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.
Highlights
The previous guidelines for MR imaging of the sonographically indeterminate adnexal mass suggested a basic examination involving T1-weighted imaging (T1WI) and T2weighted imaging (T2WI) to determine the nature and key signal characteristics of the mass, supplemented by additional oblique T2W imaging, fat-suppressed T1W (FST1W) or contrast-enhanced T1W (CET1W) imaging, depending on the key characteristic of the mass [1].Recently, much effort has been invested in improving presurgical diagnosis of adnexal tumours by developing risk models and scoring systems using sonography [2,3,4]
If the solid component of an indeterminate adnexal mass is of low signal intensity (SI) on T2WI, and the entire mass displays low signal on Diffusion-weighted imaging (DWI) obtained with a b value of 800–1000 s/mm2, there is a very high likelihood of benignity [11]
It is our recommendation that a solid adnexal mass with T2 intermediate SI or a T2 dark mass showing other than low DWI signal be further assessed by CET1W imaging, ideally with Dynamic contrast-enhanced (DCE) MRI when this is available
Summary
The previous guidelines for MR imaging of the sonographically indeterminate adnexal mass suggested a basic examination involving T1-weighted imaging (T1WI) and T2weighted imaging (T2WI) to determine the nature and key signal characteristics of the mass, supplemented by additional oblique T2W imaging, fat-suppressed T1W (FST1W) or contrast-enhanced T1W (CET1W) imaging, depending on the key characteristic of the mass [1]. Initial studies evaluating DWI in adnexal masses reported high SI in mature cystic teratomas and endometriomas as well as in malignant masses, whilst the majority of fibromas and other benign masses had low DWI signal [9, 14]. A plane selected across the maximum point of contact of the mass and uterus is required to determine whether it is ovarian or uterine in origin and to look for bridging vessels b A solid mass which has low signal on DWI sequences with b values of ≥ 800 s/mm can be regarded as benign, and CET1W imaging is unnecessary c As T2 solid masses with intermediate to high DWI signal may be benign or malignant, additional CET1W imaging is required d Ideally, with DCE MRI, where a type 3 curve is highly predictive of malignancy great majority of these lesions can be accurately diagnosed by observing their T2W features and the characteristics on T1W and FST1W imaging. If the solid component of an indeterminate adnexal mass is of low SI on T2WI, and the entire mass displays low signal on DWI obtained with a b value of 800–1000 s/mm, there is a very high likelihood of benignity [11]
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