Comparison between ultrasonography and computed tomography for detecting the pyramidal lobe of the thyroid gland: a prospective multicenter study.
OBJECTIVE
To compare the detection rates of the pyramidal lobe of the thyroid gland (TPL) using ultrasonography (US) and computed tomography (CT) in a prospective multi-center study.


METHODS
We enrolled 582 patients who underwent neck CT at six institutions. Each radiologist prospectively evaluated the presence and features of TPLs on thyroid US. Radiologists were divided into two groups according to their previous experience in detecting TPL on US or CT. The same radiologist also retrospectively assessed CT findings, blinded to the corresponding US findings.


RESULTS
The pyramidal lobe of the thyroid glands were detected in 230 cases (39.5%) on US and in 276 cases (47.6%) on CT. The TPL detection rate at the six institutions ranged from 22.0% to 59% for US and from 34.1% to 59% using CT. There were significant differences between US and CT in the detection rate, length, anteroposterior diameter, volume, and superior extent of TPL (p ≤ 0.027). The TPL detection rates on both US and CT (p < 0.001) differed significantly according to the experience level of the radiologists. When the CT result was used as a reference standard, the sensitivity, specificity, positive and negative predictive values, as well as the accuracy of US for TPL detection were 72.6%, 91.5%, 89.3%, 77.3%, and 82.1%, respectively.


CONCLUSIONS
Our prospective multicenter study revealed that US could detect TPL with relatively high diagnostic accuracy compared to CT. Because the detection rate of TPL varied significantly according to the radiologists' level of experience, careful inspection is necessary to avoid imaging pitfalls and ensure appropriate evaluation of TPL on both US and CT.
Department of Radiology, Busan Paik Hospital, Inje University College of Medicine, Busan 614-735, Korea.
Dong Wook
DW
Kim
Department of Radiology, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul 137-701, Korea.
So Lyung
SL
Jung
Department of Radiology, Severance Hospital, Yonsei University College of Medicine, Seoul 120-752, Korea.
Jinna
J
Kim
Department of Radiology, Haeundae Paik Hospital, Inje University College of Medicine, Busan 612-896, Korea.
Ji Hwa
JH
Ryu
Department of Radiology, Thyroid Center, Daerim St. Mary's Hospital, Seoul 150-822, Korea.
Jin Yong
JY
Sung
Department of Radiology, Soonchunhyang University Seoul Hospital, Soonchunhyang University College of Medicine, Seoul 140-743, Korea.
Hyun Kyung
HK
Lim
D000328:Adult; D000368:Aged; D003952:Diagnostic Imaging; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009333:Neck / Q000000981:diagnostic imaging*; D011446:Prospective Studies; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D013961:Thyroid Gland / Q000000981:diagnostic imaging* / Q000473:pathology; D014057:Tomography, X-Ray Computed / Q000379:methods*; D014463:Ultrasonography; D055815:Young Adult
Anatomy; Computed tomography; Pyramidal lobe; Thyroid; Ultrasonography; Variation