High correlation between Ki-67 expression and a novel perfusion MRI biomarker diffusion-derived vessel density (DDVD) in endometrial carcinoma

Objective: This study aimed to investigate the feasibility of diffusion-derived vessel density (DDVD) in characterizing tumor microvasculature in endometrial carcinoma (EC), and to explore the correlations with Ki-67 proliferation status and histological type based on DDVD values.

Methods: There were in total 81 EC patients. There were 64 cases of non-aggressive histological type, and 17 cases of aggressive histological type. Ki-67 labeling index was low (<50 %) in 35 cases and high (≥50 %) in 46 cases. DDVD_(b0b20) is calculated according to: DDVD_(b0b20) = S_b0/ROI_area0 - S_b20/ROI_area20, where S_b0 and S_b20 refer to the tissue signal when b is 0 or 20 s/mm². Intraclass correlation coefficient (ICC); two-tailed independent samples t-test and Mann-Whitney U test; Receiver Operating Characteristic, area under the curve (AUC).

Results: Endometrial carcinoma showed lower DDVD_(b0b20) values (34.9 ± 21.2, au/pixel) compared with myometrium (65.3 ± 37.4, P < 0.001). Tumors with Ki-67 high-proliferation or aggressive histological type had higher DDVD values than those with Ki-67 low-proliferation (44.17 (median) vs. 16.08, P < 0.001]] or non-aggressive histological type (47.92 vs. 30.77, P = 0.002). DDVD_(b0b20) ROC curve analysis shows AUC of 0.842 for distinguishing between Ki-67 low- and high-expression, and AUC of 0.771 for distinguishing between non-aggressive and aggressive histological types. DDVD_(b0b20) > 32.9 and DDVD_(b0b20) > 50.1 provided a specificity of 85 % for identifying Ki67 high expression (sensitivity 78.3 %) and histological aggressive type (sensitivity 47.1 %), respectively.

Conclusion: DDVD can act as an imaging marker reflecting Ki-67 proliferation histological aggressiveness of EC, thus helping pretreatment risk assessment in EC.