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Mathieu Charest

Phanie L Charest, Vanessa Vrolyk, Pauline Herst, Maryse Lessard, Deborah M Sloboda, Mathieu Dalvai, Julius Haruna, Janice L Bailey, Marie-Odile Benoit-Biancamano
Histological examination of the rat placenta and fetus is uncommon. Toxicological studies mainly rely on gross examination of the fetus and on fetal and placental weights. These are often insufficient to assess the fetal and placental toxicity of xenobiotics. The small size of the fetus makes its dissection labor-intensive. Thus, our objective was to develop a simple and accurate technique to evaluate the rat fetus and placenta. Sprague-Dawley rat fetuses at gestational day 19.5 ( n = 18) and their placentas ( n = 32) were fixed in formalin...
February 2018: Toxicologic Pathology
Mathieu Charest, Chantal Asselin
Purpose: The aims of the current survey were to draw a portrait of the delivered dose in nuclear medicine selected studies and to assess the degree of changes since an earlier survey performed in 2010. Methods: Each surveyed site had to fill two forms about the administered activity in selected nuclear medicine studies and about the CT parameters used in SPECT/CT imaging, if available. The administered activities were converted into effective doses using the most recent conversion factors. Diagnostic reference levels were computed for each imaging procedure, in order to provide a benchmark for comparison...
December 22, 2017: Journal of Nuclear Medicine Technology
Mathieu Charest, Josephine Pressacco, Jaramie Thomas-Gittens
A 25 year old female with known neurofibromatosis type 1 with a large anterior mediastinal mass was investigated. F18-FDG PET-CT revealed a radiotracer avid anterior mediastinal mass with SUVmax of 4.3 and demonstrating a hypoactive center. The Iodine-123 MIBG SPECT-CT study performed subsequently did not demonstrate any uptake, thereby excluding for the most part the diagnoses of paraganglioma or neuroblastoma. At final pathology, a malignant peripheral nerve sheath tumour (MPNST) of the pericardium with areas of chondrosarcomatous and angiosarcomatous differentiation was diagnosed...
November 10, 2017: Journal of Nuclear Medicine Technology
Karine Provost, Mathieu Charest
A 52-y-old man presenting with dyspnea and a massive effusion in the right pleural cavity underwent wedge biopsies of pulmonary lesions found on thoracic CT, leading to a diagnosis of pleural angiosarcoma. Bleeding developed postoperatively and was investigated using pulmonary CT angiography, which failed to identify a site of active bleeding. (99m)Tc-labeled red blood cell (RBC) SPECT/CT of the chest was performed, and the site was rapidly located. To our knowledge, this is the first case reported in the literature of localization of intrathoracic bleeding using (99m)Tc-RBC SPECT/CT...
September 2016: Journal of Nuclear Medicine Technology
Guillaume Desmarais, Gabriel Charest, Hélène Therriault, Minghan Shi, David Fortin, Rachel Bujold, David Mathieu, Benoit Paquette
PURPOSE: Irradiation of brain stimulates the expression of inflammatory mediators, some of which can modify the ability of cancer cells to infiltrate the brain. In the present study, the time window during which this stimulation occurs was determined. MATERIALS AND METHODS: Brain of Fischer rat was irradiated (15 Gy) and expression of pro-inflammatory mediators IL-1β, IL-6 and TNF-α was measured from 4 h to 20 days post-irradiation. Level of the matrix metalloproteinase 2 (MMP-2) and prostaglandin E2 (PGE2) which can favor cancer cell infiltration were also measured...
August 2016: International Journal of Radiation Biology
Anna Danilenko, Mathieu Charest, Antoine Leblond
PURPOSE: The evaluation of pulmonary nodules constitutes a large part of PET-CT studies. In this study, we aimed to evaluate the different interpretation criteria in F-fluorodeoxyglucose PET attenuation-corrected and non-attenuation-corrected studies as individual predictors of malignancy in order to propose a useful combination of criteria that can be used in daily practice to classify nodules appropriately. PATIENTS AND METHODS: We performed a historical prospective survey of all consecutive patients referred to our service for the initial assessment of pulmonary nodules and sought the final characterization of these nodules either from tissue sampling or from radiological and clinical follow-up...
