title: Cholangiocarcinoma size on magnetic resonance imaging versus pathologic specimen: Implications for radiation treatment planning.
abstract: OBJECTIVE
  The accuracy of abdominal magnetic resonance imaging (MRI) in measuring gross tumor volume in patients with resectable cholangiocarcinoma (CC) is unknown. CC is a highly difficult tumor to visualize and treatment with dose-escalated radiation therapy requires clear tumor delineation. We aim to investigate the concordance between imaging and pathologic size in patients with resected CC to determine the usefulness of MRI for image guided treatment modalities.
  
  
  METHODS
  The records of 51 patients with resected CC who underwent preoperative MRI were evaluated. Each preoperative MRI was individually reviewed by a diagnostic radiologist (P.M.), who was blinded to pathologic measurements. A combination of dynamic multiphase contrast-enhanced T1- and T2-weighted images, original imaging reports, and pathologic reports were reviewed for greatest tumor dimensions. A general linear regression model was used to examine the outcome MRI minus pathology using MRI report, T1-weighted measurement, or T2-weighted measurement. A multivariable regression model was fit to assess the association of other factors with pathologic underestimation.
  
  
  RESULTS
  The median age was 69 years. Eleven tumors were categorized distal/extrahepatic, 17 hilar, and 23 intrahepatic CC. The median tumor size on pathology report was 3.00 cm (range, 0.3-19). The median tumor size from the MRI report was 3 cm (range, 0.80-16.20) and median tumor size on independent radiological review was 3 cm (range, 0.90-17) on the T1-weighted and 3 cm (range, 0.90-17) on the T2-weighted MRI sequences. When compared with pathologic tumor size, the MRI report dimension was found to underestimate tumor size by 4.1 mm (P = .04). On multivariable analysis, pathologic size underestimation was influenced by increasing tumor size (slope, -0.20; P < .001); however, underestimation was not affected by tumor location or MRI sequence.
  
  
  CONCLUSIONS
  MRI underestimates tumor size, which was more pronounced with larger tumors, but not influenced by tumor location. The potential for gross tumor volume underestimation should be considered when planning highly conformal radiation therapy treatment of CC.
authors.affiliation: Department of Radiation Oncology, Atlanta, Georgia; Winship Cancer Institute, Emory University, Atlanta, Georgia.
authors.forename: Daniel G
authors.initials: DG
authors.lastname: Tanenbaum
authors.affiliation: Department of Radiation Oncology, Atlanta, Georgia; Department of Radiation Oncology, Medical College of Wisconsin, Milwaukee, Wisconsin.
authors.forename: William A
authors.initials: WA
authors.lastname: Hall
authors.affiliation: Department of Radiology, Atlanta, Georgia; Winship Cancer Institute, Emory University, Atlanta, Georgia.
authors.forename: Pardeep
authors.initials: P
authors.lastname: Mittal
authors.affiliation: Biostatistics and Bioinformatics Shared Resource at Winship, Atlanta, Georgia; Winship Cancer Institute, Emory University, Atlanta, Georgia.
authors.forename: Dana C
authors.initials: DC
authors.lastname: Nickleach
authors.affiliation: Department of Radiation Oncology, Atlanta, Georgia; Winship Cancer Institute, Emory University, Atlanta, Georgia.
authors.forename: John L
authors.initials: JL
authors.lastname: Mikell
authors.affiliation: Department of Radiation Oncology, Atlanta, Georgia; Department of Medicine, Memorial Sloan-Kettering Cancer Center, New York, New York.
authors.forename: Lauren E
authors.initials: LE
authors.lastname: Colbert
authors.affiliation: Department of Radiology, Atlanta, Georgia; Winship Cancer Institute, Emory University, Atlanta, Georgia.
authors.forename: Courtney C
authors.initials: CC
authors.lastname: Moreno
authors.affiliation: Department of Surgical Oncology, Atlanta, Georgia; Winship Cancer Institute, Emory University, Atlanta, Georgia.
authors.forename: Malcolm H
authors.initials: MH
authors.lastname: Squires
authors.affiliation: Department of Surgical Oncology, Atlanta, Georgia; Winship Cancer Institute, Emory University, Atlanta, Georgia.
authors.forename: Sarah B
authors.initials: SB
authors.lastname: Fisher
authors.affiliation: Department of Radiation Oncology, Atlanta, Georgia; Winship Cancer Institute, Emory University, Atlanta, Georgia.
authors.forename: David S
authors.initials: DS
authors.lastname: Yu
authors.affiliation: Department of Surgical Oncology, Atlanta, Georgia; Winship Cancer Institute, Emory University, Atlanta, Georgia.
authors.forename: David A
authors.initials: DA
authors.lastname: Kooby
authors.affiliation: Department of Surgical Oncology, Atlanta, Georgia; Winship Cancer Institute, Emory University, Atlanta, Georgia.
authors.forename: Shishir K
authors.initials: SK
authors.lastname: Maithel
authors.affiliation: Department of Radiation Oncology, Atlanta, Georgia; Winship Cancer Institute, Emory University, Atlanta, Georgia. Electronic address: jland01@emory.edu.
authors.forename: Jerome C
authors.initials: JC
authors.lastname: Landry
mesh_terms: D000368:Aged; D018281:Cholangiocarcinoma / Q000532:radiotherapy*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D020266:Radiotherapy, Conformal / Q000379:methods*