Early and late stage positron emission tomography (PET) studies on the haemocirculation and metabolism of seemingly normal brain tissue in patients with gliomas following radiochemotherapy.

Abstract

Haemocirculatory and metabolic changes in seemingly normal brain tissue following radiochemotherapy including nimustine hydrochloride (ACNU) and tegafur (FT) were analyzed using oxygen-15 and fluorine-18 positron emission tomography (PET) in seven patients with gliomas. At an early stage (within one month) after radiochemotherapy, marginal increases in regional cerebral blood flow (rCBF) and cerebral blood volume (rCBV) were found contralateral to the tumour in gray matter which was apparently normal brain structure, as seen on computerized tomography (CT). The oxygen extraction fraction (rOEF) decreased significantly (p less than 0.05 by a paired-t test) from that of the pretreatment study, due to surgical decompression and radiochemotherapy. At the late stage (three to thirty-one months with a mean of thirteen months), rCBF decreased significantly from the early stage study (p less than 0.05); oxygen consumption (rCMRO2) fell in all cases significantly from the pretreatment study (p less than 0.01) and from the early stage study (p less than 0.05); consequently, rOEF remained unchanged at a level similar to the early stage study. Glucose consumption (rCMRG1) increased slightly as compared with the early stage study but failed to be restored to the level of the pretreatment study. Noteworthy was a coupling reduction of rCBF and rCMRO2--presumably, a late delayed effect of radiochemotherapy. These preliminary results indicate that with PET studies it may be possible to predict damage to normal brain tissue after radiochemotherapy.