Common Ultrasound Artifacts: Prevention and Solutions

Ultrasound artifacts can distort medical images, leading to misdiagnoses if not properly addressed. This guide explains common artifacts like acoustic shadowing, reverberation, tissue-related issues, and motion artifacts, along with practical solutions to improve image quality and diagnostic accuracy.

Key Points:

• Acoustic Shadowing: Caused by dense structures blocking sound waves. Adjust transducer angle, pressure, or use alternative imaging techniques.

• Reverberation Effects: Occur due to repeated sound wave reflections. Modify insonation angle, lower near-field gain, and use advanced imaging methods.

• Tissue-Related Artifacts: Result from density variations. Optimize machine settings like frequency, gain, and focus zone.

• Motion and Blood Flow Artifacts: Caused by patient or transducer movement. Encourage breath-holding, adjust Doppler settings, and reduce color gain.

Quick Tips:

• Use higher frequencies for shallow imaging, lower for deeper areas.

• Enable harmonic imaging to reduce noise.

• Adjust PRF and insonation angle for accurate blood flow measurements.

Understanding and correcting artifacts ensures better diagnostic outcomes and patient care.

Acoustic Shadowing

How Shadowing Happens

Acoustic shadowing is an ultrasound artifact that appears when sound waves hit dense or highly reflective structures. These structures - like bone, calcifications, or air interfaces - block the sound waves, creating a dark "shadow" on the image beneath them.

When ultrasound waves encounter objects with high acoustic impedance, such as gallstones or bone, a significant amount of the sound energy is either reflected back or absorbed. This prevents the waves from passing through, leading to the shadow effect. Recognizing this phenomenon is key to improving image clarity and avoiding diagnostic errors.

Tips to Prevent Shadowing

To minimize shadowing, consider these practical steps:

• Transducer Positioning: Keep the transducer perpendicular to the area being scanned for clearer images.

• Pressure Control: Apply gentle, consistent pressure with the transducer to avoid tissue distortion and maintain proper blood flow.

• Focal Depth Setting: Adjust the focal depth carefully. Shadows tend to be more noticeable when the focal depth is close to the obstructing object.

Techniques to Minimize Shadowing

If shadowing becomes a challenge, try these methods:

• Alternative Scanning Approaches

  • Rotate the transducer to uncover better acoustic windows.

  • Use cross-beam imaging to reduce lateral shadows and improve visibility.

• Equipment Adjustments

  • Use standoff pads for imaging shallow structures.

  • Fine-tune the depth of focus to manage shadow intensity.

• Dynamic Scanning

  • Gradually move the transducer to maintain the best imaging angles.

  • Change the insonation angle to confirm lesion visibility.

  • Scan from different planes to reduce shadow artifacts.

Interestingly, while shadowing often complicates imaging, it can also be diagnostically helpful. For example, an acoustic shadow behind the gallbladder can indicate the presence of gallstones, even if the stones themselves are too small to see directly ^[2].

Ultrasound Artifacts, Part 1 (Shadowing, enhancement and ...

Reverberation Effects

Managing reverberation artifacts is crucial for achieving clear ultrasound images and ensuring accurate diagnoses.

Types of Reverberation

Reverberation artifacts occur when ultrasound waves repeatedly bounce between reflective surfaces, producing multiple echo lines that can obscure anatomical details ^[3].

• Comet tail artifacts: These appear as a short series of echoes originating from a highly reflective structure ^[4].

• Ring-down artifacts: These resemble comet tail artifacts but are caused by a different mechanism ^[4].

Reducing Reverberation

To minimize the impact of these artifacts, consider the following techniques:

• Transducer adjustments: Change the insonation angle to reduce parallel reflections ^[4].

• Optimizing machine settings: Lower near-field TGC (Time Gain Compensation) to help reduce comet tail artifacts ^[5].

• Advanced imaging methods: Techniques like M-mode echocardiography and multiplane transesophageal echocardiography (TEE) can help distinguish artifact types and confirm the accuracy of images ^[5].

