DELINEATION OF GLIOMAS WITH VARIOUS DOSES OF MR CONTRAST MATERIAL

PURPOSE: To examine the effects of different gadolinium doses on the d elineation of gliomas, particularly the demonstration of abnormal enha ncement on T1-weighted images extending beyond the zone of apparent si gnal abnormality on corresponding T2-weighted images. METHODS: During phase II clinical trials of gadoteridol, 23 patients with pathological ly proved gliomas were studied by MR with various doses of gadoteridol , ranging from 0.05 to 0.3 mmol/kg. RESULTS: All of the gliomas were r eadily detected by T2-weighted images. Twelve of 23 patients demonstra ted enhancement on T1-weighted images extending beyond the zone of app arent signal abnormality demonstrated on T2-weighted images. These fin dings 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 pa tients (80%) studied at 0.2 mmol/kg, and seven of seven patients (100% ) studied at 0.3 mmol/kg. CONCLUSIONS: The detection of symptomatic gl iomas does not require a contrast agent because they are generally lar ge and readily demonstrated on T2-weighted images. However, the area o f postcontrast enhancement of gliomas seems to be greater with higher doses of contrast agent. The cause of the abnormal enhancement extendi ng beyond the zone of apparent signal abnormality on T2-weighted image s seen in this limited study is unknown and probably represents tumor infiltration. The frequency of detection of such findings appears to b e proportional to the dose of contrast material used.