DWI and IVIM Imaging in a Murine Model of Rhabdomyosarcoma: Correlations with Quantitative Histopathologic Features

Abstract

Background High cellularity and abnormal interstitial structures are some of the unfavorable factors that affect the treatment outcomes and survival of rhabdomyosarcoma (RMS) patients. Purpose To explore the correlation between diffusion‐weighted imaging (DWI) and intravoxel incoherent motion (IVIM) with quantitative histopathologic features in a murine model of RMS. Study Type Prospective. Animal Model Murine model of RMS (31 female BALB/c nude mice). Field Strength/Sequence 3.0 T; fast spin‐echo (FSE) T1‐weighted imaging, fast relaxation fast spin‐echo (FRFSE) T2‐weighted imaging, DWI PROPELLER FSE imaging sequence, and IVIM echo planar imaging sequence; 10 different b‐values (0, 50, 100, 150, 200, 400, 600, 800, 1000, and 1200 s/mm2). Assessment Magnetic resonance imaging (MRI) was performed after 30–45 days of implantation. The following MRI parameters were calculated: apparent diffusion coefficient (ADC), pure diffusion coefficient (D), pseudo‐diffusion coefficient (D*), and perfusion fraction (f). Histopathologic features, which contained nuclear, cytoplasmic, and stromal fractions, and the nuclear‐to‐cytoplasmic ratio within the tumor were measured using image‐based segmentation. Statistical Tests Pearson's correlation, multiple linear regression analysis, and receiver operating characteristic curve analysis were performed. A P < 0.05 was considered statistically significant. Results The ADC value showed moderate negative correlation with nuclear fraction (r = −0.540), and moderate positive correlation with stroma fraction (r = 0.474). The D value showed moderate negative correlation with nuclear fraction (r = −0.491), and moderate positive correlation with stroma fraction (r = 0.421). The f value showed a moderate negative correlation with stroma fraction (r = −0.423). The D value showed the best diagnostic ability. The optimal cut‐off D value of 0.460 was associated with 77.8% sensitivity and 68.2% specificity (area under the curve, 0.747). Data Conclusion The ADC, D, and f values obtained from DWI and IVIM images showed moderate correlation with the quantitative histopathologic features in a murine model of RMS. Level of Evidence 1 Technical Efficacy Stage 3

Correlation of Intravoxel Incoherent Motion and Diffusion Kurtosis MR Imaging Models With Reactive Stromal Grade in Prostate Cancer

“…Possible reasons are the inclusion of multiple cancer subtypes, the use of different MRI scanners, and the fact that ADC measurements are not currently standardized 30,31 . In our study, ADC values were moderately positively correlated with RSG and differed significantly between high and low reactive stroma groups, in line with the findings of most articles 14,26–28,32,33 …”

“…Conventional DWI has been used to evaluate stromal proportions within rectal, esophageal, pancreatic, breast cancer, head and neck squamous cell carcinoma, and rhabdomyosarcoma content in varying degrees 14,26–31 . However, two studies of rectal and breast cancer showed no correlation between ADC values 30,31 .…”

“…Yao et al 37 confirmed a correlation between D ‐value and stromal content in a study of breast cancer patients. Fang et al 14 found that in a mouse model of rhabdomyosarcoma, D values showed the highest diagnostic value for differentiation of stromal content compared to other parameters. These results are comparable to those of the present study.…”

Correlations between DWI, IVIM, and HIF‐1α expression based on MRI and pathology in a murine model of rhabdomyosarcoma

“…In previous research, Doudou et al 27 compared 10 and 4 b value parameters and found that there was no significant difference between the 2 groups of parameters. In the study of Fang et al, the authors used the same value of b as in our study 28 …”

“…In the study of Fang et al, the authors used the same value of b as in our study. 28 Research investigating the correlation between ADC and HIF-1α expression has shown varying results in different types of tumors. In a study in hepatocellular carcinoma by Huang et al, 29 the ADC value showed a strong positive correlation with HIF-1α expression.…”