Contrast-enhanced ultrasound analysis of renal perfusion in normal micropigs

Contrast-enhanced ultrasound is one of method for evaluating renal perfusion. The purpose of this project was to assess perfusion patterns and dynamics in normal micropig kidney using ultrasonographic contrast media. Eight young healthy micropigs were included in this study. Micropigs were anesthetized with propofol and received an intravenous bolus of microbubble contrast media through an ear vein. Time/mean pixel value (MPV) curves were generated for selected regions in the right renal cortex and medulla. The parenchyma was enhanced in two phases. The cortex was first enhanced followed by a more gradual enhancement of the medulla. A significant difference in perfusion was detected between the cortex and medulla. Following the bolus injection, the average upslope was 0.68 +/- 0.27 MPV/sec, downslope was -0.27 +/- 0.13 MPV/sec, baseline was 73.9 +/- 16.5 MPV, peak was 84.6 +/- 17.2 MPV, and time-to-peak (from injection) was 17.5 +/- 6.6 sec for the cortex. For the medulla, the average upslope was 0.50 +/- 0.24 MPV/sec, downslope was -0.12 +/- 0.06 MPV/sec, baseline was 52.7 +/- 7.0 MPV, peak was 65.2 +/- 9.3 MPV, and time-to-peak (from injection) was 27.5 +/- 5.0 sec. These data can be used as normal reference values for studying young micropigs.

Comparison of cardiac function and coronary angiography between conventional pigs and micropigs as measured by multidetector row computed tomography

Pigs are the most likely source animals for cardiac xenotransplantation. However, an appropriate method for estimating the cardiac function of micropigs had not been established. Computed tomography (CT) analysis aimed at estimating cardiac function and assessing the coronary arteries has not been carried out in micropigs. This study determined the feasibility of evaluating cardiac function in a micropig model using multidetector row computed tomography (MDCT) and compared the cardiac function values with those of conventional pigs. The mean age of the conventional pigs and micropigs was approximately 80 days and approximately 360 days, respectively. The mean body weight in the conventional pigs and micropigs was 29.70 +/- 0.73 and 34.10 +/- 0.98 kg, respectively. Cardiac MDCT detected ejection fractions of 52.93 +/- 3.10% and 59.00 +/- 5.56% and cardiac outputs of 1.46 +/- 0.64 l/min and 1.21 +/- 0.24 l/min in conventional pigs and micropigs, respectively. There were no significant differences in cardiac function between conventional pigs and micropigs in the reconstructed CT images. There were also no differences in the coronary angiographic images obtained by MDCT. It is expected that the results of this study will help improve understanding of cardiac function in micropigs. The data presented in this study suggest that MDCT is a feasible method for evaluating cardiac function in micropigs.

Effectiveness of 99mTc-tetrofosmin for assessment of heart functions in micropigs

This study examined the suitability of a nuclear imagingtechnique using 99mTc-tetrofosmin as an agent to assess theheart functions of healthy micropigs. The mean age of thepigs was 360 days (male), and the mean body weight was35.3kg ranging from 34.5-36kg. There were no significantperfusion defects in any of the reconstructed images.Gated single-photon emission computed tomographyimaging can be used to calculate the ventricular volumeand ejection fraction (EF). In this case, an EF of 79% wascalculated from the ventricular volume of the end-systolicimage (10 ml) subtracted from that of the end-diastolicvolume (49 ml). A perfusion defect (particularly the apex,lateral wall) is unlikely because of the presence of apreserved wall motion in a segment with a defect. It isconcluded that quantitative cardiac scintigraphy, using99mTc-tetrofosmin is an adequate technique for estimatingthe heart functions of healthy micropigs.