title: Lymph node to primary tumor SUV ratio by 18F-FDG PET/CT and the prediction of axillary lymph node metastases in breast cancer.
abstract: OBJECTIVE
  The authors evaluated the usefulness of axillary lymph node (ALN) to primary breast tumor SUV ratio (determined by 18F-FDG PET/CT) for predicting the presence of ALN metastasis in breast cancer.
  
  
  METHODS
  One hundred thirty-six consecutive female patients with breast cancer were enrolled in this retrospective study between January 2009 and November 2012. All patients underwent surgical resection without neoadjuvant chemotherapy, and ALN metastases were histologically confirmed by ALN dissection (n = 75) or sentinel lymph node (LN) biopsy (n = 61). The maximum SUVs of FDG-avid ALNs (SUVLN) and of primary breast tumors were measured on preoperative 18F-FDG PET/CT images, and ALN to primary breast tumor SUV ratios (LN/T ratios) were calculated. In a subgroup of patients with FDG-avid ALNs, optimal cutoff values for SUVLN and LN/T ratio were determined by receiver operating characteristic curve analysis for predicting the presence of ALN metastasis. Subsequently, the diagnostic performances of visual analysis (presence of FDG-avidity), SUVLN, and LN/T ratio for the prediction of ALN metastasis were determined.
  
  
  RESULTS
  In a subgroup of patients with FDG-avid ALNs (n = 65), the area under the curve and the optimal criteria of SUVLN for detecting ALN metastasis were 0.655 and greater than 2.1, and those of LN/T ratio were 0.739 and greater than 0.2, respectively. For these criteria, the sensitivity, specificity, and diagnostic accuracy of detecting ALN metastasis were 71.4%, 77.3%, and 74.3%, respectively, for visual analysis; 47.1%, 93.9%, and 69.9%, respectively, for SUVLN; and 62.9%, 92.4%, and 77.2%, respectively, for LN/T ratio in all patients. The specificity of LN/T ratio was significantly higher than that of visual analysis (P = 0.0259). Although the sensitivity of LN/T ratio was higher than that of SUVLN, it did not reach a statistical significance (P = 0.0874).
  
  
  CONCLUSIONS
  The LN/T ratio better predicts the presence of ALN metastasis than visual analysis or SUVLN in breast cancer.
authors.affiliation: From the Departments of *Nuclear Medicine, †Surgery, and ‡Pathology, Seoul Korea Cancer Center Hospital, Seoul, Republic of Korea.
authors.forename: Jihyun
authors.initials: J
authors.lastname: Park
authors.forename: Byung Hyun
authors.initials: BH
authors.lastname: Byun
authors.forename: Woo Chul
authors.initials: WC
authors.lastname: Noh
authors.forename: Seung Sook
authors.initials: SS
authors.lastname: Lee
authors.forename: Hyun-Ah
authors.initials: HA
authors.lastname: Kim
authors.forename: Eun-Kyu
authors.initials: EK
authors.lastname: Kim
authors.forename: Chang Woon
authors.initials: CW
authors.lastname: Choi
authors.forename: Sang Moo
authors.initials: SM
authors.lastname: Lim
mesh_terms: D001943:Breast Neoplasms / Q000175:diagnosis* / Q000378:metabolism / Q000473:pathology*; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000378:metabolism; D006801:Humans; D008198:Lymph Nodes / Q000000981:diagnostic imaging / Q000378:metabolism*; D008207:Lymphatic Metastasis; D008875:Middle Aged; D064847:Multimodal Imaging; D049268:Positron-Emission Tomography; D012372:ROC Curve; D014057:Tomography, X-Ray Computed
chemical_list: D019788:Fluorodeoxyglucose F18