title: Comparison of macroscopic pathology measurements with magnetic resonance imaging and assessment of microscopic pathology extension for colorectal liver metastases.
abstract: OBJECTIVE
  To compare pathology macroscopic tumor dimensions with magnetic resonance imaging (MRI) measurements and to establish the microscopic tumor extension of colorectal liver metastases.
  
  
  METHODS
  In a prospective pilot study we included patients with colorectal liver metastases planned for surgery and eligible for MRI. A liver MRI was performed within 48 hours before surgery. Directly after surgery, an MRI of the specimen was acquired to measure the degree of tumor shrinkage. The specimen was fixed in formalin for 48 hours, and another MRI was performed to assess the specimen/tumor shrinkage. All MRI sequences were imported into our radiotherapy treatment planning system, where the tumor and the specimen were delineated. For the macroscopic pathology analyses, photographs of the sliced specimens were used to delineate and reconstruct the tumor and the specimen volumes. Microscopic pathology analyses were conducted to assess the infiltration depth of tumor cell nests.
  
  
  RESULTS
  Between February 2009 and January 2010 we included 13 patients for analysis with 21 colorectal liver metastases. Specimen and tumor shrinkage after resection and fixation was negligible. The best tumor volume correlations between MRI and pathology were found for T1-weighted (w) echo gradient sequence (r(s) = 0.99, slope = 1.06), and the T2-w fast spin echo (FSE) single-shot sequence (r(s) = 0.99, slope = 1.08), followed by the T2-w FSE fat saturation sequence (r(s) = 0.99, slope = 1.23), and the T1-w gadolinium-enhanced sequence (r(s) = 0.98, slope = 1.24). We observed 39 tumor cell nests beyond the tumor border in 12 metastases. Microscopic extension was found between 0.2 and 10 mm from the main tumor, with 90% of the cases within 6 mm.
  
  
  CONCLUSIONS
  MRI tumor dimensions showed a good agreement with the macroscopic pathology suggesting that MRI can be used for accurate tumor delineation. However, microscopic extensions found beyond the tumor border indicate that caution is needed in selecting appropriate tumor margins.
authors.affiliation: Department of Radiation Oncology, Erasmus MC-Daniel den Hoed Cancer Center, Rotterdam, The Netherlands. a.mendezromero@erasmusmc.nl
authors.forename: Alejandra
authors.initials: A
authors.lastname: Méndez Romero
authors.forename: Joanne
authors.initials: J
authors.lastname: Verheij
authors.forename: Roy S
authors.initials: RS
authors.lastname: Dwarkasing
authors.forename: Yvette
authors.initials: Y
authors.lastname: Seppenwoolde
authors.forename: William K
authors.initials: WK
authors.lastname: Redekop
authors.forename: Pieter E
authors.initials: PE
authors.lastname: Zondervan
authors.forename: Peter J C M
authors.initials: PJ
authors.lastname: Nowak
authors.forename: Jan N M
authors.initials: JN
authors.lastname: Ijzermans
authors.forename: Peter C
authors.initials: PC
authors.lastname: Levendag
authors.forename: Ben J M
authors.initials: BJ
authors.lastname: Heijmen
authors.forename: Cornelis
authors.initials: C
authors.lastname: Verhoef
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D015179:Colorectal Neoplasms; D003287:Contrast Media; D005260:Female; D019786:Gadolinium DTPA; D006801:Humans; D008099:Liver / Q000473:pathology; D008113:Liver Neoplasms / Q000473:pathology* / Q000556:secondary* / Q000601:surgery; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects; D011446:Prospective Studies; D016634:Radiosurgery; D011880:Radiotherapy Planning, Computer-Assisted; D012044:Regression Analysis; D012074:Remission Induction / Q000379:methods; D018709:Statistics, Nonparametric; D016707:Tissue Fixation; D047368:Tumor Burden
chemical_list: D003287:Contrast Media; D019786:Gadolinium DTPA