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PURPOSE: The aim of this prospective study is to analyze the global tumor blood flow (BF) and its heterogeneity in newly diagnosed breast cancer (BC) according to tumor biological characteristics and molecular subtypes. These perfusion parameters were compared to those classically derived from metabolic studies to investigate links between perfusion and metabolism. METHODS: Two hundred seventeen newly diagnosed BC patients underwent a 18F-FDG PET/CT exam before any treatment. A 2-min dynamic acquisition, centered on the chest, was performed immediately after intravenous injection of 3 MBq/kg of 18F-FDG, followed by a two-step static acquisition 90 min later. Tumor BF was calculated (in ml/min/g) using a single compartment kinetic model. In addition to standard PET parameters, texture features (TF) describing the heterogeneity of tumor perfusion and metabolism were extracted. Patients were divided into three groups: Luminal (HR+/HER2-), HER2 (HER2+), and TN (HR-/HER2-). Global and TF parameters of BF and metabolism were compared in different groups of patients according to tumor biological characteristics. RESULTS: Tumors with lymph node involvement showed a higher perfusion, whereas no significant differences in SUV_max or SUV_mean were reported. TN tumors had a higher metabolic activity than HER2 and luminal tumors but no significant differences in global BF values were noted. HER2 tumors exhibited a larger tumor heterogeneity of both perfusion and metabolism compared to luminal and TN tumors. Heterogeneity of perfusion appeared well correlated to that of metabolism. CONCLUSIONS: The study of breast cancer perfusion shows a higher BF in large tumors and in tumors with lymph node involvement, not paralleled by similar modifications in tumor global metabolism. In addition, the observed correlation between the perfusion heterogeneity and the metabolism heterogeneity suggests that tumor perfusion and consequently the process of tumor angiogenesis might be involved in the metabolism heterogeneity previously shown in BC.
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Neoplasias da Mama , Fluordesoxiglucose F18 , Neoplasias da Mama/diagnóstico por imagem , Humanos , Perfusão , Tomografia por Emissão de Pósitrons combinada à Tomografia Computadorizada , Tomografia por Emissão de Pósitrons , Estudos ProspectivosRESUMO
The combination of two imaging probes on the same biomolecule gives access to targeted bimodal imaging agents that can provide more accurate diagnosis, complementary information, or that may be used in different applications, such as nuclear imaging and fluorescence guided surgery. In this study, we demonstrate that dichlorotetrazine, a small, commercially available compound, can be used as a modular platform to easily assemble various imaging probes. Doubly labeled tetrazines can then be conjugated to a protein through a biorthogonal IEDDA reaction. A series of difunctionalized tetrazine compounds containing various chelating agents and fluorescent dyes was synthesized. As a proof of concept, one of these bimodal probes was conjugated to trastuzumab, previously modified with a constrained alkyne group, and the resulting dual-labeled antibody was evaluated in a mouse model, bearing a HER2-positive tumor. A significant uptake into tumor tissues was observed in vivo, by both SPECT-CT and fluorescence imaging, and confirmed ex vivo in biodistribution studies.
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Meios de Contraste , Reação de Cicloadição , Imagem Multimodal , Animais , Corantes Fluorescentes/química , Humanos , Camundongos , Estudo de Prova de Conceito , Trastuzumab/químicaRESUMO
A new generation of monomolecular imaging probes (MOMIP) based on a distyryl-BODIPY (BODIPY=boron-dipyrromethene) coupled with three DOTA macrocycles has been prepared (DOTA=1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid). The MOMIP presents good fluorescence properties and is very stable in serum. The bimodal probe was conjugated to trastuzumab, and an optical in vivo study showed high accumulation of the imaging agent at the tumor site. (111) In radiometallation of the bioconjugate was performed in high radiochemical yield, highlighting the potential of this new BODIPY-chelators derivative as a bimodal imaging probe.
