The role of diffusion-weighted imaging in the evaluation of adnexal lesions

Introduction
Magnetic resonance imaging (MRI) has been used as a problem-solving tool in the diagnosis of adnexal lesions. Both benign and malignant ovarian masses can present as complex adnexal lesions. Preoperative diagnosis of malignancy is essential for planning the surgical approach and appropriate treatment regimen. The aim of our study was to determine the role of diffusion-weighted MRI (DWI) in differentiating benign from malignant adnexal lesions.

Material and methods
Fifty-five patients (constituting 67 lesions) referred to MRI for evaluation of adnexal lesions were studied using 1.5 T MRI. The signal on DWI (qualitative) and ADC values (quantitative DWI) of the solid and cystic components of the lesions were analysed separately. Chi-square test, cross tabulation, and ROC curves were used to determine features on DWI that could distinguish benign from malignant lesions.

Results
Of the 67 lesions, 50 were benign and 17 were malignant. There was a significant association of hyperintense signal of solid components on T2W and DWI with malignancy, with a p-value of 0.003 and 0.001, respectively. Benign lesions showed hypointense signal on T2W and DWI. ADC values of the solid components could not distinguish benign from malignant lesions; p = 0.290. The signal intensity and ADC values of the cystic fluid in benign and malignant lesions showed a significant overlap.

Conclusions
Qualitative DWI acts as an adjunct to conventional MRI in differentiating benign from malignant adnexal lesions showing solid/mixed morphology. It plays no role in distinguishing lesions based on their cystic components. ADC values play no role in differentiating benign from malignant adnexal lesions irrespective of lesion morphology.