Corpus luteum cyst

Fig. 8.2a-c. Ovarian location in a woman of childbearing age. CT scans at the level of the uterine corpus (a-c) The right ovary (arrow) is located in the ovarian fossa (a). Atypical location of the left ovary (arrow) anterior to the uterine corpus near the anterior abdominal wall (b). A corpus luteum cyst (asterisk) displays attenuation values higher than water and a distinct enhancing wall (c)... 

Ovaries can be identified on CT and MRI due to their location and soft tissue characteristics. The landmark of the ovaries are follicular structures which can be best identified on T2-weighted MRI [8]. On CT, normal ovaries can be best identified after bowel contrast opacification. They are ovoid soft tissue structures with low attenuation areas which represent normal follicles (Fig. 8.2). Presence of a dominant folhde ranging more than 1 cm in size assists in ovarian identification. Hemorrhagic corpus luteum cysts may he identified by high attenuation values or a fluid-fluid level [9]. 

Corpus luteum cysts have thicker enhancing walls than follicle cysts following intravenous contrast application (Fig. 8.6). Corpus luteum cysts may contain blood with bright signal on Tl and T2 as a sign of subacute hemorrhage [8]. Resolution is expected in on follow-up after two to three menstrual cycles and proves the diagnosis of a functional cyst. 

Ovarian cysts under 3 cm are regarded as physiologic cysts. They include follicles of various stages of development, corpus luteum cysts, and surface inclusion cysts. 

The majority of ovarian cysts are foUicular cysts resulting from failure of rupture or of regression of the Graalian follicle. Under nonpregnant conditions, corpus luteum cysts derive fi om 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 anomahes. Large physiologic cysts may cause abdominal pressure or low back pain. Acute abdomen is caused by comphcations such as rupture, hemorrhage, or torsion. 

Both corpus luteum cysts and endometrioma may show intracystic hemorrhage however, only in endometrioma will a prominent T2 shortening ( shading ) be observed [54]. Furthermore, in endometriosis often multiple hemorrhagic cysts maybe found. 

In childbearing age during each menstrual cycle a number of follicles are stimulated to begin to mature, but usually only a single follicle completes the process. At mid-cycle the preovulatory dominant follicle can be identified as a thin-waUed cyst attaining a size of approximately 15-25 mm [7]. After formation of the corpus luteum the wall may involute and become irregular. Corpus lutea maybe cystic or involuted and noncystic [3]. Furthermore,... 

---