Utilization of the nephrectomized mouse for determining threshold effects of MRI contrast agents

The tissue concentration of an extravascularly distributed MRI contrast age nt required to achieve a 20 % change in the MRI signal intensity (SI) of sk eletal muscle was determined using radiolabeled gadoteridol administered to nephrectomized mice. This minimal change in the quantified SI was reliably detected qualitatively in the MR muscle images. MR images of muscle were a cquired following each intravenous injection of six sequential doses of 0.8 mu mol of Gd-153-labeled gadoteridol. A 2.0 T imaging spectrometer and a T -1-weighted spin-echo pulse sequence were used to acquire the MR images, Af ter imaging, the injected Gd-153 in muscle was measured, and the Gd-153 ass ay results were used to determine the gadoteridol concentration in muscle f ollowing each injection. The muscle concentrations of gadoteridol were then correlated to the quantified enhanced MR SI of muscle. Using the 20% facto r, it was concluded that the amount of gadoteridol necessary to achieve a r eliable change in the SI of muscle was 33 +/- 10 nmol/g-skeletal muscle. (C ) 1999 Elsevier Science Inc.