title: Comparison of the diagnostic value of FDG-PET/CT and axillary ultrasound for the detection of lymph node metastases in breast cancer patients.
abstract: BACKGROUND
  FDG-PET/CT is increasingly being used for breast cancer staging. Its diagnostic accuracy in comparison to ultrasound as the standard non-invasive imaging modality for the evaluation of axillary lymph nodes has yet not been evaluated.
  
  
  OBJECTIVE
  To retrospectively compare the diagnostic value of full-dose, intravenously contrast-enhanced FDG-PET/CT and ultrasound for the detection of lymph node metastases in breast cancer patients.
  
  
  METHODS
  Ninety patients (one patient with a bilateral carcinoma) (89 women, one man; mean age, 55.5 +/- 16.6 years) suffering from primary breast cancer underwent whole-body FDG-PET/CT and axillary ultrasound. The ipsilateral axillary fossa (n = 91) was evaluated for metastatic spread. The sensitivity, specificity, the positive predictive value (PPV), negative predictive value (NPV), and accuracy of both methods were calculated. The sensitivity and accuracy were statistically compared using the McNemar Test (P <0.05). Analyses were made on a patient basis. The number of patients with extra-axillary locoregional lymph node metastases exclusively detected by FDG-PET/CT was evaluated. For axillary lymph node metastases histopathology served as the reference standard.
  
  
  RESULTS
  The sensitivity, specificity, PPV, NPV, and accuracy of FDG-PET/CT for the detection of axillary lymph node metastases were 54%, 89%, 77%, 74%, and 75%, respectively. For ultrasound it was 38%, 78%, 54%, 65%, and 62%, respectively. FDG-PET/CT was significantly more accurate than ultrasound for the detection of axillary lymph node metastases (P = 0.019). There was no statistically significant difference between the sensitivity of both modalities (P = 0.0578). FDG-PET/CT detected extra-axillary locoregional lymph node metastases in seven patients (8%) that had not been detected by another imaging modality.
  
  
  CONCLUSIONS
  Though more accurate compared to ultrasound for evaluating the axillary lymph node status FDG-PET/CT is only as sensitive as ultrasound when it comes to the detection of axillary lymph node metastases. Due to the low sensitivity FDG-PET/CT cannot act as a substitute for Sentinel lymph node biopsy. FDG-PET/CT is able to detect previously unknown locoregional extra-axillary lymph node metastases.
authors.affiliation: Univ Dusseldorf, Medical Faculty, Department of Diagnostic and Interventional Radiology, Dusseldorf, Germany.
authors.forename: Carolin
authors.initials: C
authors.lastname: Riegger
authors.forename: Angela
authors.initials: A
authors.lastname: Koeninger
authors.forename: Verena
authors.initials: V
authors.lastname: Hartung
authors.forename: Friedrich
authors.initials: F
authors.lastname: Otterbach
authors.forename: Rainer
authors.initials: R
authors.lastname: Kimmig
authors.forename: Michael
authors.initials: M
authors.lastname: Forsting
authors.forename: Andreas
authors.initials: A
authors.lastname: Bockisch
authors.forename: Gerald
authors.initials: G
authors.lastname: Antoch
authors.forename: Till A
authors.initials: TA
authors.lastname: Heusner
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001365:Axilla; D001943:Breast Neoplasms / Q000473:pathology*; D018567:Breast Neoplasms, Male / Q000473:pathology; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008198:Lymph Nodes / Q000000981:diagnostic imaging*; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging / Q000379:methods*; D049268:Positron-Emission Tomography; D011237:Predictive Value of Tests; D019275:Radiopharmaceuticals; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed; D014463:Ultrasonography
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18