Substantial interobserver variation of thyroid volume and function by visual evaluation of thyroid (99m)Tc scintigraphy.
BACKGROUND
(99m)Tc-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 (131)I uptake (RAIU) and the thyroid volume by visual evaluation of the scintigram.


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.


CONCLUSIONS
Thyroid (99m)Tc scintigraphy has poor interobserver agreement and is inaccurate for assessment of quantitative thyroid parameters, even when performed by experienced specialists.


BACKGROUND
This study was supported by grants from the Danish Agency for Science, Technology and Innovation.


BACKGROUND
not relevant.
Endokrinologisk Afdeling M, Odense Universitetshospital, Søndre Boulevard 29, 5000 Odense C, Denmark. steen.bonnema@dadlnet.dk.
Kerstin K
KK
Soelberg
Peter
P
Grupe
Henrik
H
Boel-Jørgensen
Peter H
PH
Jørgensen
Søren
S
Fast
Viveque E
VE
Nielsen
Laszlo
L
Hegedüs
Steen J
SJ
Bonnema
D006801:Humans; D015588:Observer Variation; D009929:Organ Size; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals; D016037:Single-Blind Method; D013670:Sodium Pertechnetate Tc 99m; D013961:Thyroid Gland / Q000000981:diagnostic imaging* / Q000473:pathology / Q000503:physiopathology
D019275:Radiopharmaceuticals; D013670:Sodium Pertechnetate Tc 99m