title: Usefulness of combined BI-RADS analysis and Nakagami statistics of ultrasound echoes in the diagnosis of breast lesions.
abstract: OBJECTIVE
  To develop a method combining the statistics of the ultrasound backscatter and the Breast Imaging-Reporting and Data System (BI-RADS) classification to enhance the differentiation of breast tumours.
  
  
  METHODS
  The Nakagami shape parameter m was used to characterise the scatter properties of breast tumours. Raw data from the radiofrequency (RF) echo-signal and B-mode images from 107 (32 malignant and 75 benign) lesions and their surrounding tissue were recorded. Three different characteristic values of the shape parameters of m (maximum [mLmax], minimum [mLmin] and average [mLavg]) and differences between m parameters (Δmmax, Δmmin, Δmavg) of the lesions and their surrounding tissues were assessed. A lesion with a BI-RADS score of 3 was considered benign, while a lesion with a score of 4 was considered malignant (a cut-off of BI-RADS 3/4 was set for all patients).
  
  
  RESULTS
  The area under the receiver operating characteristic (ROC) curve (AUC) was equal to 0.966 for BI-RADS, with 100% sensitivity and 54.67% specificity. All malignant lesions were diagnosed correctly, whereas 34 benign lesions were biopsied unnecessarily. In assessing the Nakagami statistics, the sum of the sensitivity and specificity was the best for mLavg (62.5% and 93.33%, respectively). Only four of 20 lesions were found over the cut-off value in BI-RADS of 4a. When comparing the differences in m parameters, Δmavg had the highest sensitivity of 90% (only three of 32 lesions were false negative). These three lesions were classified as BI-RADS category 4c. The combined use of B-mode and mLmin parameter improve the AUC up to 0.978 (p=0.088), compared to BI-RADS alone.
  
  
  CONCLUSIONS
  The combination of the parametric imaging and the BI-RADS assessment does not significantly improve the differentiation of breast lesions, but it has the potential to better identify the group of patients with mainly benign lesions that have a low level of suspicion for malignancy with a BI-RADS score of 4a.
authors.affiliation: Department of Radiology, Cancer Center and Institute of Oncology M. Sklodowska-Curie Memorial, Warsaw, Poland; Institute of Fundamental Technological Research, PAS, Warsaw, Poland. Electronic address: kdsobczak@gmail.com.
authors.forename: K
authors.initials: K
authors.lastname: Dobruch-Sobczak
authors.affiliation: Institute of Fundamental Technological Research, PAS, Warsaw, Poland.
authors.forename: H
authors.initials: H
authors.lastname: Piotrzkowska-Wróblewska
authors.affiliation: Department of Pathology, Cancer Center and Institute of Oncology M. Sklodowska-Curie Memorial, Warsaw, Poland.
authors.forename: K
authors.initials: K
authors.lastname: Roszkowska-Purska
authors.affiliation: Institute of Fundamental Technological Research, PAS, Warsaw, Poland.
authors.forename: A
authors.initials: A
authors.lastname: Nowicki
authors.affiliation: Department of Imaging Diagnostic, Medical University of Warsaw, Poland.
authors.forename: W
authors.initials: W
authors.lastname: Jakubowski
mesh_terms: D000328:Adult; D000368:Aged; D001940:Breast / Q000000981:diagnostic imaging; D001943:Breast Neoplasms / Q000000981:diagnostic imaging*; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008875:Middle Aged; D011446:Prospective Studies; D012372:ROC Curve; D011873:Radiology Information Systems / Q000706:statistics & numerical data*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D016217:Ultrasonography, Mammary / Q000379:methods* / Q000706:statistics & numerical data*; D055815:Young Adult