title: Assessment of aggressiveness of rectal cancer using 3-T MRI: correlation between the apparent diffusion coefficient as a potential imaging biomarker and histologic prognostic factors.
abstract: BACKGROUND
  Diffusion-weighted magnetic resonance imaging (DW-MRI) permits non-invasive assessment of tumor characteristics.
  
  
  OBJECTIVE
  To assess the value of DW-MRI as a potential non-invasive marker of tumor aggressiveness in rectal cancer by analyzing the relationship between tumoral apparent diffusion coefficient (ADC) values of MRI and histopathologic prognostic parameters that are not affected by preoperative chemoradiation therapy.
  
  
  METHODS
  Forty patients with rectal cancer were assessed with primary staging 3-T MRI, including DWI, before undergoing surgical therapy. In all patients, surgery was performed without neoadjuvant therapy. Mean tumor ADC was measured and compared between subgroups based on pretreatment carcinoembryonic antigen (CEA) levels, MRI parameters (e.g. postoperative local recurrence), and histopathologic parameters, including A (invasive distance: A1, T-stage; A2, mesorectal fascia [MRF] status), B (differentiation grade: B1, poorly differentiated; B2, moderately differentiated; B3, well differentiated), C (others: C1, N-stage; C2, lymphangiovascular invasion).
  
  
  RESULTS
  Mean tumor ADCs were different when comparing groups stratified by histologic differentiation grades (P=0.0192). There was no significant difference in mean ADCs when stratifying patients according to CEA levels, T-stage, N-stage, MRF status, presence of lymphangiovascular invasion, or the presence of local recurrence.
  
  
  CONCLUSIONS
  Significant correlations were found between mean ADC values and differentiation grade. ADC may be useful as an imaging biomarker of tumor aggressiveness, but it cannot serve as an independent biomarker of advanced rectal cancer.
authors.affiliation: Department of General Surgery, Faculty of Medicine, Saga University, Saga, Japan Department of Pathology and Biodefense, Faculty of Medicine, Saga University, Saga, Japan Akashi-m@koseikan.jp.
authors.forename: Michiaki
authors.initials: M
authors.lastname: Akashi
authors.affiliation: Department of Surgery, Hukuoka Red Cross Hospital, Hukouoka, Japan.
authors.forename: Yuji
authors.initials: Y
authors.lastname: Nakahusa
authors.affiliation: Department of General Surgery, Faculty of Medicine, Saga University, Saga, Japan.
authors.forename: Tomomi
authors.initials: T
authors.lastname: Yakabe
authors.affiliation: Department of Radiology, Faculty of Medicine, Saga University, Saga, Japan.
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Egashira
authors.affiliation: Department of General Surgery, Faculty of Medicine, Saga University, Saga, Japan.
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Koga
authors.affiliation: Department of General Surgery, Faculty of Medicine, Saga University, Saga, Japan.
authors.forename: Kenji
authors.initials: K
authors.lastname: Sumi
authors.affiliation: Department of General Surgery, Faculty of Medicine, Saga University, Saga, Japan.
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Noshiro
authors.affiliation: Department of Radiology, Faculty of Medicine, Saga University, Saga, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Irie
authors.affiliation: Department of Pathology and Biodefense, Faculty of Medicine, Saga University, Saga, Japan.
authors.forename: Osamu
authors.initials: O
authors.lastname: Tokunaga
authors.affiliation: Department of General Surgery, Faculty of Medicine, Saga University, Saga, Japan.
authors.forename: Kohji
authors.initials: K
authors.lastname: Miyazaki
mesh_terms: D000230:Adenocarcinoma / Q000737:chemistry / Q000473:pathology* / Q000601:surgery; D000368:Aged; D000369:Aged, 80 and over; D002272:Carcinoembryonic Antigen / Q000032:analysis; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D009364:Neoplasm Recurrence, Local; D009367:Neoplasm Staging; D011379:Prognosis; D012004:Rectal Neoplasms / Q000737:chemistry / Q000473:pathology* / Q000601:surgery
chemical_list: D002272:Carcinoembryonic Antigen
keywords: Abdomen; MR diffusion; adults; pathology; rectum