Intravoxel Incoherent Motion Imaging in Differentiation Borderline From Malignant Ovarian Epithelial Tumors: Correlation With Histological Cell Proliferation and Vessel Characteristics

Abstract

Background: The differentiation of borderline from malignant ovarian epithelial tumors (OETs) is difficult based on morphologic characteristics. Diffusion and perfusion information from intravoxel incoherent motion (IVIM) diffusion-weighted imaging (DWI) might be useful for this distinction.

Purpose: To investigate the potential of IVIM-DWI in discriminating borderline from malignant OETs by correlating with cell proliferation and microvessel density (MVD).

Study type: Prospective.

Subjects: Sixty-six patients with OETs (22 borderline, BOETs; 44 malignant, MOETs) underwent IVIM-DWI before surgery.

Field strength: 3.0T IVIM-DWI sequence with 12 b-values (0-1000 sec/mm² ).

Assessment: Apparent diffusion coefficient (ADC) and IVIM-DWI parameters (diffusion coefficient [D], microvascular volume fraction [f], and pseudodiffusion coefficient [D*]) were measured. Cell proliferation and MVD was determined by immunohistochemical staining of Ki-67 and CD-31, respectively.

Statistical tests: Mann-Whitney U-test; two-sample t-test; intraclass correlation coefficient; Bland-Altman analysis; receiver operating characteristics (ROC) curves; and Spearman correlation.

Results: ADC and D in BOETs was significantly higher than those in MOETs (P < 0.001), while f in BOETs was significantly lower than those in MOETs (P < 0.001). No significant difference was found in D* between borderline and malignancies (P = 0.324). In the differential diagnosis of borderline from malignant OETs; D demonstrated the highest area under the curve (AUC) of 0.951, while ADC and f had a lower AUC of 0.921 and 0.847, respectively. The ADC and D was negatively correlated with cell proliferation (r = -0.682, r = -0.694, respectively, P < 0.001), while f was positively correlated with MVD of the OETs (r = 0.558, P < 0.001).

Data conclusion: IVIM-DWI may be a useful tool for differentiating BOETs from MOETs. D and f could be image biomarkers to reflect histopathological characteristics of cell proliferation and MVD in OETs.

Level of evidence: 1 Technical Efficacy Stage: 2 J. Magn. Reson. Imaging 2020;51:928-935.

Keywords: cell proliferation; diffusion-weighted imaging; epithelial ovarian tumors; intravoxel incoherent motion; microvessel density.