ORCID Profile
0000-0003-2123-145X
Current Organisations
Université Laval
,
CHU de Québec – Université Laval
,
CHU de Québec – Université Laval Research Center
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Publisher: Springer Science and Business Media LLC
Date: 18-07-2013
DOI: 10.1007/S00259-013-2504-X
Abstract: The aim of the study was to investigate the feasibility of shortening the recommended 4-h renoprotective amino acid infusion in patients receiving peptide receptor chemoradionuclide therapy (PRCRT) using radiosensitizing 5-fluorouracil. We evaluated the clearance of radiopeptide from the blood, long-term nephrotoxicity in patients undergoing PRCRT with the conventional 4-h amino acid infusion and renal uptake in patients receiving an abbreviated infusion. The whole-blood clearance of (177)Lu-DOTA-octreotate (LuTate) was measured in 13 patients receiving PRCRT. A retrospective analysis of short-term and long-term changes in glomerular filtration rate (GFR) in 96 consecutive patients receiving a 4-h infusion was performed. Renal LuTate retention estimated using quantitative SPECT/CT in 22 cycles delivered with a 2.5-h amino acid infusion was compared with that in 72 cycles with the 4-h infusion. LuTate demonstrated biexponential blood clearance with an initial clearance half-time of 21 min. Approximately 88 % of blood activity was cleared within 2 h. With the 4-h protocol, there was no significant change in GFR (1.2 ml/min mean increase from baseline 95 % CI -6.9 to 4.4 ml/min) and no grade 3 or 4 nephrotoxicity at the end of induction PRCRT. The long-term decline in GFR after a median follow up of 22 months was 2.2 ml/min per year. There was no significant difference in the renal LuTate retention measured in patients receiving a 2.5-h amino acid infusion compared to those who had a 4-h infusion. The greatest renal exposure to circulating radiopeptide occurs in the first 1 - 2 h after injection. This, combined with the safety of LuTate PRCRT, allows consideration of an abbreviated amino acid infusion, increasing patient convenience and reducing human resource allocation.
Publisher: Springer Science and Business Media LLC
Date: 27-01-2010
DOI: 10.1007/S00259-009-1352-1
Abstract: The objective of the study was to evaluate state-of-the-art clinical PET/CT technology in performing static and dynamic imaging of several mice simultaneously. A mouse-sized phantom was imaged mimicking simultaneous imaging of three mice with computation of recovery coefficients (RCs) and spillover ratios (SORs). Fifteen mice harbouring abdominal or subcutaneous tumours were imaged on clinical PET/CT with point spread function (PSF) reconstruction after injection of [18F]fluorodeoxyglucose or [18F]fluorothymidine. Three of these mice were imaged alone and simultaneously at radial positions -5, 0 and 5 cm. The remaining 12 tumour-bearing mice were imaged in groups of 3 to establish the quantitative accuracy of PET data using ex vivo gamma counting as the reference. Finally, a dynamic scan was performed in three mice simultaneously after the injection of (68)Ga-ethylenediaminetetraacetic acid (EDTA). For typical lesion sizes of 7-8 mm phantom experiments indicated RCs of 0.42 and 0.76 for ordered subsets expectation maximization (OSEM) and PSF reconstruction, respectively. For PSF reconstruction, SOR(air) and SOR(water) were 5.3 and 7.5%, respectively. A strong correlation (r (2) = 0.97, p < 0.0001) between quantitative data obtained in mice imaged alone and simultaneously in a group of three was found following PSF reconstruction. The correlation between ex vivo counting and PET/CT data was better with PSF reconstruction (r (2) = 0.98 slope = 0.89, p < 0.0001) than without (r (2) = 0.96 slope = 0.62, p < 0.001). Valid time-activity curves of the blood pool, kidneys and bladder could be derived from (68)Ga-EDTA dynamic acquisition. New generation clinical PET/CT can be used for simultaneous imaging of multiple small animals in experiments requiring high throughput and where a dedicated small animal PET system is not available.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 06-2013
