Nobuyuki Katakami, Presenter: Investigator, Bayer AG

Yasuko Aitoku BS, Abstract Co-Author: Employee, Bayer AG

Josy Breuer MD, Abstract Co-Author: Employee, Bayer AG

Gadobutrol has been marketed mainly in EU as a modern gadolinium based contrast agent (GBCA) for MRI with its high gadolinium concentration and high relaxivity. To detect small and multiple lesions such as brain metastases and multiple sclerosis, high dose of GBCA is often used in clinical practice. In this multi-center study, non-inferiority regarding lesion detectability of two different doses of gadobutrol was to be demonstrated to a double dose of gadoteridol (Prohance®).

Patients were referred to contrast enhanced MRI (CE-MRI) with known or suspected brain metastasis based on previous diagnosis by MRI or CT, or clinical symptoms. Steady-state CE-MRI was performed using SE sequence with either 1.5 or 3.0 T scanners after two injections with a total dose of 0.2 mmol/kg of either gadobutrol or gadoteridol performed with an interval of 1-14 days to compare intra-individually. Gadobutrol at 0.1 mmol/kg was also compared to gadoteridol at 0.2 mmol/kg. Three CE-MRIs of each patient were evaluated separately by 3 blinded readers. To evaluate clinical usefulness, unenhanced MRIs including T1, T2 and Flair were also considered.

A total of 151 patients were examined. The number of detected metastatic lesions per patient in CE-MRI with gadobutrol at 0.1 and total of 0.2 mmol/kg and gadoteridol were 6.3±8.3, 6.9±8.7, 6.9±8.7, respectively. Based on the prospectively defined margin, difference between the treatments ≤1 lesion, non-inferiority to gadoteridol was demonstrated for both gadobutrol doses. The lesion enhancement and border delineation did not reveal any relevant difference among 3 groups, but gadobutrol at 0.2 mmol/kg showed a slightly better performance than the others. In direct comparison between gadobutrol and gadoteridol, when considering treatment planning, the blinded evaluation team favored gadobutrol at either of doses due to clarification of radiation area in approximately 40% of the patients eligible for stereotactic radiosurgery. In contrast, Gadoteridol was favored in only 20 %.

Lesion detectability in CE-MRI with gadobutrol at 0.1mmol/kg was non-inferior to gadoteridol at 0.2 mmol/kg. Gadobutrol is considered to be of benefit for imaging of brain metastasis.

Imaging diagnosis of brain metastasis for stereotactic radiosurgery planning can be sufficiently performed using a single dose of gadobutrol instead of a double dose of gadoteridol.

Katakami, N, Aitoku, Y, Breuer, J, Comparison of Two Different Doses of Gadobutrol (Gadovist®) to a Double Dose of Gadoteridol for the Detection of Brain Metastases.  Radiological Society of North America 2009 Scientific Assembly and Annual Meeting, November 29 - December 4, 2009 ,Chicago IL. http://archive.rsna.org/2009/8004876.html