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Книги по МРТ КТ на английском языке / MRI and CT of the Female Pelvis Hamm B., Forstner R..pdf
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Adnexal Masses: Benign Ovarian Lesions and Characterization

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4\ Benign Adnexal Lesions

4.1\ Non-neoplastic Lesions

of the Ovaries and Adnexa

4.1.1\ Physiological Ovarian Cysts: Follicular and Corpus Luteum Cysts

The ovaries change their appearance periodically during their ovarian cycle. The ovarian cycle consists of development of the ovarian follicle, rupture, discharge of the ovum, formation, and regression of corpus luteum. Ovaries may contain follicles of various stages of development, corpus luteum cysts, and surface inclusion cysts.

Physiological ovarian cysts constitute the vast majority of cystic adnexal lesions. In the reproductive age ovarian cysts are defined as ovarian cysts if they are larger than 3 cm in size, whereas smaller lesions present follicles (Levine et al. 2010). Cysts may be classified as functional, which means they are associated with hormone production, or nonfunctional. In nonpregnant patients, corpus luteum cysts derive from failure of regression or hemorrhage into the corpus luteum.

Functional cysts are asymptomatic in the majority of cases. Progesterone production may persist in corpus luteum cysts, resulting in delayed menstruation or bleeding anomalies. Large physiologic cysts may cause abdominal pressure or low back pain. Acute abdomen is caused by complications such as rupture, hemorrhage, or torsion.

With an estimated prevalence of 18% ovarian cysts are a common finding in the reproductive age. Less commonly small cystic lesions may be also found in the postmenopausal age. In a series of 74 normal ovaries, the average size of the largest cyst was 1 cm (range, 0.2–4.7 cm) (Outwater and Mitchell 1996). Functional cysts usually do not exceed 5 cm in size, but may occasionally grow as large as 8–10 cm (Fig. 7). In most cases, they are self-limiting and will regress spontaneously. In contrast to follicular cysts, corpus luteum cysts often require a period of up to 3 months to regress.

a

b

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Fig. 7  Functional cyst in a 29-year-old woman. Transaxial T1 (a), T2-weighted (b), and contrast-­ enhanced T1-weighted images with FS (c). An 8-cm cystic ovarian lesion (arrow) displays intermediate signal intensity on T1-weighted image similar to the myometrium (a) and very high SI on T2-weighted image (b). It has a thin wall well demonstrated on T2-weighted image (b) and after contrast administration (c). A functional cyst, most likely a corpus luteum cyst, could not be differentiated from an ovarian cystadenoma. The sonographic follow-up showed a considerable decrease in size within 3 months. Small amount of physiologic fluid is seen in the cul-de-sac

4.1.1.1\ Imaging Findings in Physiological Ovarian Cysts

Transvaginal sonography is the gold standard for the diagnosis of ovarian cysts. According to recent management guidelines simple ovarian cysts of less than 5 cm in size do not require