Ultrasonic integrated backscatter in assessing liver steatosis before and after liver transplantation

BACKGROUND： Liver steatosis affects 20%-30% of adults.Because of the increasing gap between graft supplies and demands, livers with steatosis are frequently used in liver transplantation. But severely steatotic liver grafts are associated with a high risk of intraoperative and postoperative complications. Accurate assessment of fat content of donor livers and monitoring of the extent of steatosis in recipients are required for liver transplantation. The present study aimed to determine the correlation between liver echogenicity and fat content, and to evaluate the use of an ultrasonic integrated backscatter system（IBS） in the assessment of changes in fat content after liver transplantation.METHODS： Seventy-nine consecutive patients receiving liver grafts from living donors were evaluated in our center. Of these recipients, 67 survived for more than two years and were included in this study. Each liver graft was evaluated with IBS and ultrasound before operation and the fat content was estimated. The fat content of the grafts in the recipients was again assessed with ultrasound at 18 months after surgery.RESULTS： A correlation was detected between each graft＇s IBS value and its fat content（P=0.001）. The IBS value in fatty grafts with various degrees of steatosis was significantly decreased in 3（P=0.02）, 12, 15 and 18（P=0.001） months after orthotopic liver transplantation. The IBS value returned to normal in all patients in 18 months after liver transplantation.CONCLUSIONS： Decreased fat content in steatotic grafts can be observed in all recipients. Ultrasonic IBS is useful in determining the steatotic degree of grafts in donors as well as in monitoring the grafts after liver transplantation.

Influence of Contractility on Myocardial Ultrasonic Integrated Backscatter and Cyclic Variation in Integrated Backscatter

To evaluate the effects of left ventricular contractility on the changes of aver age image intensity (AII) of the myocardial integrated backscatter (IB) and cyclic variation in IB (CVIB), 7 adult mongrel dogs were studied. The magnitude of AII and CVIB were measured from myocardial IB carves before and after dobuta mine or propranolol infusion. Dobutamine or propranolol did not affect the magnitude of AII (13.8±0.7 vs 14.7±0.5, P >0.05 or 14.3±0.5 vs 14.2±0.4, P >0.05). However, dobutamine produced a significant increase in the magnitude of CVIB (6.8±0.3 vs 9.5±0.6, P <0.001) and propranolol induced significant decrease in the magnitude of CVIB (7.1±0.2 vs 5.2±0.3, P <0.001). The changes of the magnitude of AII and CVIB in the myocardium have been demonstrated to reflect different myocardial physiological and pathological changes respectively. The alteration of contractility did not affect the magnitude of AII but induced significant change in CVIB. The increase of left ventricular contractility res ulted in a significant rise of the magnitude of CVIB and the decrease of left ventricular contractility resulted in a significant fall of the magnitude of CVIB.

Clinical Study of Ultrasonic Tissue Characterizaton with Integrated Backscatter and Echo Intensity in the Diagnosis of Acute Myocardial Infarction

Objectives The purpose of this study was to determine if the ultrasonic integrated backscatter and echo intensity could be used in clinical diagnosis of acute myocardial infarction. Methods and Results Within 2 weeks after acute myocardial infarction,35 patients underwent ultrasonic tissue characterization from the papillary short - axis view. The cyclic variation of integrated backscatter and echo intensity of three different myocardial regions perfused by left anterior descending coronary artery, left circumflex coronary and right coronary were measured . The value of cyclic variation of integrated backscatter and integrated backscatter and echo intensity≤ half of the highest value of three different myocardial regions on a same view were define as the criteria for diagnosing acute myocardial infarction , and the results were compared with coronary angiography. The sensitivity of diagnosing acute myocardial infarction by both Ultrasonic tissue characterization with integrated backscatter and echo intensity were 91. 43 % . The location of myocardial infarction detected by this tech-nique corresponded with the damaged myocardial region determined by coronary angiography. Conclusions Ultrasonic tissue characterization with integrated backscatter and echo intensity could clinically be used as a noninvasive approach in the diagnosis of acute myocardial infarction.

The observations on Polar Stratospheric Clouds at Zhongshan Station，Antarctica

lidar system (694 nm) was used to measure the stratospheric aerosol layer at Zhongshan Station (69°22'S, 76°22'E ) in 1993. A total of 53 sets of lidar data presented in this paper were obtained over a period of 224 days between March 27 and November 5, 1993. The average vertical profiles of stratospheric aerosol backscattering ratio and the integrated backscatter coefficient over the 12 km～30 km altitude range were reversed from the return signal of lidar. The results of observations show that the stratospheric aerosol content more noticeably enhanced in 1993 than that in 1990 due to Mt. Pinatubo eruption in Philippines in June of 1991. Polar Stratospheric Clouds (PSCs) were observed from late May until early August. The vertical profiles of stratospheric aerosol backscattering ratio at Antarctica in 1993 show a clear double-layer structure. One layer is at an altitude of about 12 km,the other is at an altitude of about 25 km. The upper layer is varied with season.