Feasibility of radiomic feature harmonization for pooling of [F]FET or [F]GE-180 PET images of gliomas.

Introduction: Large datasets are required to ensure reliable non-invasive glioma assessment with radiomics-based machine learning methods. This can often only be achieved by pooling images from different centers. Moreover, trained models should perform with high accuracy when applied to data from different centers.

TERT-Promoter Mutational Status in Glioblastoma - Is There an Association With Amino Acid Uptake on Dynamic F-FET PET?

Objective: The mutation of the 'telomerase reverse transcriptase gene promoter' (TERTp) has been identified as an important factor for individual prognostication and tumorigenesis and will be implemented in upcoming glioma classifications. Uptake characteristics on dynamic F-FET PET have been shown to serve as additional imaging biomarker for prognosis. However, data on the correlation of TERTp-mutational status and amino acid uptake on dynamic F-FET PET are missing.

Simpson Grade Revisited - Intraoperative Estimation of the Extent of Resection in Meningiomas Versus Postoperative Somatostatin Receptor Positron Emission Tomography/Computed Tomography and Magnetic Resonance Imaging.

Background: Surgeon's intraoperative estimation of meningioma extent of resection (Simpson Grade, SG) is widely used as a prognostic factor for recurrence. However, the validity of SG is still a matter of debate. In preoperative imaging, 68Ga-DOTATATE/PET-CT has been shown to detect meningioma tissue even more sensitively than magnetic resonance imaging (MRI).

Identification of Distant Metastases From Recurrent Gliosarcoma Using Whole-Body 18F-FDG PET/CT.

A 51-year-old man presented with recurrent gliosarcoma and increasing cough over the last months. On F-FDG PET/CT, solid lung masses with high F-FDG uptake were present. A biopsy taken from a lung lesion indicated distant metastases from gliosarcoma.

Long-term outcome of rare oncocytic papillary (Hürthle cell) thyroid carcinoma following (adjuvant) initial radioiodine therapy.

Purpose: Oncocytic (Hürthle cell) papillary thyroid carcinoma (OPTC) is a rare variant of the papillary thyroid carcinoma (PTC) which comprises approximately 1 to 11 % of PTC cases. Its clinical course and prognosis have not been comprehensively documented and the clinical outcome remains a controversial issue. Therefore, we investigated the long-term prognosis after thyroidectomy and (adjuvant) initial radioactive iodine therapy (RIT) of OPTC compared to PTC.

68Ga-DOTATOC PET/CT Differentiates Meningioma From Dural Metastases.

A 77-year-old woman with history of breast cancer presented with 2 unclear dural contrast-enhancing lesions on MRI; differential diagnoses were breast cancer metastases and meningiomas. On Ga-DOTATOC PET/CT, the temporal lesion showed high uptake and was classified as meningioma, whereas the lesion at the falx showed barely any Ga-DOTATOC uptake uncharacteristic for meningioma and suggestive for a brain metastasis. After resection, histological specimens from the temporal lesion showed meningioma tissue with distinct SSTR2A expression, whereas the falx lesion revealed a breast cancer metastasis without significant SSTR2A expression.

Voxel-wise analysis of dynamic F-FET PET: a novel approach for non-invasive glioma characterisation.

Background: Glioma grading with dynamic F-FET PET (0-40 min p.i.) is typically performed by analysing the mean time-activity curve of the entire tumour or a suspicious area within a heterogeneous tumour.

Neurosarcoidosis Mimics High-Grade Glioma in Dynamic 18F-FET PET Due to LAT Expression.

We present a 45-year-old man with newly generalized tonic-clonic seizures due to a contrast-enhancing frontal lesion with perifocal edema suggestive for high-grade glioma (HGG). For further evaluation, a dynamic F-FET PET scan was performed, which showed high F-FET-uptake with early peak and constantly decreasing time-activity curves, a characteristic feature of HGG. Stereotactic biopsy and histological evaluation excluded a neoplastic lesion but confirmed a manifestation of neurosarcoidosis with strong expression of the L-amino-acid-transporter considered responsible for F-FET-uptake.

F-FET-PET as a biomarker for therapy response in non-contrast enhancing glioma following chemotherapy.

Background: Monitoring treatment response after chemotherapy of gadolinium-(Gd)-negative gliomas is challenging as conventional MRI often indicates no radiological changes. We hypothesize that F-FET-PET can be used as a biomarker for response assessment in Gd-negative gliomas undergoing chemotherapy.

Methods: Sixty-one patients harboring Gd-negative WHO grade II or III glioma receiving alkylating agents (temozolomide or CCNU/procarbacine) were included.

Recurrence pattern analysis after [Ga]-DOTATATE-PET/CT -planned radiotherapy of high-grade meningiomas.