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In molecular imaging, multimodal imaging agents can provide complementary information, for improving the accuracy of disease diagnosis or enhancing patient management. In particular, optical/nuclear imaging may find important preclinical and clinical applications. To simplify the preparation of dual-labeled imaging agents, we prepared versatile monomolecular multimodal imaging probe (MOMIP) platforms containing both a fluorescent dye (BODIPY) and a metal chelator (polyazamacrocycle). One of the MOMIP was conjugated to a cyclopeptide (i.e., octreotide) and radiolabeled with (111) In. In vitro and in vivo studies of the resulting bioconjugate were conducted, highlighting the potential of these BODIPY-based bimodal probes. This work also confirmed that the biovector and/or the bimodal probes must be chosen carefully, due to the impact of the MOMIP on the overall properties of the resulting imaging agent.
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Objective. We introduce a versatile methodology for the accurate modelling of PET imaging systems via Monte Carlo simulations, using the Geant4 application for tomographic emission (GATE) platform. Accurate Monte Carlo modelling involves the incorporation of a complete analytical signal processing chain, called the digitizer in GATE, to emulate the different count rates encountered in actual positron emission tomography (PET) systems.Approach. The proposed approach consists of two steps: (1) modelling the digitizer to replicate the detection chain of real systems, covering all available parameters, whether publicly accessible or supplied by manufacturers; (2) estimating the remaining parameters, i.e. background noise level, detection efficiency, and pile-up, using optimisation techniques based on experimental single and prompt event rates. We show that this two-step optimisation reproduces the other experimental count rates (true, scatter, and random), without the need for additional adjustments. This method has been applied and validated with experimental data derived from the NEMA count losses test for three state-of-the-art SiPM-based time-of-flight (TOF)-PET systems: Philips Vereos, Siemens Biograph Vision 600 and GE Discovery MI 4-ring.Main results. The results show good agreement between experiments and simulations for the three PET systems, with absolute relative discrepancies below 3%, 6%, 6%, 7% and 12% for prompt, random, true, scatter and noise equivalent count rates, respectively, within the 0-10 kBq·ml-1activity concentration range typically observed in whole-body18F scans.Significance. Overall, the proposed digitizer optimisation method was shown to be effective in reproducing count rates and NECR for three of the latest generation SiPM-based TOF-PET imaging systems. The proposed methodology could be applied to other PET scanners.
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Processamento de Imagem Assistida por Computador , Método de Monte Carlo , Tomografia por Emissão de Pósitrons , Tomografia por Emissão de Pósitrons/métodos , Processamento de Imagem Assistida por Computador/métodosRESUMO
In medical imaging, accurate segmentation is crucial to improving diagnosis, treatment, or both. However, navigating the multitude of available architectures for automatic segmentation can be overwhelming, making it challenging to determine the appropriate type of architecture and tune the most crucial parameters during dataset optimisation. To address this problem, we examined and refined seven distinct architectures for segmenting the liver, as well as liver tumours, with a restricted training collection of 60 3D contrast-enhanced magnetic resonance images (CE-MRI) from the ATLAS dataset. Included in these architectures are convolutional neural networks (CNNs), transformers, and hybrid CNN/transformer architectures. Bayesian search techniques were used for hyperparameter tuning to hasten convergence to the optimal parameter mixes while also minimising the number of trained models. It was unexpected that hybrid models, which typically exhibit superior performance on larger datasets, would exhibit comparable performance to CNNs. The optimisation of parameters contributed to better segmentations, resulting in an average increase of 1.7% and 5.0% in liver and tumour segmentation Dice coefficients, respectively. In conclusion, the findings of this study indicate that hybrid CNN/transformer architectures may serve as a practical substitute for CNNs even in small datasets. This underscores the significance of hyperparameter optimisation.
