Probably, the most used and useful display is multiplanar display, which simultaneously shows three perpendicular planes (axial, sagital and coronal), allowing navigation through these three planes with the possibility of switch over any desired plane (Alcazar et al, 2006). The digitally stored volume data can be manipulated and presented in various displays: multiplanar display, "niche" mode or surface rendering mode.
This provides more accuracy to this method as compared with the freehand systems, in which speed of sweep is more difficult to maintain constant manually by the operator. When these probes are activated, the transducer elements automatically sweep through the ROI selected by the operator (the so-called "volume box") while the probe is held stationary. The automated method acquires the images using dedicated 3D transducers.
The freehand method requires manual movement of the transducer through the ROI. Technical aspects and three dimensional data analysisģD US images can be obtained by two methods: freehand and automated. 3D surface rendering at 4xmagnification can show the blood vessels in the follicular wall and can identify features incompatible with successfull oocyte retrieval ( Cambell,2010).Ģ.1. This allows identificationof those follicles likely to produce high quality eggsand embryos. The surge in perifolicullar angiogenesis during selection of dominant follicles and following the LH surge or HCG can be detected by measurment of perifolicular flow/velocities. The follicular blood flow seemsto play a major role during the growth and development of the follicle containing the oocyte ( Chui et al.,1997 ),( Coulam et al.,1999). Therefore, three dimensional ultrasound and power Doppler angiography (3D US-PDA) have advantage of assessing simultaneously both the endometrial blood flow and endometrial volume (EV) (Merce et al., 2008 ) andimproves better traditional ultrasound scanningimagingwith the posibility of storing informationforfurther analysis orsharedatasets through telemedicine. Is it limited, however, byproviding flow depictionin a single plane as opposed to the sample volume as obtained byfree dimensional imaging. Two dimensionalDoppler sonography provides a subjective estimation of uterine and ovarian vascularity. Allows to calculate partial volumes and at the same time the of vascular system and flows into the region of interest. The VOCAL (VirtualOrgan Computer – aided Analysis) and volume calculation is semi-authomatic type of calculating volumes starting fromtherotation of the organ target of study. Using 3D Power Doppler Angiography we can assess both arterial and venous circulationalsothe whole architecture of the vascular net into a volumetric image with the posibility of an overallevaluationof blood flows, and computer analysis makes this assessment objective ( Jokubkiene et al., 2006). It is reasonable to believe that an analysis of power Doppler signals in a volume better reflects the overall vascularization in an organ than analysis of a two-dimensional (2D) ultrasound image or measurement of blood flow velocity in a single or a few vessels. Current advances in transvaginal 3D ultrasonography have allowed us to examine in detail and visualize pelvic organ structures to analyse their volumes with great accuracy ( Alcazar et al., 2006),( Raga et al., 1999 ). To asses uterine receptivity one must take various factors into account.
The success of human andembryo implantation depends on maternal and embryonic factors and their interactions.