Background: The aim of the present study was to evaluate the influence of the applied safety margins of modern intensity-modulated radiotherapy (IMRT) in patients with high-grade meningiomas on local control and recurrence patterns.

Methods: Twenty patients with a neuropathological diagnosis of a high-grade meningioma (WHO°II or °III) treated with adjuvant or definitive radiotherapy between 2010 and 2015 were included in the present retrospective analysis. All patients were planned PET-based.

Dynamic 18F-FET PET is a powerful imaging biomarker in gadolinium-negative gliomas.

Background: We aimed to elucidate the place of dynamic O-(2-[18F]-fluoroethyl)-L-tyrosine (18F-FET) PET in prognostic models of gadolinium (Gd)-negative gliomas.

Methods: In 98 patients with Gd-negative gliomas undergoing 18F-FET PET guided biopsy, time activity curves (TACs) of each tumor were qualitatively categorized as either increasing or decreasing. Additionally, post-hoc quantitative analyses were done using minimal time-to-peak (TTPmin) measurements.

68Ga-DOTATATE PET/CT Reveals Epstein-Barr Virus-Associated Nasopharyngeal Carcinoma in a Case of Suspected Sphenoid Wing Meningioma.

In this case of suspected sphenoid wing meningioma, Ga-DOTATATE PET/CT showed a somatostatin receptor (SSR)-expressing tumor with extension to the nasopharynx and SSR-expressing cervical lymph nodes. Subsequent biopsy from the nasopharynx revealed an Epstein-Barr virus (EBV)-associated, undifferentiated World Health Organization type 3 nasopharyngeal carcinoma (NPC), a potential clinical pitfall due to the reported high SSR expression of this tumor subtype. In consideration of the high target-to-background contrast, SSR ligands might be superior to F-FDG for EBV-associated NPC PET imaging, particularly at the skull base.

Imaging of Glial Activation after Unilateral Labyrinthectomy in the Rat: A [F]GE180-PET Study.

The functional relevance of reactive gliosis for recovery from acute unilateral vestibulopathy is unknown. In the present study, glial activation was visualized by [F]GE180-PET in a rat model of unilateral labyrinthectomy (UL) and compared to behavioral vestibular compensation (VC) overtime. 14 Sprague-Dawley rats underwent a UL by transtympanic injection of bupivacaine/arsenilate, 14 rats a SHAM UL (injection of normal saline).

TSPO imaging using the novel PET ligand [F]GE-180: quantification approaches in patients with multiple sclerosis.

Background: PET ligands targeting the translocator protein (TSPO) represent promising tools to visualise neuroinflammation. Here, we analysed parameters obtained in dynamic and static PET images using the novel TSPO ligand [F]GE-180 in patients with relapsing remitting multiple sclerosis (RRMS) and an approach for semi-quantitative assessment of this disease in clinical routine. Seventeen dynamic [F]GE-180 PET scans of RRMS patients were evaluated (90 min).

Epidural Metastases From Follicular Thyroid Cancer Mimicking Meningiomas in 68Ga-DOTATATE PET.

We report a woman with multifocal lesions suggestive of meningiomas in MRI, which also presented with high Ga-DOTATATE uptake in PET, a finding characteristic for meningioma. A whole-body staging due to a pathological fracture revealed multiple neoplastic lesions throughout the body without detection of a primary site. Subsequent pathological workup of a lung lesion revealed multifocal metastases from follicular thyroid cancer despite thyroidectomy 10 years ago (without pathological finding), and posttreatment scans after radioiodine therapy confirmed the multiple brain lesions to be metastases as well.

Suspected recurrence of brain metastases after focused high dose radiotherapy: can [F]FET- PET overcome diagnostic uncertainties?

Background: After focused high dose radiotherapy of brain metastases, differentiation between tumor recurrence and radiation-induced lesions by conventional MRI is challenging. This study investigates the usefulness of dynamic O-(2-F-Fluoroethyl)-L-Tyrosine positron emission tomography (F-FET PET) in patients with MRI-based suspicion of tumor recurrence after focused high dose radiotherapy of brain metastases.

Methods: Twenty-two patients with 34 brain metastases (median age 61.

Usefulness of PET Imaging to Guide Treatment Options in Gliomas.

Magnetic resonance imaging (MRI) is the gold standard guiding diagnostic and therapeutic management in glioma with its high resolution and possibility to depict blood-brain-barrier disruption when contrast medium is applied. In light of the shifting paradigms revealing distinct tumor subtypes based on the molecular and genetic characterization and increasing knowledge about the variability of glioma biology, additional imaging modalities such as positron emission tomography (PET) depicting metabolic processes gain further importance in the management of glioma.