Compound Imaging in Ultrasound
Compound imaging (also called spatial compound imaging) is an ultrasound technique that acquires images from multiple different angles and averages them together in real-time, and it significantly DECREASES artifacts while improving image quality.
What is Compound Imaging?
Compound imaging uses electronic beam steering to rapidly acquire 3-9 overlapping scans of the same structure from different view angles. These single-angle scans are then averaged to form a multiangle compound image that updates in real-time 1. This differs fundamentally from conventional ultrasound, which images from a single angle.
Effect on Artifacts: Reduction Across Multiple Types
Compound imaging consistently reduces or eliminates most ultrasound artifacts, though with some important nuances:
Artifacts That Are Reduced or Eliminated:
- Speckle artifact: Significantly reduced, improving tissue differentiation and contrast resolution 1, 2, 3
- Clutter: Markedly decreased, particularly noticeable in fluid-filled structures like the urinary bladder 4 and cystic lesions 2
- Edge shadowing: Either eliminated completely or substantially reduced 4
- General acoustic noise: Significantly decreased 3
- Needle artifacts: Reduced in procedural applications, improving needle visualization 5
Artifacts That Are Modified (Not Eliminated):
- Ring-down artifacts: Produce multiple diverging patterns from a single source with increasing width but decreasing intensity 4
- Acoustic shadowing: Becomes wider but with reduced intensity 4
- Acoustic enhancement: No apparent difference with compound imaging 4
Important Caveat - Artifacts That May Be Diminished:
Some diagnostically useful artifacts may be reduced with compound imaging, which can occasionally be disadvantageous:
- Posterior acoustic enhancement behind cysts is better preserved with conventional imaging 2
- Lateral edge shadowing from cysts and fibroadenomas is recorded better in conventional imaging 2
These specific artifacts can be helpful for characterizing lesions (e.g., confirming cystic nature), so their reduction may occasionally limit diagnostic information.
Clinical Benefits
The artifact reduction translates to tangible clinical improvements:
- Enhanced tissue-plane definition: Particularly valuable in musculoskeletal imaging 3
- Improved lesion conspicuity: Low-contrast lesions become more visible 2
- Better boundary delineation: Capsular margins and ducts are more clearly defined 2
- Superior internal architecture visualization: Solid lesions show improved internal detail 2
- Enhanced needle visibility: Beneficial for ultrasound-guided procedures 5
Practical Considerations
When using compound imaging, recognize that the appearance of artifacts differs from conventional ultrasound 4. The diverging pattern of some artifacts becomes more conspicuous when the focal point is in the far field 4. Despite these modifications, the overall effect is improved image quality with reduced artifact interference in clinical interpretation.
In summary: Compound imaging is an artifact-reduction technology that improves diagnostic image quality, though clinicians should be aware that certain diagnostically useful artifacts (posterior enhancement, edge shadowing) may be diminished.