ESUR recommendations for MR imaging of the sonographically indeterminate adnexal mass: an update

Abstract

An update of the 2010 published ESUR recommendations of MRI of the sonographically indeterminate adnexal mass integrating functional techniques is provided. An algorithmic approach using sagittal T2 and a set of transaxial T1 and T2WI allows categorization of adnexal masses in one of the following three types according to its predominant signal characteristics. T1 'bright' masses due to fat or blood content can be simply and effectively determined using a combination of T1W, T2W and FST1W imaging. When there is concern for a solid component within such a mass, it requires additional assessment as for a complex cystic or cystic-solid mass. For low T2 solid adnexal masses, DWI is now recommended. Such masses with low DWI signal on high b value image (e.g. > b 1000 s/mm²) can be regarded as benign. Any other solid adnexal mass, displaying intermediate or high DWI signal, requires further assessment by contrast-enhanced (CE)T1W imaging, ideally with DCE MR, where a type 3 curve is highly predictive of malignancy. For complex cystic or cystic-solid masses, both DWI and CET1W-preferably DCE MRI-is recommended. Characteristic enhancement curves of solid components can discriminate between lesions that are highly likely malignant and highly likely benign.

Key points: • MRI is a useful complementary imaging technique for assessing sonographically indeterminate masses. • Categorization allows confident diagnosis in the majority of adnexal masses. • Type 3 contrast enhancement curve is a strong indicator of malignancy. • In sonographically indeterminate masses, complementary MRI assists in triaging patient management.

Keywords: Diagnostic imaging; Magnetic resonance imaging; Ovarian cancer; Ovarian neoplasm; Recommendations.

Fig. 1

Characterization of adnexal masses by combining T2WI and DWI

Fig. 2

Ovarian carcinoma confined to the right ovary (arrow) displaying intermediate SI on T2WI and restricted diffusion characterized by high SI on the high-b-value (b1200) image and loss of signal on ADC

Fig. 3

Technical assessment of DCE MR imaging in complex adnexal masses. This example shows a complex right ovarian mass with a solid component in intermediate T2W signal (a) that heterogeneously enhances after gadolinium injection. Parametric map (maximal slope) helps to determine the most suspicious location (hot spot) where the region of interest should be placed to build the time–intensity curve (b). To compare this curve with the myometrial curve, 3D T1W sequence must be reformatted in the coronal plane to place the two ROI (solid component and external myometrium) (c). Comparison of time–intensity curves shows that the solid component enhances according to a time–intensity curve type 3 (curve steeper than that of myometrium)

Fig. 4

Flow charts with revised algorithm for T1 ‘bright’ masses (a), T2 solid masses (b), and complex cystic or cystic-solid masses (c)

Fig. 5

Differentiation of ovarian versus uterine origin. Beak sign indicating ovarian origin in a benign teratoma (arrows and outlined in a and b). The most important differential diagnosis of a solid adnexal mass includes uterine leiomyoma, which can be differentiated by the claw sign (arrow and outlined in c and d) or in broad-based leiomyomas by bridging vessels (arrow in e and f)