Quantitation of peritumoural oedema and the effect of steroids using NMR-relaxation time imaging and blood-brain barrier analysis.

A new method of in vivo quantitation of peritumoural brain oedema using NMR relaxation time imaging (T1-maps) and Gd-DTPA-enhanced Blood-Tumour-Barrier (BTB) analysis is presented. The method is based on image pixel histogram analysis and a fast imaging method combined with arterial [Gd-DTPA]-measurement. The method was applied in 26 brain tumour patients, studied prior to--and 1, 3 and 7 days after initiation of dexamethasone. Oedema resorption rate following dexamethasone treatment was almost equal in glioblastomas and metastases, mean T1 being reduced by ca. 12% in 7 days. In meningiomas no significant changes in peritumoural oedema could be detected. Simultaneous BTB-analysis was obtained in 4 patients showing correlation between oedema resorption in vivo and reduction of BTB transport rate constant Ki after 7 days of steroid treatment. This method is a powerful tool in quantitation and monitoring of brain oedema in vivo, as both steroid influence on oedema resorption and on BTB-defect can be monitored simultaneously.