MRI can also help determine the origin of the lesion, with up to 9% of presumed adnexal lesions on US being nonadnexal origin [73]. Sonographically visualized lesions >10 cm may need contrast-enhanced MRI to ensure complete visualization and assessment of the lesion and ensure there are no associated solid components. The presence or absence of enhancing solid tissue and enhancement curve characteristics as evaluated on perfusion dynamic contrast-enhanced imaging drives the risk of malignancy on MRI [17,69,71,74-80]. The absence of enhancement renders the risk of malignancy to nearly 0%, which is of particular value in the sonographically indeterminate lesions because it confirms the benignity of the lesion [71]. Solid tissue with time intensity curves (TIC) with rapid enhancement greater than the myometrium (type 3) are only found in invasive malignant tumors with a sensitivity of 67% versus slow low level enhancement (type 1) found in benign tumors with a sensitively of 70% and specificity of 89% [79]. Diffusion-weighted imaging (DWI) and apparent diffusion coefficient (ADC) values of benign and malignant lesions overlap, with Fujii et al [81] demonstrating teratomas, some endometriomas, and malignant tumors demonstrating abnormal DWI signal. The primary value of DWI is in the setting of a low T2 signal mass, with low signal on DWI predicting a high likelihood of benignity [69,81,82]. MRI Pelvis Without IV Contrast Contrast-enhanced MRI performs superiorly to both US and noncontrast MRI due to its ability to confirm the presence of internal enhancing soft tissue components [18]. Both the ADNEX and O-RADS MRI risk stratification systems will have some decreased usefulness in the noncontrast setting given the limited ability to identify enhancing solid tissue and its enhancement pattern, both crucial for characterizing indeterminate lesions [17,71,73].
Clinically Suspected Adnexal Mass No Acute Symptoms. MRI can also help determine the origin of the lesion, with up to 9% of presumed adnexal lesions on US being nonadnexal origin [73]. Sonographically visualized lesions >10 cm may need contrast-enhanced MRI to ensure complete visualization and assessment of the lesion and ensure there are no associated solid components. The presence or absence of enhancing solid tissue and enhancement curve characteristics as evaluated on perfusion dynamic contrast-enhanced imaging drives the risk of malignancy on MRI [17,69,71,74-80]. The absence of enhancement renders the risk of malignancy to nearly 0%, which is of particular value in the sonographically indeterminate lesions because it confirms the benignity of the lesion [71]. Solid tissue with time intensity curves (TIC) with rapid enhancement greater than the myometrium (type 3) are only found in invasive malignant tumors with a sensitivity of 67% versus slow low level enhancement (type 1) found in benign tumors with a sensitively of 70% and specificity of 89% [79]. Diffusion-weighted imaging (DWI) and apparent diffusion coefficient (ADC) values of benign and malignant lesions overlap, with Fujii et al [81] demonstrating teratomas, some endometriomas, and malignant tumors demonstrating abnormal DWI signal. The primary value of DWI is in the setting of a low T2 signal mass, with low signal on DWI predicting a high likelihood of benignity [69,81,82]. MRI Pelvis Without IV Contrast Contrast-enhanced MRI performs superiorly to both US and noncontrast MRI due to its ability to confirm the presence of internal enhancing soft tissue components [18]. Both the ADNEX and O-RADS MRI risk stratification systems will have some decreased usefulness in the noncontrast setting given the limited ability to identify enhancing solid tissue and its enhancement pattern, both crucial for characterizing indeterminate lesions [17,71,73].