Search PubMed⌕ Search

Biomedical subjects

Masayuki Suzuki

Publications and source records attributed to Masayuki Suzuki.

At least 37 records · Page 2Linked to original sources
PubMed2005

[Clinical efficacy of 3D-MR cholangiopancreatography (MRCP) with the T2Plus technique].

The T2Plus technique is an MR method in which longitudinal magnetization is recovered by the application of a -90 degrees radiofrequency pulse in the recovery period after data acquisition. The present study was performed to evaluate the efficacy of the 3D-fast advanced spin echo (FASE) sequence with T2Plus technique in improving the image quality of respiratory-triggered 3D-MRCP. We performed a phantom study and clinical study in 60 cases. In the clinical study, ERCP and CT images were used as the gold standard for evaluating visualization of the pancreato-biliary system with the T2Plus technique. In the phantom study, the signal-to-noise ratio (SNR) of distilled water was higher in the shorter TR owing to the effectiveness of the T2Plus technique. The contrast-to-noise ratio (CNR) of the biliary tract and the pancreatic duct to the liver were significantly higher (P<0.05) with the T2Plus technique. On visual evaluation by two experienced abdominal radiologists, the left and right hepatic duct, common hepatic duct, common bile duct, main pancreatic duct, and accessory pancreatic duct were visualized more clearly with the T2Plus technique (P<0.05). Improvement of the image quality of MRCP can be obtained by applying the T2Plus technique.

Cholangiopancreatography, Magnetic Resonance↗
PubMed2005

[Evaluation and comparison of dose profiles and patient doses among X-ray CT scanners].

The increased clinical use of multi-detector-row CT (MDCT) may result in increased radiation doses for patients. The objective of this study was to compare radiation dose profiles between MDCT with 16 data acquisition systems, MDCT with 4 data acquisition systems, and single-detector-row CT (SDCT), and to compare effective doses among them to measure specific organ doses. When comparing radiation dose profiles on the Z-axis, doses outside the scanning range increased, especially when a 20 mm X-ray beam width was used. Effective doses also were higher with MDCT (low helical pitch) than with SDCT (helical pitch 1.0:1), but were not higher with MDCT (high helical pitch) than with SDCT (helical pitch 1.0:1). When a 20 mm X-ray beam width or high helical pitch was used, scanning time was shortened, but doses outside the scanning range were increased. When the standard deviation (SD) is the same, there is not much difference between SDCT and MDCT in terms of effective doses if the helical pitch is 1.0:1. It can be expected that X-ray over-wrap under low helical pitch and incorrect parameter setting cause increased radiation dose to the patient. Therefore, high helical pitch should be used if it is possible to disregard the influence of image noise. It is important to be cautious in regard to patient radiation dose when MDCT is used, and it is necessary to perform high-quality examinations at as low a dose as possible. Optimization of the scan parameters is an important issue for the future.

Organ Specificity↗
PubMed2005

[Study of automated segmentation of the cerebellum and brainstem on brain MR images].

MR imaging is an important method for diagnosing abnormalities of the brain. This paper presents an automated method to segment the cerebellum and brainstem for brain MR images. MR images were obtained from 10 normal subjects (male 4, female 6; 22-75 years old, average 31.0 years) and 15 patients with brain atrophy (male 3, female 12; 62-85 years of age, average 76.0 years). The automated method consisted of the following four steps: (1) segmentation of the brain on original images, (2) detection of an upper plane of the cerebellum using the Hough transform, (3) correction of the plane using three-dimensional (3D) information, and (4) segmentation of the cerebellum and brainstem using the plane. The results indicated that the regions obtained by the automated method were visually similar to those obtained by a manual method. The average rates of coincidence between the automated method and manual method were 83.0+/-9.0% in normal subjects and 86.4+/-3.6% in patients.

Adult↗
PubMed2005

High-order harmonic generation from boron plasma in the extreme-ultraviolet range.

We demonstrate the generation of up to the 63rd harmonic (lambda = 12.6 nm) of a Ti:sapphire laser pulse (150 fs, 10 mJ), using a prepulse- (210-ps,24-mJ) produced boron plasma as the nonlinear medium. The influence of various parameters on the harmonic conversion efficiency was analyzed. The steep decrease in intensity for low-order harmonics (up to 19th order) was followed by a plateau. Typical conversion efficiencies were evaluated to be 10(-4) (for a 3rd harmonic) to 10(-7) (within the plateau region). Harmonic generation appeared to be efficient for the plasma that comprised neutral atoms and singly ionized boron.

