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Biomedical subjects

A Koyano

Publications and source records attributed to A Koyano.

6 recordsLinked to original sources
PubMed1988

Studies on frequency-dependent attenuation in the normal liver and spleen and in liver diseases, using the spectral-shift zero-crossing method.

This report presents results of studies using the spectral-shift zero-crossing method to measure frequency-dependent attenuation (FDA) in normal liver and spleen and in diseased liver. We developed a new system for attenuation analysis that calculated FDA in dB/cm/MHz according to the following equation: (formula: see text). Data are collected from the region of interest on the scan image. Graphite-gel phantoms of known attenuation value are used to create a high degree of accuracy in this new system. Mean attenuation of normal livers was 0.55 +/- 0.05 dB/cm/MHz, while that of normal spleen was 0.37 +/- 0.06 dB/cm/MHz. No correlation between FDA and age could be seen. FDA was 0.81 +/- 0.17 dB/cm/MHz in fatty liver, 0.63 +/- 0.13 dB/cm/MHz in liver cirrhosis, and 0.64 +/- 0.12 dB/cm/MHz in chronic hepatitis. These values are higher than those obtained from normal liver, while tumor masses in the liver (hepatocellular carcinoma, hepatoblastoma, hemangioma) and diffuse infiltration by malignant lymphoma produced lower than normal values, averaging 0.38 +/- 0.08 dB/cm/MHz.

Adolescent↗
PubMed1985

Acoustic intensity histogram pattern diagnosis of liver diseases.

Display information on the histogram pattern includes echo intensity and echo frequency in the region of interest (ROI). The level and frequency of the center of gravity and the width of the echo level at 0%, 10%, and 50% of normalized frequency are calculated from the histogram. The width of the echo from the liver is significantly elongated on the X axis (P less than 0.001) but that of the center of gravity is not. Fatty liver shows the same attenuation rate curve as normal liver, although echo intensity is greatly increased. The curve of the attenuation rate derived from the histogram can be used to distinguish between liver cirrhosis and the tissue of normal or fatty liver. This study clearly demonstrates the clinical usefulness of the histogram as a diagnostic tool.

Carcinoma, Hepatocellular↗
PubMed1984

The development of real-time two-dimensional Doppler echocardiography and its clinical significance in acquired valvular diseases. With special reference to the evaluation of valvular regurgitation.

A noninvasive method for real time blood-flow imaging using ultrasound has long been required in the fields of cardiology and cardiovascular surgery. Recently, we developed a method of two-dimensional Doppler echocardiography (hereafter abbreviated as "2-D Doppler") for clinical use which allows us to obtain noninvasively, intracardiac blood-flow images in real time. The main purpose of this paper is to describe the newly developed blood-flow imaging system "2-D Doppler" and to demonstrate its clinical usefulness in acquired valvular diseases, particularly in the evaluation of valvular regurgitation. The device, in principle, combines a conventional pulsed-Doppler system and a newly developed auto-correlator, in which blood-flow images within a given cross section of a beating heart are noninvasively displayed in real time, simultaneously with conventional two-dimensional echocardiograms. The system can provide three kinds of information, direction, velocity and turbulence of blood flow. The 2-D Doppler examinations were carried out on 72 patients with acquired valvular diseases whose diagnoses were confirmed by angiography and/or surgery. Studies were performed comparing the findings of the 2-D Doppler and those of angiography (for aortic and mitral lesions) or with operative findings (for tricuspid lesions) in the quantitative evaluation of valvular regurgitation. Aortic, mitral and tricuspid valvular regurgitation have been quantitatively demonstrated with 2-D Doppler, and, for each value, the severity of the regurgitation showed a high correlation between the findings of 2-D Doppler and of angiography or surgery. In conclusion, we have found that (1) 2-D Doppler is very useful in detecting and estimating the severity of valvular regurgitation, and that (2) 2-D Doppler may replace conventional angiography in some situations.

Aortic Valve Insufficiency↗
PubMed1983

A new technique in echocardiology: B-mode to M-mode transformation.

In conventional two-dimensional Echocardiography with sector scanning, M-mode is simultaneously displayed on TV-monitor as the time based ultrasound signals. With conventional system, one end of the cursor-line in B-mode image which indicates the beam direction of M-mode, is always fixed at the point corresponding to the transducer tip. This system has the capability to transform B-mode to M-mode images in any desired direction. However, the time resolution in M-mode is limited to about 33 milli-seconds.

Biometry↗