Correlation analysis of [F]fluorodeoxyglucose and [F]fluoroazomycin arabinoside uptake distributions in lung tumours during radiation therapy.

Background: PET-guided dose painting (DP) aims to target radioresistant tumour regions in order to improve radiotherapy (RT) outcome. Besides the well-known [F]fluorodeoxyglucose (FDG), the hypoxia positron emission tomography (PET) tracer [F]fluoroazomycin arabinoside (FAZA) could provide further useful information to guide the radiation dose prescription. In this study, we compare the spatial distributions of FDG and FAZA PET uptakes in lung tumours.

F-Fluoroform: a F-trifluoromethylating agent for the synthesis of SCFF-aromatic derivatives.

Herein the synthesis of various SCFF-containing derivatives is reported by a transition metal-free process. By using HCFF, readily generated from a bench-stable difluoromethyl sulfonium salt, various aromatic disulfides were easily converted into the desired radiolabelled trifluoromethylthiolated compounds in the presence of a base. This protocol allowed the formation of the SCFF-containing aromatic derivatives in good to excellent radiochemical yields.

Evolution of [F]fluorodeoxyglucose and [F]fluoroazomycin arabinoside PET uptake distributions in lung tumours during radiation therapy.

Background: Dose painting (DP) aims to improve radiation therapy (RT) outcome by targeting radioresistant tumour regions identified through functional imaging, e.g., positron emission tomography (PET).

Radiosynthesis and validation of (±)-[18F]-3-fluoro-2-hydroxypropionate ([18F]-FLac) as a PET tracer of lactate to monitor MCT1-dependent lactate uptake in tumors.

Cancers develop metabolic strategies to cope with their microenvironment often characterized by hypoxia, limited nutrient bioavailability and exposure to anticancer treatments. Among these strategies, the metabolic symbiosis based on the exchange of lactate between hypoxic/glycolytic cancer cells that convert glucose to lactate and oxidative cancer cells that preferentially use lactate as an oxidative fuel optimizes the bioavailability of glucose to hypoxic cancer cells. This metabolic cooperation has been described in various human cancers and can provide resistance to anti-angiogenic therapies.

DW-MRI and (18) F-FLT PET for early assessment of response to radiation therapy associated with hypoxia-driven interventions. Preclinical studies using manipulation of oxygenation and/or dose escalation.

Early markers of treatment response may help in the management of patients by predicting the outcome of a specific therapeutic intervention. Here, we studied the potential value of diffusion-weighted MRI (DW-MRI) and (18)F-fluorothymidine ((18)F-FLT), markers of cell death and cell proliferation respectively, to predict the response to irradiation. In addition, dose escalation and/or carbogen breathing were used to modulate the response to irradiation.

Predictive value of (18)F-FAZA PET imaging for guiding the association of radiotherapy with nimorazole: a preclinical study.

Purpose: To assess the predictive value of hypoxia imaging by (18)F-FAZA PET in identifying tumors that may benefit from radiotherapy combined with nimorazole, a hypoxic radiosensitizer.

Material And Methods: Rats of two tumor models (Rhabdomyosarcoma and 9L-glioma) were divided into two treated groups: radiotherapy (RT) alone or RT plus nimorazole. (18)F-FAZA PET images were obtained to evaluate tumor hypoxia before the treatment.

Hypoxia-guided adaptive radiation dose escalation in head and neck carcinoma: a planning study.

Objective: To evaluate from a planning point of view the dose distribution of adaptive radiation dose escalation in head and neck squamous cell carcinoma (HNSCC) using (18)F-Fluoroazomycin arabinoside (FAZA) positron emission tomography/computed tomography (PET-CT).

Material/methods: Twelve patients with locally advanced HNSCC underwent three FAZA PET-CT before treatment, after 7 fractions and after 17 fractions of a carboplatin-5FU chemo-radiotherapy regimen (70 Gy in 2 Gy per fraction over 7 weeks). The dose constraints were that every hypoxic voxel delineated before and during treatment (newborn hypoxic voxels) should receive a total dose of 86 Gy.

Potential role of hypoxia imaging using (18)F-FAZA PET to guide hypoxia-driven interventions (carbogen breathing or dose escalation) in radiation therapy.

Background And Purpose: Hypoxia-driven intervention (oxygen manipulation or dose escalation) could overcome radiation resistance linked to tumor hypoxia. Here, we evaluated the value of hypoxia imaging using (18)F-FAZA PET to predict the outcome and guide hypoxia-driven interventions.

Material And Methods: Two hypoxic rat tumor models were used: rhabdomyosarcoma and 9L-glioma.

Reprogramming of tumor metabolism by targeting mitochondria improves tumor response to irradiation.

