Proton MR properties of lyophilized urine samples from normal and stone former individuals

Proton MR measurements were performed in lyophilized urine samples collected from 5 normals (N) and 5 idiopathic hypercalciuric recurrent stone formers (SF). T1 and T2 relaxation times were measured with a Bruker PC Multispec at 20 MHz and 37 degrees C in the lyophilized samples and in samples gradually rehydrated. Significantly (p less than 0.01) prolonged T1 and T2 relaxation times were measured after addition of water to the lyophilized samples. The relaxation time prolongation patterns were significantly different (p less than 0.01) for the two groups; the rehydration curves of the lyophilized urine samples from the SF group had relatively shorter lag than that of N group. In calculations of water compartmentalization for similar water content, significant (p less than 0.01) differences in the fraction of bound water (FB) were found between the two groups. These results may reflect differences in the macromolecular properties, contents, in the amount of water binding sites and/or in the water multilayer thickness between the two groups. These differences, expressed as changes of the relaxation times values may provide new diagnostic possibilities of different renal pathologies.