| Objective To evaluate the clinical value of second harmonic contrast ultrasound(US) imaging and acoustic densitometry (AD) by comparing perfusion of renal allograft. To evaluate the value of intermittent second harmonic contrast imaging (SHCI) and acoustic densitometry(AD) in perfusion of acute renal allograft rejection, compared with resistance index(RI) of Color Doppler Flowing Imaging (CDFI).Methods 15 healthy dogs were selected, ranging in weight from 15.5kg to 27kg. Anesthesias with 3% pentobarbital sodium (30mg/kg) were administrated both to donors and recipients before allogenetic renal transplantation. The warm ischemic time was controlled to less than 4 minutes and the cold ischemic time less than 1 hour. The index Cr was observed and percutaneous kidney biopsy was performed for the pathologic diagnosis after the transplantation. 8 cases of acute renal rejection were diagnosed at last, which were divided into 2 groups by self comparison before and after transplantation. The ultrasound (US) examinations were performed by using a L7540 transducer (frequency 4-10MHz) and a S4 transducer (frequency 2-4MHz) with a model 5500 Hewlett-Packard(HP) unit. The transducer transmitted a mean frequency of 2.1MHz and received a mean frequency of 4.2MHz while performing harmonic imaging. During each examination, the data of T-INT triggered by system interval time (1000ms) was recorded under the same unit condition. CDFI and SHCIwere performed everyday since the first day after transplantation and then Cr and BUN were examined in 24 hours. With the dog lied down, we got appropriate slice of the renal allograft in the right iliac fossa first, then put the sampling frame of pulsed Doppler on the interlobar artery and the angle between ultrasound beams and the blood flow was adjusted less than 60? So we got the spectrum images which were saved in the MO disk for further analysis. The US unit was switched to acoustic densitometry (AD) mode with S4 transducer (frequency 2-4MHz). The transducer transmitted a mean frequency of 2.1MHz and received a mean frequency of 4.2MHz while performing harmonic imaging. When the cortex was shown clear, the contrast agent (0.02ml/kg) was administered into vein in a way of a "bolus-like" injection for contrast imaging and then 10ml physiological saline was administered to wash out the tube. The images were recorded into MO disk on the mode AD-INT for further analysis. Image analysis: 1 Choose an image with clear spectrum and then measure the maximum systolic blood velocity (S), the minimum diastolic blood velocity (D) and total average velocity (TAV). The resistance index was calculated by computer according to the following formula: RI=S-D/S. 2.Use AD analysis software of HP Sonus 5500 unit to review the images. The ROI sampling frame (41+41) was put on the cortex to measure the mean density of cortex. Then the baseline density of cortex was subtracted from the mean density of cortex, so we got increased mean density of cortex. The parameters of time-intensity curve were calculated according to the r-fitting function and the following parameter were also calculated: peak intensity(PI), area under the curve (AUC).Results 1.The TIC parameters of normal renal allograft group changed after contrast imaging. PI,AUC and HT increased significantly after contrast imaging(P < 0.01) while MTT showed no significant difference. The time-intensity curve was around the baseline before contrast imaging and increased promptly after contrast imaging, then went back down to the baseline. 2.Compared with normal renal allograft group, the TIC parameters PI and AUC of acute rejected renal allograft group decreased significantly(P<0.01) while the HT and MTT had no significant difference(P>0.05). 3.The time-intensity curve (TIC) parameters AUC, PI (gained from AD ) had a linear correlation with Cr as well as RI and the correlation coefficient r was 0.972,0.978 and 0.708 respectively. The relationship between PI-Cr, AUC-Cr was closer than that between RI-Cr.Conclusion Using contrast imagin...
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