Introduction

MSI is considered to be one of the pathogenesis of endometrial carcinoma (EC) [1]. At present, immunohistochemical is the common method to determine the MSI status of EC so that to detect the expression of four mismatch repair proteins in tumor tissues of patients with EC, including MLH-1, MSH-2, MSH-6 and PMS-2[2]. This method is mostly obtained after postoperative analysis, so it is expected that some methods can predict MSI status of EC before surgery. The diffusion kurtosis imaging (DKI) sequence is an extension of the diffusion weighted imaging (DWI) and the diffusion tensor imaging (DTI) sequence, which is a MR imaging technique based on the non-Gaussian distribution model of water molecules[3-5]. This study intends to explore the value of multiple quantitative parameters of DKI sequence in predicting MSI status of EC, with the hope to provide new ideas for preoperatively, non-invasively predicting MSI status, and to expand the application of DKI sequence in uterine diseases.

Materials and Methods

Data of 38 patients with EC were collected in the study, including 12 in the MSI group (age from 47 to 82 years old, with an average of 64.1±9.8) and 26 in the MSS group (age from 35 to 78 years old, with an average of 56.7±12.8). All patients have undergone 1.5T MRI (GE Signa HDxt, America) examination in our hospital within 2 weeks before the operation, and the scanning sequence contained DKI. The scanning parameter settings were as follows: using single excited spin echo plane echo (SE-EPI) sequence, TR/TE=3000/98 ms, matrix=128×128, NEX=2.0, FOV=32 cm×32 cm, slice thickness = 0.5cm, with 0, 1000 s/mm2 and 2000 s/mm2 of b values. The scanning time was about 3'. The quantitative values were independently measured by two radiologists. The workstation Function software package was used to post-process the original DKI images to obtain pseudo-color images (Fig. 1). Referring to the T2WI images, the largest section of the lesion and its upper and lower 1-2 levels were selected, and the regions of interest (ROIs) were manually drawn in the tumor parenchymal area. The intra-class correlation coefficient was used to test the consistency between measurements by the two radiologists. The Mann Whitney U test was used to analyze the difference between the values of DKI parameters of MSI and MSS. The ROC curve was used to test potency of the predictive value in distinguishing the two statuss of EC.

Results

Measurements by the two radiologists were in good agreement (ICC=0.985). The MK, Ka, Kr, FA, FAk, MD, Da, and Dr values of MSI group were 1.074±0.162, 1.253±0.229, 0.886±0.205, 0.207±0.041, 0.397±0.129, 0.890±0.158 μm2/ms, 1.083±0.218 μm2/ms and 0.793±0.133 μm2/ms; of MSS group were 0.956 (0.889,1.002), 1.048±0.211, 0.831±0.099, 0.188±0.061, 0.334 (0.241,0.410), 1.043±0.217 μm2/ms, 1.235±0.229 μm2/ms and 0.946±0.215 μm2/ms. The MK and Ka values of MSI group were significantly higher than those of MSS group (P<0.05), and the MD and Dr values were significantly lower than that of MSS group (P<0.05) (Tab. 1). The AUC of MK, Ka, MD, and Dr values in predicting MSI status of EC were 0.763, 0.729, 0.731, 0.748, respectively. The sensitivity were 58.3%, 50.0%, 65.4%, 61.5%, and the specificity were 96.2%, 92.3%, 75.0%, 83.3%, respectively (Fig. 2).

Discussion and Conclusion

The MK and Ka values of MSI group were significantly higher than those of MSS group, and the MD and Dr values were significantly lower than that of MSS group. And the ROC curve indicated that they had favorable accuracy and specificity. All in all, as a non-enhanced functional imaging of MR, DKI can provide multiple quantitative parameters for non-invasive predicting MSI status of EC, such as MK, Ka, MD, and Dr and it has certain clinical application value.

Acknowledgements

No acknowledgement

References

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