Background: The Warburg phenotype identified decades ago describes tumor cells with increased glycolysis and decreased mitochondrial respiration even in the presence of oxygen. This particular metabolism also termed 'aerobic glycolysis' reflects an adaptation of tumor cells to proliferation in a heterogeneous tumor microenvironment. Although metabolic alterations in cancer cells are common features, their impact on the response to radiotherapy is not yet fully elucidated.

[(18) F]CuCF3 : a [(18) F]trifluoromethylating agent for arylboronic acids and aryl iodides.

Positron emission tomography has emerged as the leading method for medical imaging with fluorine-18 as the most widely used radioactive isotope. Here we report a semi-automated method for the preparation of valuable [(18) F]trifluoromethylcopper, as well as its use for the radiosynthesis of [(18) F]trifluoromethylarenes and heteroarenes. Mild conditions of [(18) F]trifluoromethylation make this method particularly useful for the radiosynthesis of pharmacologically relevant [(18) F]trifluoromethylarenes and heteroarenes.

A prospective clinical study of ¹⁸F-FAZA PET-CT hypoxia imaging in head and neck squamous cell carcinoma before and during radiation therapy.

Purpose: Hypoxia in head and neck squamous cell carcinoma (HNSCC) is associated with poor prognosis and outcome. (18) F-Fluoroazomycin arabinoside (FAZA) is a positron emission tomography (PET) tracer developed to enable identification of hypoxic regions within tumor. The aim of this study was to evaluate the use of (18) F-FAZA-PET for assessment of hypoxia before and during radiation therapy.

(89)Zr-labeled anti-endoglin antibody-targeted gold nanoparticles for imaging cancer: implications for future cancer therapy.

Aims: Antibody-labeled gold nanoparticles represent an attractive tool for cancer imaging and therapy. In this study, the anti-CD105 antibody was conjugated with gold nanoparticles (AuNPs) for the first time. The antibody biodistribution in mice before and after conjugation to AuNPs was studied, with a focus on tumor targeting.

Antibody-functionalized nanoparticles for imaging cancer: influence of conjugation to gold nanoparticles on the biodistribution of 89Zr-labeled cetuximab in mice.

Antibody-labeled gold nanoparticles represent a promising novel tool regarding cancer imaging and therapy. Nevertheless, the characterization of biodistribution of such immunonanocarriers has been poorly documented. In this study, the biodistribution of (89)Zr-labeled cetuximab before and after the coupling reaction to gold nanoparticles (AuNPs) was compared and the quantitative imaging performance of (89)Zr immuno-PET was evaluated.

Synthesis of new 18F-radiolabeled silicon-based nitroimidazole compounds.

The syntheses of new nitroimidazole compounds using silicon-[(18)F]fluorine chemistry for the potential detection of tumor hypoxia are described. [(18)F]silicon-based compounds were synthesized by coupling 2-nitroimidazole with silyldinaphtyl or silylphenyldi-tert-butyl groups and labeled by fluorolysis or isotopic exchange. Dinaphtyl compounds (6, 10) were labeled in 56-71% yield with a specific activity of 45 GBq/μmol, however these compounds ([(18)F]7 and [(18)F]11) were not stable in plasma.

Multimodal imaging of tumor response to sorafenib combined with radiation therapy: comparison between diffusion-weighted MRI, choline spectroscopy and 18F-FLT PET imaging.

The purpose of this study was to determine the value of different imaging modalities, that is, magnetic resonance imaging/spectroscopy (MRI/MRS) and positron emission tomography (PET), to assess early tumor response to sorafenib with or without radiotherapy. Diffusion-weighted (DW)-MRI, choline (1)H MRS at 11.7 T, and (18)F-FLT PET imaging were used to image fibrosarcoma (FSaII) tumor-bearing mice over time.

Hypoxia imaging with the nitroimidazole 18F-FAZA PET tracer: a comparison with OxyLite, EPR oximetry and 19F-MRI relaxometry.

Background And Purpose: (18)F-FAZA is a nitroimidazole PET tracer that can provide images of tumor hypoxia. However, it cannot provide absolute pO(2) values. To qualify (18)F-FAZA PET, we compared PET images to pO(2) measured by OxyLite, EPR oximetry and (19)F-MRI.

Early monitoring of external radiation therapy by [18F]-fluoromethylcholine positron emission tomography and 3-T proton magnetic resonance spectroscopy: an experimental study in a rodent rhabdomyosarcoma model.

Purpose: To assess early radiation therapy (RT)-induced variations in total choline (tCho) concentration measured by proton magnetic resonance spectroscopy (H-MRS) and in (18)F-labelled fluoromethylcholine (FCH) uptake measured by PET in a rodent tumour model.

