Introduction: Basic Ultrasound Principles

Figure 1.1

B-mode imaging: Brightness mode imaging of the heart. Brightness mode or B-mode is the standard ultrasound mode for all clinical imaging

Figure 1.2

M-mode imaging: Motion mode imaging of the heart. Motion mode or M-mode cardiac evaluates the movement of structures within the body. This image demonstrates the utilization of M-mode to evaluate movement of the left ventricle over time

Figure 1.3

High gain: This image demonstrates the parasternal long view of a heart with high gain. Gain is related to brightness of the image. When the gain is too high, the image will be bright and details are lost

Figure 1.4

Low gain: This image demonstrates the parasternal long view of a heart with low gain. Gain is related to brightness of the image. When the gain is too low, the image will be dark and details are lost

Figure 1.5

High depth: This image demonstrates the parasternal long view of a heart with the depth set too deep. The structure of interest should be centered in the screen

Figure 1.6

Shallow depth: This image demonstrates the parasternal long view of a heart with the depth set too low. The structure of interest should be centered in the screen

Figure 1.7

Ideal depth: This image demonstrates the parasternal long view of a heart with ideal depth and gain settings to properly vision the entire structure of interest as well as the appropriate level of detail

Figure 1.8

Color Doppler: Color Doppler measures shifts in velocity which are color coded according to direction of flow in relationship to the transducer; flow away from the transducer will appear blue, and flow toward the transducer will appear red. Note that it does not relate to venous and arterial flow. In this image, the testicles are being assessed for vascular flow with color Doppler

Figure 1.9

Power Doppler: Power Doppler will display a signal in color if there is any motion at all. It does not indicate velocity or direction. In this image, the testicles are being assessed for vascular flow with power Doppler

Transducer Selection

Curvilinear Transducer
- Low frequency with a wide field of view.
- Greater tissue penetration allows for imaging of deeper structures.
- Ideal for abdominal imaging.
- Typical frequency range is 2–5 MHz [3].
  
  Figure 1.10—Curvilinear transducer
Phased Array Transducer
- Smaller flat footprint.
- Uses electronic beam steering to produce a pie-shaped field of view.
- Allows for imaging through small areas such as between ribs.
- Most commonly used for cardiac imaging.
- Typical frequency range is 2–7 MHz [4].
  
  Figure 1.11—Phased array transducer
Linear Array Transducer
- Produces a rectangular image.
- High frequency makes this transducer ideal for imaging superficial structures including soft tissue, muscles, nerves, arteries, and veins.
- Often used for procedural guidance.
- Typical frequency range is 5–10 MHz [2].
  
  Figure 1.12—Linear transducer
Endocavitary Transducer
- Produces an image with a wide field of view, up to 180° [2].
- Specialized high-frequency curvilinear transducer that is commonly used for obstetric, gynecologic, or ear, nose, and throat (ENT) applications.
- Typical frequency range is 8–13 MHz [2].
  
  Figure 1.13—Endocavitary transducer