Recognition of these limitations of 2DE led to burgeoning research and clinical interest in the modality of 3-D echocardiography (3DE). Early reconstructive approaches were based on 2DE acquisitions and subsequent stacking of 2DE images to recreate a 3-D dataset. However, the need for offline processing imposed fundamental limitations on the practicality of these approaches. More recently, the focus has shifted toward the acquisition of a 3-D ‘wedge’ or trapezoid in realtime. New transducer technology has enabled this, evolving from the familiar phased array of 2DE (with 128 elements) to the matrix array that is designed for 3DE (with 2,500–3,000 elements). 3DE matrix array transducers have been commercially available since the spring of 2003. Given the early phase of technology development at the time, it is not surprising that these transducers were heavy, with a large footprint, low frame rates, and limited features. The inherently low frequency of these transducers translated into poor spatial resolution. As a result, the pediatric community continued to view 3DE with skepticism. The gap between existing imaging technologies and the ideal imaging modality has remained large. But what is ideal?

The Ideal Modality
The ideal modality for non-invasive imaging of the heart would have the following characteristics:

For the echocardiographer:

• the modality should be able to image the entire region of interest in three dimensions in realtime;
• the modality should be integrated into current imaging equipment;
• the modality should be portable and easily performed and repeated;
• spatial and temporal resolution should be of diagnostic quality;
• it should be adaptable to patients of varying sizes and heart rates;
• the modality should overcome the limitations imposed by the 2-D display; and
• images should be easily viewed, manipulated, and quantified at any time, and should be accessible from any PC.

For the hospital:

• the modality should be financially viable;
• it should lead to improvements in work flow; and
• it should be integrated into existing image management systems.

For the operator:

• the modality should have a realistic learning curve;
• it should be fun to use and easy to interpret; and
• the ergonomics of the modality should be reasonable.

For the surgeon:

• images should be amenable to post-processing. This provides the potential for viewing perspectives that may be critical for surgery, but not necessarily obvious to others.

For the patient:

• the modality should provide valuable additional information;
• it should provide the potential for making a real difference to the patient’s care and outcome; and
• it should be quick, risk-free and easy.

For the researcher:

• the researcher should be able to rely on the industry’s commitment (in its on-going research and development) to the new technology; and
• the modality should yield new information that is important enough to make the researcher’s proposals competitive for grant funding.

While the ideal modality as detailed above does not exist currently, recent advances hold great promise for the future. This review focuses on the new pediatric matrix transthoracic X7-2 3DE transducer (Philips Medical Systems, Andover, MA), which our laboratory has helped to develop, optimize, and validate.