequential MR scans performed using a 3D fast imaging with steady-state precession sequence on 13 patients. The imaging start time after a bolus injection of 10 ml Gd-DTPA was determined from the results of the pilot study. We hoped that the acquisition of the center of k-space of the first MRA was matched to the period of maximum effect of the first pass bolus for the pulmonary arteries. RESULTS: In a pilot study on average, pulmonary artery signal intensities were relatively high from 10.4 to 20.7 s after the contrast medium injection. The MR angiograms obtained at the optimal time were superior to those that followed. All pulmonary trunks and the right and left main pulmonary arteries were accurately recognized. MRA had a sensitivity of 80.0%, a specificity of 95.0%, and an accuracy of 94.5% for the detection of segmental artery stenosis or occlusion. Abnormal vessels were visualized in both patients with pulmonary sequestration. CONCLUSION: Pulmonary 3D TOF MRA using breath holding and a contrast medium is useful in demonstrating proximal pulmonary vasculature and pulmonary sequestration.

Adult↗

PubMedDate not supplied

Case report. Antenatal diagnosis of chorioangioma of the placenta: MR features.

We report a case of chorioangioma of the placenta, in which MR findings were useful in establishing the antenatal diagnosis. Polyhydramnios and a placental tumor that was 5 cm in size were visualized. The tumor had relatively high signal intensities on proton density imaging and T2-weighted imaging and showed partially high intensity signal rims on T1-weighted imaging, especially when using a breath-holding technique. Magnetic resonance imaging has an important role in detection and diagnosis of these lesions, particularly the larger tumors, so that appropriate steps can be taken to deal with the complications that may accompany this tumor.

Adult↗

PubMedDate not supplied

Pseudodynamic imaging of the temporomandibular joint: SE versus GE sequences.

Pseudodynamic MR imaging of the temporomandibular joints (TMJs) has been used for the evaluation of the functional aspects of the TMJs. To evaluate the value of T1-weighted spin-echo (SE) and gradient-echo (GE) techniques, both techniques were performed in 9 asymptomatic (mean 25.7 years, 22-23 years), and 25 symptomatic (mean 44.9 years, 20-71 years) subjects with signs and symptoms of internal derangement or osteoarthrosis of the TMJs. The imaging time for the SE (180 ms/15 ms/110 degrees; repetition time/echo time/flip angle) and GE (fast low angle shot; FLASH, 90 ms/12 ms/40 degrees) sequences was 27 and 28 s, respectively. In asymptomatic and symptomatic subjects, the confidence of the identification of the meniscal position was better on SE than GE images (3.6 +/- 0.6 vs. 2.9 +/- 0.9, p < 0.01, 3.2 +/- 0.8 vs. 2.8 +/- 0.8, p < 0.05), respectively and the sizes of the menisci were bigger on SE than GE images. The delineation of the condylar cortex was better on GE than SE images. For pseudodynamic imaging display of the TMJs, the SE images might be better than GE images to provide the stable recognition of the menisci.

Adult↗

PubMedDate not supplied

MRI of dumbbell-shaped spinal tumors.

PURPOSE: The purpose of our study is to review the clinical features and MR findings in patients with dumbbell-shaped spinal tumors that affect the intervertebral foramen. METHOD: Two radiologists retrospectively evaluated a total of 19 tumors from the period 1989-1994 that exhibited dumbbell configuration. These included 11 benign tumors, including 9 neurogenic ones, and 8 malignant tumors. RESULTS: The time between onset of symptoms and admission was shorter in patients with malignant tumors (mean 3.9 months) than in patients with benign tumors (mean 41.1 months). There was a statistically significant difference (p < 0.05) in the short/long axis ratios (minimum tumor diameter divided by maximum tumor diameter) in the vertebral canal components between benign and malignant tumors. All malignant tumors in this study were extradural and paraspinal type (p < 0.05). Most benign tumors had regular margins and enlarged intervertebral foramina, while most malignant ones had irregular margins (p < 0.05). Many neurogenic tumors had regular margins and enlarged intervertebral foramina, while most malignant ones had irregular margins (p < 0.05> Many neurogenic tumors had cystic lesions (77.8%) and a string-of-beads structure (44.4%). Those tumors that surrounded the thecal sac in the vertebral canal and whose adjacent vertebral bodies had abnormal signal intensities were infiltrating and malignant. CONCLUSION: There are many kinds of dumbbell-shaped spinal tumors other than neurogenic ones. MRI is useful in diagnosing dumbbell-shaped spinal tumors, especially those of neurogenic origin, and aids in distinguishing benign from malignant tumors.

