UNLABELLED: Although iodinated radiopharmaceuticals usually contain a small quantity of unbound iodine, it is difficult to establish the degree to which thyroid activity on scintigraphic images reflects uptake of free radioiodine. The objective of the present study was to examine the effectiveness of thyroid blockade in subjects undergoing (123)I-meta-iodobenzylguanidine (mIBG) imaging and to estimate the relative contribution of bound and unbound radioiodine to imaging findings. METHODS: All subjects were participants in prospective trials of (123)I-mIBG cardiac imaging in which pretreatment with thyroid blockade was optional unless locally required. In a pilot project, 15 subjects (6 blocked) had thyroid uptake measured at 4 h using a probe system. Fifteen-minute (early) and 4-h (late) anterior planar chest images that included the thyroid region were visually scored for thyroid uptake (scale of 0-4) in another group of 152 subjects (98 blocked). Quantitative analysis based on thyroid regions of interest was performed on anterior planar images from a further sample of 669 subjects (442 blocked). For all 3 investigations, quantitative comparisons of thyroid uptake were made between the blocked and nonblocked subjects. RESULTS: There was no statistical difference between probe uptake of the 6 blocked and 9 nonblocked subjects. However, in the second series, mean visual score on the late images was significantly lower for blocked than nonblocked subjects (P < 0.001). In the region-of-interest analyses, net thyroid counts were significantly higher on the late images of nonblocked subjects (P < 0.0001), and compared with early images, 87% of subjects who received blockade showed decreased or unchanged counts whereas 75% of nonblocked subjects had increased net thyroid activity. In nonblocked subjects, an estimated 79% of thyroid counts on late images could be attributed to unbound (123)I. CONCLUSION: On the basis of 3 different methods for assessing thyroid uptake of (123)I, use of thyroid blockade pretreatment in (123)I-mIBG imaging prevents increase of thyroid activity over time because of uptake of unbound (123)I. In most subjects, there is a low level of (123)I-mIBG thyroid activity that probably represents specific uptake in sympathetic nerve terminals.
UNLABELLED: Although iodinated radiopharmaceuticals usually contain a small quantity of unbound iodine, it is difficult to establish the degree to which thyroid activity on scintigraphic images reflects uptake of free radioiodine. The objective of the present study was to examine the effectiveness of thyroid blockade in subjects undergoing (123)I-meta-iodobenzylguanidine (mIBG) imaging and to estimate the relative contribution of bound and unbound radioiodine to imaging findings. METHODS: All subjects were participants in prospective trials of (123)I-mIBG cardiac imaging in which pretreatment with thyroid blockade was optional unless locally required. In a pilot project, 15 subjects (6 blocked) had thyroid uptake measured at 4 h using a probe system. Fifteen-minute (early) and 4-h (late) anterior planar chest images that included the thyroid region were visually scored for thyroid uptake (scale of 0-4) in another group of 152 subjects (98 blocked). Quantitative analysis based on thyroid regions of interest was performed on anterior planar images from a further sample of 669 subjects (442 blocked). For all 3 investigations, quantitative comparisons of thyroid uptake were made between the blocked and nonblocked subjects. RESULTS: There was no statistical difference between probe uptake of the 6 blocked and 9 nonblocked subjects. However, in the second series, mean visual score on the late images was significantly lower for blocked than nonblocked subjects (P < 0.001). In the region-of-interest analyses, net thyroid counts were significantly higher on the late images of nonblocked subjects (P < 0.0001), and compared with early images, 87% of subjects who received blockade showed decreased or unchanged counts whereas 75% of nonblocked subjects had increased net thyroid activity. In nonblocked subjects, an estimated 79% of thyroid counts on late images could be attributed to unbound (123)I. CONCLUSION: On the basis of 3 different methods for assessing thyroid uptake of (123)I, use of thyroid blockade pretreatment in (123)I-mIBG imaging prevents increase of thyroid activity over time because of uptake of unbound (123)I. In most subjects, there is a low level of (123)I-mIBG thyroid activity that probably represents specific uptake in sympathetic nerve terminals.
Authors: Ian R Marsh; Joseph Grudzinski; Dana C Baiu; Abigail Besemer; Reinier Hernandez; Justin J Jeffery; Jamey P Weichert; Mario Otto; Bryan P Bednarz Journal: J Nucl Med Date: 2019-03-29 Impact factor: 10.057
Authors: Milena J Henzlova; W Lane Duvall; Andrew J Einstein; Mark I Travin; Hein J Verberne Journal: J Nucl Cardiol Date: 2016-06 Impact factor: 5.952
Authors: David Taïeb; Rodney J Hicks; Elif Hindié; Benjamin A Guillet; Anca Avram; Pietro Ghedini; Henri J Timmers; Aaron T Scott; Saeed Elojeimy; Domenico Rubello; Irène J Virgolini; Stefano Fanti; Sona Balogova; Neeta Pandit-Taskar; Karel Pacak Journal: Eur J Nucl Med Mol Imaging Date: 2019-06-29 Impact factor: 9.236
Authors: Sarah C Clement; Godelieve A M Tytgat; A S Paul van Trotsenburg; Leontien C M Kremer; Hanneke M van Santen Journal: Ann Nucl Med Date: 2022-05-02 Impact factor: 2.258
Authors: Alexander Bolaender; Danuta Zatorska; Huazhong He; Suhasini Joshi; Sahil Sharma; Chander S Digwal; Hardik J Patel; Weilin Sun; Brandon S Imber; Stefan O Ochiana; Maulik R Patel; Liza Shrestha; Smit K Shah; Shuo Wang; Rashad Karimov; Hui Tao; Pallav D Patel; Ananda Rodilla Martin; Pengrong Yan; Palak Panchal; Justina Almodovar; Adriana Corben; Andreas Rimner; Stephen D Ginsberg; Serge Lyashchenko; Eva Burnazi; Anson Ku; Teja Kalidindi; Sang Gyu Lee; Milan Grkovski; Bradley J Beattie; Pat Zanzonico; Jason S Lewis; Steve Larson; Anna Rodina; Nagavarakishore Pillarsetty; Viviane Tabar; Mark P Dunphy; Tony Taldone; Fumiko Shimizu; Gabriela Chiosis Journal: Nat Commun Date: 2021-08-03 Impact factor: 14.919