Volume Measurements by Three‐dimensional Ultrasound

One of the first applications of three-dimensional ultrasonography (3DUS) in gynaecology and obstetrics was for measuring volume. Previously, volume was measured by two-dimensional ultrasonography (2DUS) assuming that the scanned object was a regular structure like an ellipsoid. With the advent of 3DUS at the beginning of the 1990s, volumetric measurement became more reliable because 3DUS permitted the outer surface of the structure to be assessed, unlike 2DUS, which used mathematical formulas. The first technique available was the multiplanar method or planimetry, which consisted of volume assessment using the three orthogonal planes (x, y, and z). Later came virtual organ computer-aided analysis (VOCAL), a method that assesses volume by rotating the object in question around an axis. More recently, two new techniques have been introduced: extended imaging virtual organ computer-aided analysis (XI VOCAL) and sonography-based automated volume count (SonoAVC). The former consists of defining pre-established areas on the device screen, while the latter measures the volume of liquid structures. In this chapter, we shall discuss the main techniques of volumetric assessment using 3DUS in gynaecology and obstetrics.

Keywords: Extended imaging virtual organ computer‐aided analysis, Volume measurements, Multiplanar, Sonography-based automatic volume calculation, Three-dimensional ultrasound, Virtual organ computer‐aided analysis.