Methods: Nine rats bearing syngenic rhabdomyosarcoma grafts in both thighs were irradiated (13 Gy, one fraction). H-MRS data and FCH-PET were acquired in the same imaging session prior to and 3, 9 and 16 days after external RT.

Is (18)F-FDG a surrogate tracer to measure tumor hypoxia? Comparison with the hypoxic tracer (14)C-EF3 in animal tumor models.

Introduction: Fluorodeoxyglucose (FDG) has been reported as a surrogate tracer to measure tumor hypoxia with positron emission tomography (PET). The hypothesis is that there is an increased uptake of FDG under hypoxic conditions secondary to enhanced glycolysis, compensating the hypoxia-induced loss of cellular energy production. Several studies have already addressed this issue, some with conflicting results.

Rodent rhabdomyosarcoma: comparison between total choline concentration at H-MRS and [18F]-fluoromethylcholine uptake at PET using accurate methods for collecting data.

Purpose: To compare choline concentration/amount at proton magnetic resonance spectroscopy (H-MRS) and [18F]-fluoromethylcholine (FCH) uptake at positron emission tomography (PET) in a tumour animal model.

Procedures: Twenty-two rats bearing grafted syngenic rhabdomyosarcoma in both thighs were examined on a 3T MR system and on a small animal PET system. Total choline concentration was measured on proton MR spectra using a so-called 'best internal fitting' volume of interest.

[18F]EF3 is not superior to [18F]FMISO for PET-based hypoxia evaluation as measured in a rat rhabdomyosarcoma tumour model.

Purpose: The aim of this investigation was to quantitatively compare the novel positron emission tomography (PET) hypoxia marker 2-(2-nitroimidazol-1-yl)-N-(3[(18)F],3,3-trifluoropropyl)acetamide ([(18)F]EF3) with the reference hypoxia tracer [(18)F]fluoromisonidazole ([(18)F]FMISO).

Methods: [(18)F]EF3 or [(18)F]FMISO was injected every 2 days into two separate groups of rats bearing syngeneic rhabdomyosarcoma tumours. In vivo PET analysis was done by drawing regions of interest on the images of selected tissues.

Comparative pharmacokinetics, biodistribution, metabolism and hypoxia-dependent uptake of [18F]-EF3 and [18F]-MISO in rodent tumor models.

Background And Purpose: [18F]-EF3 allows non-invasive detection of hypoxia. In the framework of its validation, we aimed at comparing its pharmacokinetics, biodistribution, metabolism and specificity for hypoxia with the hypoxia tracer [18F]-FMISO.

Materials And Methods: C3H mice were injected IV with 3.

Alginate moulding: an empirical method for magnetic resonance imaging/positron emission tomography co-registration in a tumor rat model.

Background And Purpose: In the experimental field of animal models, co-registration between positron emission tomography (PET) and magnetic resonance imaging (MRI) data still relies on non-automated post-processing using sophisticated algorithms and software developments. We assessed the value of an empirical method using alginate moulding for PET-MR co-registration in a tumor rat model.

Methods: Male WAG/RijHsd rats bearing grafted syngenic rhabdomyosarcoma were examined under general anesthesia by MRI using a clinical whole-body 3-T system equipped with a sensitivity-encoding four-channel wrist coil and by a small animal PET system using labelled [(18)F]-fluorocholine as tracer.

Determination of tumour hypoxia with the PET tracer [18F]EF3: improvement of the tumour-to-background ratio in a mouse tumour model.

Purpose: The 2-(2-nitroimidazol-1-yl)-N-(3,3,3-trifluoropropyl)acetamide (EF3) is a 2-nitroimidazole derivative which undergoes bioreductive activation under hypoxic conditions. Using the PET tracer [18F]EF3 in mice, tumour-to-muscle ratios ranging from 1.3 to 3.

Perfluorinated markers for hypoxia detection: synthesis of sulfur-containing precursors and [18F]-labelling.

Synthetic pathways of two novel sulfurated precursors for [18F]-labelling by oxidative fluorodesulfurization reaction are described. A three-step sequence starting from N-phthalimido-beta-alanine allows the preparation of a new trithioorthoester as valuable precursor of the synthesis of [18F]-3,3,3-trifluoropropylamine, a convenient radiolabelled intermediate for [18F]-EF3. A five-step sequence for the preparation of methyl 4-phthalimido-2,2-difluoropropanedithioate from ethyl 2,2-difluoropropanoate, via the key conversion step of alpha,alpha'-difluorothioamidate to the corresponding alpha,alpha'-difluorodithioester, and the first results of its use as precursor for oxidative fluorodesulfurization in [18F]-radiochemistry are also presented.