Biomedical subjects

Tamotsu Suzuki

Publications and source records attributed to Tamotsu Suzuki.

3 recordsLinked to original sources

PubMed2005

[Trial of signal-to-noise ratio adjustment by repetition time in magnetic resonance imaging].

The purpose of this study was to find an equation between signal-to-noise ratio (SNR) and repetition time (TR) in order to adjust SNR by changing TR in magnetic resonance imaging (MRI) examinations. Using a phantom for SNR measurement, according to NEMA MS 1-1988, measurement of SNR was performed by spin-echo pulse sequences for various TR values. An equation of SNR and scanning parameters including TR were obtained from these results. In order to determine the range of TR where the images showed contrast suitable for diagnosis, the contrast-to-noise ratio (CNR) was measured for various TR values. CNR measurement was performed by scanning a brain phantom, and CNR was defined as the contrast of white matter and gray matter divided by noise. Scanning of a resolution phantom was carried out with various scanning parameters, and the usefulness of the equation obtained was determined by whether or not pins in the phantom were visible. The reliability of the equation was confirmed from this verification. Results showed that TR can be used for the adjustment of SNR using the equation obtained in this study.

Artifacts↗

PubMed2004

[Performance evaluation of X-ray CT using visible scintillation light].

We proposed a new method of performance evaluation for X-ray CT using visible scintillation light and examined its usefulness in this study. When we scanned a plastic scintillator disk in a gantry opening of the X-ray CT, we could observe visible scintillation light. The rotation of the light-emitting area of the disk corresponded to that of the X-ray tube. We were able to record the scintillation light by digital video camera. By analyzing the area of visible scintillation light, the rotation speed of the X-ray tube, angular spread of the X-ray beam, uniformity of the incident X-rays, and change in X-ray energy were measured. No other method is available to obtain the above parameters of X-ray CT during a single CT scan. In the measurements of the uniformity of incident X-rays and change of X-ray energy, our method showed good accuracy in detecting the attenuation caused by the couch between the X-ray tube and the plastic scintillator disc. The proposed method is inexpensive and easy-to-use. We conclude that the method is a useful tool for performance evaluation as well as a maintenance tool for X-ray CT.

Evaluation Studies as Topic↗

PubMed2002

Total synthesis of spicamycin.

The first total synthesis of one of the spicamycin congeners, SPM VIII (3), is described. A preliminary model study for construction of the characteristic N-glycoside linkage in spicamycin using tetra-O-benzyl-beta-D-mannopyranosylamine (13) and halopurines 5 revealed that Pd-catalyzed conditions successfully provided the coupling products 14 and 15 in good yields. It was also shown that thermal anomerization of the N-glycosides easily occurred, which resulted in the predominant formation of the beta-anomer as the thermodynamically favored compound, and the activation energy of anomerization of 15 was estimated to be ca. 30 kcal/mol. The novel aminoheptose unit of spicamycin 6 was prepared stereoselectively by carbon elongation of an acyclic aldehyde, prepared by ring cleavage reaction of a highly functionalized cyclohexane derived from naturally abundant myo-inositol. The Pd-catalyzed coupling reaction of the beta-heptopyranosylamine 6 with protected 6-chloropurine 5d, followed by deprotection, provided spicamycin amino nucleoside 2, whose condensation with dodecanoylglycine completed the total synthesis of 3. This study confirmed the proposed unique structure of a novel nucleoside antibiotic.

Anti-Bacterial Agents↗