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Processamento de Imagem Assistida por Computador , Neoplasias Hepáticas , Humanos , Teorema de Bayes , Processamento de Imagem Assistida por Computador/métodos , Imageamento por Ressonância Magnética/métodos , Neoplasias Hepáticas/diagnóstico por imagemRESUMO
BACKGROUND: The aim of this study is to investigate the added value of combining tumour blood flow (BF) and metabolism parameters, including texture features, with clinical parameters to predict, at baseline, the pathological complete response (pCR) to neoadjuvant chemotherapy (NAC) in patients with newly diagnosed breast cancer (BC). METHODS: One hundred and twenty-eight BC patients underwent a 18F-FDG PET/CT before any treatment. Tumour BF and metabolism parameters were extracted from first-pass dynamic and delayed PET images, respectively. Standard and texture features were extracted from BF and metabolic images. Prediction of pCR was performed using logistic regression, random forest and support vector classification algorithms. Models were built using clinical (C), clinical and metabolic (C+M) and clinical, metabolic and tumour BF (C+M+BF) information combined. Algorithms were trained on 80% of the dataset and tested on the remaining 20%. Univariate and multivariate features selections were carried out on the training dataset. A total of 50 shuffle splits were performed. The analysis was carried out on the whole dataset (HER2 and Triple Negative (TN)), and separately in HER2 (N=76) and TN (N=52) tumours. RESULTS: In the whole dataset, the highest classification performances were observed for C+M models, significantly (p-value<0.01) higher than C models and better than C+M+BF models (mean balanced accuracy of 0.66, 0.61, and 0.64 respectively). For HER2 tumours, equal performances were noted for C and C+M models, with performances higher than C+M+BF models (mean balanced accuracy of 0.64, and 0.61 respectively). Regarding TN tumours, the best classification results were reported for C+M models, with better performances than C and C+M+BF models but not significantly (mean balanced accuracy of 0.65, 0.63, and 0.62 respectively). CONCLUSION: Baseline clinical data combined with global and texture tumour metabolism parameters assessed by 18F-FDG PET/CT provide a better prediction of pCR after NAC in patients with BC compared to clinical parameters alone for TN, and HER2 and TN tumours together. In contrast, adding BF parameters to the models did not improve prediction, regardless of the tumour subgroup analysed.
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BACKGROUND: We propose a comprehensive evaluation of a Discovery MI 4-ring (DMI) model, using a Monte Carlo simulator (GATE) and a clinical reconstruction software package (PET toolbox). The following performance characteristics were compared with actual measurements according to NEMA NU 2-2018 guidelines: system sensitivity, count losses and scatter fraction (SF), coincidence time resolution (CTR), spatial resolution (SR), and image quality (IQ). For SR and IQ tests, reconstruction of time-of-flight (TOF) simulated data was performed using the manufacturer's reconstruction software. RESULTS: Simulated prompt, random, true, scatter and noise equivalent count rates closely matched the experimental rates with maximum relative differences of 1.6%, 5.3%, 7.8%, 6.6%, and 16.5%, respectively, in a clinical range of less than 10 kBq/mL. A 3.6% maximum relative difference was found between experimental and simulated sensitivities. The simulated spatial resolution was better than the experimental one. Simulated image quality metrics were relatively close to the experimental results. CONCLUSIONS: The current model is able to reproduce the behaviour of the DMI count rates in the clinical range and generate clinical-like images with a reasonable match in terms of contrast and noise.
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PURPOSE: The aim of this study was (a) to optimise the99mTc-SPECT reconstruction parameters for the pre-treatment dosimetry of90Y-selective internal radiation therapy (SIRT) and (b) to compare the accuracy of clinical dosimetry methods with full Monte-Carlo dosimetry (fMCD) performed with Gate. METHODS: To optimise the reconstruction parameters, two hundred reconstructions with different parameters were performed on a NEMA phantom, varying the number of iterations, subsets, and post-filtering. The accuracy of the dosimetric methods was then investigated using an anthropomorphic phantom. Absorbed dose maps were generated using (1) the Partition Model (PM), (2) the Dose Voxel Kernel (DVK) convolution, and (3) the Local Deposition Method (LDM) with known activity restricted to the whole phantom (WP) or to the liver and lungs (LL). The dose to the lungs was calculated using the "multiple DVK" and "multiple LDM" methods. RESULTS: Optimal OSEM reconstruction parameters were found to depend on object size and dosimetric criterion chosen (Dmean or DVH-derived metric). The Dmean of all three dosimetric methods was close (≤ 10%) to the Dmean of fMCD simulations when considering large segmented volumes (whole liver, normal liver). In contrast, the Dmean to the small volume (∅=31) was systemically underestimated (12%-25%). For lungs, the "multiple DVK" and "multiple LDM" methods yielded a Dmean within 20% for the WP method and within 10% for the LL method. CONCLUSIONS: All three methods showed a substantial degradation of the dose-volume histograms (DVHs) compared to fMCD simulations. The DVK and LDM methods performed almost equally well, with the "multiple DVK" method being more accurate in the lungs.
