title: Evaluation of lymph node status after neoadjuvant chemotherapy in breast cancer patients: comparison of diagnostic performance of ultrasound, MRI and ¹⁸F-FDG PET/CT.
abstract: OBJECTIVE
  To evaluate the diagnostic performance of ultrasound, MRI and fluorine-18 fludeoxyglucose positron emission tomography (¹⁸F-FDG PET)/CT for the diagnosis of metastatic axillary lymph node (ALN) after neoadjuvant chemotherapy (NAC) and to find out histopathological factors affecting the diagnostic performance of these imaging modalities.
  
  
  METHODS
  From January 2012 to November 2014, 191 consecutive patients with breast cancer who underwent NAC before surgery were retrospectively reviewed. We included 139 patients with ALN metastasis that was confirmed on fine needle aspiration or core needle biopsy at initial diagnosis.
  
  
  RESULTS
  After NAC, 39 (28%) patients showed negative conversion of ALN on surgical specimens of sentinel lymph node (LN) or ALN. The sensitivity of ultrasound, MRI and PET/CT was 50% (48/96), 72% (70/97) and 22% (16/73), respectively. The specificity of ultrasound, MRI and PET/CT was 77% (30/39), 54% (21/39) and 85% (22/26), respectively. The Az value of combination of ultrasound and PET/CT was the highest (0.634) followed by ultrasound (0.626) and combination of ultrasound, MRI and PET/CT (0.617). The size of tumour deposit in LN and oestrogen receptor was significantly associated with the diagnostic performance of ultrasound (p < 0.001 and p = 0.009, respectively) and MRI (p = 0.045 and p = 0.036, respectively). The percentage diameter decrease, size of tumour deposit in LN, progesterone receptor, HER2 and histological grade were significantly associated with the diagnostic performance of PET/CT (p = 0.023, p = 0.002, p = 0.036, p = 0.044 and p = 0.008, respectively). On multivariate logistic regression analysis, size of tumour deposit within LN was identified as being independently associated with diagnostic performance of ultrasound [odds ratio, 13.07; 95% confidence interval (CI), 2.95-57.96] and PET/CT (odds ratio, 6.47; 95% CI, 1.407-29.737).
  
  
  CONCLUSIONS
  Combination of three imaging modalities showed the highest sensitivity, and PET/CT showed the highest specificity for the evaluation of ALN metastasis after NAC. Ultrasound alone or combination of ultrasound and PET/CT showed the highest positive-predictive value. The size of tumour deposit within ALN was significantly associated with diagnostic performance of ultrasound and PET/CT.
  
  
  CONCLUSIONS
  This study is about the diagnostic performance of ultrasound, MRI, PET/CT and combination of each imaging modality for the evaluation of metastatic ALN after NAC. Of many histopathological factors, only the size of tumour deposit within ALN was an independent factor associated with the diagnostic performance of ultrasound and PET/CT.
authors.affiliation: Department of Radiology, Ajou University School of Medicine, Suwon, Republic of Korea.
authors.forename: S
authors.initials: S
authors.lastname: You
authors.affiliation: Department of Radiology, Ajou University School of Medicine, Suwon, Republic of Korea.
authors.forename: D K
authors.initials: DK
authors.lastname: Kang
authors.affiliation: Department of Radiology, Ajou University School of Medicine, Suwon, Republic of Korea.
authors.forename: Y S
authors.initials: YS
authors.lastname: Jung
authors.affiliation: Department of Radiology, Ajou University School of Medicine, Suwon, Republic of Korea.
authors.forename: Y-S
authors.initials: YS
authors.lastname: An
authors.affiliation: Department of Radiology, CHA Bundang Medical Center, CHA University, College of Medicine, Seongnam, Republic of Korea.
authors.forename: G S
authors.initials: GS
authors.lastname: Jeon
authors.affiliation: Department of Radiology, Ajou University School of Medicine, Suwon, Republic of Korea.
authors.forename: T H
authors.initials: TH
authors.lastname: Kim
mesh_terms: D001943:Breast Neoplasms / Q000188:drug therapy / Q000473:pathology*; D017024:Chemotherapy, Adjuvant; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008207:Lymphatic Metastasis; D008279:Magnetic Resonance Imaging / Q000592:standards; D008875:Middle Aged; D064847:Multimodal Imaging / Q000379:methods / Q000592:standards*; D049268:Positron-Emission Tomography / Q000592:standards; D012372:ROC Curve; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000592:standards; D016217:Ultrasonography, Mammary / Q000592:standards
chemical_list: D019788:Fluorodeoxyglucose F18