Indications for Differential Diagnosis of Nontumor Central Nervous System Diseases from Tumors

Abstract

To accurately differentiate nontumor central nervous system (CNS) diseases from brain tumors, we retrospectively evaluated the cerebral circulation and metabolism in patients with nontumor CNS diseases using positron emission tomography (PET). Regional cerebral blood flow (rCBF), cerebral blood volume (rCBV), oxygen extraction fraction (rOEF), the metabolic rates of oxygen (rCMRO2), and of glucose (rCMRGI), and the uptake of 11C-methyl-L-methionine (11C-Met) were visually evaluated in lesions and compared with values for the contralateral white matter regions. PET findings were correlated with those of x-ray computed tomography (CT) and magnetic resonance imaging (MRI), and were analyzed for nontumor CNS diseases and cerebral gliomas. rCBF and rCBV were changeable from disease to disease or from stage to stage of disease progression. rOEF and rCMRO2 remained low in 5 and 6, respectively, of 9 nontumor CNS diseases examined, whereas these parameters were increased in CNS infections such as brain abscess. Overall, noteworthy was the locally increased rOEF and rCMRO2 in the patients with a brain abscess in contrast to the values for patients with gliomas. rCMRGI reflected biological characteristics of each disease, and correlated with cell density, whether reactive glial cells or inflammatory cells. 11C-Met was accumulated at a certain stage of nontumor CNS diseases, which implied uptake of the tracer as a result of disruption of the blood-brain barrier as well as metabolic incorporation.

Differential Uptake of O-(2-18F-Fluoroethyl)-L-Tyrosine, L-3H-Methionine, and 3H-Deoxyglucose in Brain Abscesses

“…This is in contrast to other experimental studies that reported uptake of 14 C-MET predominantly in viable tumor cells, with low uptake in macrophages and other cells (21). Our observations, however, are in line with case reports and studies on small patient groups that have shown accumulation of 11 C-MET in brain abscesses (22)(23)(24).…”

Semiquantitative analysis of C-11 methionine PET may distinguish brain tumor recurrence from radiation necrosis even in small lesions

“…We experienced several cases with radiation necrosis which had high accumulation of 11 Cmethionine. There have been some reports of radiation necrosis with 11 C-methionine accumulation, and the reason is considered to be inflammatory change, reactive gliosis or blood-brain barrier disruption [11,[25][26][27][28].…”

11C-methionine PET/CT findings in benign brain disease

“…In general, MET uptake is lower in low-grade than in high-grade gliomas, although there is considerable overlap between these two groups, as well as between histological types [4,5]. However, several previous reports have demonstrated MET uptake in lesions associated with benign brain diseases [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23]. Although Ito et al [6] have already reported on the imaging spectrum and pitfalls of MET-PET/CT in intracranial lesions, in this review we focus on and introduce imaging characteristics of MET uptake in benign brain disease through a literature review.…”

“…High MET uptake has also been reported with cerebrovascular diseases (CVDs) such as cerebral infarction [8][9][10][11]. Nakagawa, et al [8] reported that the mean MET uptake in cerebral infarctions was 1.07 ± 0.28 (range 0.67-1.31) the TNR, with this value depending on the day of onset.…”