Falk Gühne1, Christian Kühnel1, Martin Freesmeyer2. 1. Clinic of Nuclear Medicine, Jena University Hospital, Jena, Germany. 2. Clinic of Nuclear Medicine, Jena University Hospital, Jena, Germany. martin.freesmeyer@med.uni-jena.de.
Abstract
PURPOSE: 124I-PET/CT can be used for pre-therapeutic assessment of radioactive iodine uptake in benign thyroid disorders, however systematic comparisons with intra-therapeutic uptake are still lacking for these disorders. The goals of this study were to compare 124I RAIU and conventional 131I RAIU tests with each other; to compare both tests with intra-therapeutic uptake (reference); and to verify the time course of radioactive iodine uptake at three time points (30, 102, and 336 h [14 days] post administration; p.a.). METHODS: Thirteen patients with benign thyroid diseases underwent 131I RAIU test and 124I RAIU test one after another before the intra-therapeutic 131I uptake (reference) was measured via short-range and long-range measurements. After correction for decay, relative uptake differences were calculated and subjected to the Bland-Altman method for the evaluation of levels of agreement. RESULTS: Radioactive iodine uptake tests with 124I-PET/CT and 131I probe did not show systematic deviations at any time point. Likewise, at 30 and 102 h p.a. there was no systematic discrepancy between pre-therapeutic and intra-therapeutic uptake levels. At 14 days p.a., however, both pre-therapeutic tests tended to overestimate the uptake compared to reference. Findings showed, for the first time with 124I, that radioiodine therapy has some early radiobiological effects possibly limiting the accuracy of pre-therapeutic dosimetry. CONCLUSIONS: 124I RAIU tests represent a feasible alternative to standard 131I RAIU tests. The additional benefits of 124I-PET/CT (e.g., functional topography, inclusion of retrosternal areas, possibility to enable fusion imaging) may thus increase the scope of this technology in benign thyroid disorders.
PURPOSE: 124I-PET/CT can be used for pre-therapeutic assessment of radioactive iodine uptake in benign thyroid disorders, however systematic comparisons with intra-therapeutic uptake are still lacking for these disorders. The goals of this study were to compare 124I RAIU and conventional 131I RAIU tests with each other; to compare both tests with intra-therapeutic uptake (reference); and to verify the time course of radioactive iodine uptake at three time points (30, 102, and 336 h [14 days] post administration; p.a.). METHODS: Thirteen patients with benign thyroid diseases underwent 131I RAIU test and 124I RAIU test one after another before the intra-therapeutic 131I uptake (reference) was measured via short-range and long-range measurements. After correction for decay, relative uptake differences were calculated and subjected to the Bland-Altman method for the evaluation of levels of agreement. RESULTS:Radioactive iodine uptake tests with 124I-PET/CT and 131I probe did not show systematic deviations at any time point. Likewise, at 30 and 102 h p.a. there was no systematic discrepancy between pre-therapeutic and intra-therapeutic uptake levels. At 14 days p.a., however, both pre-therapeutic tests tended to overestimate the uptake compared to reference. Findings showed, for the first time with 124I, that radioiodine therapy has some early radiobiological effects possibly limiting the accuracy of pre-therapeutic dosimetry. CONCLUSIONS: 124I RAIU tests represent a feasible alternative to standard 131I RAIU tests. The additional benefits of 124I-PET/CT (e.g., functional topography, inclusion of retrosternal areas, possibility to enable fusion imaging) may thus increase the scope of this technology in benign thyroid disorders.
Authors: Lutz S Freudenberg; Walter Jentzen; Alexander Stahl; Andreas Bockisch; Sandra J Rosenbaum-Krumme Journal: Eur J Nucl Med Mol Imaging Date: 2011-04-12 Impact factor: 9.236