Chang K H, Ra D G, Han M H, Cha S H, Kim H D, Han M C
Department of Radiology, Seoul National University College of Medicine, Korea.
AJNR Am J Neuroradiol. 1994 Sep;15(8):1413-9; discussion 1420-3.
To compare the degree of MR contrast enhancement of 0.5 T and 2.0 T in various brain tumors.
MR images were studied prospectively in each of 31 patients with brain tumors (11 gliomas, 6 meningiomas, 6 neurinomas, and 8 others) before and after intravenous injection of gadopentetate dimeglumine. In every patient, both 0.5-T and 2.0-T MR studies were done within 1 week. Each patient received an initial standard dose (0.1 mmol/kg) of gadopentetate dimeglumine, followed by a subsequent 0.1-mmol/kg dose (total, double dose) in MR of each field strength. MR was done before and after each injection of the contrast agent. Degree of contrast enhancement in the lesions was assessed both visually and quantitatively.
With standard-dose study, the tumor enhancement was visually stronger at 2.0 T than at 0.5 T in 9 gliomas. In extraaxial tumors there was visually no or minimal difference between 0.5 T and 2.0 T. Overall mean contrast-enhancement ratio and tumor and brain contrast-to-noise ratio were higher at 2.0 T than at 0.5 T by 53% and 108%, respectively. The double-dose study showed higher contrast-enhancement ratio and contrast-to-noise ratio than the standard-dose study at both field strengths, and the differences between 0.5 T and 2.0 T were almost similar to those of the standard-dose study. The degree of contrast enhancement with the standard dose at 2.0 T was comparable to that of the double dose at 0.5 T in most intraaxial tumors.
The results suggest that effect of contrast enhancement increases with the field strength. Therefore, reevaluation of optimal doses of contrast media may be needed in a variety of brain lesions at each field strength.
比较0.5T和2.0T磁共振成像（MRI）对各种脑肿瘤的对比增强程度。
对31例脑肿瘤患者（11例胶质瘤、6例脑膜瘤、6例神经鞘瘤和8例其他肿瘤）进行前瞻性研究，在静脉注射钆喷酸葡胺前后进行MRI检查。每位患者在1周内分别进行了0.5T和2.0T的MRI检查。每位患者先接受初始标准剂量（0.1mmol/kg）的钆喷酸葡胺，然后在每个场强的MRI检查中再给予0.1mmol/kg剂量（总剂量为双倍剂量）。在每次注射造影剂前后进行MRI检查。通过视觉和定量评估病变的对比增强程度。
在标准剂量研究中，9例胶质瘤在2.0T时的肿瘤增强在视觉上比0.5T时更强。在脑外肿瘤中，0.5T和2.0T之间在视觉上无差异或差异极小。总体平均对比增强率以及肿瘤与脑的对比噪声比在2.0T时分别比0.5T时高53%和108%。双倍剂量研究显示，在两个场强下，对比增强率和对比噪声比均高于标准剂量研究，且0.5T和2.0T之间的差异与标准剂量研究几乎相似。在大多数脑内肿瘤中，2.0T时标准剂量的对比增强程度与0.5T时双倍剂量的相当。
结果表明，对比增强效果随场强增加。因此，可能需要重新评估每种场强下各种脑病变的造影剂最佳剂量。