November 2015: Nuclear Medicine Communications
Julie Constanzo, Benoit Paquette, Gabriel Charest, Laurence Masson-Côté, Mathieu Guillot
PURPOSE: Targeted and whole-brain irradiation in humans can result in significant side effects causing decreased patient quality of life. To adequately investigate structural and functional alterations after stereotactic radiosurgery, preclinical studies are needed. The purpose of this work is to establish a robust standardized method of targeted irradiation on small regions of the rat brain. METHODS: Euthanized male Fischer rats were imaged in a stereotactic bed, by computed tomography (CT), to estimate positioning variations relative to the bregma skull reference point...
May 2015: Medical Physics
Guillaume Desmarais, Gabriel Charest, David Fortin, Rachel Bujold, David Mathieu, Benoit Paquette
PURPOSE: Radiation induces a neuro-inflammation that is characterized by the expression of genes known to increase the invasion of cancer cells. In Fischer rats, brain irradiation increases the infiltration of cancer cells and reduced the median survival of the animals. In this study, we have determined whether these adverse effects of radiation can be prevented with the cyclooxygenase-2 (COX-2) inhibitor meloxicam. MATERIALS AND METHODS: Brain of Fischer rats treated or not with meloxicam were irradiated (15 Gy) and then implanted with the F98 glioma cells...
August 2015: International Journal of Radiation Biology
Sonia R Skamene, Rajan Rakheja, Kristina R Dahlstrom, Kristina R Dalhstrom, David Roberge, Ayoub Nahal, Mathieu Charest, Robert Turcotte, Marc Hickeson, Carolyn Freeman
OBJECTIVE: To explore the relationship between metabolic activity and outcome in patients with extremity sarcomas. METHODS: Between June 2004 and December 2011, 120 patients with newly diagnosed limb and girdle sarcomas underwent FDG-PET/CT for disease staging prior to curative intent treatment. The maximum standardized uptake value (SUV(max)) was measured for each primary tumor and correlated with outcome. Progression-free survival and overall survival (OS) were analyzed using the Kaplan-Meier method...
April 2014: Journal of Surgical Oncology
Gabriel Charest, Léon Sanche, David Fortin, David Mathieu, Benoit Paquette
Treatment of glioblastoma with platinum compounds modestly improves progression-free survival and may cause toxic effects which prevent use at higher dose that would otherwise improve the antineoplastic effect. To reduce toxicity, we propose to encapsulate the platinum drug in a liposome. We have also tested three methods of drug administration (intra-venous, intra-arterial and intra-arterial combined with blood brain barrier disruption) to determine which one optimizes the tumor cell uptake, limits the toxicity and delivers the best concomitance effect with radiotherapy...
December 2013: Journal of Neuro-oncology
Gabriel Charest, Léon Sanche, David Fortin, David Mathieu, Benoit Paquette
PURPOSE: Treatments of glioblastoma with cisplatin or oxaliplatin only marginally improve the overall survival of patients and cause important side effects. To prevent adverse effects, improve delivery, and optimize the tumor response to treatment in combination with radiotherapy, a potential approach consists of incorporating the platinum agent in a liposome. METHODS AND MATERIALS: In this study, cisplatin, oxaliplatin, carboplatin, Lipoplatin (the liposomal formulation of cisplatin), and Lipoxal (the liposomal formulation of oxaliplatin) were tested on F98 glioma orthotopically implanted in Fischer rats...
September 1, 2012: International Journal of Radiation Oncology, Biology, Physics
Mathieu Charest, Shadia Armanious
PURPOSE: Findings not associated with thromboembolic disease on routine perfusion lung scan may sometimes have particular clinical significance. We wanted to assess the clinical importance and overall survival after the recognition of a lymphangitic carcinomatosis pattern on perfusion lung scan. CASE REPORT: We report a case of lymphangitic carcinomatosis pattern on perfusion lung scan performed in a previously healthy patient who had rapid progressive course and died the next day...
