title: Real-time ultrasound elastography in 180 axillary lymph nodes: elasticity distribution in healthy lymph nodes and prediction of breast cancer metastases.
abstract: BACKGROUND
  To determine the general appearance of normal axillary lymph nodes (LNs) in real-time tissue sonoelastography and to explore the method's potential value in the prediction of LN metastases.
  
  
  METHODS
  Axillary LNs in healthy probands (n=165) and metastatic LNs in breast cancer patients (n=15) were examined with palpation, B-mode ultrasound, Doppler and sonoelastography (assessment of the elasticity of the cortex and the medulla). The elasticity distributions were compared and sensitivity (SE) and specificity (SP) were calculated. In an exploratory analysis, positive and negative predictive values (PPV, NPV) were calculated based upon the estimated prevalence of LN metastases in different risk groups.
  
  
  RESULTS
  In the elastogram, the LN cortex was significantly harder than the medulla in both healthy (p=0.004) and metastatic LNs (p=0.005). Comparing healthy and metastatic LNs, there was no difference in the elasticity distribution of the medulla (p=0.281), but we found a significantly harder cortex in metastatic LNs (p=0.006). The SE of clinical examination, B-mode ultrasound, Doppler ultrasound and sonoelastography was revealed to be 13.3%, 40.0%, 14.3% and 60.0%, respectively, and SP was 88.4%, 96.8%, 95.6% and 79.6%, respectively. The highest SE was achieved by the disjunctive combination of B-mode and elastographic features (cortex >3mm in B-mode or blue cortex in the elastogram, SE=73.3%). The highest SP was achieved by the conjunctive combination of B-mode ultrasound and elastography (cortex >3mm in B-mode and blue cortex in the elastogram, SP=99.3%).
  
  
  CONCLUSIONS
  Sonoelastography is a feasible method to visualize the elasticity distribution of LNs. Moreover, sonoelastography is capable of detecting elasticity differences between the cortex and medulla, and between metastatic and healthy LNs. Therefore, sonoelastography yields additional information about axillary LN status and can improve the PPV, although this method is still experimental.
authors.affiliation: Hannover Medical School, Department for Obstetrics and Gynecology, OE 6410, Carl-Neuberg-Straße 1, Hannover 30625, Germany. s@wojcinski.de
authors.forename: Sebastian
authors.initials: S
authors.lastname: Wojcinski
authors.forename: Jennifer
authors.initials: J
authors.lastname: Dupont
authors.forename: Werner
authors.initials: W
authors.lastname: Schmidt
authors.forename: Michael
authors.initials: M
authors.lastname: Cassel
authors.forename: Peter
authors.initials: P
authors.lastname: Hillemanns
mesh_terms: D001365:Axilla; D001943:Breast Neoplasms / Q000000981:diagnostic imaging* / Q000503:physiopathology / Q000556:secondary*; D003199:Computer Systems; D055119:Elastic Modulus; D054459:Elasticity Imaging Techniques / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008198:Lymph Nodes / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D008207:Lymphatic Metastasis; D008875:Middle Aged; D012016:Reference Values; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D016217:Ultrasonography, Mammary / Q000706:statistics & numerical data*