MRI of adnexal masses in pregnancy

Abstract

Objective: The objective of this article is to provide a practical review of the incremental benefit of MRI in the assessment of adnexal masses in pregnancy.

Conclusion: MRI can assist sonographic assessment of adnexal masses in pregnancy by depicting the characteristic findings of exophytic leiomyoma, red degeneration of leiomyoma, endometrioma, decidualized endometrioma, and massive ovarian edema. Accordingly, MRI should be considered as a useful adjunct when sonography is inconclusive or insufficient to guide management of adnexal masses discovered in pregnancy.

Fig. 1. 36-year-old pregnant woman who presented for routine early pregnancy sonography

A, Routine early pregnancy transabdominal sonogram obtained at 7 weeks’ gestation shows solid mass (arrow) of indeterminate origin and nature in pelvis posterior to uterus (UT). B, Sagittal single-shot RARE T2-weighted image shows large mixed solid and cystic pelvic mass inferoposterior to gravid uterus. Note that solid parts (arrow) of mass are of low T2 signal intensity. C, Axial RARE T2-weighted image with fat saturation shows mass has beak- or clawlike interface with myometrium (arrows), consistent with uterine origin. Overall findings are those of cystic degeneration in exophytic uterine leiomyoma.

Fig. 2. 34-year-old pregnant woman who presented with lower abdominal pain

A, Transvaginal sonogram obtained at 25 weeks’ gestation shows solid 3.8-cm mass (between calipers) thought to be of right adnexal origin. B, Axial RARE T2-weighted image shows mass (arrow) arises from uterus and is of low T2 signal intensity; also, note “claw sign,” similar to Figure 1. Findings are those of exophytic uterine leiomyoma. C, Axial spoiled gradient-echo T1-weighted MR image shows exophytic uterine leiomyoma (arrow) is of increased T1 signal intensity; this finding indicates red degeneration (i.e., spontaneous hemorrhagic infarction).

Fig. 3

Sagittal single-shot RARE T2-weighted image in 29-year-old woman with ectopic pregnancy at 22 weeks’ gestation shows fetus in extrauterine location. Empty endometrial cavity (arrow) is seen anterior to large leiomyoma (Fibroid).

Fig. 4

Axial RARE T2-weighted image with fat saturation obtained at 24 weeks’ gestation in 29-year-old woman shows complex mixed solid and cystic left adnexal mass (arrow). No increased signal was seen on T1-weighted images (not shown). MRI appearances are nonspecific, although diagnostic considerations include cystic malignancy. Mass was resected and found to be benign hemorrhagic cyst.

Fig. 5. 37-year-old pregnant woman

A, Transvaginal sonogram obtained at 21 weeks’ gestation shows uniformly hypoechoic left adnexal mass (arrow) of indeterminate nature. B, Axial spin-echo T1-weighted MR image shows mass (arrow) is of increased T1 signal intensity. C, Axial spin-echo T1-weighted MR image with fat saturation shows mass (arrow) remains of increased signal intensity, excluding macroscopic fat and suggesting blood. D, Axial single-shot RARE T2-weighted MR image shows mass (arrow) of reduced T2 signal intensity (“T2 shading”). Overall findings are consistent with endometrioma.

Fig. 6. 34-year-old pregnant woman

A, Axial Doppler sonography image obtained at 21 weeks’ gestation shows right adnexal mass (arrow) with smoothly lobulated mural nodules and prominent internal vascularity. B, Axial T1-weighted spoiled gradient-echo MR image shows that fluid in cystic part of mass is of high T1 signal intensity (arrow), which is consistent with blood. C, Axial RARE T2-weighted MR image shows solid component (white arrow) of mass is strikingly similar to decidualized endometrium (between black arrows) in uterus, both with respect to signal intensity and texture. Findings are considered consistent with decidualized endometrioma; postnatal resection confirmed diagnosis.

Fig. 7

Coronal single-shot RARE T2-weighted MR image obtained at 22 weeks’ gestation in 31-year-old woman. Large bilateral multilocular adnexal masses (vertical arrows) are typical of theca lutein cysts, which in this case were associated with twin pregnancy; note two fetal heads (horizontal arrows) in uterus.

Fig. 8. 32-year-old woman with persistent right-sided pelvic pain

A, Transvaginal sonogram obtained at 24 weeks’ gestation shows enlarged right ovary with preservation of peripheral follicles. B, Sagittal RARE T2-weighted MR image shows right ovary (asterisk) is of markedly increased T2 signal intensity to degree that mass might be considered cystic if MRI findings had not been interpreted in conjunction with sonographic findings. Appearance is of massive ovarian edema. Cause of this condition is not well understood but may reflect chronic or subacute low-grade torsion. Beaklike pedicle (arrow) arising from superior aspect of ovary is compatible with this pathogenesis.

Fig. 9

Axial RARE T2-weighted MR image obtained at 18 weeks’ gestation in 29-year-old woman shows large predominantly cystic right adnexal mass with somewhat thickened internal septae (arrow). Resection showed benign cystadenofibroma.

Fig. 10. 22-year-old pregnant woman

A, Axial spin-echo T1-weighted MR image obtained at 24 weeks’ gestation shows adnexal mass is posterior to uterus and contains focus (arrow) of increased T1 signal intensity. B, Axial spin-echo T1-weighted MR image with fat saturation shows that focus of increased T1 signal intensity in A is now of low signal intensity (arrow), confirming presence of macroscopic fat and indicating diagnosis of mature cystic teratoma (dermoid cyst).

Fig. 11. 24-year-old pregnant woman

A, Axial T1-weighted spoiled gradient-echo MR image with fat saturation obtained at 25 weeks’ gestation shows bilateral cystic adnexal masses (arrows) with thick septations and stained-glass appearance due to variable signal intensity among different compartments of lesion. B, Axial RARE T2-weighted MR image shows internal complexity in masses (white arrows) with thick septations (vertical black arrow) and solid nodules (horizontal black arrow). Findings are considered suggestive of malignancy. Resection showed bilateral mucinous cystic tumors of low malignant potential (borderline tumors).

Fig. 12. 34-year-old pregnant woman

A, Axial RARE T2-weighted MR image obtained at 23 weeks’ gestation shows bilateral solid adnexal masses (arrows). B, Axial RARE T2-weighted MR image through upper abdomen shows large tumor deposit (arrow) abutting liver. Appearances are considered indicative of malignancy. Cesarean hysterectomy and bilateral salpingo-oophorectomy were performed at 28 weeks’ gestation because of progression of subphrenic tumor with diaphragmatic irritation. Pathology results showed benign metastasizing leiomyoma. Masses spontaneously regressed after surgery and patient remains free of disease 3 years after surgery.