Thyroid volume measured by ultrasonography and CT.
OBJECTIVE
To evaluate measurements of thyroid volume by two different US methods and CT in a blinded design.


METHODS
Four observers evaluated 27 patients. Observer 1 used US and calculated thyroid volume based on recordings of cross-sections through the gland. Observer 2 used US and calculated the volume of each lobe as a rotation ellipsoid. Observers A and B used CT images and calculated thyroid volume based on recordings of cross-sections through the gland. All measurements were made twice.


RESULTS
The median thyroid volume was 81 ml (range 7-470 ml) evaluated by CT. All three methods had fair reproducibility. When correlating the two different methods using US, an r of 0.837 was found. When correlating data from patients without intrathoracic goitre evaluated by US (Observer 1) and CT, r = 0.945. The method based on a rotation ellipsoid systematically produced smaller thyroid volumes than those of the cross-sectional method. Evaluation by US systematically produced smaller thyroid volumes than CT.


CONCLUSIONS
Calculation of thyroid volume based on US recordings of cross-sectional areas is a reproducible method in patients without substernal goitre extension. The US method calculating thyroid volume as a rotation ellipsoid is less reproducible, especially in large goitres. Measurement of thyroid volume using CT should be preferred in goitres with substernal extension.
Nygaard
B
B
Department of Endocrinology, Herlev Hospital, University of Copenhagen, Denmark.
Nygaard
T
T
Court-Payen
M
M
Jensen
L Ingeman
LI
Søe-Jensen
P
P
Gerhard Nielsen
K
K
Fugl
M
M
Hegedüs
L
L
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006042:Goiter / Q000175:diagnosis; D006801:Humans; D008297:Male; D008875:Middle Aged; D011859:Radiography; D015203:Reproducibility of Results; D012399:Rotation; D013961:Thyroid Gland / Q000000981:diagnostic imaging*; D014463:Ultrasonography