1998 Fiscal Year Final Research Report Summary
Ultrasound harmonic imaging system for detection of microbubbles using specified sequences
| Project/Area Number |
09558117
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 展開研究 |
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| Research Field |
Biomedical engineering/Biological material science
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| Research Institution | KYOTO UNIVERSITY |
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Principal Investigator |
MORIYASU Fuminori Kyoto University, Associate Professor, 医学研究科, 助教授 (80191055)
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| Co-Investigator(Kenkyū-buntansha) |
MINE Yoshitaka Toshiba medical systems engineering co., ltd, 医用機器技術研究所・開発第二担当, 主務
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| Project Period (FY) |
1997 – 1998
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| Keywords | hepatocellular carcinoma / harmonic imaging / ultrasound contrast agent / intermittent scanning / microbubble / hepatic artery / portal blood flow / tumor blood flow |
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| Research Abstract |
The following results were obtained from studies performed in 1997 and 1998.
1) Contrast agents such as A1bunex^<TM> which are composed of microbubbles are easily destroyed by receiving ultrasound exposure with a low amplitude in which MI (mechanical index) is less than 0.6.2) Liver parenchyma can not opacified with contrast agents when the frame rate is more than 10 frames/second, because the scanning erases microbubble contrast agent which is perfusing the liver parenchyma. 3) Blood supply to the malignant liver tumors is mainly from hepatic artery and perfusion of the tumor is more rapid than thai of the non-tumor liver tissue. Therefore, an optimal intermittent time should be set for visualization of liver cancer. 4) Characteristics of the transducer and resonance frequency should be considered in order to decide the optimal transmitting frequency for harmonic imaging. 5) Contrast enhancement was strong enough when the pulse length was longerbut the spatial resolution became poorer. The optimal pulse length seemed to be two pulses.
The test instrument has been improved accordingto the results mentioned above in 1999. The frame rate was reduced from the original harmonic imaging system and the optimal frame rate can be chosen accordingtc purpose of the study. The acoustic power can be controlled optimally according to attenuation of the humar body.
The good results have been obtained using prototype system. Contrast enhancement effect has been drastically improved by controllingpulse length of emitting ultrasound. Both high spatial resolution and high contrast were effective to visualize small sized hep atocellular carcinoma. Blood perfusion of the Livertumors was estimated quantitatively by varying intermittent time of the scanning, helping us to differentiate malignancy from benign tumors. Ultrasound contrast enhancement has been useful in clinical diagnosis by comparing with CT and MRI in liver tumors.
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