Abstract
Purpose: To determine the effective time window for MR imaging of tumors with blood-brain barrier (BBB) damage after injection of Gd-containing contrast media.
Material and Methods: Eleven patients with 15 brain lesions (metastasis, glioma, abscess) were studied with a T1-weighted spin-echo sequence repeated over periods of up to 43 min after contrast injection. A quotient was calculated between the signals in the lesion and in the gray matter, and plotted against time.
Results: All lesions reached 70% of the maximum RATIO within 3.5 min. After 25 min 12 out of 15 lesions showed persistent enhancement within 15% of the maximal RATIO.
Conclusion: The peak enhancement of BBB damage occurs around 3.5 min after injection. The effect does not change during the next 25 min. Scanning should not be started until 2–5 min after injection of the contrast medium, and there is no advantage in waiting longer as no major increase (or decline) of contrast can be expected.
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