Introduction

In the modern echocardiography laboratory, three-dimensional transthoracic echocardiography (3D-TTE) complements the standard two-dimensional transthoracic echocardiographic (2D-TTE) examination. 3D-TTE adds value, improves workflow, and substantially improves accuracy in the quantification of cardiac chambers by avoiding errors inherent in the geometric assumptions made in 2D-TTE ( Figs. 10.1 and 10.2 , and Video 10.1 ). 3D TTE provides a more accurate assessment of cardiac morphology and pathology, native and prosthetic valve structure and function, and guidance in interventional intracardiac procedures.

Three-dimensional transthoracic echocardiography (3D-TTE) 3D-TTE employed in the assessment of LV volumes and ejection fraction (EF). 3D-TTE substantially improves the workflow and accuracy in the quantification of cardiac volumetric measures, and avoiding errors inherent in the geometric assumptions made in 2D-TTE, such as LV foreshortening. See also Video 10.1 . (See text and Box 10.1 .) EDV, End-diastolic volume; EF, ejection fraction (LV); ESV, end-systolic volume; SV, stroke volume.

Three-dimensional transthoracic echocardiography (3D-TTE) delivers improved workflow in the modern echocardiography laboratory. Until recently, the 3D exam involved switching from the two-dimensional (2D) phased array transducer to a separate 3D matrix array transducer. However, newer 3D transducer designs facilitate simultaneous 2D and 3D image acquisition using a single probe. (See text and Boxes 10.2 and 10.3 .)

This chapter presents an overview of the basic 3D-TTE image acquisition and optimization techniques used in the echo lab. Optimal utilization of 3D-TTE requires an understanding of the clinical or research application ( Box 10.1 and Table 10.1 ). A comprehensive understanding of the clinical application helps determine the optimal 3D-TTE technique employed in image optimization, acquisition, rendering, display, and analysis ( Fig. 10.3 and ). The specific clinical applications of 3D-TTE employed in the assessment of cardiac structure and function are covered elsewhere in this book (see Chapter 5 ).

Optimizing the three-dimensional (3D) transthoracic echocardiography imaging involves a series of techniques, including optimization of the two-dimensional image, acquisition of the 3D image based on the clinical question, rendering the image, finalizing the image display, and postprocessing analysis. See also . (See text and Box 10.2 .)

The Three-Dimensional Transthoracic Echocardiography Data Acquisition Protocol

The optimization of both patient and machine preparation for 3D-TTE, consistent with the 2D-TTE examination, is important (see Chapter 11 ). Electrocardiography (ECG) gating is critical for 3D trigger-mode imaging. Therefore it is important to obtain a good ECG signal with clearly visible R-waves. Until recently, the 3D-TTE exam required switching from the standard 2D phased array transducer to a 3D matrix array transducer. Today, the most recent 3D “all-in-one” transducer designs facilitate simultaneous 2D and 3D image acquisition using a single probe. This improves workflow efficiency (see Fig. 10.2 ). The following steps are generally required during 3D-TTE image acquisition ( Box 10.2 ; see also Fig. 10.3 and ).

• 1.
  

  2D image optimization

  
  
• 2.
  

  Acquisition modes

  
  
  
  
  • •
    

    Narrow volume vs. wide (full) volume

    
    
  • •
    

    Single-beat vs. multibeat

    
    
  • •
    

    3D zoom

    
    
  • •
    

    3D color

  
  
  
  
• 3.
  

  Rendering

  
  
• 4.
  

  Final image display and analysis

Two-Dimensional Image Optimization

Optimal 3D image acquisition is contingent on acquiring an optimal 2D image, as the same physical principles of B-mode imaging apply ( Box 10.3 ; see Chapter 11 ). If the 2D images are poor, so will be the resultant 3D images. Appropriate transducer frequency selection is necessary for acquisition of the 3D data set. Using a lower-frequency transducer improves image penetration, and is important at greater depths. Harmonic imaging modality is also recommended, as this improves the blood-tissue definition. In order to obtain the best possible images, the operator should (1) optimize the region of interest by reducing the angle, depth, and density of the 3D scan sector volume; (2) maximize the number of subvolumes and increase system gain; (3) avoid or minimize imaging artifacts, including image drop-out or attenuation artifact; and (4) optimize time-gain compensation (TGC). Most times, it is better to over-gain on the 2D image, as the 3D data set can be optimized postacquisition if there is too much gain, to a lower optimal gain setting.

BOX 10.3

• 1.
  

  Optimize your two-dimensional images, including imaging depth, sector size.

  
  
• 2.
  

  Change transducer frequency to penetration harmonics.

  
  
• 3.
  

  Make sure your region of interest is encompassed within the sector by using multiplane scanning.

  
  
• 4.
  

  Use an automated gain optimization tool on your machine.

  
  
• 5.
  

  Turn the overall gain compensation to a little more than half (55–60 units).

  
  
• 6.
  

  Optimize the electrocardiography.

  
  
• 7.
  

  Set the number of beats for acquisition (2-4-6 beats) six beats for added color Doppler.

  
  
• 8.
  

  Once you are ready, ask your patient to take a breath in, and then slowly exhale.

  
  
• 9.
  

  See the image is optimal and ask patient to hold breath.

  
  
• 10.
  

  Press Full Volume, review, check for stitches artifacts, and approve.

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