Substantial interobserver variation of thyroid volume and function by visual evaluation of thyroid (99m)Tc scintigraphy

Kerstin Soelberg, Peter Grupe, Henrik Boel-Jørgensen, Peter Jørgensen, Søren Fast, Viveque E Nielsen, Laszlo Hegedüs, Steen J Bonnema

Research output: Contribution to journalJournal articleResearchpeer-review


Introduction: 99mTc-pertechnetate scintigraphy is much used in the evaluation of patients with nodular goitre. We investigated the ability of experienced observers to estimate the thyroid 24-h 131I uptake (RAIU) and the thyroid volume by visual evaluation of the scintigram. Material and methods: Two endocrinologists and two nuclear medicine specialists visually evaluated thyroid scintigrams from 171 patients with nodular goitre. The variables were assessed in a blinded fashion according to predefined categories and then compared with the true values. The assessments were repeated after four weeks. Kappa (κ ω) statistics were used. Results: There was a low probability (range 6-22%) for the observers to assess the thyroid RAIU correctly. The probability of assessing the thyroid volume correctly was in the 14-22% range. Endocrinologists tended to underestimate the thyroid RAIU, mostly in patients with a RAIU > 30%. All observers significantly underestimated the thyroid volume if this was > 80 ml. There was a low interobserver agreement for the thyroid RAIU assessment (κ ω-values: 0.03- 0.43) as well as for the thyroid volume assessment (κ ω- values: 0.19-0.48). The corresponding κ ω-values for the intraobserver agreement were 0.34-0.68 and 0.37-0.62, respectively. Nuclear medicine specialists achieved a significantly higher agreement than endocrinologists in their evaluation of both thyroid parameters. Conclusion: Thyroid 99mTc scintigraphy has poor interobserver agreement and is inaccurate for assessment of quantitative thyroid parameters, even when performed by experienced specialists.

Original languageEnglish
Article numberA4768
JournalDanish Medical Journal
Issue number2
Number of pages5
Publication statusPublished - Feb 2014


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