Ultrasound Score Is More Predictive than Serum Creatinine in Assessment of Cellular Rejection in Cynomolgus Monkey Renal Allografts

Abstract

Gaschen L, Schuurman HJ. Ultrasound score is more predictive than serum creatinine in assessment of cellular rejection in cynomolgus monkey renal allografts. Invest Radiol 2002;37:376–380. To investigate whether ultrasound (US), in particular the use of an ultrasound scoring system, can provide more diagnostic information than clinical parameters, such as serum creatinine, for the diagnosis and determination of the degree of cellular rejection in renal allografts in the cynomolgus monkey (Macaca fascicularis). Sixty-eight cynomolgus monkeys with life-supporting renal allografts were examined with a 7.5MHz linear ultrasound transducer. One-hundred fifty two-dimensional, spectral, and power Doppler examinations were performed and four ultrasound parameters, percentage increase in graft volume, cortical thickness, resistive index (RI) of the renal arcuate artery, and power Doppler (PD) scores were recorded from serial examinations. An ultrasound score was assigned to each graft based on the number of those parameters that were abnormal; a score of 1 indicated that all four were normal, and a score of 5 that all four were abnormal. Each parameter and the combined score were compared with serum creatinine values and histology and evaluated statistically using Spearman rank correlation. In animals with dysfunctioning allografts (serum creatinine elevations >200 μmol/L), Spearman rank correlation showed a significant correlation between the US score and the histology score: between 200 and 500 μmol/L, r = 0.309, P = 0.046, n = 31 and if > 500 μmol/L, r = 0.486, P = 0.005, n = 30. In those same animals, no correlation could be shown between serum creatinine values and the US score or between the serum creatinine values and the histologic diagnosis. In contrast to the US score, single ultrasound parameters were not found to correlate to histologic findings. The application of ultrasound imaging in nonhuman primate renal transplant models provides valuable information concerning the presence and severity of cellular rejection in cases of graft dysfunction and the US score has a better predictive value of histology than serum creatinine values alone.