[Changes in tissue T1 of brain tumor following GD-DTPA administration--differences in T1 time course and tissue-blood ratio by histological types].

Effect of Gd-DTPA on tissue T1 were studied in 10 patients with intracranial tumors, including 4 meningiomas, 2 gliomas, 3 metastatic tumors and 1 brain abscess. T1 values were comparatively measured in the various portions of tumor tissue, peritumoral edema and normal brain before and after intravenous injection of 0.1 mmol Gd-DTPA per kg weight, with the time ranges between 5 and 60 minutes. In vivo T1 was determined by means of field focusing technique of a FONAR QED 80-alpha system (0.05T). T1 values of blood sample were also seriously measured and applied to estimate the enhancement pattern in the varied tumors. Meningiomas showed the maximal decrease of T1 5 minutes after Gd-DTPA administration and rapid recovery of T1 fairly paralleling to that of whole blood. On the other hand, such tumors as gliomas and metastasis revealed very slowly recovery of T1 followed by the similar T1 decrease just after administration of Gd-DTPA. In the portions of peritumoral edema and normal brain, there were no significant changes in tissue T1 by Gd-DTPA administration. In order to evaluate the clearance pattern of Gd-DTPA in tumor tissue, tissue-blood ratio (TBR) was calculated from the relaxation values at the terms of 5 and 30 minutes following Gd-DTPA administration. The ratios of relaxation rates, TBR 30/TBR 5, were ranged from 1.0 to 1.5 in cases of meningiomas, whereas they distributed in the ranges from 1.5 to 3.0 in the other types of brain tumors. This value of TBR 30/TBR 5 convincingly depends upon the differences in histological types of tumors.(ABSTRACT TRUNCATED AT 250 WORDS)