Adolescent↗

PubMedDate not supplied

Interleukin-6 inhibits radiation induced apoptosis in pancreatic cancer cells.

We have examined the relationship between the expression and activation of the IL-6 receptor and the possible involvement of IL-6 in the resistance of radiation-induced apoptosis in pancreatic cancer cells. Levels of IL-6 in the incubation media measured with ELISA were 1900 pg/ml in CFPAC-1, 54 pg/ml in HPAC and less than 0.2 pg/ml in MIAPaCa-2 and AsPC-1. Western blot demonstrated gp80 protein (IL-6 receptor a subunit) in all pancreatic cancer cell lines except in AsPC-1. When immunoprecipitation was performed, the bands indicating phosphorylated gp130 (IL-6Rbeta) were observed in CFPAC-1 and HPAC, however, no band was found in MIAPaCa-2 or in AsPC-1 cells. RT-PCR and Western blot demonstrated that mRNA and protein expression for Bcl-2 and Bcl-XL was substantially increased by the IL-6 treatment in CEPAC-1 cells, but not in AsPC-1 cells. Neither exogenous IL-6 nor neutralizing anti-IL-6 mAb affected the proliferation of CFPAC-1 and AsPC-1 cells. However, the IL-6 treatment significantly attenuated the susceptibility to radiation in CFPAC-1 cells but not in AsPC-1 cells, and the neutralizing anti-IL-6 mAb significantly increased the radiosensitivity of CFPAC-1 cells. The results indicated that IL-6 might be produced in a paracrine and/or autocrine fashion in pancreatic cancer cells. In-6 inhibits radiation-induced apoptosis and enhances the survival of the cells through a functional receptor system, which is associated with the up-regulation of anti-apoptotic Bcl-2 family proteins, especially Bcl-XL.

Apoptosis↗

PubMedDate not supplied

Simultaneous liquid chromatographic determination of water-soluble vitamins, caffeine, and preservative in oral liquid tonics.

A rapid, simple, and reliable liquid chromatographic method has been developed for the simultaneous determination of nicotinamide (niacinamide), thiamine, riboflavin, riboflavin sodium phosphate, pyridoxine, caffeine, and sodium benzoate in commercial oral liquid tonics. The 7 components are separated on a reverse phase C18 column using a mobile phase of acetonitrile-0.01M potassium dihydrogen phosphate-triethylamine (8 + 91.5 + 0.5 v/v/v) containing 5mM sodium octanesulfonate and adjusted to pH 2.8 with phosphoric acid. Components are detected at 254 nm with attenuation 0.02 AUFS. Acetanilide is used as an internal standard. In addition to the 7 components mentioned, nicotinic acid (niacin), cyanocobalamin, and folic acid are also separated under the same conditions. Sample preparation involves only addition to internal standard solution and dilution with mobile phase and then filtration. Recoveries of the 7 components and cyanocobalamin from spiked preparations ranged from 97 to 104% with coefficients of variation of 0.9-4.2%.

Caffeine↗

PubMedDate not supplied

Liquid chromatographic determination of L-ascorbic acid in candies and soft drinks.

The L-ascorbic acid (AsA) contents of candies and soft drinks available in the market were determined by liquid chromatography (LC). Samples are cleaned up on a disposable Sep-Pak C18 cartridge followed by reverse phase separation on an ODS column using a mobile phase of 0.1% phosphoric acid (pH 2.2). The AsA peak is detected on the basis of the UV absorption at 254 nm. The detection limit was 1 microgram/mL final concentration. Recoveries of AsA added at levels of 1-10 mg/g candy and 1-10 mg/10 mL soft drink were 99.2-101.7% with a coefficient of variation of 0.52-1.20% (n = 5). The present method allows rapid and accurate assays because it is a simple procedure compared with the official dye-titration method, and it is suitable for the routine analysis of AsA in selected candies and soft drinks.

Ascorbic Acid↗

PubMedDate not supplied

Determination of p-hydroxybenzoic acid esters in cosmetics by liquid chromatography with ultraviolet and fluorescence detection.

A simple, precise, and accurate liquid chromatographic method with both ultraviolet (UV) and fluorescence detection is described for the determination of methyl, ethyl, propyl, and butyl p-hydroxybenzoates (PHBA-esters) in cosmetics. sec-Butyl p-hydroxybenzoate is added to the sample as an internal standard. Then the PHBA-esters are extracted with ether, the ether is evaporated to dryness, and the residue is dissolved in 60% (v/v) acetonitrile. The acetonitrile solution is passed through a Sep-Pak C18 cartridge to remove co-extracted lipids. PHBA-esters are determined by reverse-phase liquid chromatography with UV detection at 254 nm and fluorescence detection at ex 280 nm, em 305 nm. The mobile phase is acetonitrile-water (35 + 65). The method was linear over the concentration range of 0.005-0.15 mg/mL. Mean recoveries of each PHBA-ester were 98.9-102.7% (coefficients of variation less than or equal to 2.0%).

