河野 通一¹, 林 紀夫¹, 佐々木 裕¹, 鈴木 都男¹, 笠原 彰紀¹, 房本 英之¹, 今井 豊², 鎌田 武信¹

Michikazu KONO¹, Norio HAYASHI¹, Yutaka SASAKI¹, Kunio SUZUKI¹, Akinori KASAHARA¹, Hideyuki FUSAMOTO¹, Yutaka IMAI², Takenobu KAMADA¹

¹大阪大学医学部第一内科, ²島津製作所プロセス計測事業部

¹First Department of Medicine, Osaka University Medical School, ²R/D Engineering, Process Instrumentation Div., Shimadzu Corp.

キーワード : Ultrasonic tissue characterization, Cepstrum, Chronic liver disease

Numerous pathological changes in the liver tissue are seen in patients with chronic liver disease. They include varying degrees of fibrosis and, in cases of liver cirrhosis, nodule formation with fibrotic septae. In this study, we developed an ultrasonic measurement system for tissue characterization and attempted to evaluate pathological changes in the human liver.
Our system consists of a 10 MHz transducer (Shimadzu Corp.) , a pulse generator (Shimadzu Corp.) , an A/D converter (Sony-Tektronix) , a personal computer (NEC) and an oscilloscope. During peritoneoscopy, the transducer was held in contact with the liver surface. One-hundred ultrasonic signals from the liver were digitized at a sampling rate of 60 MHz by the A/D converter, and were then stored on a floppy disc. The ultrasonic signals were then fast Fourier transformed twice to yield cepstra. From the maximum cepstrum peak, the space among scatterers (SAS) of the liver could be estimated. Afterwards, from the SAS distribution, the mode and kurtosis were obtained for each patient.
The SAS mode in liver cirrhosis (LC) cases was significantly higher than in chronic hepatitis (CH) and non-specific change (NS) cases. The SAS kurtosis in NS was significantly higher than in CH and LC. These findings indicate that the SAS mode and kurtosis reflect the degree of enlargement and irregularity of hepatic texture, respectively.
In conclusion, the progress of chronic liver disease can be evaluated by analysing acoustic parameters using our ultrasonic measurement system.