title: Extramural depth of tumor invasion at thin-section MR in rectal cancer: associating with prognostic factors and ADC value.
abstract: OBJECTIVE
  To assess the value of maximal extramural depth (EMD) of T3 tumor spread on MRI as a potential noninvasive imaging biomarker of tumor aggressiveness in rectal cancer, by analyzing the relationship between tumoral EMD values and clinical or histological prognostic parameters. In addition, we try to investigate the relationship between EMD and apparent diffusion coefficient (ADC) values.
  
  
  METHODS
  Ninety rectal cancer patients who underwent primary MRI staging and diffusion weighted imaging (DWI) as T3 tumor were included. Tumor EMD was measured, and the EMD values of the subgroups based on pretreatment CEA, CA19-9 levels, N stage, and histological parameters were compared. The correlation between EMD and ADC values was compared.
  
  
  RESULTS
  Interobserver agreement of confidence levels for observers 1 and 2 was good for cN stage (k = 0.678) and EMD measurement(k = 0.612) and was excellent for ADC measurement (k = 0.880). Tumor EMDs differ between CEA <5 ng/mL versus ≥ 5 ng/mL (P = 0.013), CA19-9 < 27 U/mL versus ≥ 27 U/mL (P = 0.012), the groups of cN0 versus cN+ cancers (P = 0.049), and between the several groups of histological differentiation grades (P = 0.033). There was no significant difference in EMDs between the various groups of vessel carcinoma embolus and neural invasion. A significant negative correlation (r = -0.581; P = 0.001) between ADC and EMD values was found.
  
  
  CONCLUSIONS
  Significant correlations were found between EMD values and CEA, CA19-9 level, differentiation grade and ADC value. As been found, higher EMD values were associated with a more aggressive tumor profile and, therefore, EMD has the potential to become an imaging biomarker of tumor aggressiveness indicator.
authors.affiliation: Department of Radiology, Fudan University Shanghai Cancer Center, Shanghai, China.
authors.forename: Tong
authors.initials: T
authors.lastname: Tong
authors.forename: Zhenwei
authors.initials: Z
authors.lastname: Yao
authors.forename: Linhui
authors.initials: L
authors.lastname: Xu
authors.forename: Sanjun
authors.initials: S
authors.lastname: Cai
authors.forename: Rui
authors.initials: R
authors.lastname: Bi
authors.forename: Chao
authors.initials: C
authors.lastname: Xin
authors.forename: Yajia
authors.initials: Y
authors.lastname: Gu
authors.forename: Weijun
authors.initials: W
authors.lastname: Peng
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D003287:Contrast Media; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D005682:Gadolinium; D006801:Humans; D008297:Male; D008875:Middle Aged; D009361:Neoplasm Invasiveness / Q000473:pathology*; D009367:Neoplasm Staging; D009942:Organometallic Compounds; D011379:Prognosis; D012004:Rectal Neoplasms / Q000473:pathology*; D012189:Retrospective Studies
chemical_list: D003287:Contrast Media; D009942:Organometallic Compounds; D005682:Gadolinium; C109932:gadofosveset trisodium
keywords: MRI; depth of invasion; diffusion-weighted imaging; prognosis; rectal cancer