Evaluation of treatment effects in brain abscess with positron emission tomography: Comparison of fluorine-18-fluorodeoxyglucose and carbon-11-methionine

Abstract

Positron emission tomography (PET) imaging is in common use preoperatively to clinically evaluate patients who present with central nervous system mass lesions. The usefulness of PET is also recognized as a method to detect intracranial tumorous lesions. A number of papers reportthat some inflammatory processes also showed the uptake of Fluorine-18-Fluorodeoxyglucose (FDG) and Carbon-11-Methionine (Met) tracers. We performed two PET studies before and after treatment in 4 patients with brain abscess. PET showed the uptake of both tracers to thebrain abscess before treatment. The area showing an increased uptake of Met corresponded closely to the enhanced area on both CT and MR images. FDG-PET visually showed an uptake of FDG in a small area corresponding to an enhanced lesion within the CT and MR images. After treatment the area of lesions became small on enhancement CT or MRI and both PET studies showed reduced lesion and decreased uptake. The mechanism of Met uptake in the inflammatory area may be related to the higher metabolic rate and the active transport of amino acids as well as disruption of the blood brain barrier. Furthermore, it appears that the mechanism of FDG uptake is also related to a higher metabolic rate and, in addition, is related to the increased density of inflammatory cells. PET studies, more directly, reflect the degree of inflammatory response in brain abscess than enhancement CT or MRI. Therefore, PET is useful in detecting the inflammatory lesion and assessing the clinical effects of antibiotics treatment on brain abscesses.

Guidelines for diagnosis, prevention and management of central nervous system involvement in diffuse large B-cell lymphoma patients by the Spanish Lymphoma Group (GELTAMO)

“…However, due to their limited specificity, additional studies are still necessary to define their precise value in the diagnosis of CNSL. 37,38 Histopathology: Histopathological and immunohistochemical analysis of stereotactic biopsy samples is considered a standard procedure for the diagnosis of PCNSL, 32,39 but is not a routine procedure in patients who already have been diagnosed with DLBCL. Stereotactic biopsy is an invasive procedure, which is of relatively limited sensitivity (20%-65% in immunocompetent patients), particularly in patients treated with corticosteroids.…”

The Role of18F-Fluorodeoxyglucose Positron Emission Tomography in the Treatment of Brain Abscess

“…Functional imaging using PET is expected to be more sensitive than anatomical imaging such as CT and MRI in detecting abnormalities of the brain; therefore, PET imaging might have a high clinical value in some cases 13) . Several studies have shown high FDG uptake in an abscess 3,4,8,12,15,19,20) . Yamada et al 20) showed that FDG uptake increased in turpentine-induced inflammatory tissue.…”

“…It was suggested that macrophages and neurotrophils in inflammatory tissue utilize glucose as an energy source for chemotaxis and phagocytosis. Although the mechanism of FDG uptake in abscesses remains unclear, it may be related to increased glucose metabolism associated with the inflammatory process and increased cellularity, rather than disruption of the BBB in the brain abscess 19) . Ichiya et al 6) reported that FDG-PET can be successfully used for the detection of infectious lesions as well as in the evaluation of lesion activity.…”

“…The disappearance of hot uptake on the FDG-PET indicates a treatment of brain abscess. Tsuyuguchi et al 19) reported that PET studies more directly reflect the degrees of inflammatory response in brain abscess than enhancement on MRI-thus suggesting that PET is useful in detecting inflammatory lesions and in assessing the clinical effects of antibiotics treatment. FDG uptake corresponds closely to the area of contrast enhancement on MRI.…”

“…It has been reported that contrast enhancement did not disappear completely, although DWI demonstrated low signal on the followup 2) . Recently, several studies have reported that brain abscesses have high uptake of 18 F-Fluorodeoxyglucose (FDG) 3,8,12,17,19) . Tsuyuguchi et al 19) suggested that positron emission tomography (PET) studies might more directly reflect the degree of the inflammatory response in a brain abscess than the enhancement pattern of the computed tomography (CT) or MRI; their findings showed decreased PET tracer uptake with treatment.…”