title: Diffusion-weighted and hepatobiliary phase gadoxetic acid-enhanced quantitative MR imaging for identification of complete pathologic response in colorectal liver metastases after preoperative chemotherapy.
abstract: OBJECTIVE
  To evaluate the diagnostic performance of diffusion-weighted imaging (DWI) and gadoxetic acid-enhanced magnetic resonance imaging (MRI) to differentiate colorectal liver metastasis (CRLM) with complete pathologic response from those with incomplete response in patients treated with preoperative chemotherapy.
  
  
  METHODS
  Gadoxetic acid-enhanced liver MRI and DWI were performed after completion of preoperative chemotherapy in patients with CRLM scheduled for liver resection. Metastases were classified as those with complete pathologic response (CR-CRLM) or incomplete response (IR-CRLM) according to postsurgical histopathology. Quantitative analysis was performed on non-contrast-enhanced images and hepatobiliary phase images following gadoxetic acid administration. Apparent diffusion coefficient values (ADC), normalized relative enhancement (NRE), and relative signal intensity difference (RSID) along with their diagnostic measures for detection of CR-CRLM were calculated for all lesions.
  
  
  RESULTS
  In 23 patients, 10 CR-CRLM and 35 IR-CRLM (mean diameter, 21.2 mm) were evaluated. In CR-CRLM, ADC was significantly higher after exclusion of the outliers (p = 0.030); and RSID was significantly lower (p = 0.008). Combined indices range of ADC = 1.25-1.9 × 10(-3) mm(2)/s, NRE = 0-35% and RSID <120 had 60% sensitivity and 100% specificity for detection of CR-CRLM.
  
  
  CONCLUSIONS
  DWI and gadoxetic acid-enhanced MRI appear promising for the detection of CRLM with complete response to preoperative chemotherapy. This could have significant implications for liver resection planning after preoperative chemotherapy.
authors: Joint Department of Medical Imaging, University Health Network, Mount Sinai Hospital and Women's College Hospital, Toronto, ON, Canada.
authors: Hooman
authors: H
authors: Hosseini-Nik
authors: Department of Pathology, University Health Network, University of Toronto, Toronto, ON, Canada.
authors: Sandra E
authors: SE
authors: Fischer
authors: Department of Surgery, University Health Network, University of Toronto, Toronto, ON, Canada.
authors: Carol-Anne E
authors: CA
authors: Moulton
authors: Joint Department of Medical Imaging, University Health Network, Mount Sinai Hospital and Women's College Hospital, Toronto, ON, Canada.
authors: Gautam
authors: G
authors: Karbhase
authors: Joint Department of Medical Imaging, University Health Network, Mount Sinai Hospital and Women's College Hospital, University of Toronto, Toronto, ON, Canada.
authors: Ravi J
authors: RJ
authors: Menezes
authors: Department of Surgery, University Health Network, University of Toronto, Toronto, ON, Canada.
authors: Steven
authors: S
authors: Gallinger
authors: Joint Department of Medical Imaging, University Health Network, Mount Sinai Hospital and Women's College Hospital, University of Toronto, Toronto, ON, Canada. kartik.jhaveri@uhn.ca.
authors: Kartik S
authors: KS
authors: Jhaveri
mesh_terms: D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use*; D015179:Colorectal Neoplasms / Q000188:drug therapy* / Q000473:pathology*; D003287:Contrast Media; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D019786:Gadolinium DTPA; D006498:Hepatectomy; D006801:Humans; D008113:Liver Neoplasms / Q000000981:diagnostic imaging* / Q000556:secondary* / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D018365:Neoplasm, Residual / Q000000981:diagnostic imaging; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D016896:Treatment Outcome
chemical_list: D003287:Contrast Media; C073590:gadolinium ethoxybenzyl DTPA; D019786:Gadolinium DTPA
keywords: Chemotherapy; Colorectal liver metastasis; Diffusion-weighted imaging; Gadoxetic acid; MRI; Pathologic response