Chromatography, Liquid↗

PubMedDate not supplied

Liquid chromatographic determination of barbaloin (aloin) in foods.

A simple and rapid liquid chromatographic method is described for the determination of barbaloin (aloin, 10-D-glucopyranosyl-1,8-dihydroxy-3-(hydroxymethyl)-9(10H)-anthraceno ne) in foods. Barbaloin is extracted with water from foods containing aloe and the extract is cleaned up on a disposable cartridge by using methanol-water (55 + 45) as eluant. The eluted barbaloin is separated by liquid chromatography on a YMC A-302 column with methanol-water (50 + 50) mobile phase, and detected at 293 nm. Recoveries of barbaloin added to foods at the levels of 0.05 and 0.50 mg/g were 94.4-100%. Assay results for commercial food samples indicated that the present method is applicable to a variety of foods supplemented with aloe.

Aloe↗

PubMedDate not supplied

MR angiography of the coronary arteries.

Coronary vessels have been the most difficult regions to demonstrate by magnetic resonance (MR) imaging because of their motion with respiration and heart beat. MR coronary angiography may be utilized for evaluation of the coronary arteries. The purposes of the present study were to demonstrate coronary arteries in normal volunteers by using a fast MR imaging technique and to evaluate the feasibility of this imaging technique. Thirteen healthy volunteers in a prone position were imaged with a 1.5 Tesla unit by using an ECG-gated fat-suppressed Turbo fast low-angle shot (FLASH) sequence with k-space segmentation. The imaging time for one slice was approximately 15-23 seconds, within one breath-hold. The left main coronary trunk (LMT), left anterior descending (LAD), circumflex (LCX), and right coronary (RC) arteries were imaged at rates of 92.3, 100, 92.3, and 84.6%, respectively. Diameters of the LMT, LAD, LCX, and RC in proximal portions were 5.2 +/- 1.1, 3.2 +/- 1.3, 2.2 +/- 0.6, and 4.0 +/- 1.6 mm, respectively. The segmented Turbo FLASH technique was able to image the normal coronary arteries, and is a promising method by which to evaluate coronary artery diseases.

Adult↗

PubMedDate not supplied

Pulmonary MR angiography: a comparison of 2D and 3D time-of-flight.

OBJECTIVE: To compare two-dimensional (2D) time-of-flight (TOF) MR angiography and three-dimensional (3D) TOF MR angiography for visualization of pulmonary arteries and to determine whether pulmonary veins can be viewed selectively. MATERIALS AND METHODS: Imaging was performed using a 1.5 T superconducting MR system with a body coil. Three kinds of 2D TOF MR angiography were compared in four normal volunteers: using a 2D fast low angle shot (FLASH) without cardiac gating and both with and without breath-holding and using a T2-weighted TurboFLASH with cardiac gating and breath-holding. Two-dimensional TOF MR angiography using a T2-weighted TurboFLASH with cardiac gating and breath-holding and 3D TOF MR angiography using fast imaging with steady precession with neither cardiac gating nor breath-holding were compared in four other normal volunteers. Two-dimensional TOF MR venography with a presaturation pulse to suppress artery signals was evaluated in another four normal volunteers. RESULTS: Three-dimensional TOF MR angiography appeared to be better than 2D TOF MR angiography for delineating pulmonary arteries in the volunteers. The third order branches of peripheral pulmonary veins were distinguishable on 2D TOF MR venography using a presaturation pulse. CONCLUSION: Three-dimensional pulmonary TOF MR angiography is useful in demonstrating pulmonary arteries whereas 2D TOF MR venography with a presaturation pulse is useful in showing pulmonary veins.

Adult↗

PubMedDate not supplied

Preliminary study of pulmonary three-dimensional time-of-flight MR angiography with breath-holding using a contrast medium.

