Development of an animal in vivo 124-I-MicroPET/MicroCAT imaging model of the thyroid
(2007)Medical Physics Programme
- Abstract (Swedish)
- Introduction: To our knowledge a biomedical model for validation of combined MicroPET/MicroCAT studies of the thyroid with 124I has not yet been developed. Such an in vivo physiological rat model could be of great interest for enhancing the possibilities of studying common thyroid diseases realistically and repeatedly. Furthermore, a well developed, realistic, and flexible model can also be of great importance for studies of pre 131I-therapy dose calculations. Materials and Methods: Seven adult, healthy Wistar rats (354 – 533.4 g) were used for thyroid imaging performed with the MicroCAT II scanner (Siemens Medical Solutions USA, Inc.) and the MicroPET scanner (Focus 120, Siemens Medical Solutions USA, Inc.). The rats were anesthetized... (More)
- Introduction: To our knowledge a biomedical model for validation of combined MicroPET/MicroCAT studies of the thyroid with 124I has not yet been developed. Such an in vivo physiological rat model could be of great interest for enhancing the possibilities of studying common thyroid diseases realistically and repeatedly. Furthermore, a well developed, realistic, and flexible model can also be of great importance for studies of pre 131I-therapy dose calculations. Materials and Methods: Seven adult, healthy Wistar rats (354 – 533.4 g) were used for thyroid imaging performed with the MicroCAT II scanner (Siemens Medical Solutions USA, Inc.) and the MicroPET scanner (Focus 120, Siemens Medical Solutions USA, Inc.). The rats were anesthetized with Hypnorm/Dormicum and divided into four groups, each group receiving injections of ~20 MBq, ~10 MBq, ~5 MBq and ~0.7 MBq of 124I-NaCl solution. The rats were scanned in the MicroPET for 40 minutes at approximately 0, 3, 24, 48 and 72 hours post injection. The acquired MicroPET images were analyzed using the ASIPro toolbox (Siemens Medical Solutions USA, Inc.). A 6.5-minute MicroCAT scan was acquired directly after the last MicroPET scan, using a volume of 4-5 ml of a contrast agent (Ultravist® 300 mg I/ml) continuously injected in the lateral tail vein during the entire scan time. The Amira 4.1 analysis program (Mercury Computer Systems) was used for image evaluations. For control of the system performance, a phantom mimicking the thyroid was designed and scanned with the same protocols as for the rats. Results and Conclusion: Volumetric measurements based on the MicroCAT images showed a difference in thyroid volume ranging from 34.3 – 70.6 l in the seven rats. The wide span in thyroid volume between the individual rats demonstrates the importance of a good volume measuring technique. Corresponding measurements based on MicroPET images proved that MicroPET images alone cannot be used for correct volume determination of the thyroid due to the limitation in the resolution. These results indicate that a combination between MicroCAT and 124I-MicroPET is necessary for an accurate thyroid imaging. Measurements of the distribution of 124I in the thyroid showed a maximum uptake of 4.0 – 6.2% of administrated activity at 24 h post infusion. Furthermore the study shows that this physiological model could be applied for absorbed dose measurements, resulting in absorbed doses to the rats’ thyroids ranging from 5.2 – 225.7 Gy. These are the maximum absorbed dose to the thyroid, but because of technical problems the minimum absorbed dose could not be calculated. The model could however be suitable for further in vivo studies of the thyroid e.g. pre 131I-therapy absorbed dose calculations. (Less)
Please use this url to cite or link to this publication:
http://lup.lub.lu.se/student-papers/record/2157019
- author
- Emanuelsson, Martin
- supervisor
- organization
- year
- 2007
- type
- H2 - Master's Degree (Two Years)
- subject
- keywords
- Nukleärmedicin
- language
- English
- id
- 2157019
- date added to LUP
- 2011-09-13 15:12:08
- date last changed
- 2011-09-13 15:12:08
@misc{2157019,
abstract = {{Introduction: To our knowledge a biomedical model for validation of combined MicroPET/MicroCAT studies of the thyroid with 124I has not yet been developed. Such an in vivo physiological rat model could be of great interest for enhancing the possibilities of studying common thyroid diseases realistically and repeatedly. Furthermore, a well developed, realistic, and flexible model can also be of great importance for studies of pre 131I-therapy dose calculations. Materials and Methods: Seven adult, healthy Wistar rats (354 – 533.4 g) were used for thyroid imaging performed with the MicroCAT II scanner (Siemens Medical Solutions USA, Inc.) and the MicroPET scanner (Focus 120, Siemens Medical Solutions USA, Inc.). The rats were anesthetized with Hypnorm/Dormicum and divided into four groups, each group receiving injections of ~20 MBq, ~10 MBq, ~5 MBq and ~0.7 MBq of 124I-NaCl solution. The rats were scanned in the MicroPET for 40 minutes at approximately 0, 3, 24, 48 and 72 hours post injection. The acquired MicroPET images were analyzed using the ASIPro toolbox (Siemens Medical Solutions USA, Inc.). A 6.5-minute MicroCAT scan was acquired directly after the last MicroPET scan, using a volume of 4-5 ml of a contrast agent (Ultravist® 300 mg I/ml) continuously injected in the lateral tail vein during the entire scan time. The Amira 4.1 analysis program (Mercury Computer Systems) was used for image evaluations. For control of the system performance, a phantom mimicking the thyroid was designed and scanned with the same protocols as for the rats. Results and Conclusion: Volumetric measurements based on the MicroCAT images showed a difference in thyroid volume ranging from 34.3 – 70.6 l in the seven rats. The wide span in thyroid volume between the individual rats demonstrates the importance of a good volume measuring technique. Corresponding measurements based on MicroPET images proved that MicroPET images alone cannot be used for correct volume determination of the thyroid due to the limitation in the resolution. These results indicate that a combination between MicroCAT and 124I-MicroPET is necessary for an accurate thyroid imaging. Measurements of the distribution of 124I in the thyroid showed a maximum uptake of 4.0 – 6.2% of administrated activity at 24 h post infusion. Furthermore the study shows that this physiological model could be applied for absorbed dose measurements, resulting in absorbed doses to the rats’ thyroids ranging from 5.2 – 225.7 Gy. These are the maximum absorbed dose to the thyroid, but because of technical problems the minimum absorbed dose could not be calculated. The model could however be suitable for further in vivo studies of the thyroid e.g. pre 131I-therapy absorbed dose calculations.}},
author = {{Emanuelsson, Martin}},
language = {{eng}},
note = {{Student Paper}},
title = {{Development of an animal in vivo 124-I-MicroPET/MicroCAT imaging model of the thyroid}},
year = {{2007}},
}