Colon tumor growth and antivascular treatment in mice: complementary assessment with MR elastography and diffusion-weighted MR imaging.
OBJECTIVE
To investigate the potential value of magnetic resonance (MR) elastography and diffusion-weighted (DW) MR imaging in the detection of microstructural changes of murine colon tumors during growth and antivascular treatment.


METHODS
The study was approved by the regional ethics committee for animal care. Sixty Balb-C mice, bearing ectopic and orthotopic colon tumors, were monitored for 3 weeks with high-resolution T2-weighted MR imaging, three-dimensional steady-state MR elastography, and DW MR imaging at 7 T. The same imaging protocol was performed 24 hours after injection of combretastatin A4 phosphate (CA4P) in 12 mice. The absolute value of the complex shear modulus (|G*|) and the apparent diffusion coefficient (ADC) were measured in the viable zones of tumors and compared with microvessel density (MVD), cellularity, and micronecrosis by using the Pearson correlation coefficient.


RESULTS
During tumor growth, |G*| increase was correlated with MVD (r = 0.70 [P = .08] and r = 0.78 [P = .002], for both the ectopic and orthotopic models, respectively). Moreover, the ectopic tumors displayed decreased ADC, which correlated with increased cellularity (r = 0.77, P = .04), whereas no changes in ADC and cellularity were observed in orthotopic tumors. After CA4P administration, |G*| decreased in the ectopic model (P < .0001), similar to the MVD evolution (P = .03), whereas no significant changes in |G*| (P = .7) and MVD (P = .6) were observed in the orthotopic model. ADC increased in both models (P = .047 and P = .01 for the ectopic and the orthotopic models, respectively) in relation to increased micronecrosis.


CONCLUSIONS
Imaging of mechanical properties and diffusivity provide complementary information during tumor growth and regression that are respectively linked to vascularity and tumor cell alterations, including cellularity and micronecrosis.
Université Paris Diderot, Centre de Recherche Biomédicale Bichat Beaujon, Clichy, France. lauriane.juge@inserm.fr
Lauriane
L
Jugé
Bich-Thuy
BT
Doan
Johanne
J
Seguin
Miguel
M
Albuquerque
Benoît
B
Larrat
Nathalie
N
Mignet
Guy G
GG
Chabot
Daniel
D
Scherman
Valérie
V
Paradis
Valérie
V
Vilgrain
Bernard E
BE
Van Beers
Ralph
R
Sinkus
D000818:Animals; D003110:Colonic Neoplasms / Q000188:drug therapy* / Q000473:pathology*; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D054459:Elasticity Imaging Techniques / Q000379:methods*; D005260:Female; D051379:Mice; D008807:Mice, Inbred BALB C; D008833:Microcirculation / Q000187:drug effects; D009389:Neovascularization, Pathologic / Q000188:drug therapy* / Q000473:pathology*; D013267:Stilbenes / Q000494:pharmacology*
D013267:Stilbenes; C058728:fosbretabulin