Spectral-based Ultrasonic Characterization of Renal Allografts in vivo

Kidney transplantation is the preferred long-term treatment modality for patients with end-stage renal disease as it confers improved survival and quality of life devoid of dialysis constraints. However, graft loss is still a concern in transplant recipients, necessitating close monitoring. The estimated glomerular filtration rate (eGFR) is often used as a surrogate marker of kidney function. Many transplant centers use a decline in eGFR to identify injury to the allograft, but this can miss early injury before there is substantial nephron damage. The use of quantitative ultrasound (QUS) parameters could aid in increasing the sensitivity for determining rejection particularly at early stages when management strategies may be implemented to avoid graft loss. In this prospective study, two parameters derived from ultrasonic backscatter coefficients (i.e., the slope and the intercept) were estimated. The cohort consisted of 16 renal transplant patients presenting for protocol renal biopsies. Seven volunteers had mild or moderate interstitial fibrosis with tubular atrophy (IFTA) and nine exhibited no signs of rejection. Even though both QUS parameters increased between the No IFTA and the IFTA groups, with the intercept parameter exhibiting statistically significant differences between the No IFTA and IFTA groups (p<0.05). These preliminary results suggest the potential of QUS analysis for the noninvasive characterization of renal allografts.