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Definitions
Coronal plane: image through coronal axis.
Surface rendering: a picture of surface features in a 3D volume.
Three-dimensional inversion display: a method by which the volume is rendered by forming a cast of all of the cystic areas within the volume and having the solid areas become lucent such that only the cast is visible. Positive display of anechoic structures.
Volumetric imaging: assessment of volumetric aspects.
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Three-dimensional (3D) volume imaging of the female pelvis is one of the most important advances in women's imaging within the last decade.1,2 Volume imaging is not new to radiology, as it has been used extensively as part of computed tomography (CT) and magnetic resonance (MR) imaging for several decades. Ultrasound, on the other hand, had been relegated for more than 30 years to individual acquisitions of thin two-dimensional (2D) image slices that are very operator dependent and time consuming to obtain.3 These individual 2D images are largely dependent on the expertise of the operator that produces them, and even a careful review of these individual "snapshots" will often fail to demonstrate the anatomy if the operator does not specifically perceive the finding.
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More recently, 3D sonography has enabled us to move ultrasound into the new era of rapid, automated, and comprehensive imaging and displays.1,2,3, and 4 Images of the entire pelvis can be accomplished with only 3 volume acquisitions: 1 of the uterus and 1 of each ovary.4 These volume acquisitions typically contain all of the sonographic anatomic information within the pelvis and can subsequently be rescanned electronically in any plane by a different operator who may be off site.1,2,3, and 4
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The current methods of sonographic volume acquisition entail automated transducers, which have a dedicated 3D probe within their housing, mechanized to gather 2D ultrasound information from one side of the probe to the other (Figures 47-1,47-2,47-3,47-4,47-5,47-6, and 47-7). The operator holds the transducer still, while the probe sweeps from one side of the housing to the other and the volume is acquired in a systematic and reproducible fashion. However, the faster the speed of this mechanical acquisition, the lower the resolution of the images. Different types of processing can also modify the quality and appearance of the volume data acquired, such as the use of harmonics or other types of image-modification settings.
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