Ischemia after high grade glioma surgery are frequent and may constitute potential cause of false-positive results in postsurgical evaluation using 18F fluorocholine positron emission tomography. On the other hand, hypoxia caused by ischemia promotes invasive glioma growth.
García Vicente et al., presented 3 cases of patients with different grades of ischemic injury after resection of high grade glioma. The combined interpretation of diffusion weighted imaging and apparent diffusion coefficient map on MRI, in this clinical setting, is mandatory to avoid PET/CT misinterpretations 1).
Paudel et al., present a case where fluorocholine PET/CT performed for characterizing a space-occupying lesion in the brain revealed intensely tracer-avid skull lesions with intracranial soft tissue component and multiple other skeletal lesions. Fine-needle aspiration cytology from the skull and chest wall lesions confirmed the diagnosis of plasma cell neoplasm 2).
In a case report FCH PET/CT represented the final diagnostic technique to confirm the suspicious of a cystic GBM. The case demonstrated the potential role of 18F-FCH PET/CT for discrimination of higher proliferation area over intraparenchymal hemorrage, supporting the potential use of this imaging biomarker in surgical or radiosurgical approach. Obviously, further prospective studies are needed to confirm this role and to exactly define possible routinely applications 3).
Brain MRI and F-fluorocholine PET/CT were performed before and after surgery to establish the extent of resection (EOR) and residual volume. Postoperative brain MRI and PET parameters showed discordant results in all the reported cases. PET was able to assess properly the EOR; however, the rules for the EOR establishment and its prognostic implication should be validated in prospective studies 4).
Sollini et al., aimed to: 1) to evaluate the diagnostic performances of [18F]fluoroethylcholine positron emission tomography/computed tomography ([18F]FECH PET/CT), and 2) correlate PET imaging derived parameters of [18F]FECH to survival in brain tumors.
From 2009 to 2012, we enrolled 30 patients who underwent [18F]FECH PET/CT. Final diagnosis was established by clinical and radiological follow-up.
Final diagnosis was consistent with tumor disease in 27/30 cases. In 3/30 cases tumor disease was ruled out. [18F]FECH PET/CT resulted true positive and negative in 21/30 and 9/30 patients, respectively. Sensitivity, specificity, positive predictive value, negative predictive value and accuracy of [18F]FECH PET/CT were 78%, 100%, 100%, 33%, and 80%, respectively. Mean and maximum standardized uptake value (SUVmean and SUVmax) resulted statistically correlated to histology (P=0.0255 and P=0.0222, respectively). Using a SUVmax cut-off of 2.0 or 3.2, we distinguished between low- and high-grade gliomas with a good specificity (70% and 80%, respectively). SUVmax and histology resulted correlated to overall survival and disease related survival at multivariate analysis.
The results, worthy of further investigations, show high diagnostic performances of [18F]FECH PET/CT, and a correlation between PET imaging derived parameters and survival 5).
The efficacy of hybrid 18F-Fluroethyl-Choline (FEC) positron emission tomography (PET)/magnetic resonance imaging (MRI) was investigated as an imaging modality for diagnosis and assessment of treatment response and remission status in four patients with proven or suspected intracranial non-germinomatous germ cell tumours (NGGCT). In two patients faint or absent choline avidity correlated with negative histology, whereas in other two patients, persistent choline avidity in the residual mass was suggestive of presence of viable tumour, subsequently confirmed histologically. We conclude that FEC-PET/MRI may be an effective imaging tool in detecting viable residual tumour in patients with intracranial NGGCT post treatment 6).