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The Combination of In vivo 124I-PET and CT Small Animal Imaging for Evaluation of Thyroid Physiology and Dosimetry
Cluster for Molecular Imaging, Faculty of Health Sciences, University of Copenhagen, Copenhagen DK-2200, Denmark
Department of Clinical Physiology, Nuclear Medicine & PET, Rigshospitalet, Blegdamsvej 9, Copenhagen 2100, Denmark
Medical Radiation Physics, Department of Clinical Sciences, University of Lund, Lund SE-221 85, Sweden
* Author to whom correspondence should be addressed.
Received: 27 April 2012; in revised form: 24 May 2012 / Accepted: 29 May 2012 / Published: 5 June 2012
Abstract: Objective: A thyroid rat model combining functional and anatomical information would be of great benefit for better modeling of thyroid physiology and for absorbed dose calculations. Our aim was to show that 124I-PET and CT small animal imaging are useful as a combined model for studying thyroid physiology and dose calculation. Methods: Seven rats were subjects for multiple thyroid 124I-imaging and CT-scans. S-values [mGy/MBqs] for different thyroid sizes were simulated. A phantom with spheres was designed for validation of performances of the small animal PET and CT imaging systems. Results: Small animal image-based measurements of the activity amount and the volumes of the spheres with a priori known volumes showed a good agreement with their corresponding actual volumes. The CT scans of the rats showed thyroid volumes from 34–70 mL. Conclusions: The wide span in volumes of thyroid glands indicates the importance of using an accurate volume-measuring technique such as the small animal CT. The small animal PET system was on the other hand able to accurately estimate the activity concentration in the thyroid volumes. We conclude that the combination of the PET and CT image information is essential for quantitative thyroid imaging and accurate thyroid absorbed dose calculation.
Keywords: thyroid rat model; rat S-values; 124I-thyroid imaging; molecular imaging; animal PET/CT co-registration; small animal dosimetry
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El-Ali, H.H.; Eckerwall, M.; Skovgaard, D.; Larsson, E.; Strand, S.-E.; Kjaer, A. The Combination of In vivo 124I-PET and CT Small Animal Imaging for Evaluation of Thyroid Physiology and Dosimetry. Diagnostics 2012, 2, 10-22.
El-Ali HH, Eckerwall M, Skovgaard D, Larsson E, Strand S-E, Kjaer A. The Combination of In vivo 124I-PET and CT Small Animal Imaging for Evaluation of Thyroid Physiology and Dosimetry. Diagnostics. 2012; 2(2):10-22.
El-Ali, Henrik H.; Eckerwall, Martin; Skovgaard, Dorthe; Larsson, Erik; Strand, Sven-Erik; Kjaer, Andreas. 2012. "The Combination of In vivo 124I-PET and CT Small Animal Imaging for Evaluation of Thyroid Physiology and Dosimetry." Diagnostics 2, no. 2: 10-22.