title: Apparent diffusion coefficient and pituitary macroadenomas: pre-operative assessment of tumor atypia.
abstract: OBJECTIVE
  Pituitary macroadenomas are predominantly benign intracranial neoplasms that can be locally aggressive with invasion of adjacent structures. Biomarkers of aggressive behavior have been identified in the pathology literature, including the proliferative marker MIB-1. In the radiology literature, diffusion weighted imaging and low ADC values provide similar markers of aggressive behavior in brain tumors. The purpose of this study was to determine if there is a correlation between ADC and MIB-1 in pituitary macroadenomas.
  
  
  METHODS
  A retrospective review of diffusion imaging and immunohistochemical characteristics of pituitary macroadenomas was performed. The ADC ratio and specimen Ki-67 (MIB-1) indices were measured. Linear regression analysis of normalized ADC values and MIB-1 indices was used to compare these parameters.
  
  
  RESULTS
  There were 17 patients with available ADC maps and MIB-1 indices. Local invasion was confirmed by imaging and intraoperative visualization in 11 patients. The mean ADC ratio for the invasive group was 0.68, with a mean MIB-1 index of 2.21 %. In the noninvasive group, the mean ADC ratio was 1.05, with a mean MIB-1 index of 0.9 %. Linear regression analysis of normalized ADC values versus MIB-1 demonstrates a negative correlation, with a linear slope significantly different from zero (p = 0.003, correlation coefficient of 0.77, and r squared = 0.59).
  
  
  CONCLUSIONS
  We determine a strong correlation of low ADC values and MIB-1, demonstrating the potential of diffusion imaging as a possible biomarker for atypical, proliferative adenomas, which may ultimately affect the surgical approach and postoperative management.
authors.affiliation: Department of Radiology, University of California San Francisco, 505 Parnassus Avenue, M-391, San Francisco, CA, 94143-0628, USA. btamrazi@chla.usc.edu.|Department of Radiology #81, Children's Hospital Los Angeles, Los Angeles, CA, 90027, USA. btamrazi@chla.usc.edu.
authors.forename: Benita
authors.initials: B
authors.lastname: Tamrazi
authors.affiliation: Department of Pathology, University of California San Francisco, 505 Parnassus Avenue, M-391, San Francisco, CA, 94143-0628, USA.
authors.forename: Melike
authors.initials: M
authors.lastname: Pekmezci
authors.affiliation: Department of Radiology, University of California San Francisco, 505 Parnassus Avenue, M-391, San Francisco, CA, 94143-0628, USA.
authors.forename: Mariam
authors.initials: M
authors.lastname: Aboian
authors.affiliation: Department of Pathology, University of California San Francisco, 505 Parnassus Avenue, M-391, San Francisco, CA, 94143-0628, USA.
authors.forename: Tarik
authors.initials: T
authors.lastname: Tihan
authors.affiliation: Department of Radiology, University of California San Francisco, 505 Parnassus Avenue, M-391, San Francisco, CA, 94143-0628, USA.
authors.forename: Christine M
authors.initials: CM
authors.lastname: Glastonbury
mesh_terms: D000328:Adult; D014408:Biomarkers, Tumor / Q000378:metabolism; D038524:Diffusion Magnetic Resonance Imaging; D005260:Female; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D010911:Pituitary Neoplasms / Q000175:diagnosis* / Q000378:metabolism; D012189:Retrospective Studies
chemical_list: D014408:Biomarkers, Tumor
keywords: Diffusion weighted imaging; Magnetic resonance imaging; Pituitary adenoma; Proliferation index (MIB-1)