[Problems of SNR evaluation method in parallel MRI].
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Image Enhancement↗
Biomedical subjects
Yoshio Machida
Publications and source records attributed to Yoshio Machida.
Enantiomeric purity determination of acetyl-L-carnitine by NMR with chiral lanthanide shift reagents.
Enantiomer signal separation of acetyl-carnitine chloride was obtained on a 500 MHz Nuclear Magnetic Resonance (1H NMR) analysis by fast diastereomeric interaction with chiral shift reagents such as chiral lanthanide-camphorato or chiral samarium-pdta shift reagents. Effects of the kinds of chiral shift reagents and the molar ratio of chiral shift reagent to acetyl-carnitine chloride on enantiomer signal separation were investigated and evaluated. Optimization of the experimental conditions provided two significant split signals for the enantiomers, leading to the successful quantitative analysis. Distinguishment of 0.5% of the minor enantiomer (D-form) in acetyl-L-carnitine chloride was found to be possible by 1H NMR with tris[3-(heptafluoropropylhydroxymethylene)-D-camphorato] and praseodymium derivative, (Pr[hfc]3), as chiral shift reagents.
Acetylcarnitine↗
Enhancement of blood vessel visualization in 3D time-of-flight MR angiography utilizing surface array coil.
Array coils play an important role in improving the signal-to-noise ratio (SNR) and achieving parallel imaging; however, one disadvantage of array coils is the nonuniformity of their sensitivity. We propose a simple algorithm to enhance blood vessel visualization in 3D-TOF-MRA (three-dimensional time-of-flight magnetic resonance angiography) utilizing this surface array sensitivity, and we apply it to the MRA data of normal volunteers. We have verified that visualization of peripheral vessels has been remarkably improved.
Adult↗
Comparison of conventional fast spin echo, single-shot two-dimensional and three-dimensional half-fourier RARE for T2-weighted female pelvic imaging.
PURPOSE: To evaluate the usefulness of the three-dimensional half-Fourier RARE sequence in comparison with single-shot two-dimensional half-Fourier RARE and conventional fast spin echo (FSE) for female pelvic imaging. MATERIALS AND METHODS: Imaging with all sequences was performed in 146 patients with 166 focal lesions on a 1.5-T system. The images were compared on the basis of quality, lesion conspicuity, and lesion to the uterus contrast-to-noise ratio (CNR). RESULTS: The sharpness of intrapelvic organs on the three-dimensional half-Fourier RARE sequence was better than that on two-dimensional half-Fourier RARE and worse than that on FSE. Motion-related artifacts for three-dimensional half-Fourier RARE were more frequent than those for two-dimensional half-Fourier RARE. There was no statistical difference between the three-dimensional half-Fourier RARE sequence and FSE in regard to lesion conspicuity and overall image quality. The CNR of leiomyoma to myometrium and cervical cancer to cervical stroma was the highest with three-dimensional half-Fourier RARE (P< 0.05). CONCLUSION: The three-dimensional half-Fourier RARE sequence generates images with higher contrast and better image resolution than two-dimensional-RARE. The three-dimensional data set provided images that can be observed in any orientation without acquiring an additional scan by using the multiplanar reconstruction (MPR) method.
Adult↗
Nuclear magnetic resonance studies for the chiral recognition of (+)-(R)-18-crown-6-tetracarboxylic acid to amino compounds.
Chiral recognition capability of (+)-(R)-18-crown-6-tetracarboxylic acid (18C6H(4)) to various amino compounds containing 16 amino acids, five alkyl amines, seven aminoalcohols and other amino compounds in nuclear magnetic resonance (1H-NMR) analysis was investigated. In general, amino compounds having an aromatic ring were well chiral recognized with 18C6H(4) compared with those having no aromatic ring. Effects of 18C6H(4) concentration and the kind of deuterated solvents (D(2)O, CD(3)OD and CD(3)CN) for measurement on the chiral recognition was investigated in detail. Concentration of 5 equivalent 18C6H(4) to the amino compounds was found to be sufficient for the chiral recognition. On the other hand, an effective deuterated solvent (D(2)O, CD(3)OD or CD(3)CN) for measurement was different in each compound. Distinguishment of 1.0% of the minor enantiomer (D-form) in L-alanine-beta-naphthylamide was found to be possible by 1H-NMR employing 18C6H(4) as a chiral shift reagent.
Amino Acids↗