[Ultrasonic study on tissues of parotid tumors--measurement of attenuation of ultrasound within tumors in vivo].
Pulse transmission technique has been used and developed in the Department of Otorhinolaryngology, Chiba University, in order to estimate attenuation of ultrasound within tumors of the parotid gland in vitro. A new apparatus to measure the attenuated ultrasound within the tissue was devised by using a pulse reflection method. After the measurement in vivo, the same examination was performed in a specimen of the removed tumor in vitro after surgery. Correlation between the characteristic of attenuation of ultrasound within the tissue in vivo and in vitro was investigated. The results in malignant parotid tumors were compared with ones in benign tumors of the parotid gland, too. The measurement of attenuation of ultrasound within a tumor in vivo was also compared with regard to the posterior echoes in ultrasound imaging, and then pathohistological study of the tumor was carried out in each case. The results of this study were summarized as follows: 1) Characteristics of ultrasound-attenuation within tumors in vivo were well correlated with ones in vitro. 2) Attenuation of ultrasound in malignant tumors tended to be stronger than that in benign ones. 3) Values of ultrasound-attenuation within tissues in vivo were also affected by the contents of collagen in them, which was reported in my previous study on tissues in vitro. 4) Posterior echoes in ultrasound imagings were influenced by attenuations of ultrasound in tissues. However, the measurement of attenuation of ultrasound in tumors of the parotid gland is assumed to be helpful to promote the diagnostic value of sonographical examinations, and especially it would be useful for differential diagnosis of malignancies.
Ohyachi
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Department of Otolaryngology, School of Medicine, Chiba University.
D006801:Humans; D010307:Parotid Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology; D014463:Ultrasonography / Q000379:methods