Journal Article↗
PubMed2005

[Method for determining scan timing based on analysis of formation process of the time-density curve].

A strict determination of scan timing is needed for dynamic multi-phase scanning and 3D-CT angiography (3D-CTA) by multi-detector row CT (MDCT) . In the present study, contrast media arrival time (T(AR)) was measured in the abdominal aorta at the bifurcation of the celiac artery for confirmation of circulatory differences in patients. In addition, we analyzed the process of formation of the time-density curve (TDC) and examined factors that affect the time to peak aortic enhancement (T(PA)). Mean T(AR) was 15.57+/-3.75 s. TDCs were plotted for each duration of injection. The rising portions of TDCs were superimposed on one another. TDCs with longer injection durations were piled up upon one another. Rise angle was approximately constant in response to each flow rate. Rise time (T(R)) showed a good correlation with injection duration (T(ID)). T(R) was 1.01 TID (R(2)=0.994) in the phantom study and 0.94 T(ID)-0.60 (R(2)=0.988) in the clinical study. In conclusion, for the selection of optimal scan timing it is useful to determine T(R) at a given point and to determine the time from T(AR).

Contrast Media↗
PubMed2005

[Visualization of the lower cranial nerves by 3D-FIESTA].

MR cisternography has been introduced for use in neuroradiology. This method is capable of visualizing tiny structures such as blood vessels and cranial nerves in the cerebrospinal fluid (CSF) space because of its superior contrast resolution. The cranial nerves and small vessels are shown as structures of low intensity surrounded by marked hyperintensity of the CSF. In the present study, we evaluated visualization of the lower cranial nerves (glossopharyngeal, vagus, and accessory) by the three-dimensional fast imaging employing steady-state acquisition (3D-FIESTA) sequence and multiplanar reformation (MPR) technique. The subjects were 8 men and 3 women, ranging in age from 21 to 76 years (average, 54 years). We examined the visualization of a total of 66 nerves in 11 subjects by 3D-FIESTA. The results were classified into four categories ranging from good visualization to non-visualization. In all cases, all glossopharyngeal and vagus nerves were identified to some extent, while accessory nerves were visualized either partially or entirely in only 16 cases. The total visualization rate was about 91%. In conclusion, 3D-FIESTA may be a useful method for visualization of the lower cranial nerves.

Accessory Nerve↗
PubMed2005

Dynamic MR imaging for diagnosis of lesions adjacent to pituitary gland.

In this study, we evaluated the usefulness of dynamic studies for the preoperative diagnosis of tumor lesions adjacent to the pituitary gland. We examined 13 tumors. We obtained pre- and post-contrast thin slice T1-weighted images of the sellar regions. FSE sequences were used for dynamic study. The capability to distinguish the tumor from the pituitary gland and additional information obtained from the dynamic study were evaluated. Two meningiomas were identified more clearly on the dynamic than on the delayed study. In two cavernous hemangiomas, the peripheral nodular stains gradually increased during the dynamic study. For the preoperative evaluation of lesions adjacent to the pituitary gland, the dynamic study can often identify the lesions more clearly and may provide additional information.

Adult↗
PubMed2005

CT arteriography for orbital tumors: diagnostic and surgical value.

The aim of this study is to investigate the efficacy of dynamic computed tomography (CT) during selective angiography (CT-arteriography) of orbital tumors in the evaluation of intratumoral vascular anatomy, feeding artery territory, and histological diagnosis. Among 35 consecutive cases with various orbital lesions, those cases showing tumor staining or pooling of the contrast medium on digital subtraction angiography (DSA) were evaluated by CT-arteriography (n = 14). The information obtained by CT-arteriography was compared with that provided by enhanced MRI (n = 31) and dynamic MRI (n = 21), in which the contrast medium was injected intravenously. In addition to the visualization of fine vascular anatomy, CT-arteriography emphasized areas of nodular enhancement and non-enhancing cystic/necrotic components as well as the intratumoral feeding arteries. Patterns of CT-arteriography were categorized into three subgroups: homogeneous enhancement (benign lymphoid lesion), partial enhancement (schwannomas and carcinomas), and patchy multinodular enhancement (specific for cavernous angiomas). In addition, CT-arteriography with selective arterial catheterization clearly delineated the feeding artery territories. CT-arteriography, with a minimal dose of contrast medium, can offer significant advantages over intravenously injected dynamic neuroimaging, and provides additional valuable preoperative information about the orbital tumor under investigation.

