In vivo measurement of gadolinium concentration in a rat glioma model by monochromatic quantitative computed tomography: comparison between gadopentetate dimeglumine and gadobutrol.

Rationale and Objectives: Monochromatic quantitative computed tomography allows a nondestructive and quantitative measurement of gadolinium (Gd) concentration. This technique was used in the C6 rat glioma model to compare gadopentetate dimeglumine and gadobutrol.
Methods: Rats bearing late-stage gliomas received 2.5 mmol/kg (392.5 mg Gd/kg) of gadopentetate dimeglumine (n = 5) and gadobutrol (n = 6) intravenously before the imaging session performed at the European Synchrotron Radiation Facility.
Results: Monochromatic quantitative computed tomography enabled in vivo follow-up of Gd concentration as a function of time in specified regions of interest. Surprisingly, after gadobutrol injection, Gd concentrations in the center and periphery of the tumor were higher than those after gadopentetate injection, although identical in normal and contralateral area of the brain.
Conclusion: The in vivo assessment of absolute Gd concentrations revealed differences in gadobutrol and gadopentetate dimeglumine behaviors in tumoral tissues despite injections in the same conditions. These differences might be attributed to different characteristics of the contrast agents.