title: Apparent diffusion coefficient as a potential surrogate marker for Ki-67 index in mucinous breast carcinoma.
abstract: OBJECTIVE
  To examine the association between apparent diffusion coefficient (ADC), cellularity, and Ki-67 index in mucinous breast carcinoma (MBC) compared with invasive carcinoma of no special type (NST). ADC's ability to identify lesions with highly proliferating MBC was also examined.
  
  
  METHODS
  Pathologically confirmed MBCs (mucinous group, n = 18) and NSTs (control group, n = 18) were retrospectively analyzed. ADC was calculated from signal intensity of diffusion-weighted imaging at b values of 0 and 1000 sec/mm(2) . The Ki-67 index and cellularity were histopathologically evaluated. The mucinous group was classified into high Ki-67 mucinous group (Ki-67 index ≥14%, highly proliferating) and low Ki-67 mucinous group.
  
  
  RESULTS
  In the mucinous group, minimum ADC (ADCmin) showed an inverse correlation with cellularity (r = -0.802, P < 0.0001) and Ki-67 index (r = -0.825, P < 0.0001). In the control group, ADCmin showed inverse correlation with cellularity (r = -0.537 P = 0.022), but no correlation with Ki-67 index (r = 0.035, P = 0.892). ADCmin of high Ki-67 mucinous group was significantly lower than that of low Ki-67 mucinous group (P = 0.005).
  
  
  CONCLUSIONS
  This study demonstrates an inverse correlation between ADC and Ki-67 index in MBC and the ability of ADC to identify highly proliferating MBC. Considering that ADC can evaluate whole lesions noninvasively, ADC may be a promising noninvasive surrogate marker for Ki-67 index in the risk stratification of MBC.
authors.affiliation: Department of Diagnostic Imaging and Nuclear Medicine, Kyoto University Graduate School of Medicine, Kyoto, Japan.
authors.forename: Natsuko
authors.initials: N
authors.lastname: Onishi
authors.forename: Shotaro
authors.initials: S
authors.lastname: Kanao
authors.forename: Masako
authors.initials: M
authors.lastname: Kataoka
authors.forename: Mami
authors.initials: M
authors.lastname: Iima
authors.forename: Rena
authors.initials: R
authors.lastname: Sakaguchi
authors.forename: Makiko
authors.initials: M
authors.lastname: Kawai
authors.forename: Tatsuki R
authors.initials: TR
authors.lastname: Kataoka
authors.forename: Yoshiki
authors.initials: Y
authors.lastname: Mikami
authors.forename: Masakazu
authors.initials: M
authors.lastname: Toi
authors.forename: Kaori
authors.initials: K
authors.lastname: Togashi
mesh_terms: D002288:Adenocarcinoma, Mucinous / Q000175:diagnosis*; D000328:Adult; D000368:Aged; D001940:Breast / Q000473:pathology; D001943:Breast Neoplasms / Q000175:diagnosis*; D018270:Carcinoma, Ductal, Breast / Q000175:diagnosis; D003287:Contrast Media; D005260:Female; D005682:Gadolinium; D019786:Gadolinium DTPA; D006571:Heterocyclic Compounds; D006801:Humans; D007089:Image Enhancement; D007091:Image Processing, Computer-Assisted; D019394:Ki-67 Antigen; D008875:Middle Aged; D009942:Organometallic Compounds; D012189:Retrospective Studies
chemical_list: D003287:Contrast Media; D006571:Heterocyclic Compounds; D019394:Ki-67 Antigen; D009942:Organometallic Compounds; C062402:gadoteridol; C064925:gadodiamide; D005682:Gadolinium; D019786:Gadolinium DTPA
keywords: ADC; Ki-67 index; breast cancer; cellularity; mucinous carcinoma