P1120994

The ukrasomc image of a foOide in cro» sectioo b seen as an anechoic area on tbe monitor. The latter can be dełineated by a narrow hrighter linę which fofiows tbe outlme of tbe fofficie. Tbe anechoic naturę of tbe foOide a caused by tbe bek of reflection of sound waves as tbey trawi tbrougb tbe relatively ceO free_t dear folii-cułar fluid. Occasiooally, and partkularly in larger folłides, there wiD be dumps of reflerions pabłe dose to tbe foflicular wali The shape of folłides varies brom drcuiar to oval to irregularły połygonal to nearły angu-lar (Fig. 1.10). These variations in shape are tbe result of differences in pressure between neighboring fofli-des. corpora hitea or even the ovarian stroma itsełf (Ginther and Person 1984 a). Wben adjacent foł-tides are of equal pressure their adjoining walk are often completeły straight. In contrast, gnali foflides of high inner pressure may deariy bulge into the lumen of larger. softer folłides (Fig. Ul). When the ovary contains numerous gnali, tense folłides its ułtrasound image may resemble a honeycomb.

Tbe folbcular waB is hyperecboic and thin. A narrow hyperechoic Hue is often vigble where the ultrasound

warcs impact vcrticaUy onto the front and back wali of the foOide (Fig. 1.9 and 1.10). LateraOy to th» koe the ecbogerucny is reduced along the obbqucły orknled walk. The echo intensńy in thk area fe. cotnparable to that of moderately dense tissue and k hardy dktingaiKb-able ftom the surrotindmg sirom In the region of lao-gentialwaw niipart tbe IbiliciiIarwaBBtJSualfyiiocWsi-ble- These areas are firequently marked by the origins of the shadow artifacts that begin here and stretch into the depth of the image.

The echo enhancement of the tissues behind larget folłides is one of their typical features. The size of thk enhancement area is conelated with the aze of the fot-hde.

Using ułtrasound at a freąuency of 3i MHz one can relatively rehabły detect fołhcłes that are 6 to 8 mm in size, but whh ułtrasound at 5.0 MHz foihdes of 3 to 5 mm are detectable with relathe ease (Palmer and Driancourt 1980, Ginther and Person 1984 b).