title: Significance of the ADC ratio in the differential diagnosis of breast lesions.
abstract: BACKGROUND
  Magnetic resonance imaging (MRI) has high sensitivity but low specificity for breast cancer, and consequently, new techniques to improve the specificity of breast MRI in diagnosing breast cancer are under development.
  
  
  OBJECTIVE
  To assess the ability of the apparent diffusion coefficient (ADC) compared with the ADC ratio (ADCr) to differentially diagnose benign compared with malignant breast lesions.
  
  
  METHODS
  Forty-eight women with breast lesions (average age, 45 years) underwent MRI scanning including T1-weighted dynamic contrast-enhanced (DCE) scanning and diffusion-weighted imaging (DWI). The average ADC and ADCr values for both lesions and pectoralis major muscles (ADCrmuscle and ADCrmuscle) were measured in patients with malignant (n = 25) and benign (n = 23) breast lesions. The ADCr of the contralateral breast (ADCr contralateral) was also evaluated. All histology was confirmed by pathological analysis of biopsied tissue. ADC and ADCr values were analyzed using receiver-operating characteristic (ROC) curves.
  
  
  RESULTS
  For benign lesions compared with malignant lesions, lesion-side ADC was 1.45 vs. 1.05, respectively (P < 0.001), normal-side ADC was 1.82 vs.1.64 (P = 0.002), ADCrmuscle was 1.35 vs. 0.9 (P < 0.001), and ADCrcontralateral was 0.79 vs. 0.64 (P = 0.001). ADCrmuscle showed higher sensitivity (82.61%) and specificity (96.00%) than ADCrcontralateral (60.87% and 92.00%, respectively) and ADC (69.57% and 96.00%) for discriminating malignant from benign lesions. The AUC using ADCrmuscle had higher discriminatory power (0.92, P < 0.001) for malignant versus benign breast lesions compared with either ADC (0.82, P < 0.001) or ADCrcontralateral (0.78, P = 0.001).
  
  
  CONCLUSIONS
  The ADCrmuscle value showed higher sensitivity and specificity and improved diagnostic accuracy compared with either ADC or ADCrcontralateral in differentiating benign from malignant breast lesions.
authors.affiliation: Department of Radiology, Affiliated Hospital of Nantong University, Nantong, Jiangsu Province, PR China.
authors.forename: Jinli
authors.initials: J
authors.lastname: Zhao
authors.affiliation: Department of Ultrasound, The Third People's Hospital of Nantong, Nantong, Jiangsu Province, PR China.
authors.forename: Haitao
authors.initials: H
authors.lastname: Guan
authors.affiliation: Department of Radiology, Affiliated Hospital of Nantong University, Nantong, Jiangsu Province, PR China.
authors.forename: Minda
authors.initials: M
authors.lastname: Li
authors.affiliation: Department of Radiology, Affiliated Hospital of Nantong University, Nantong, Jiangsu Province, PR China.
authors.forename: Hongmei
authors.initials: H
authors.lastname: Gu
authors.affiliation: Department of Radiology, Affiliated Hospital of Nantong University, Nantong, Jiangsu Province, PR China.
authors.forename: Jufeng
authors.initials: J
authors.lastname: Qin
authors.affiliation: Department of Radiology, Affiliated Hospital of Nantong University, Nantong, Jiangsu Province, PR China wxh637295@sina.com.
authors.forename: Xianhua
authors.initials: X
authors.lastname: Wu
mesh_terms: D000328:Adult; D000368:Aged; D001940:Breast / Q000473:pathology*; D001943:Breast Neoplasms / Q000473:pathology*; D003287:Contrast Media; D003937:Diagnosis, Differential; D038524:Diffusion Magnetic Resonance Imaging; D005260:Female; D006801:Humans; D007089:Image Enhancement; D008279:Magnetic Resonance Imaging; D008875:Middle Aged; D012372:ROC Curve; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D055815:Young Adult
chemical_list: D003287:Contrast Media
keywords: ADC ratio; breast; breast cancer; breast lesions; magnetic resonance imaging (MRI)