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Fígado , Radiometria , Método de Monte Carlo , Imagens de Fantasmas , Tomografia Computadorizada de Emissão de Fóton Único , Radioisótopos de ÍtrioRESUMO
The availability of preclinical simultaneous PET/MR imaging systems has been increasing in recent years. Therefore, this technique is progressively moving from the hands of pure physicists towards those of scientists more involved in pharmacology and biology. Unfortunately, these combined scanners can be prone to artefacts and deviation of their characteristics under the influence of external factors or mutual interference between subsystems. This may compromise the image quality as well as the quantitative aspects of PET and MR data. Hence, quality assurance is crucial to avoid loss of animals and experiments. A possible risk to the acceptance of quality control by preclinical teams is that the complexity and duration of this quality control are increased by the addition of MR and PET tests. To avoid this issue, we have selected over the past 5 years, simple tests that can be easily and quickly performed each day before starting an animal PET/MR acquisition. These tests can be performed by the person in charge of the experiment even if this person has a limited expertise in instrumentation and performance evaluation. In addition to these daily tests, other tests are suggested for an advanced system follow-up at a lower frequency. In the present paper, the proposed tests are sorted by periodicity from daily to annual. Besides, we have selected test materials that are available at moderate cost either commercially or through 3D printing.
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Imageamento por Ressonância Magnética , Tomografia por Emissão de Pósitrons , Animais , Tomografia por Emissão de Pósitrons/métodos , Imageamento por Ressonância Magnética/métodos , Imagens de Fantasmas , ArtefatosRESUMO
PURPOSE: A strategy for management of radioactive waste associated with 177Lu-dotatate (Lutathera®) treatments was established in our institution, based on predicted storage times of 3-5 years extrapolated from the results of a 2-year measurement study. The aim of this work was to validate this strategy by identifying contaminants and confirming disposal based on the clearance level twice-the-background was within expected time frames. METHODS: We conducted a prospective series of measurements of radioactive waste associated with the first 65 treatments administered. Sequential measurements of the first 45 vials used were performed on a dose calibrator to identify contaminants. Exposure rates in contact were monitored with a dose ratemeter on a 6-monthly basis for all waste stored: 46 empty vials, 19 vials partially used and 61 biohazard containers. RESULTS: Initial median activity of the first vials used was 118 MBq [4-4188 MBq]. For each vial, the decay curve of activity obtained was adjusted to a bi-exponential model. The major component, representing 99.7% of the activity, has a median half-life of 6.6 days [5.7-7.2 days] corresponding to 177Lu. The second, representing only 0.3% of the activity and having a median half-life of 152 days [104-205 days] corresponding to 177mLu, determines necessary storage times. Partially used vials can be disposed of after 5 years, other waste after 3 years. Compliance with the regulatory clearance level is achieved within expected time frames. CONCLUSION: Although only present as traces, 177mLu associated with the direct production route results in major radioactive waste disposal issues for hospitals. Availability of radiopharmaceuticals without impurities appears to be crucial for an expanding use of targeted radionuclide therapy.
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Improved bifunctional chelating agents (BFC) are required for indium-111 radiolabeling of monoclonal antibodies (mAbs) under mild conditions to yield stable, target-specific agents. 2,2',2"-(10-(2,6-Dioxotetrahydro-2H-pyran-3-yl)-1,4,7,10-tetraazacyclododecane-1,4,7-triyl)triacetic acid (DOTAGA-anhydride) was evaluated for mAb conjugation and labeling with indium-111. The DOTA analogue was synthesized and conjugated to trastuzumab-which targets the HER2/neu receptor-in mild conditions (PBS pH 7.4, 25 °C, 30 min) and gave a mean degree of conjugation of 2.6 macrocycle per antibody. Labeling of this immunoconjugate with indium-111 was performed in 75% yield after 1 h at 37 °C, and the proportion of (111)In-DOTAGA-trastuzumab reached 97% after purification. The affinity of DOTAGA-trastuzumab was 5.5 ± 0.6 nM as evaluated by in vitro saturation assays using HCC1954 breast cancer cell line. SPECT/CT imaging and biodistribution studies were performed in mice bearing breast cancer BT-474 xenografts. BT-474 tumors were clearly visualized on SPECT images at 24, 48, and 72 h postinjection. The tumor uptake of [(111)In-DOTAGA]-trastuzumab reached 65%ID/g 72 h postinjection. These results show that the DOTAGA BFC appears to be a valuable tool for biologics conjugation.
