Breast imaging reporting and data system lexicon for US: interobserver agreement for assessment of breast masses.
OBJECTIVE
To retrospectively evaluate the interobserver agreement of radiologists who used the Breast Imaging Reporting and Data System (BI-RADS) lexicon to characterize and categorize ultrasonographic (US) features of breast masses.


METHODS
No institutional review board approval or patient consent was required. Five breast radiologists retrospectively independently evaluated 267 breast masses (113 benign and 154 malignant masses in 267 patients) by using the BI-RADS US lexicon. Reviewers were blinded to mammographic images, medical history, and pathologic findings. Interobserver agreement was assessed with the Aickin revised kappa statistic.


RESULTS
Interobserver agreement varied from fair for evaluation of mass margins (kappa = 0.36) to moderate for evaluation of lesion boundary (kappa = 0.48), echo pattern (kappa = 0.58), and posterior acoustic features (kappa = 0.47) to substantial for evaluation of mass orientation (kappa = 0.70) and shape (kappa = 0.64). For small (< or =0.7 cm; n = 49) or malignant (n = 154) masses, low concordance was noted for margin descriptors (kappa = 0.30 and 0.28, respectively) and BI-RADS category (kappa = 0.21 and 0.26, respectively). Overall, only fair agreement was obtained for BI-RADS category (kappa = 0.30). Agreement for subdivisions 4a, 4b, and 4c of BI-RADS category 4 was fair (kappa = 0.33), fair (kappa = 0.32), and poor (kappa = 0.17), respectively.


CONCLUSIONS
Reproducibility of US BI-RADS terminology is good except for margin evaluation. A trend toward lower concordance was noted for the evaluation of small masses and malignant lesions. Classification into subdivisions 4a, 4b, and 4c was poorly reproducible.
Abdullah
Nouf
N
Department of Radiology, Cedar Breast Clinic, McGill University Health Center, Royal Victoria Hospital, 687 Pine Ave W, Montreal, QC, Canada.
Mesurolle
Benoît
B
El-Khoury
Mona
M
Kao
Ellen
E
D001941:Breast Diseases / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D008327:Mammography / Q000706:statistics & numerical data*; D015588:Observer Variation; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D009626:Terminology as Topic; D016217:Ultrasonography, Mammary / Q000706:statistics & numerical data*