Ultrasonography (US) utilizes the interaction of sound waves with tissue to produce an image or to determine the velocity of moving contents such as blood in Doppler imaging. US waves are produced by a transducer, which can both emit US waves and detect reflected US echoes. The transducer emits US waves from 3 to 25 MHz and receives reflected sound from the acoustic interface, which is then digitally visualized.
Echogenicity refers to the ability to reflect or transmit ultrasonographic waves in the context of surrounding tissue.
| Echogenicity Type | US Appearance | Common Tissues |
|---|---|---|
| Hyperechoic | Bright white | Ligaments, fasciae, bone surface |
| Hypoechoic | Dark gray | Muscles, cartilage |
| Anechoic | Black (dark) | Vessels, filler materials |
| Isoechoic | Similar to surrounding | Areas with similar tissue structure |
| Frequency | Resolution | Penetration Depth |
|---|---|---|
| 30 MHz | 52 μm | 4–6 mm |
| 22 MHz | 72 μm | 8–10 mm |
| 10 MHz | 158 μm | 35 mm |
| 7.5 MHz | 210 μm | 50–70 mm |
Adjusting the gain changes image brightness. By increasing the gain value, electrical signals are amplified, which increases overall brightness. However, increased background noise may potentially raise artifacts and lower lateral resolution.
| Technique | English | Description |
|---|---|---|
| Pressure | Pressure | Applying vertical pressure to the transducer to position the target structure |
| Alignment (Sliding) | Alignment | Moving the transducer antero-posteriorly and laterally to align the sonic window with the target |
| Rotation | Rotation | Rotating the transducer parallel (long-axis view) or 90° (short-axis view) to the target structure |
| Tilting | Tilting | Tilting the transducer to achieve a 90° insonating angle, increasing resolution |
Recognizing common ultrasound artifacts is essential to avoid misinterpreting images during aesthetic procedures.
| Artifact Type | Cause | US Appearance |
|---|---|---|
| Posterior Acoustic Shadowing | Bone, calcified material, high-echo foreign bodies, or air bubbles | Nonechoic (dark) area behind bright structures |
| Posterior Acoustic Enhancement | Fluid-filled structures (cysts, vessels) adjacent to tissue | Tissue appears hyperechoic behind fluid-filled areas |
| Reverberation Artifact | Vertically parallel structures reflecting multiple echoes at uniform intervals | Multiple equally spaced echoes (commonly seen at metallic needle tips) |
| Bayonet Artifact (Speed Distortion) | Varying speed of US waves penetrating different soft tissues (muscle vs. adipose) | Needle appears bent or distorted |
Converts reflection echoes into bright dot images. The brightness of dots is proportionate to the frequency of reflected sounds. Anatomical structures and movement are digitalized in real time — this is the standard mode used in most US diagnostic machines.
Analyzes periodic waveforms and provides quantitative data for vascular flow direction, speed, and volume.
The needle view depends on the plane used. The long-axis (in-plane) and short-axis (out-of-plane) approaches each have distinct advantages.
| View | Description |
|---|---|
| Long-Axis View (In-Plane) | Shows the entire needle; easier to manipulate but needle tip location is difficult to detect |
| Short-Axis View (Out-of-Plane) | Needle tip appears as a bright “star”; tracing from proximal direction helps locate precise tip position |