Protocols

Protocols

A complete 3D echocardiographic study includes an

assessment of ventricular function, valvular morphology,

and hemodynamic status. Unlike 2D echocardiography,

in which standard views are described based on

the plane through which they pass, 3D echocardiography

is inherently volumetric. As such, it permits both

an external view of the heart and multiple internal

perspectives (through cropping).

Table 1 lists the components of a complete 3D

echocardiographic study. A general approach is to

describe cardiac structures using both the ultrasound

plane and the viewing perspective. Three

orthogonal planes are recommended: (1) the sagittal

plane, which corresponds to a vertical, longaxis

view of the heart; (2) the coronal plane,

which corresponds to a 4-chamber view; and (3)

the transverse plane, which corresponds to a

short-axis view (Figure 5). Each plane can be

viewed from 2 sides, which represent opposite

perspectives; for example, the transverse plane,

which represents the short-axis view, can be

visualized from the perspective of the apex or

base; the coronal plane can be viewed from above

or below; and the sagittal plane can be viewed

from the left or right. The choice of narrow-angle

or wide-angle imaging acquisition modes depends

on the cardiac structure to be examined. For

imaging of the ventricles, it is best to use a

wide-angle acquisition in the apical window (4-

chamber) so as to include the entire ventricle. For

smaller structures, such as the aortic valve, a

narrow-angle acquisition may be adequate.

As an alternative to a complete 3D study, 3D echocardiography

can be performed selectively as a complement

to a 2D study. Instead of a complete 3D

echocardiogram, a more focused 3D imaging study

may be appropriate in some cases. For example, in a

patient with mitral stenosis, the 3D portion of the

study may be limited to visualization and quantification

of the mitral orifice. Focused 3D imaging for LV

volume calculation, typically performed with an apical

4-chamber wide-angle acquisition, also can be used to

complement standard 2D imaging.

The ability to extract hemodynamic information

derived from 3D color Doppler ultrasonography is

currently being investigated. To capture and analyze

color flow imaging in 3 dimensions, the area of interest

should be obtained within the 3D data set, with the

angle of the ultrasound beam aligned as parallel as

possible to the direction of blood flow. Depth and

sector settings should be optimized for color Doppler

resolution. Extraneous flows can be cropped so that

only the area of interest is displayed. The color Doppler

flow patterns can be analyzed in multiple views to

provide a complete assessment of the color Doppler

data (Figure 6).