DWI and IVIM are predictors of Ki67 proliferation index: direct comparison of MRI images and pathological slices in a murine model of rhabdomyosarcoma
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The purpose of this study was to investigate the correlation of diffusion-weighted imaging (DWI) and intravoxel incoherent motion (IVIM) with the Ki67 proliferation index in a murine model of rhabdomyosarcoma.
The rhabdomyosarcoma model was established by injecting RD cells into the right hind flank of nude mice. The mice underwent 3.0T magnetic resonance imaging (MRI), including DWI and IVIM. The apparent diffusion coefficient (ADC), D, D*, and f were calculated with the ADW4.7 workstation. A specialized method was employed to ensure the pathological sections corresponded to the correct MRI slices. The Ki67 proliferation index was analyzed by immunohistochemistry, and any possible correlations were assessed between the DWI and IVIM parameters and Ki67 proliferation index.
Twenty-seven rhabdomyosarcoma mice were established successfully. After 46 days, the average tumor volume reached 1094.78 ± 678.77 mm3. The average ADC, D, and D* values were 1.0470 ± 0.2036 × 10−3 mm2/s, 0.7237 ± 0.0971 × 10−3 mm2/s, and 4.8497 ± 1.6293 × 10−3 mm2/s, respectively. The range in f values was 0.102–0.229. The ADC and D values showed a moderate negative correlation with the Ki67 proliferation indexes (r = − 0.543, p = 0.003; r = − 0.491, p = 0.009, respectively). In addition, the f value showed a weak negative correlation with the Ki67 proliferation indexes (r = − 0.151, p = 0.451), while the D* value showed no association with the Ki67 proliferation indexes (r = − 0.037, p = 0.853).
The ADC value of DWI, along with the D value of IVIM, may be reflective of Ki67 proliferation indexes in murine models of rhabdomyosarcoma.
• DWI and IVIM parameters are correlated with Ki67 proliferation indexes in rhabdomyosarcoma mouse models.
• A specialized method ensured a strong correlation between pathological sections and MRI slices, resulting in a robust radiological-pathological correlation.
KeywordsRhabdomyosarcoma Diffusion magnetic resonance imaging Mice Ki-67 antigen
Apparent diffusion coefficient
Echo planar imaging
Fast relaxation fast spin-echo
Hematoxylin and eosin
Intravoxel incoherent motion
Magnetic resonance imaging
Region of interest
This study has received funding by the National Natural Science Foundation of China (81771804).
Compliance with ethical standards
The scientific guarantor of this publication is Shaowu Wang, MD, PhD.
Conflict of interest
The authors of this manuscript declare no relationships with any companies whose products or services may be related to the subject matter of the article.
Statistics and biometry
One of the authors has significant statistical expertise.
Approval from the institutional animal care committee was obtained.
Institutional Review Board approval was obtained.
• Performed at one institution