Tissue Effects on Images

Tissue density plays a key role in ultrasound image quality and how well sound waves travel through the body. To improve imaging and reduce artifacts like shadowing and reverberation, understanding how tissues interact with ultrasound waves is crucial. Let’s explore how tissue variations impact imaging and how machine settings can be adjusted to address these challenges.

Tissue Density Effects

Ultrasound waves behave differently when they pass through tissues with varying densities ^[1]. This interaction can create artifacts that influence diagnostic accuracy.

• Dense tissues, such as bone or calcifications, reflect most of the ultrasound waves, limiting penetration.

• Fluid-filled areas allow waves to pass through more easily, improving image clarity.

These tissue differences affect:

• Signal strength and how deep the waves can penetrate

• Image clarity, including resolution

• Artifact patterns, which may obscure details

• Overall diagnostic precision

Spotting Image Artifacts

Artifacts caused by tissue variations can be identified with careful observation ^[6]. Watch for:

• Brightness changes that don’t match tissue composition

• Irregular shadowing

• Blurred or inconsistent tissue boundaries

• Unusual echo patterns

"During their training, sonographers are taught, and encouraged, to use the minimum amount of acoustic power to obtain a quality image. The common term is ALARA (As Low As Reasonably Achievable)." - Innovatus Imaging ^[7]

Machine Setting Adjustments

Adjusting ultrasound machine settings can help minimize the impact of tissue-related artifacts and improve image quality. Here’s a quick guide:

For best results when scanning through tissues with varying densities:

• Frequency Selection: Use higher frequencies for shallow targets and lower frequencies for deeper areas.

• Focus Zone: Set the focal zone at or just beneath the area of interest for sharper imaging.

• Gain Adjustments: Modify gain and time gain compensation (TGC) to balance tissue attenuation and improve visibility.

Motion and Blood Flow Artifacts

Motion and blood flow artifacts can reduce the accuracy of diagnostic imaging. Recognizing their causes and adjusting techniques can help improve results. Similar challenges arise in Doppler exams, impacting flow measurements.

Causes of Motion Artifacts

Motion artifacts can show up as blurring, streaking, or shading in ultrasound images, sometimes mimicking pathological conditions and obscuring important details ^[8]. These artifacts often stem from:

• Patient Movement: Voluntary actions like breathing or shifting during the scan.

• Physiological Motion: Involuntary movements, such as those caused by heartbeat, breathing, or blood vessel pulsation.

• Transducer Movement: Unsteady handling of the ultrasound transducer.

Blood Flow Measurement Challenges

Doppler settings can also introduce issues with blood flow measurements. One common problem is aliasing, which happens when the pulse repetition frequency (PRF) is too low compared to the Doppler shift ^[9].

Here are some common challenges in blood flow measurement:

Addressing Motion and Flow Issues

To improve imaging quality and accuracy, try these adjustments:

• Reducing Motion Artifacts: Encourage patients to hold their breath during critical scans. Use faster scanning techniques or cardiac gating when necessary ^[8].

• Optimizing Doppler Settings: For better blood flow measurements, lower the insonation angle to under 60°, set the sample volume to about two-thirds of the vessel diameter, and increase the PRF when aliasing occurs ^[11].

• Adjusting Color Doppler: Lower the color gain, tweak wall filters, and correct the baseline to enhance flow visualization ^[10].

For vascular access sampling, where high velocities can cause aliasing, increasing the PRF or using Continuous Wave Doppler can improve accuracy ^[9][11].

Summary

Managing ultrasound artifacts effectively is crucial for accurate diagnoses. Below, you'll find an overview of common imaging artifacts, their causes, and practical solutions.

Quick Reference Guide

CME Resources at IAME

IAME provides ACCME-accredited courses designed to help healthcare professionals master ultrasound artifact recognition and management. The curriculum includes:

• Advanced techniques for reducing artifacts

• Optimizing machine settings for various clinical scenarios

• Hands-on workshops for practical learning

For reference, here’s a frequency guide based on imaging depth:

IAME's 2025 Unlimited CME package is available for $93.49. It includes automatic credit transfers to ARDMS, CCI, and ACCME, along with full audit protection. For ongoing access, the Lifetime CME option is priced at $599.99, offering premium courses and exclusive content.