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Pino F.,University of Barcelona | Roe N.,University of Barcelona | Orero A.,Hospital Clinic Of Barcelona | Orero A.,Institute Fisica Corpuscular | And 11 more authors.
Revista Espanola de Medicina Nuclear | Year: 2011

Objective: To develop a small-animal SPECT system using a low cost commercial portable gamma camera equipped with a pinhole collimator, a continuous scintillation crystal and a position-sensitive photomultiplier tube. Material and methods: The gamma camera was attached to a variable radius system, which enabled us to optimize sensitivity and resolution by adjusting the radius of rotation to the size of the object. To investigate the capability of the SPECT system for small animal imaging, the dependence of resolution and calibration parameters on radius was assessed and acquisitions of small phantoms and mice were carried out. Results: Resolution values, ranging from 1.0. mm for a radius of 21.4. mm and 1.4. mm for a radius of 37.2. mm were obtained, thereby justifying the interest of a variable radius SPECT system. Conclusions: The image quality of phantoms and animals were satisfactory, thus confirming the usefulness of the system for small animal SPECT imaging. © 2011 Elsevier España, S.L. and SEMNIM.

Burdio F.,Hospital del Mar | Berjano E.,Polytechnic University of Valencia | Millan O.,Institute dAlta Tecnologia IAT | Grande L.,Hospital del Mar | And 4 more authors.
Physica Medica | Year: 2013

Purpose: To track the saline during infusion with a 15 G needle into healthy pig livers at high and low infusion rates for 300 s. Methods: In each experiment, the needle was inserted into a single lobe of the liver to a depth of at least 2 cm following its longer axis. Two sets of experiments were defined: 1) low infusion rate of 0.1 mL/min (n = 6) and 2) high infusion rate of 1 mL/min (n = 6). Cine CT scans were carried out and three transverse planes were defined around the infusion point (IP), which corresponds with needle tip. Two assessments were performed: 1) a dynamic plane study focused on the time progress of the saline distribution on a single plane, which provided the Mean Percentage of Grayscale Intensity (MPGI); and 2) a volumetric study focused on the three dimensional distribution of the saline around IP at the end of the experiment, which provided the High Intensity Volume Ratio (HIVR). Results: The saline solution was conspicuous around the IP and shortly after heterogeneously inside the vessels. At the high infusion rate, the saline became conspicuous not only much sooner (evident at 20 s) but farther away (mean value of MPGI over 2%, up to 17 mm from the IP) and at a much higher intensity (mean value of MPGI over 10% up to 4 mm from the IP). The lower the radial distance to the IP, the greater the difference in HIVR between both groups. Conclusions: The high infusion rate leads to a faster, wider and a more marked presence of saline than the low rate. The rapid drainage into the hepatic veins may explain the heterogeneous distribution. © 2012 Associazione Italiana di Fisica Medica.

Bullich S.,Biomedical Imaging Center | Slifstein M.,Columbia University | Passchier J.,Glaxosmithkline | Murthy N.V.,Glaxosmithkline | And 13 more authors.
Molecular Imaging and Biology | Year: 2011

Purpose: 11C-GSK931145 is a novel radioligand suitable for imaging the glycine transporter 1 (GlyT-1) in brain. In the present study, human dosimetry is estimated from baboon and human biodistribution data. Procedures: Three baboons and eight healthy human volunteers underwent whole-body positron emission tomography (PET) scans. Human dosimetry was estimated using three different region-of-interest (ROI) delineation methods that ranged in their complexity and execution time: ROIs drawn on anterior-posterior compressed PET images, on subsamples of the organs, and covering the whole-organ. Residence times for each organ were calculated as the area under the time-activity curves divided by the injected activity. Radiation dose estimates were calculated from organ residence times using the OLINDA/EXM software package. Results: The overall distribution of activity was similar in baboons and humans. Early scans presented high activity in the liver, and moderate activity in the lungs and kidneys. The principal route of clearance was intestinal and no urinary excretion was observed. The limiting organ with the highest radiation-absorbed dose was the liver. The mean effective dose in humans was 4.02 μSv/MBq (male phantom) and 4.95 μSv/MBq (female phantom) (ROIs drawn on subsamples of the organs). The human effective dose estimated from baboon data was ~15% larger than the effective dose estimated from human data. Conclusion: Human PET imaging of the glycine transporter-1 with 11C-GSK931145 results in a moderate effective human radiation dose, which allows for multiple PET examinations in the same individual. Among the three methods compared to delineate ROIs, the organ subsampling method shows the best balance between quantitative accuracy and practical application. © Academy of Molecular Imaging and Society for Molecular Imaging, 2010.

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