Publisher: E-MED LTD
Date: 2011
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 10-2012
Publisher: Springer Science and Business Media LLC
Date: 15-07-2010
DOI: 10.1007/S11307-010-0378-X
Abstract: The aim of the study was to improve abdominal tumor detection by use of a dual radiologic contrast protocol. eXia160® (Benitio international) was mixed with 2-deoxy-2-[¹⁸F]fluoro-D: -glucose or 3'-[¹⁸F]fluoro-3'-deoxythymidine for intravenous (IV) injections. Omnipaque® 300 (GE healthcare) was used for intraperitoneal (IP) injections. Positron emission tomography/computed tomography (PET/CT) scans were acquired on a Siemens Biograph® equipped with point spread function reconstruction. The optimal concentration and injection schedule of IP contrast agent was studied in 12 mice. The impact of IP contrast media on PET quantitative accuracy was investigated by phantom studies and by imaging six mice before and after IP injection of Omnipaque®. The impact of a dual contrast media protocol on tumor delineation and quantitation was evaluated in 15 tumor-bearing mice using ex vivo counting as the reference. The optimal sequence was a mixture of tracer plus IV contrast agent followed by 1 mL of IP contrast agent (20 mg iodine/mL) administered 10 min before PET/CT acquisition. Phantom studies showed that the use of a 20-mg iodine/mL concentration of Omnipaque® led to a 4.8% overestimation of radioactivity concentration, as compared to saline. This was confirmed by animal studies that demonstrated a 4.3% overestimation. Tumor detection was excellent and correlation between PET/CT quantitative data and ex vivo counting was good (r² = 0.91, slope = 0.7). A dual radiologic contrast protocol is useful in PET/CT scanning of mice bearing abdominal tumors. Contrast agents used in this manner lead to a small but acceptable overestimation of quantitative PET data.
Publisher: Springer Science and Business Media LLC
Date: 20-09-2012
DOI: 10.1007/S00259-011-1937-3
Abstract: Tumour sequestration of radiotracer may lead to decreased bioavailability in healthy tissue resulting in lower absorbed radiation dose to critical organs. This study aims to assess the impact of disease burden, body habitus and urinary excretion on the biodistribution of (68)Ga-DOTA-octreotate. Ten patients with highly varied burden of somatostatin receptor-positive neuroendocrine tumour on (68)Ga-DOTA-octreotate positron emission tomography (PET)/CT were selected. Volumes of interest were drawn to derive the average uptake of renal parenchyma, spleen and body background, as well as to compute the fraction of injected activity sequestered in tumour and excreted in urine. Uptake values were assessed for correlation with tumour sequestration, weight, lean body weight, body surface area and urinary excretion. There was a trend for tumour sequestration, body habitus and urinary excretion to inversely influence all healthy tissue uptake values. In particular, renal uptake, splenic intensity and background soft tissue activity were all significantly correlated to composite factors combining tumour sequestration with body habitus and renal excretion. When combined with body habitus index or a body habitus index and renal excretion, tumour sequestration was strongly and significantly correlated inversely with renal uptake. Our results suggest that tumour sequestration of (68)Ga-DOTA-octreotate is a major factor leading to a sink effect that decreases activity concentration in healthy organs such as the kidney. However, body habitus and renal function also influence tissue biodistribution, in a synergistic fashion. Compared with a fixed-dose peptide receptor radionuclide therapy protocol, an adjusted-dose regimen tailored to tumour burden, body habitus and renal function may allow greater radiation dose to in idual lesions without substantially adding to toxicity in normal tissues.
