Contrast-enhanced sonography of the renal transplant using triggered pulse-inversion imaging: preliminary results

The purpose of our study was to quantify renal transplant parenchymal sonographic enhancement using pulse-inversion imaging (PII) and intermittent emission after contrast administration by means of bolus and infusion techniques, and to evaluate renal perfusion functional indices. A total of 34 patients, presenting with minor abnormalities (n = 14) and cortical perfusion changes due to parenchymal disorders (n = 12) or renal artery stenosis (n = 8) were included. Cardiac-triggered contrast-enhanced PII ultrasound (US) was performed after administration of SHU 508 A (Schering AG, Berlin, Germany), using a high mechanical index, a frame rate of one image every four cardiac cycles for bolus study, and a decreasing frame rate for infusion study. Compared to baseline values, peak enhancement ratio ranged from 5.6 to 14.7 using a bolus administration, and reached a value of 2.1 to 4.0 using infusion technique. Qualitative analysis showed heterogeneous enhancement in most allografts presenting with acute parenchymal disease (p = 0.03). In bolus studies, time to peak, wash-in and wash-out slopes increased in renal transplants with parenchymal disease and renal artery stenosis (p = 0.0001). Infusion administration exhibited no plateau in signal level, and no significant difference in enhancement ratio was found between groups of patients. Triggered PII after contrast agent administration provides morphologic and quantitative information about cortical vascularity in renal transplants.