INDICATIONS FOR DIFFERENTIAL-DIAGNOSIS OF NONTUMOR CENTRAL-NERVOUS-SYSTEM DISEASES FROM TUMORS - A POSITRON EMISSION TOMOGRAPHY STUDY

To accurately differentiate nontumor central nervous system (CNS) dise ases from brain tumors, we retrospectively evaluated the cerebral circ ulation and metabolism in patients with nontumor CNS diseases using po sitron emission tomography (PET). Regional cerebral blood flow (rCBF), cerebral blood volume (rCBV), oxygen extraction fraction (rOEF), the metabolic rates of oxygen (rCMRO(2)), and of glucose (rCMRGI), and the uptake of C-11-methyl-L-methionine (C-11-Met) were visually evaluated in lesions and compared with values for the contralateral white matte r regions. PET findings were correlated with those of x-ray computed t omography (CT) and magnetic resonance imaging (MRI), and were analyzed for nontumor CNS diseases and cerebral gliomas. rCBF and rCBV were ch angeable from disease to disease or from stage to stage of disease pro gression. rOEF and rCMRO, remained low in 5 and 6, respectively, of 9 nontumor CNS diseases examined, whereas these parameters were increase d in CNS infections such as brain abscess. Overall, noteworthy was the locally increased rOEF and rCMRO(2) in the patients with a brain absc ess in contrast to the values for patients with gliomas, rCMRGI reflec ted biological characteristics of each disease, and correlated with ce ll density, whether reactive glial cells or inflammatory cells. C-11-M et was accumulated at a certain stage of nontumor CNS diseases, which implied uptake of the tracer as a result of disruption of the blood-br ain barrier as well as metabolic incorporation.