November 2012: Canadian Association of Radiologists Journal, Journal L'Association Canadienne des Radiologistes
Gabriel Charest, Benoit Paquette, David Fortin, David Mathieu, Léon Sanche
Despite significant advances, the radiotherapy and chemotherapy protocols marginally improve the overall survival of patients with glioblastoma. Lipoplatin(TM), and Lipoxal(TM), the liposomal formulations of cisplatin and oxaliplatin respectively, were tested on the F98 glioma cells for their ability to improve the cell uptake and increase the synergic effect when combined with ionizing radiation. The cytotoxicity and synergic effect of platinum compounds were assessed by colony formation assay, while the cellular uptake was measured by Inductively Coupled Plasma Mass Spectrometer (ICP-MS)...
April 2010: Journal of Neuro-oncology
Mathieu Charest, Marc Hickeson, Robert Lisbona, Javier-A Novales-Diaz, Vilma Derbekyan, Robert E Turcotte
PURPOSE: The aims of this study are to evaluate the sensitivity of FDG PET/CT for detection of soft tissue and osseous sarcomas on the basis of FDG avidity. METHODS: We retrospectively evaluated 212 consecutive patients with known soft tissue or osseous sarcoma who had undergone a FDG PET/CT study for the initial staging or assessment of recurrence of disease. The maximum standardized uptake value (SUVmax) of each primary and/or most intense metastatic lesion was measured and compared with the histological data provided in the final pathological reports...
December 2009: European Journal of Nuclear Medicine and Molecular Imaging
Gabriel Charest, David Mathieu, Martin Lepage, David Fortin, Benoit Paquette, Léon Sanche
PURPOSE: Accurate targeting is crucial for the irradiation of a small-volume animal brain. We propose an original method, based on a polymer gel, to determine the accuracy and reproducibility of irradiation using a new stereotactic frame. METHODS: An in-house designed rat stereotactic frame, compatible with the Gamma Knife, was constructed. The rat brain was then removed through a small burr hole and the intracranial cavity was washed and filled with a polymer gel...
June 2009: Acta Neurochirurgica
Mathieu Charest, Amit Singnurkar, Marc Hickeson, J A Novales, Vilma Derbekyan
A growing number of studies have demonstrated the usefulness of FDG PET-CT in the preoperative assessment of soft tissue sarcomas. We report a case of a patient with a known low-grade liposarcoma demonstrating only mild hypermetabolism on a FDG PET-CT study. An incidental osseous lesion was found in the distal tibia of the same extremity during the initial workup. This tibial lesion was significantly more intense on the FDG PET-CT study than the primary sarcoma. Further investigation showed this to be an unexpected benign fibrous dysplasia...
July 2008: Clinical Nuclear Medicine
A Charest, A Pépin, R Shetty, C Côté, P Voisine, F Dagenais, P Pibarot, P Mathieu
OBJECTIVE: To examine the hypothesis that degenerative aortic stenosis (AS) is associated with the development of blood vessels and the expression of the secreted protein, acidic and rich in cysteine/osteonectin (SPARC), a matricellular protein that is involved in ossification, the modulation of angiogenesis and the production of metalloproteinases. METHODS: 30 surgically excised AS valves and 20 normal aortic valves were studied. RESULTS: Blood vessels were detected in the aortic valves from patients with degenerative AS, whereas normal valves were avascular structures...
December 2006: Heart: Official Journal of the British Cardiac Society
R Shetty, A Pepin, A Charest, J Perron, D Doyle, P Voisine, F Dagenais, P Pibarot, P Mathieu
OBJECTIVE: To test the hypothesis that valve allograft (VA) calcification results from an ossification process in which bone-regulatory proteins are expressed. METHODS: 15 VA that were explanted at the time of surgery for dysfunction were studied. VA were analysed and compared with normal aortic valves (n = 20). RESULTS: All the VA (5 aortic, 10 pulmonary) exhibited heavy calcification and important fibrosis. Immunohistochemistry studies showed that the bone-specific transcription factor Cbfa-1 was expressed by stromal cells...
September 2006: Heart: Official Journal of the British Cardiac Society
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