Endometriomas on routine pelvic ultrasound (US) as an indication for MRI for deep endometriosis (DE)

To determine whether presence of endometriomas on routine pelvic ultrasound (US) can predict presence of deep infiltrating endometriosis (DE) on magnetic resonance imaging (MRI) and correlate endometrioma size with the presence of DE on MRI.

In this IRB approved, HIPAA compliant study, radiology data base was queried for MRI exams dedicated for endometriosis evaluation in patients with surgically proven endometriosis over a three-year period (2016-2019). Imaging reports were reviewed for the presence of endometriomas and DE on MRI. For the patients with endometriomas, records were reviewed for concurrent routine pelvic US imaging, which were not tailored to DE protocols. US images were reviewed for the presence of endometriomas, their total number, laterality and largest dimension. Descriptive statistics and receiver operating curve (ROC) analysis were performed. Pathology and surgical notes were used as reference standard.

253 patients with surgically confirmed endometriosis underwent MRI for DIE over a 3-year duration. 47 patients had a concurrent US exam. 33/47 patients (70.2%) had endometriomas seen on US (size range 0.9-7.0 cm). 12 had bilateral endometriomas and 13 had multiple (more than 1) endometriomas. 27/33 (82%) of these patients had DE on MRI. 6/33 (18%) patients had additional sites of DE on surgery, which was not reported preoperatively on MRI. When endometriomas more than 3 cm as were evaluated, 19/21 (90%) of patients had DE on MRI. AUC was 0.7106. Using ROC analysis, a threshold of 3.8 cm, provided a sensitivity of 71% and specificity of 78% for detection of DE on MRI.

Presence of endometriomas on routine pelvic US is associated with a high frequency of DE detected on MRI performed for endometriosis. The frequency of DE on MRI was higher in patients with endometrioma size > 3 cm compared to endometriomas of all size range.