Adult↗
PubMed2005

Mathematical analysis of urea rebound in long-term hemodialysis patients.

Quantifying hemodialysis (HD) treatment requires knowledge of the equilibrated concentrations of the post-HD small molecule rebounds. However, measurement of the equilibrated concentrations is only possible after resting in bed after HD for at least 30 min, and this is often impractical. Therefore, we have analyzed mathematically the time course of post-HD urea rebound, and from this, have derived a new formula for predicting its equilibrated concentration. The blood urea nitrogen (BUN) was measured at 10 time points (immediately following HD, and 0.5, 2.5, 5, 7.5, 10, 15, 20, 25, and 30 min post-HD) in 12 anuric HD patients. The absolute change in the urea rebound (DeltaeqBUN) was approximated (DeltaestBUN) using the equation: DeltaestBUN = b -[1-exp x (-c x time (min))] + a x time (min). After the good correlation between DeltaeqBUN and DeltaestBUN, we compared the value of DeltaeqBUN measured at 30 min (DeltaeqBUN(30)) with that calculated (DeltaestBUN(30)) using only four sample points (immediately following HD, and 2.5, 5 and 10 min post-HD). Based on this result, we tried to predict post-HD BUN at 30 min (estBUN(30)). This study was undertaken to determine whether estBUN(30) may be representative of the equilibrated BUN (eqBUN(30)), and to compare with Kt/V using estBUN(30) and eqBUN(30). There was a significant correlation between DeltaeqBUN and DeltaestBUN (0.97 < r < 0.99, P < 0.001). Thus, there was a significant positive linear correlation between eqBUN(30) and estBUN(30) (eqBUN(30): 25.7 +/- 2.25 mg/dL, estBUN(30): 26.3 +/- 2.31 mg/dL; r(2) = 0.99, P < 0.001). A Kt/V measurement was obtained with single pool model using BUN just after HD (Kt/V(sp)), eqBUN(30) (Kt/V(eq)), and estBUN(30) (Kt/V(est)), and with double pool model using Kt/V(sp) (Kt/V(dp)) and was compared with them. Though Kt/V(sp) was significantly higher than Kt/V(eq) (1.26 +/- 0.08 vs. 1.09 +/- 0.07, P < 0.001), there were no differences among Kt/V(eq), Kt/V(est) and Kt/V(dp) (Kt/V(est): 1.06 +/- 0.07, Kt/V(dp): 1.10 +/- 0.07) and all values were clinically acceptable. Furthermore, there was a significant positive linear correlation between Kt/V(eq) and Kt/V(est) (r(2) = 0.98, P < 0.001). In conclusion, we have devised the method to predict equilibrated BUN and calculate double pool Kt/V, which requires samples up to 10 min post-HD.

Aged↗
PubMed2005

MR findings of nine cases of palatal tumor.

PURPOSE: To assess the magnetic resonance imaging (MRI) findings of pathologically confirmed palatal tumors. METHODS: Nine cases of palatal tumor were studied. Clinical data, MRI findings, and pathological diagnoses were evaluated. RESULTS: Five cases were tumors of the hard palate and four of the soft palate. Signal intensity on T1-weighted images varied, and hyperintensity was observed on T2-weighted images. Adenoid cystic carcinoma and diffuse large B cell lymphoma showed homogenous signal intensity. Other tumors showed heterogeneous signal intensities. On dynamic contrast analysis, malignant pleomorphic adenoma, adenoid cystic carcinoma, diffuse large B cell lymphoma, and peripheral T cell lymphoma showed early enhancement. On post-contrast T1-weighted images, hard palate pleomorphic adenoma, malignant pleomorphic adenoma, adenoid cystic carcinoma, diffuse large B cell lymphoma, and peripheral T cell lymphoma showed strong enhancement. Although the borders of the tumors were classified as clear in 6 cases treated surgically, macroscopic and microscopic borders of the tumors were unclear. Adenoid cystic carcinoma and hard palate diffuse large B cell lymphoma invaded the maxillary bone. CONCLUSION: Magnetic resonance findings of palatal tumor varied in different histologies. Even with a small palpable portion, malignant tumors could directly infiltrate surrounding structures, which demonstrated well on MRI.

