Delineation of gliomas with various doses of MR contrast material

To examine the effects of different gadolinium doses on the delineation of gliomas, particularly the demonstration of abnormal enhancement on T1-weighted images extending beyond the zone of apparent signal abnormality on corresponding T2-weighted images.

During phase II clinical trials of gadoteridol, 23 patients with pathologically proved gliomas were studied by MR with various doses of gadoteridol, ranging from 0.05 to 0.3 mmol/kg.

All of the gliomas were readily detected by T2-weighted images. Twelve of 23 patients demonstrated enhancement on T1-weighted images extending beyond the zone of apparent signal abnormality demonstrated on T2-weighted images. These findings were seen in none of the six patients (0%) studied at 0.05 mmol/kg, one of five patients (20%) studied at 0.1 mmol/kg, four of five patients (80%) studied at 0.2 mmol/kg, and seven of seven patients (100%) studied at 0.3 mmol/kg.

The detection of symptomatic gliomas does not require a contrast agent because they are generally large and readily demonstrated on T2-weighted images. However, the area of postcontrast enhancement of gliomas seems to be greater with higher doses of contrast agent. The cause of the abnormal enhancement extending beyond the zone of apparent signal abnormality on T2-weighted images seen in this limited study is unknown and probably represents tumor infiltration. The frequency of detection of such findings appears to be proportional to the dose of contrast material used.