title: Measurement of apparent diffusion coefficient with simultaneous MR/positron emission tomography in patients with peritoneal carcinomatosis: comparison with 18F-FDG-PET.
abstract: OBJECTIVE
  To characterize peritoneal carcinomatosis (PC) of different histologically proven primary tumors based on diffusion-weighted imaging (DWI) and (18) F-FDG positron emission tomography (PET).
  
  
  METHODS
  Forty-one patients underwent simultaneous MR/PET after clinically indicated (18) F-FDG-PET/CT. For all patients, histology of the primary tumor was obtained. MR protocol comprised anatomical imaging and axial DWI. Apparent diffusion coefficient (ADC) maps and FDG-PET were co-registered for evaluation of ADC and standard uptake value (SUV) of peritoneal lesions. Both lesion- and patient-based analysis was performed. Up to four peritoneal lesions were evaluated per patient. Mean and maximum standard uptake value (SUVmean , SUVmax ), mean and minimum ADC (ADCmean , ADCmin ) of each lesion were assessed. Spearman rank correlation (rs ) of ADC and SUV were calculated. SUV and ADC of ovarian and colorectal cancer lesions were compared using Wilcoxon test.
  
  
  RESULTS
  Measurable lesions (n = 52) were found in 20 of 41 PC patients. Moderate, but significant correlation existed between ADC and SUV in the lesion-based as well as the patient-based analysis (lesion-based: SUVmean versus ADCmean rs = -0.58; SUVmax versus ADCmin rs = -0.56, all P < 0.0001; patient-based: SUVmean versus ADCmean rs = -0.64, P = 0.002; SUVmax versus ADCmin rs = -0.60, P = 0.005). ADC and SUV differed significantly between ovarian and colorectal cancer lesions (ADCmin : P < 0.0001; ADCmean : P < 0.0001; SUVmax : P = 0.002; SUVmean : P = 0.005). Overall, mucinous tumor entities showed a tendency to higher ADC and lower SUV.
  
  
  CONCLUSIONS
  PC lesions showed significant differences in glucose uptake and diffusion characteristics depending on primary tumor histology. These differences should be considered when interpreting FDG-PET and DWI in PC patients.
authors.affiliation: Department of Radiology, Diagnostic and Interventional Radiology, Eberhard-Karls University Tuebingen, Germany.
authors.forename: Nina F
authors.initials: NF
authors.lastname: Schwenzer
authors.forename: Holger
authors.initials: H
authors.lastname: Schmidt
authors.forename: Sergios
authors.initials: S
authors.lastname: Gatidis
authors.forename: Cornelia
authors.initials: C
authors.lastname: Brendle
authors.forename: Mark
authors.initials: M
authors.lastname: Müller
authors.forename: Ingmar
authors.initials: I
authors.lastname: Königsrainer
authors.forename: Claus D
authors.initials: CD
authors.lastname: Claussen
authors.forename: Anna C
authors.initials: AC
authors.lastname: Pfannenberg
authors.forename: Christina
authors.initials: C
authors.lastname: Schraml
mesh_terms: D000328:Adult; D000368:Aged; D002277:Carcinoma / Q000175:diagnosis*; D015179:Colorectal Neoplasms / Q000175:diagnosis*; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging / Q000379:methods*; D010051:Ovarian Neoplasms / Q000175:diagnosis*; D010534:Peritoneal Neoplasms / Q000175:diagnosis*; D049268:Positron-Emission Tomography / Q000379:methods*; D011446:Prospective Studies; D012680:Sensitivity and Specificity
chemical_list: D019788:Fluorodeoxyglucose F18
keywords: DWI; FDG-PET; MR/PET; MRI; PET/MR; colorectal cancer; diffusion weighted imaging; ovarian cancer; peritoneal carcinomatosis