Nmr contrast enhancement of brain tumours: comparison of the blood brain barrier tracer GdDTPA and the tumour-selective contrast agent MnTPPS

Abstract

Contrast enhancement of two different NMR contrast agents, GdDTPA and MnTPPS, was compared. Sequential recording ofT1-weighted images at 50s intervals allowed the observation of the temporal and spatial evolution of the contrast effect in rats with glioma implanted into the right brain hemisphere. The maximum signal intensity ratio of tumour over contralateral striatum was 1.80±0.10 for GdDTPA and 1.61±0.15 for MnTPPS. The enhancement was maximal 3min after application of GdDTPA and fell rapidly to reach half maximum after 24 min. MnTPPS led to maximum tumour enhancement within 11 min and did not return to control level within the observation period (150 min). In the peritumoural edema, an enhancement effect was absent for MnTPPS, but GdDTPA spread out from the tumour resulting in a delayed but strong enhancement outside the tumour. Thus, GdDTPA, as a blood-brain-barrier tracer, led only to a transient contrast enhancement between tumour and surrounding tissue and no unambiguous demarcation of the tumour against peritumoural edema. Application of MnTPPS resulted in a long-lasting strong tumour enhancement and reliable delineation from peritumoural edema.