Correlation between IVIM parameters and microvessel architecture: direct comparison of MRI images and pathological slices in an orthotopic murine model of rhabdomyosarcoma

ObjectiveThis study aimed to explore the correlation between intravoxel incoherent motion (IVIM) parameters and microvessel architecture (microvessel density (MVD), vasculogenic mimicry (VM), and pericyte coverage index (PCI)) in an orthotopic murine model of rhabdomyosarcoma.MethodsThe murine model was established by injecting rhabdomyosarcoma-derived (RD) cells into the muscle. Nude mice underwent routine magnetic resonance imaging (MRI) and IVIM examinations with ten b values (0, 50, 100, 150, 200, 400, 600, 800, 1000, and 2000 s/mm(2)). D, D*, and f values were calculated with the ADW4.7 workstation. MRI images and pathological slices were directly compared to ensure that radiology parameters accurately reflect pathology. MVD, VM, PCI, and cellularity were obtained by histological analysis. The correlations were assessed between IVIM parameters (D, D*, f, and fD* values) and pathological markers (MVD, VM, PCI, and cellularity).ResultsThe average of D, D*, f, and fD* values were 0.55 & PLUSMN; 0.07 x 10(-3 )mm(2)/s, 5.25 & PLUSMN; 0.73 x 10(-3 )mm(2)/s, 13.39 & PLUSMN; 7.68%, and 0.73 & PLUSMN; 0.49 x 10(-3 )mm(2)/s, respectively. The average of MVD, VM, PCI, and cellularity were 41.91 & PLUSMN; 10.98, 1.16 & PLUSMN; 0.83, 0.49 & PLUSMN; 0.18, and 39.15 & PLUSMN; 9.00%. D*, f, and fD* values showed a positive correlation with MVD separately, while the D value did not correlate with MVD. D value negatively correlated to VM moderately, and other parameters did not associate with VM. D* and fD* values were positively correlated with PCI, but no correlation was observed between other parameters and PCI.ConclusionsIVIM may evaluate the tumor microvessel architecture. D*, f, and fD* may reflect the endothelial lining blood vessel; D could indirectly reflect the VM; D* and fD* could reflect PCI(the normal degree of the tumor blood vessel).

Automated summary

This study investigated the correlation between IVIM parameters (D, D*, f, and fD* values) and microvessel architecture (MVD, VM, and PCI) in a murine model of rhabdomyosarcoma. The results showed that D*, f, and fD* values were positively correlated with MVD, while D value did not correlate with MVD. D value was negatively correlated with VM, and D* and fD* values were positively correlated with PCI.