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Anidridos , Anticorpos Monoclonais Humanizados , Neoplasias da Mama/diagnóstico , Compostos Heterocíclicos com 1 Anel , Imunoconjugados , Radioisótopos de Índio , Receptor ErbB-2/análise , Anidridos/química , Animais , Anticorpos Monoclonais Humanizados/química , Mama/patologia , Linhagem Celular Tumoral , Feminino , Compostos Heterocíclicos com 1 Anel/química , Humanos , Imunoconjugados/química , Radioisótopos de Índio/química , Camundongos , Camundongos Endogâmicos BALB C , Modelos Moleculares , Tomografia Computadorizada de Emissão de Fóton Único , TrastuzumabRESUMO
PURPOSE: Assessment of tumour blood flow (BF) heterogeneity using first-pass FDG PET/CT and textural feature (TF) analysis is an innovative concept. We aim to explore the relationship between BF heterogeneity measured with different TFs calculation methods and the response to neoadjuvant chemotherapy (NAC) in patients with newly diagnosed breast cancer (BC). METHODS: One hundred and twenty-five patients were enrolled. Dynamic first-pass and delayed FDG PET/CT scans were performed before NAC. Nine TFs were calculated from perfusion and metabolic PET images using relative (RR) or absolute (AR) rescaling strategies with two textural matrix calculation methods. Patients were classified according to presence or absence of a pathologic complete response (pCR) after NAC. The relationship between BF texture features and conventional features were analysed using spearman correlations. The TFs' differences between pCR and non-pCR groups were evaluated using Mann-Whitney tests and descriptive factorial discriminant analysis (FDA). RESULTS: Relation between tumour BF-based TFs and global BF parameters were globally similar to those observed for tumour metabolism. None of the TFs was significantly different between pCR and non-pCR groups in the Mann-Whitney analysis, after Benjamini-Hochberg correction. Using a RR led to better discriminations between responders and non-responders in the FDA analysis. The best results were obtained by combining all the PET features, including BF ones. CONCLUSION: A better differentiation of patients reaching a pCR was observed using a RR. Moreover, BF heterogeneity might bring a useful information when combined with metabolic PET parameters to predict the pCR after neoadjuvant chemotherapy.
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Neoplasias da Mama , Fluordesoxiglucose F18 , Humanos , Feminino , Neoplasias da Mama/metabolismo , Tomografia por Emissão de Pósitrons combinada à Tomografia Computadorizada/métodos , Terapia Neoadjuvante/métodos , Tomografia por Emissão de Pósitrons/métodos , Compostos Radiofarmacêuticos/uso terapêuticoRESUMO
BACKGROUND: During anthracycline treatment of cancer, there is a lack for biomarkers of cardiotoxicity besides the cardiac dysfunction. The objective of the present study was to compare [18F]FDG and [123I]MIBG (metaiodobenzylguanidine) in a longitudinal study in a doxorubicin-induced cardiotoxicity rat model. METHODS: Male Wistar Han rats were intravenously administered 3 times at 10 days' interval with saline or doxorubicin (5 mg/kg). [123I]MIBG SPECT/CT (single photon emission computed tomography-computed tomography) and simultaneous [18F]FDG PET (positron emission tomography)/7 Tesla cardiac MR (magnetic resonance) imaging acquisitions were performed at 24 h interval before first doxorubicin / saline injection and every 2 weeks during 6 weeks. At 6 weeks, the heart tissue was collected for histomorphometry measurements. RESULTS: At week 4, left ventricle (LV) end-diastolic volume was significantly reduced in the doxorubicin group. At week 6, the decreased LV end-diastolic volume was maintained, and LV end-systolic volume was increased resulting in a significant reduction of LV ejection fraction (47 ± 6% vs. 70 ± 3%). At weeks 4 and 6, but not at week 2, myocardial [18F]FDG uptake was decreased compared with the control group (respectively, 4.2 ± 0.5%ID/g and 9.2 ± 0.8%ID/g at week 6). Moreover, [18F]FDG cardiac uptake correlated with cardiac function impairment. In contrast, from week 2, a significant decrease of myocardial [123I]MIBG heart to mediastinum ratio was detected in the doxorubicin group and was maintained at weeks 4 and 6 with a 45.6% decrease at week 6. CONCLUSION: This longitudinal study precises that after doxorubicin treatment, cardiac [123I]MIBG uptake is significantly reduced as early as 2 weeks followed by the decrease of the LV end-diastolic volume and [18F]FDG uptake at 4 weeks and finally by the increase of LV end-systolic volume and decrease of LV ejection fraction at 6 weeks. Cardiac innervation imaging should thus be considered as an early key feature of anthracycline cardiac toxicity.
