31P-Magnetic resonance spectroscopy (31P-MRS) of human allografts after renal transplantation

Abstract

Background. 31P-Magnetic resonance spectroscopy (31P-MRS) can be used as a non-invasive tool for measuring the relative intracellular concentrations of several phosphorus metabolites in different organs. Various pathological conditions are characterized by different metabolic patterns. We studied the value of 31P-MRS after renal transplantation with both an uneventful and a clinically complicated course. Methods. We determined the relative concentrations of phosphate-containing metabolites in renal allografts of humans with 31P-MRS (1.5 Tesla) in the first few weeks after transplantation; 18 patients with an uneventful clinical course and 10 patients who required dialysis after transplantation were examined. Six patients with a stable allograft function 2-3 months after transplantation served as controls. Results. In patients with primary allograft function, we found a significant correlation between the phosphomonoester/phosphodiester-ratio (PME/PDE) (r = 0.66, r < 0.01) and the time after transplantation, but no correlation between the nucleoside triphosphate (β-NTP)-concentration (r = -0.11) and the time course. In the patients with primary or early allograft dysfunction caused by histologically proven rejection (n = 5), we found a low β-NTP compared to patients with an uncomplicated clinical course (0.09 ± 0.01 vs 0.15 ± 0.03), but no differences in the PME/PDE ratio (0.73 ± 0.21 vs 0.80 ± 0.21). In contrast, the PME/PDE ratio was lowered in three patients with delayed graft function caused by acute tubular necrosis (0.45 ± 0.07 vs 0.80 ± 0.21), but the β-NTP concentration was not reduced (0.15 ± 0.003 vs 0.15 ± 0.03). The 31P-MR spectrum of two patients with cyclosporin A damage was not altered compared to the controls. Conclusions. 31P-MRS can be used in patients in the early period after renal transplantation. A significant correlation between the PME/PDE ratio and the time course but no change in the β-NTP concentration was found in patients with primary allograft function in the first 4 weeks after renal transplantation. Different patterns of 31P-MR spectra were observed depending on the different causes of primary and early transplant dysfunction.