Twisted ovarian fibroma with high signal intensity on T1-weighted MR image: a new sign of torsion of ovarian tumors?

Comprehensive review of imaging features of sex cord-stromal tumors of the ovary

Sex cord-stromal tumors of the ovary (SCST) are uncommon ovarian tumors arising from sex cord and/or stromal cells of the ovaries. They may be nonfunctional and asymptomatic or functional presenting with hyperestrogenic, hyperandrogenic or cushingoid symptoms. They present in a wide age group of women, mostly in early stages and follow a nonaggressive clinical course after surgical resection. They differ from more prevalent epithelial ovarian tumors which tend to present in older women in advanced stages with poor prognosis. Some of SCSTs are associated with clinical syndromes. We will review imaging features on ultrasound, computed tomography and magnetic resonance imaging, epidemiology and clinical presentations of these tumors.

Magnetic resonance imaging features of ovarian fibroma, fibrothecoma, and thecoma

OBJECTIVE

To retrospectively evaluate the conventional and functional (diffusion- or perfusion-weighted) magnetic resonance (MR) imaging features of ovarian fibroma, fibrothecoma, and thecoma.

MATERIALS AND METHODS

Histologically proven ovarian fibromas (n = 19), fibrothecomas (n = 7), and thecomas (n = 2) were reviewed (26 patients). The morphologic and signal intensity (SI) characteristics on conventional MR imaging (n = 28, all cases) were analyzed. The b 1000 signal intensity on diffusion-weighted image (DWI) (n = 22) and the time-to-signal intensity curve on perfusion-weighted image (PWI) (n = 7) were also analyzed. The presence and shape of the ipsilateral ovarian tissue surrounding the lesions were evaluated on T2-weighted image.

RESULTS

Twenty-two cases (79%) were predominantly solid tumor. Majority of the detected lesions exhibited the characteristic homogeneous low SI on T1- (24/28, 86%) and T2- (19/28, 68%) weighted image. Conversely, a number of lesions exhibited high SI (9/28, 32%) on T2-weighted image. Most lesions presented with a detectable ipsilateral ovary on T2-weighted image (24/28, 86%). Tumors larger than 6 cm more likely showed atypical morphology (mixed solid and cystic, cystic), atypical SI (high on T1- and T2-weighted image), and large amount ascites. Larger tumor group (>6 cm) was more likely diagnosed as fibrothecoma or thecoma than fibroma by pathology. On DWI, 16 lesions showed low b 1000 signal intensity (16/22, 73%). On PWI, all lesions showed curve type 1 or 2 (7/7, 100%), which tends to characterize benign lesions. All (16/16, 100%) pre-menopausal women had a detectable ipsilateral ovary, and six (60%) out of 10 post-menopausal women had a detectable ipsilateral ovary (p < 0.05).

CONCLUSIONS

Combining conventional morphologic and signal intensity characteristics with the findings from DWI or PWI might help differentiate ovarian fibroma, fibrothecoma, and thecoma from ovarian malignancy, although further prospective larger scale study using DWI and PWI is needed.

Benign and Suspicious Ovarian Masses-MR Imaging Criteria for Characterization: Pictorial Review

Ovarian masses present a special diagnostic challenge when imaging findings cannot be categorized into benign or malignant pathology. Ultrasonography (US), Computed Tomography (CT), and Magnetic Resonance Imaging (MRI) are currently used to evaluate ovarian tumors. US is the first-line imaging investigation for suspected adnexal masses. Color Doppler US helps the diagnosis identifying vascularized components within the mass. CT is commonly performed in preoperative evaluation of a suspected ovarian malignancy, but it exposes patients to radiation. When US findings are nondiagnostic or equivocal, MRI can be a valuable problem solving tool, useful to give also surgical planning information. MRI is well known to provide accurate information about hemorrhage, fat, and collagen. It is able to identify different types of tissue contained in pelvic masses, distinguishing benign from malignant ovarian tumors. The knowledge of clinical syndromes and MRI features of these conditions is crucial in establishing an accurate diagnosis and determining appropriate treatment. The purpose of this paper is to illustrate MRI findings in neoplastic and non-neoplastic ovarian masses, which were assessed into three groups: cystic, solid, and solid/cystic lesions. MRI criteria for the correct diagnosis and characteristics for differentiating benign from malignant conditions are shown in this paper.

MR features of physiologic and benign conditions of the ovary

In reproductive women, various physiologic conditions can cause morphologic changes of the ovary, resembling pathologic conditions. Benign ovarian diseases can also simulate malignancies. Magnetic resonance imaging (MRI) can play an important role in establishing accurate diagnosis. Functional cysts should not be confused with cystic neoplasms. Corpus luteum cysts typically have a thick wall and are occasionally hemorrhagic. Multicystic lesions that may mimic cystic neoplasms include hyperreactio luteinalis, ovarian hyperstimulation syndrome, and polycystic ovary syndrome. Recognition of clinical settings can help establish diagnosis. In endometrial cysts, MRI usually provides specific diagnosis; however, decidual change during pregnancy should not be confused with secondary neoplasm. Peritoneal inclusion cysts can be distinguished from cystic neoplasms by recognition of their characteristic configurations. Ovarian torsion and massive ovarian edema may mimic solid malignant tumors. Recognition of normal follicles and anatomic structures is useful in diagnosing these conditions. In pelvic inflammatory diseases, transfascial spread of the lesion should not be confused with invasive malignant tumors. Radiologic identification of abscess formation can be a diagnostic clue. Many benign tumors, including teratoma, Brenner tumor, and sex-cord stromal tumor, frequently show characteristic MRI features. Knowledge of MRI features of these conditions is essential in establishing accurate diagnosis and determining appropriate treatment.

Adnexal torsion: Magnetic resonance findings in the viable adnexa with emphasis on stromal ovarian appearance

PURPOSE

To evaluate ultrasound (US) and magnetic resonance (MR) findings in the viable twisted adnexa.

MATERIALS AND METHODS

Ten patients underwent US and MR studies before surgical detorsion. Corrected cross-sectional area of the ovary was defined as cross-sectional area minus areas of cysts and follicles superior to 1 cm. On T2-weighted images, signal intensity of the stroma was graded as type 1 when it was equal to that of urine and type 2 when it was less than that of urine but markedly more than the contralateral side.

RESULTS

The tube was twisted in six cases and the ovary in nine cases. All adnexa were viable. The largest ovarian cross-sectional area and the largest corrected ovarian cross-sectional area of the twisted ovary were significantly larger than those of the contralateral ovary (P = 0.043 for US; P = 0.012 and 0.017, respectively, for MR). These ovaries contained types 1 and 2 hyperintensity in six cases and only type 2 hyperintensity in three cases. Tubal thickening was seen on MR in five cases.

CONCLUSION

Tubal thickening, enlargement of ovarian stroma as reflected by the corrected cross-sectional area, and hyperintensity of this stroma on T2-weighted images probably related to edema were useful findings in these viable torsions.