18F-FACBC PET/MRI in Diagnostic Assessment and Neurosurgery of Gliomas

Abstract

Purpose: This pilot study aimed to evaluate the amino acid tracer 18 F-FACBC with simultaneous PET/MRI in diagnostic assessment and neurosurgery of gliomas. Materials and Methods: Eleven patients with suspected primary or recurrent low-or high-grade glioma received an 18 F-FACBC PET/MRI examination before surgery. PET and MRI were used for diagnostic assessment, and for guiding tumor resection and histopathological tissue sampling. PET uptake, tumor-to-background ratios (TBRs), time-activity curves, as well as PET and MRI tumor volumes were evaluated. The sensitivities of lesion detection and to detect glioma tissue were calculated for PET, MRI, and combined PET/MRI with histopathology (biopsies for final diagnosis and additional image-localized biopsies) as reference. Results: Overall sensitivity for lesion detection was 54.5% (95% confidence interval [CI], 23.4-83.3) for PET, 45.5% (95% CI, 16.7-76.6) for contrast-enhanced MRI (MRI CE), and 100% (95% CI, 71.5-100.0) for combined PET/MRI, with a significant difference between MRI CE and combined PET/MRI (P = 0.031). TBRs increased with tumor grade (P = 0.004) and were stable from 10 minutes post injection. PET tumor volumes enclosed most of the MRI CE volumes (>98%) and were generally larger (1.5-2.8 times) than the MRI CE volumes. Based on image-localized biopsies, combined PET/MRI demonstrated higher concurrence with malignant findings at histopathology (89.5%) than MRI CE (26.3%). Conclusions: Low-versus high-grade glioma differentiation may be possible with 18 F-FACBC using TBR. 18 F-FACBC PET/MRI outperformed MRI CE in lesion detection and in detection of glioma tissue. More research is required to evaluate 18 F-FACBC properties, especially in grade II and III tumors, and for different subtypes of gliomas.

18F-FACBC PET/MRI in the evaluation of human brain metastases: a case report

“…The results of this study show that 18 F-FACBC could provide useful information with regard to tumour detection. In particular, there was low 18 F-FACBC tracer uptake (SUV bkg ) in healthy brain tissue as well as high tracer uptake (SUV peak and SUV max ) (Tables 2 and 3 ) in both cerebral and cerebellar tumour VOIs, consistent with previous studies on gliomas (Bogsrud et al 2019 ; Karlberg et al 2017 ; Karlberg et al 2019 ; Tsuyuguchi et al 2017 ; Michaud et al 2020 ). We reported an increase in 18 F-FACBC uptake in healthy brain tissue (SUV bkg ) after radiation therapy in scan 2 (Table 2 ), but regardless of this increase, the distinctively low 18 F-FACBC tracer uptake in healthy tissue (SUV bkg ) played a large role in the high tumour contrast (TBR max and TBR peak ) in this patient.…”

“…However, MRI has some limitations, such as micro-metastasis detection, lesion boundary delineation and discrimination between progression and pseudo-progression after treatment (Bogsrud et al 2019 ). Dynamic and static data acquired from amino acid (AA) positron emission tomography (PET) could provide the opportunity for a more detailed analysis of brain tumour extent and malignancy (Karlberg et al 2017 ; Karlberg et al 2019 ). Additionally, AA PET has been shown to detect malignant glioma progression as well as treatment efficacy earlier than MRI (Galldiks et al 2013 ; Unterrainer et al 2016 ).…”

“…The combination of PET and MRI is a promising, non-invasive and relatively novel method. It can improve the detection of brain tumours, in addition to advancing precision and navigation during surgical and radiotherapy treatment (Karlberg et al 2017 ; Karlberg et al 2019 ). Hence, combined PET/MRI data can provide physicians with a better overview in the diagnosis of gliomas and brain metastases and influence clinical decision-making.…”

“…Anti-1-amino-3-[18F]fluorocyclobutane-1-carboxylic acid ( 18 F-FACBC) is another AA PET tracer with even higher TBRs than other AA PET tracers, which could aid the differentiation between high-grade and low-grade gliomas (Bogsrud et al 2019 ; Karlberg et al 2017 ; Karlberg et al 2019 ). Furthermore, 18 F-FACBC can reveal satellite tumours not detected with MRI in high-grade gliomas (Bogsrud et al 2019 ).…”

Use of PET Imaging in Neuro-Oncological Surgery

“…However, it has only limited clinical value in neuro-oncology due to the poor contrast between neoplastic and normal brain tissue. In contrast to 18 F-FDG uptake, protein metabolism is clearly elevated in brain tumor cells compared to healthy brain tissue, making radiolabeled amino acids, such as [ 11 C]-methyl-L-methionine ( 11 C-MET), O -(2-[ 18 F]fluoroethyl)-L-tyrosine ( 18 F-FET), 3,4-dihydroxy-6-[ 18 F]-fluoro-L-phenylalanine ( 18 F-FDOPA), or 18 F-fluciclovine ( 18 F-FACBC) important targets for brain tumor imaging [ 3 , 4 , 5 ]. In correspondence to its increased availability, a high number of studies, including multicenter trials, have shown that amino acid PET (AA-PET) provides additional information on the metabolic properties of brain tumors.…”