Adenoma, Pleomorphic↗
PubMed2005

Lossless compression based on inter-frame coding for MDCT.

Many images are generated by medical equipment and the number of images to be stored increases yearly. To cope with the large digital storage and transmission requirements, data compression techniques have been studied. In the present study, grayscale data (2 bytes/pixel) were divided into high bytes and low bytes, and then the original medical images were also divided into high byte (1byte/pixel format) and low byte (1byte/pixel format) images. Inter-frame coding with and without division into high and low byte images was applied to MDCT images. Prediction (inter-frame) coding is a very common method to compress sequence images. The division process can be added to inter-frame coding easily. The compression ratio of the archived file produced by application of Lemple-Ziv compression and prediction coding with the division process was 0.39 at 700 images.

Algorithms↗
PubMed2004

Molecular cloning and characterization of a human multisubstrate specific nucleotide-sugar transporter homologous to Drosophila fringe connection.

Nucleotide-sugar transporters are crucial components in the synthesis of glycoconjugates. We identified a novel human nucleotide-sugar transporter gene, hfrc1, which is homologous to Drosophila melanogaster fringe connection, Caenorhabditis elegans sqv-7, and human UGTrel7. HFRC1 was localized within the Golgi apparatus following its transient expression in HCT116 cells. In human tissues, hfrc1 and UGTrel7 exhibited similar tissue distributions, although hfrc1 transcripts showed a 10 times greater abundance than those of UGTrel7. The heterologous expression of HFRC1 in the yeast revealed the multisubstrate specific transport activity of HFRC1 (for UDP-N-acetylglucosamine (UDP-GlcNAc), UDP-glucose (UDP-Glc), and GDP-mannose (GDP-Man), with apparent K(m) values of 8.0, 2.1, and 0.14 microm, respectively). In the mammalian cells, HFRC1 transported UDP-GlcNAc and UDP-Glc, but not GDP-Man. Overexpression of the hfrc1 gene in HCT116 cells modulated the cell surface heparan sulfate expression status. These results suggest that HFRC1 takes part in the synthesis of heparan sulfate by regulating the level of UDP-GlcNAc, a donor substrate for the heparan sulfate synthases.

Amino Acid Sequence↗
PubMed2004

Relationship between antibacterial activity of (+)-catechin derivatives and their interaction with a model membrane.

(+)-Catechin derivatives with different alkyl chain lengths were synthesized from (+)-catechin and various straight chain alkylaldehydes in the presence of methyl mercaptan, and their antibacterial activities against Gram-positive bacteria were evaluated. The antibacterial activity increased markedly with elongation of the alkyl chain lengths of the derivatives and reached a maximum at a chain of four to seven carbons. Subsequently, interaction of the (+)-catechin derivatives with a model membrane using liposome was investigated. The derivatives with a chain of three carbons or more were found to have very strong affinity for the membrane. The injury action of the derivatives against the membrane was examined with liposome in which calcein was enclosed as a fluorescent indicator. The leakage was observed in the derivatives with chain lengths of four carbons or more. Particularly the derivatives with chains longer than five carbons are considered to destroy the liposome membrane judging from the degree of the fluorescent leakage. These results implied that the lipophilicity and disrupting ability of the (+)-catechin derivatives to the liposome membrane participate in their antibacterial activity.

Anti-Bacterial Agents↗
PubMed2004

13C-Urea breath test, using a new compact nondispersive isotope-selective infrared spectrophotometer: comparison with mass spectrometry.

