Diffusion Weighted (DW) MRI in Correlation with Dynamic Contrast Enhanced MRI for Characterization of Ovarian Masses

Background: Ovarian tumors; are the second most common gynecological tumor and in women
are the fifth commonest tumor. Preoperative differentiation between benign and malignant tumors is essential to decide whether surgery is required, and which type of surgery is appropriate avoiding unnecessary surgery. In addition to conventional imaging, dynamic contrast and diffusion weighted images can aid in the separation of benign from malignant ovarian tumors. DWI is based on the notion that water molecules can freely diffuse in a low-cellular environment, but tissue hypercellularity restricts this. As a result, unlike most benign tumors, malignant ovarian tumors have restricted diffusion due to their hypercellular structure. DCE-MRI depends on contrast agent leaking from capillaries into extravascular extracellular space to allow for quantitative ovarian lesions characterisation.

Aim of the Work: To evaluate the role of diffusion- weighted MR imaging correlated to dynamic contrast enhanced MRI in characterization of ovarian masses.

Patients and Methods: thirty female patients were included in this study. Who referred to the radiology department by ovarian masses. All patients underwent detailed history taking, laboratory investigations, Pelvic ultrasound examination and MRI examination with DWI and DCE MRI. The correlation was done between MRI findings and the final pathological diagnosis.

Results: The sensitivity of conventional MRI was 72.73% while that of DWI was 100%. The specificity was lower for DWI (57,89%) compared to conventional MRI (73.68%), The mean ADC values for malignant lesions were (0.91 x 10-3 ± 0.25 SD mm2/s), while that for benign lesions were (1.68 x 10-3 ± 0.65 SD mm2/s), with cut off 1.2 x 10-3. Mature teratomas and endometriomas showed restricted diffusion with low ADC values (false positive).

Sensitivity of conventional MRI was 72.73% while that of DCE-MRI was 90.91%. The specificity was higher for DCE 100% compared to conventional MRI sequences 72.73%, as well as the accuracy which was 73.33% for conventional MRI while that of DCE was 96.67% and so addition of DCE to the MRI is expected to increase the specificity

and the accuracy of examination.

Conclusion: Adding DWI and DCE to conventional MRI signifies: utilising a completely non-invasive procedure with no exposure to radiation. It enhances the specificity of MRI, hence enhancing the radiologist's confidence in image interpretation, which will ultimately affect the prognosis and outcome of patients.