Pulmonary three-dimensional (3D) time-of-flight (TOF) MR angiography with breath-holding using a paramagnetic contrast medium and a 1.5 Tesla superconducting MR system was performed on a volunteer and five patients with hilar or mediastinal tumors in order to visualize the main pulmonary arteries. Six MR scans (one before and five after a Gd-DTPA injection) were obtained using fast imaging with a steady-state precession (FISP) sequence while the subjects held their breath. The acquisition time was 21 seconds, and images were obtained every 30 seconds. In the normal volunteer, the pulmonary MR angiogram obtained in the first postcontrast scan was successful in visualizing the main pulmonary artery, and its right and left branches to the level of the lobar branches. In the five patients, at the first postcontrast scanning, the pulmonary arteries had higher signal intensities than the surrounding structures. Therefore, during this imaging period, most tumors could be clearly distinguished from vessels. In images made much later after contrast medium injection, the pulmonary arteries could not be distinguished from the others. Pulmonary 3D TOF MR angiography with breath-holding using a contrast medium is very useful in demonstrating pulmonary vessels and tumors.

Adult↗

PubMedDate not supplied

Meningeal hemangiopericytoma metastatic to the heart.

We report for the first time the metastasis of intracranial hemangiopericytoma to the heart. In evaluating cardiac conditions, MRI provided useful information regarding the location and features of paracardiac tumors.

Female↗

PubMedDate not supplied

Pituitary prolactinoma mimicking tumor originating from the sphenoid sinus or clivus.

We report a case of a pituitary prolactinoma mimicking a sphenoid sinus or clival tumor. On magnetic resonance (MR) images, a soft tissue mass located inferior to the apparently normal pituitary gland, and occupied the posterior third of the sphenoid sinus and eroded the upper portion of the clivus. It had iso- to low intensity on the T1-weighted image, and slightly high intensity on the T2-weighted image. Careful observation revealed that the floor of the sella turcica was not identified and there was sulcus formation between the tumor and clivus, probably suggesting extraclival tumor, pituitary tumor. Transsphenoidal tumor resection and histopathological study revealed that it was a prolactinoma.

Cranial Fossa, Posterior↗

PubMedDate not supplied

Ras gene point mutations in gallbladder lesions associated with anomalous connection of pancreatobiliary ducts.

BACKGROUND/AIMS: The present study was undertaken to investigate possible changes in the K-ras oncogene in patients with gallbladder lesions (carcinoma, adenoma or hyperplasia) in relation to the presence or absence of an anomalous connection of pancreatobiliary ducts (ACPBD). METHODOLOGY: Gallbladder specimens were obtained from 44 patients with lesions that were either with or without ACPBD, and DNA samples were analyzed using PCR-SSCP. Point mutations in codons 12, 13 and 61 were analyzed by direct sequencing methods with oligonucleotide primers. RESULTS: The K-ras codon 12 was detected in 83.3% (5/6) of carcinomas the one adenoma tested and in 35.7% (5/14) of hyperplastic lesions with ACPBD, as opposed to only 36.4% (4/11) of carcinomas without ACPBD. The one case of gallbladder adenoma and 11 cases of normal gallbladder without ACPBD studied demonstrated no point mutations in the K-ras oncogene. CONCLUSIONS: Alteration of the K-ras oncogene appears to be involved in the early stages of gallbladder carcinogenesis when in association with ACPBD. The results further suggest that hyperplasia in cases with ACPBD may be a significant pre-cancerous lesion.

Adenocarcinoma↗

PubMedDate not supplied

Evaluation of reconstructed hepatic veins with breath-hold 2D time-of-flight MR venography.

PURPOSE: The purpose of this study was to assess the ability of magnetic resonance (MR) venography to evaluate the patency of reconstructed hepatic veins after surgery. PATIENTS AND METHODS: Five normal volunteers with normal hepatic veins and eight patients who underwent reconstruction of the hepatic veins after resection of hepatic tumors were included. All subjects underwent breath-hold two-dimensional (2D) time-of-flight MR venography using a fast low angle shot (FLASH) technique with a 1.5 Tesla magnet. The initial imaging plane was coronal, and sagittal and/or transverse planes were added when necessary. Data were postprocessed with a maximum intensity projection (MIP) algorithm. In six patients, the MR findings were verified by iodinated hepatic venography. RESULTS: The confidence level increased when patency was evaluated using a combination of MIP and source images or other imaging planes compared with the use of MIP images alone (3.0 to 3.6, p < 0.05). A signal drop near the orifice at the inferior vena cava was observed in three normal patients. The severity of stenosis was overestimated by MR venography in five patients. Obstruction was correctly suggested in one patient. CONCLUSION: Although 2D time-of-flight MR venography overestimated stenosis of the hepatic vein at the site of connection, it might provide information on the patency of reconstructed hepatic veins especially when more than one orthogonal plane is used and both MIP and source images are evaluated.

Adult↗