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We present the design and performance of a new compact preclinical system combining positron emission tomography (PET) and magnetic resonance imaging (MRI) for simultaneous scans. The PET contains sixteen SiPM-based detector heads arranged in two octagons and covers an axial field of view (FOV) of 102.5 mm. Depth of interaction effects and detector's temperature variations are compensated by the system. The PET is integrated in a dry magnet operating at 7 T. PET and MRI characteristics were assessed complying with international standards and interferences between both subsystems during simultaneous scans were addressed. For the rat size phantom, the peak noise equivalent count rates (NECR) were 96.4 kcps at 30.2 MBq and 132.3 kcps at 28.4 MBq respectively with and without RF coil. For mouse, the peak NECR was 300.0 kcps at 34.5 MBq and 426.9 kcps at 34.3 MBq respectively with and without coil. At the axial centre of the FOV, spatial resolutions expressed as full width at half maximum / full width at tenth maximum (FWHM/FWTM) ranged from 1.69/3.19 mm to 2.39/4.87 mm. The peak absolute sensitivity obtained with a 250-750 keV energy window was 7.5% with coil and 7.9% without coil. Spill over ratios of the NEMA NU4-2008 image quality (NEMA-IQ) phantom ranged from 0.25 to 0.96 and the percentage of non-uniformity was 5.7%. The image count versus activity was linear up to 40 MBq. The principal magnetic field variation was 0.03 ppm/mm over 40 mm. The qualitative and quantitative aspects of data were preserved during simultaneous scans.
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Imageamento por Ressonância Magnética , Tomografia por Emissão de Pósitrons , Animais , Cabeça , Camundongos , Imagens de Fantasmas , Ondas de Rádio , RatosRESUMO
Liver tumors are common and may be unamenable to surgery or ablative treatments. Consequently, other treatments have been devised. To assess the safety and efficacy of transarterial radioembolization (TARE) with Yttrium-90 for hepatocellular carcinoma (HCC), liver-dominant hepatic colorectal cancer metastases (mCRC), and cholangiocarcinoma (CCA), performed according to current recommendations, we conducted a single-center retrospective study in 70 patients treated with TARE (HCC, n = 44; mCRC, n = 20; CCA, n = 6). Safety and toxicity were assessed using the National Cancer Institute Common Terminology Criteria. Treatment response was evaluated every 3 months on imaging studies using Response Evaluation Criteria in Solid Tumors (RECIST) or mRECIST criteria. Overall survival and progression-free survival were estimated using the Kaplan-Meier method. The median delivered dose was 1.6 GBq, with SIR-Spheres® or TheraSphere® microspheres. TARE-related grade 3 adverse events affected 17.1% of patients. Median follow-up was 32.1 months. Median progression-free survival was 5.6 months and median overall time from TARE to death was 16.1 months and was significantly shorter in men. Progression-free survival was significantly longer in women (HR, 0.49; 95%CI, 0.26-0.90; p = 0.031). Risk of death or progression increased with the number of systemic chemotherapy lines. TARE can be safe and effective in patients with intermediate- or advanced-stage HCC, CCA, or mCRC refractory or intolerant to appropriate treatments.
