Related Experiment Video
Updated: Jun 7, 2025
A Whole Body Dosimetry Protocol for Peptide-Receptor Radionuclide Therapy PRRT: 2D Planar Image and Hybrid 2D+3D SPECT/CT Image Methods
Published on: April 24, 2020
Effect of Methimazole Withdrawl Period on the I-131 Uptake Estimation Using Tc-99 m Thyroid Scanning in Graves'
Hui Wang1, Weijian Li1, Pengpeng Chang1
1Department of Nuclear Medicine, Tianjin Medical University General Hospital, Tianjin 300052, China.
Purpose:
The effect of methimazole withdrawal period (MWP) on the estimation of 24-hour-radioiodine thyroid uptake (131IU24h) from 99mTc-pertechnetate thyroid uptake (99mTcTU) remains unclear for patients with Graves' disease (GD). This study aims to investigate the feasibility and reliability of 99mTcTU-based 131IU24h estimation with different MWPs.
Methods:
We enrolled 116 GD patients scheduled for 131I therapy at our hospital between April 2022 and April 2023. Based on MWP, the patients were categorized as standard (no methimazole or MWP > 1 month), MWP1 (MWP ≤ 1 week), MWP2 (MWP > 1 week to ≤2 weeks), and MWP3 (MWP > 2 weeks to <1 month). Fisher's exact test, one-way ANOVA, or Kruskal-Wallis test were used to compare variables. Fitted curves of 99mTcTU20min vs 131IU24h were plotted for the standard group. Linear relationships and Bland-Altman plots were used to illustrate the relationship and consistency between estimated and measured 131IU24h.
Results:
131IU24h was higher in the MWP1 group compared to MWP2 (70.22 ± 7.95% vs 61.92 ± 9.84%, P = .001), and thyroid mass was greater in the MWP1 group (36.15 ± 22.38 g) vs MWP3 (21.25 ± 11.90 g, P = .005). The relationship between 131IU24h and 99mTcTU20min in the standard group is described by the following algorithm: estimated 131IU24h = 11.3ln (99mTcTU20min) + 39.4 (R2 = 0.62). Based on it, the correlation between estimated and measured 131IU24h was weak in MWP1 and MWP2 (both P > .05) but strong in MWP3 (r = 0.66, P = .002). Additionally, the agreement between estimated and measured 131IU24h was highest in the MWP3 group (95% confidence interval, -15.86 to 15.52%) compared to the MWP1and MWP2 groups.
Conclusion:
Estimated 131IU24h based on 99mTcTU is not suitable for GD patients with MWP less than 2 weeks at our institution, necessitating further prospective multicenter studies for validation.
Related Concept Videos
01:25Imaging Studies II: Positron Emission Tomography and Scintigraphy
Fundamental Principles of PET
01:20Synthesis and Regulation of Thyroid Hormones
Upon reaching the thyroid gland, TSH stimulates the follicular cells' active uptake of iodide ions from the blood. The ions diffuse to the apical surface of the cells and are oxidized to iodine. The...
01:30Radiological Investigation I: X-ray and CT
01:14Imaging Studies I: CT and MRI
Description of the Procedures
Computed Tomography (CT) scan:
Computed Tomography (CT) scans use X-ray technology to generate detailed images of bones, organs, and tissues. During the scan, the patient lies on a moving table...
01:26Imaging Studies III: Gastrointestinal Motility Studies and Virtual Colonoscopy
Radionuclide Testing
Radionuclide testing is a sophisticated medical technique for assessing gastrointestinal motility. It focuses on gastric emptying and colonic transit time. Radioactive markers track the movement of food through the digestive system, providing insights into gastrointestinal disorders.
In gastric emptying studies, a meal's liquid and...
01:13Radiological Investigation III: Pulmonary Angiogram and PET Scan
Pulmonary Angiogram
A Pulmonary Angiogram is an invasive procedure involving injecting a contrast medium through a catheter threaded into the pulmonary artery or the right side of the heart to visualize the pulmonary vasculature. Computed Tomography (CT) scans have mainly replaced this...