title: High accuracy of mesoscopic epi-fluorescence tomography for non-invasive quantitative volume determination of fluorescent protein-expressing tumours in mice.
abstract: OBJECTIVE
  To compare mesoscopic epi-fluorescence tomography (MEFT) and EPRI-illumination reflectance imaging (EPRI) for quantitative tumour size assessment in mice.
  
  
  METHODS
  Tumour xenografts of green/red fluorescent protein (GFP/RFP)-expressing colon cancer cells were measured using MEFT, EPRI, ultrasound (US) and micro computed tomography (μCT) at day 14 post-injection (n = 6). Results from MEFT and EPRI were correlated with each other and with US and μCT (reference methods). Tumour volumes were measured ex vivo by GFP and RFP fluorescence imaging on cryoslices and compared with the in vivo measurements.
  
  
  RESULTS
  High correlation and congruency were observed between MEFT, US and μCT (MEFT/US: GFP: r (2) = 0.96; RFP: r (2) = 0.97, both P < 0.05; MEFT/μCT: GFP: r (2) = 0.93; RFP: r (2) = 0.90; both P < 0.05). Additionally, in vivo MEFT data were highly correlated and congruent with ex vivo cryoslice imaging results (GFP: r (2) = 0.96; RFP: r (2) = 0.99; both P < 0.05). In comparison, EPRI significantly overestimated tumour volumes (P < 0.05), although there was a significant correlation with US and μCT (EPRI/US: GFP: r (2) = 0.95; RFP: r (2) = 0.94; both P < 0.05; EPRI/μCT GFP: r (2) = 0.86; RFP: r (2) = 0.86; both P < 0.05).
  
  
  CONCLUSIONS
  Fluorescence distribution reconstruction using MEFT affords highly accurate three-dimensional (3D) tumour volume data showing superior accuracy compared to EPRI. Thus, MEFT is a very suitable technique for quantitatively assessing fluorescence distribution in superficial tumours at high spatial resolution.
authors.affiliation: Department of Experimental Molecular Imaging, Medical Faculty, RWTH Aachen University, Pauwelstraße 30, 52074 Aachen, Germany.
authors.forename: Lotfi
authors.initials: L
authors.lastname: Abou-Elkacem
authors.forename: Saskia
authors.initials: S
authors.lastname: Björn
authors.forename: Dennis
authors.initials: D
authors.lastname: Doleschel
authors.forename: Vasilis
authors.initials: V
authors.lastname: Ntziachristos
authors.forename: Ralf
authors.initials: R
authors.lastname: Schulz
authors.forename: Robert M
authors.initials: RM
authors.lastname: Hoffman
authors.forename: Fabian
authors.initials: F
authors.lastname: Kiessling
authors.forename: Wiltrud
authors.initials: W
authors.lastname: Lederle
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D003110:Colonic Neoplasms / Q000378:metabolism* / Q000473:pathology*; D005260:Female; D049452:Green Fluorescent Proteins / Q000378:metabolism*; D051379:Mice; D008819:Mice, Nude; D057054:Molecular Imaging / Q000379:methods*; D009363:Neoplasm Proteins / Q000378:metabolism*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D009363:Neoplasm Proteins; D049452:Green Fluorescent Proteins