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INTRODUCTION: The aim of this study was to evaluate the impact of the contouring methods on dose metrics and their predictive value on tumor control and survival, in both situations of pre-treatment and post-treatment dosimetry, for patients with advanced HCC treated with SIRT. METHODS: Forty-eight patients who underwent SIRT between 2012 and 2020 were retrospectively included in this study. Target volumes were delineated using two methods: MRI-based contours manually drawn by a radiologist and then registered on SPECT/CT and PET/CT via deformable registration (Pre-CMRI and Post-CMRI), 99mTc-MAA-SPECT and 90Y-microspheres-PET 10% threshold contouring (Pre-CSPECT and Post-CPET). The mean absorbed dose (Dm) and the minimal absorbed dose delivered to 70% of the tumor volume (D70) were evaluated with both contouring methods; the tumor-to-normal liver uptake ratio (TNR) was evaluated with MRI-based contours only. Tumor response was assessed using the mRECIST criteria on the follow-up MRIs. RESULTS: No significant differences were found for Dm and TNR between pre- and post-treatment. TNR evaluated with radiologic contours (Pre-CMRI and Post-CMRI) were predictive of tumor control at 6 months on pre- and post-treatment dosimetry (OR 5.9 and 7.1, respectively; p = 0.02 and 0.01). All dose metrics determined with both methods were predictive of overall survival (OS) on pre-treatment dosimetry, but only Dm with MRI-based contours was predictive of OS on post-treatment images with a median of 23 months for patients with a supramedian Dm versus 14 months for the others (p = 0.04). CONCLUSION: In advanced HCC treated with SIRT, Dm and TNR determined with radiologic contours were predictive of tumor control and OS. This study shows that a rigorous clinical workflow (radiologic contours + registration on scintigraphic images) is feasible and should be prospectively considered for improving therapeutic strategy.
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This 37-year-old woman was diagnosed with breast cancer during pregnancy. After multidisciplinary meeting, she was referred to our department for an FDG PET/CT for staging, and chemotherapy with weekly infusion of paclitaxel was initiated before childbirth. We estimated the fetal dose from the PET/CT procedure, and our results show that, if deemed necessary, this examination can reasonably be performed during pregnancy. The patient gave birth vaginally at term to an apparently healthy girl.
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Neoplasias da Mama/diagnóstico por imagem , Fluordesoxiglucose F18 , Processamento de Imagem Assistida por Computador , Imageamento por Ressonância Magnética , Tomografia por Emissão de Pósitrons combinada à Tomografia Computadorizada , Complicações na Gravidez/diagnóstico por imagem , Adulto , Neoplasias da Mama/patologia , Feminino , Humanos , Estadiamento de Neoplasias , Gravidez , Complicações na Gravidez/patologia , Fatores de TempoRESUMO
Superparamagnetic iron oxide nanoparticles were developed as positron emission tomography (PET) and magnetic resonance imaging (MRI) bimodal imaging agents. These nanoparticles (NPs), with a specific nanoflower morphology, were first synthesized and simultaneously functionalized with 3,4-dihydroxy-l-phenylalanine (LDOPA) under continuous hydrothermal conditions. The resulting NPs exhibited a low hydrodynamic size of 90 ± 2 nm. The functional groups of LDOPA (-NH2 and -COOH) were successfully used for the grafting of molecules of interest in a second step. The nanostructures were modified by poly(ethylene glycol) (PEG) and a new macrocyclic chelator MANOTA for further 64Cu radiolabeling for PET imaging. The functionalized NPs showed promising bimodal (PET and MRI) imaging capability with high r 2 and r 2* (T 2 and T 2* relaxivities) values and good stability. They were mainly uptaken from liver and kidneys. No cytotoxicity effect was observed. These NPs appear as a good candidate for bimodal tracers in PET/MRI.
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A novel trifunctional imaging probe containing a chelator of radiometal for PET, a NIR heptamethine cyanine dye, and a bioconjugatable handle, has been grafted onto AGuIX® nanoparticles via a Michael addition reaction. The resulting functionalized nanoparticles have been fully characterized, radiolabelled with 64Cu, and evaluated in a mice TSA tumor model using multimodal (PET/MRI/optical) imaging.