BACKGROUND: The (13)C-urea breath test ((13)C-UBT) is the most commonly used noninvasive method of detecting Helicobacter pylori infection. The isotope ratio mass spectrometer (IRMS) is the most commonly used device for this test, but the UBiT-IR300 infrared spectrophotometer, which, by comparison, is a more compact, less expensive, and easier to use analytical device, has now become widely used in the clinical setting in Japan. The objective of this study was to examine the diagnostic performance of the (13)C-UBT, using the UBiT-IR300. METHODS: A multicenter open-label study was performed, in which the (13)C-UBT was conducted using 100 mg of (13)C-urea. Analysis of (13)CO(2) in the expired breath was performed by infrared spectroscopy and mass spectrometry, and assessment of H. pylori infection was performed by culture, histological examination, and rapid urease test. RESULTS: In 255 cases of H. pylori infection diagnosed by biopsy methods, the (13)C-UBTs, performed with two different (13)C-ruea formulations, and using infrared spectroscopy for evaluation, showed a sensitivity of 97.7%, specificity of 98.0%, and accuracy of 97.8% (total number of evaluable cases, n = 505). The rate of agreement in the assessment of H. pylori infection between infrared spectroscopy and mass spectrometry was 100% ( n = 505). The regression equation for infrared spectroscopy to mass spectrometry was y = 0.9822x - 0.0809 ( n = 2542), with a correlation coefficient of r = 0.99989 ( P = 0.0001). CONCLUSIONS: Diagnosis of H. pylori infection can be performed using infrared spectroscopy as well as mass spectrometry.

Breath Tests↗
PubMed2004

Comparison between a new 13C-urea breath test, using a film-coated tablet, and the conventional 13C-urea breath test for the detection of Helicobacter pylori infection.

BACKGROUND: In Japan, urea breath-testing includes mouth rinsing with water immediately after the ingestion of (13)C-urea solution, to prevent false-positive results that are caused by oral bacteria with urease activity. Our objective was to evaluate the diagnostic performance of a urea breath test using a film-coated (13)C-urea tablet and omitting mouth rinsing. METHODS: The study was a multicenter trial comparing the solution- and tablet-based urea breath tests (UBTs). Helicobacter pylori status was determined by histology, culture, and rapid urease testing. RESULTS: Of the 255 subjects who completed the study, evaluation of the tablet-based UBT was possible in 254, and comparison of the tablet-based UBT and the solution-based UBT was possible in 250 patients. When the assessment achieved by a combination of biopsy-based methods was used as a reference standard, the sensitivity, specificity, and accuracy of the tablet-based method were determined to be 97.7%, 98.4%, and 98.0%, respectively. When the results of the solution-based UBT were used as a reference standard, the sensitivity, specificity, and accuracy of the tablet-based UBT were determined to be 96.9%, 97.6%, and 97.2%, respectively. CONCLUSIONS: The (13)C-urea tablet-based method proved to be a simple and accurate test for the diagnosis of H. Pylori infection. Mouth rinsing was not required.

Adult↗
PubMed2004

Recurrent peptic ulcers in patients following successful Helicobacter pylori eradication: a multicenter study of 4940 patients.

OBJECTIVE: Although curative treatment of Helicobacter pylori infection markedly reduces the relapse of peptic ulcers, the details of the ulcers that do recur is not well characterized. The aim of this study is to describe the recurrence rate and specific features of peptic ulcers after cure of H. pylori infection. METHODS: This was a multicenter study involving 4940 peptic ulcer patients who were H. pylori negative after successful eradication treatment and were followed for up to 48 months. The annual incidence of ulcer relapse in H. pylori-cured patients, background of patients with relapsed ulcers, time to relapse, ulcer size, and site of relapsed ulcers were investigated. RESULTS: Crude peptic ulcer recurrence rate was 3.02% (149/4940). The annual recurrence rates of gastric, duodenal and gastroduodenal ulcer were 2.3%, 1.6%, and 1.6%, respectively. Exclusion of patients who took NSAIDs led annual recurrence rates to 1.9%, 1.5% and 1.3%, respectively. The recurrence rate was significantly higher in gastric ulcer. Recurrence rates of patients who smoked, consumed alcohol, and used NSAIDs were significantly higher in those with gastric ulcer recurrence compared to duodenal ulcer recurrence (e.g. 125 of 149 [83.9%] relapsed ulcers recurred at the same or adjacent sites as the previous ulcers). CONCLUSIONS: Curative treatment of H. pylori infection is useful in preventing ulcer recurrence. Gastric ulcer is more likely to relapse than duodenal ulcer. Recurrent ulcer tended to recur at the site of the original ulcers.

Alcohol Drinking↗