Publisher: Society of Nuclear Medicine
Date: 09-09-2011
DOI: 10.2967/JNUMED.111.093344
Abstract: Ventilation-perfusion (V/Q) scintigraphy is established for regional assessment of lung function in a variety of diseases, including pulmonary embolism (PE). PET/CT may further improve the accuracy and utility of V/Q imaging because of its superior technical characteristics. This pilot study assessed the feasibility of performing V/Q PET/CT and compared diagnostic utility with conventional V/Q imaging in patients with clinical suspicion of PE. Ten patients undergoing conventional V/Q imaging were prospectively recruited. PET/CT V/Q imaging was performed after inhalation of (68)Ga-carbon nanoparticles ("Galligas") and administration of (68)Ga-macroaggregated albumin. Blinded to the results of the other study, SPECT/CT (n = 9) or SPECT (n = 1) images and PET/CT images were graded by a predefined scoring system for scan quality. The number of matched or unmatched defects and diagnosis were also measured and compared with a final diagnosis. PET image quality was equivalent or superior to SPECT in all patients, with more homogeneous radiotracer distribution for both ventilation and perfusion studies (P < 0.01). Based on conventional V/Q imaging, the diagnosis was acute PE in 2 patients and no PE in 7 patients, and the imaging results were nondiagnostic in 1 patient. The PET/CT diagnosis was concordant in 8 patients, and these studies demonstrated a similar number and distribution of matched and unmatched defects. In 1 discordant case, a patient with a SPECT/CT study that was nondiagnostic because of severe airway disease showed no PE on PET/CT. In another, the diagnosis of PE established on SPECT/CT was not reported on PET/CT 2 d later, possibly because of interval clot lysis or migration. This intrain idual comparative study demonstrated that V/Q PET/CT with (68)Ga-labeled radiotracers can be performed in clinical practice. Compared with conventional V/Q imaging, advantages include higher-resolution, fully tomographic images with potentially better regional quantitation of lung function. The short half-life of (68)Ga also enables more flexible acquisition protocols with the option of performing ventilation studies selectively on patients with abnormal perfusion. On the basis of our results, further studies are indicated to assess whether V/Q PET/CT can improve diagnostic algorithms for patients with suspected PE.
Publisher: Wiley
Date: 18-08-2010
DOI: 10.1111/J.1754-9485.2010.02178.X
Abstract: Conventional imaging (CI) is known to have limitations with respect to staging of patients with primary or relapsed prostate cancer. Positron emission tomography/computed tomography (PET/CT) with (18)F-flurodeoxyglucose (FDG) is also often suboptimal because of low tracer avidity, but (18)F-fluorocholine (FCH) appears to be a promising alternative molecular imaging probe. We report a prospective pilot study of PET/CT comparing both tracers for staging and restaging of patients with prostate cancer. Sixteen prostate cancer patients were evaluated (7 for staging and 9 for restaging). All patients also underwent CI, comprising at least an abdominopelvic CT and a bone scan. All imaging results and other relevant data were extracted from the imaging reports and medical charts. Based on all imaging-detected disease sites, both FCH-PET/CT and FDG-PET/CT (79%) were more sensitive than CI (14%), with the highest number of sites of nodal and distant disease on FCH PET/CT. FCH-PET/CT alone would have provided sufficient clinical information to form an appropriate management plan in 88% of cases, as compared with 56% for CI. FCH-PET/CT has the potential to impact on the management of patients with prostate cancer significantly more often than CI.
Publisher: Wiley
Date: 10-10-2013
DOI: 10.1118/1.4824318
Abstract: To create an accurate map of the distribution of radiation dose deposition in healthy and target tissues during radionuclide therapy. Serial quantitative SPECT∕CT images were acquired at 4, 24, and 72 h for 28 (177)Lu-octreotate peptide receptor radionuclide therapy (PRRT) administrations in 17 patients with advanced neuroendocrine tumors. Deformable image registration was combined with an in-house programming algorithm to interpolate pharmacokinetic uptake and clearance at a voxel level. The resultant cumulated activity image series are comprised of values representing the total number of decays within each voxel's volume. For PRRT, cumulated activity was translated to absorbed dose based on Monte Carlo-determined voxel S-values at a combination of long and short ranges. These dosimetric image sets were compared for mean radiation absorbed dose to at-risk organs using a conventional MIRD protocol (OLINDA 1.1). Absorbed dose values to solid organs (liver, kidneys, and spleen) were within 10% using both techniques. Dose estimates to marrow were greater using the voxelized protocol, attributed to the software incorporating crossfire effect from nearby tumor volumes. The technique presented offers an efficient, automated tool for PRRT dosimetry based on serial post-therapy imaging. Following retrospective analysis, this method of high-resolution dosimetry may allow physicians to prescribe activity based on required dose to tumor volume or radiation limits to healthy tissue in in idual patients.
No related grants have been discovered for Jean-Mathieu Beauregard.