Welcome to Day 11 of your ARDMS SPI journey!
If there’s one topic that shows up again and again on the SPI exam and catches many off guard, it’s ultrasound artifacts. The good news? Once you understand the why and how behind them, you can answer artifact-related questions with full confidence.
Let’s break down this high-yield topic in the simplest and most exam-focused way.
🎯 What Are Artifacts?
Artifacts are errors in imaging that result in structures being displayed inaccurately in terms of:
- Location
- Size
- Shape
- Brightness
- Number
They’re caused by violations of ultrasound assumptions, like:
- Sound travels in a straight line.
- Sound travels at exactly 1540 m/s.
- Echoes come from the main beam only.
- Each reflector produces only one echo.
When these assumptions break — artifacts happen.
🔍 Key Artifacts You MUST Know for SPI
Here’s a list of the most commonly tested artifacts:
1. Reverberation
- 🔁 Multiple, equally spaced echoes.
- 🎯 Caused by: Sound bouncing between two strong reflectors.
- 📍 Common in: Anterior bladder wall, pleura.
2. Comet Tail / Ring Down
- 🔻 Form of reverberation with closely spaced echoes or solid streak.
- 🎯 Associated with: Gas bubbles, cholesterol crystals, metallic clips.
- 📍 Seen in: Gallbladder, lung, bowel.
3. Shadowing
- ⚫ Dark shadow behind highly attenuating structures.
- 🎯 Caused by: Bone, stones, calcifications.
- 📍 Important clue: No echoes distal to the object.
4. Enhancement (Through-Transmission)
- 💡 Increased brightness behind fluid-filled structures.
- 🎯 Caused by: Low attenuation in cysts or bladder.
- 📍 Useful to confirm: True cysts or ascites.
5. Mirror Image
- 🪞 Duplication of a structure on the opposite side of a strong reflector (usually diaphragm).
- 🎯 Caused by: Sound reflecting off a strong interface and duplicating echoes.
- 📍 Example: Liver and lung appearance across diaphragm.
6. Refraction Artifact
- 🔀 Displacement or duplication of structures due to bending of sound wave.
- 🎯 Occurs when beam hits an interface obliquely between tissues with different speeds.
- 📍 Common near rectus abdominis in transverse fetal scans.
7. Side Lobes / Grating Lobes
- 🌊 Extra echoes from off-axis beams.
- 🎯 Can create false echoes in anechoic regions.
- 📍 Important in: Cystic structures.
8. Speed Error
- 📏 Structure appears too deep or too shallow.
- 🎯 Caused by: Sound traveling faster or slower than 1540 m/s.
- 📍 Key point: Misplacement of structures on vertical axis.
🧠 Memory Tip:
Use the mnemonic “R-R-S-E-M-R-S-S”
Reverberation
Ring Down
Shadowing
Enhancement
Mirror
Refraction
Side lobes
Speed error
📝 SPI Exam Pointers:
✅ You must identify artifacts on images (especially reverberation, mirror image, and shadowing).
✅ You must understand the cause and implication of artifacts.
✅ 2–4 questions on artifacts are guaranteed in most SPI exams.
🎯 Daily Goal for Today:
- Review at least 5 major artifacts and sketch them with arrows and labels.
- Watch a short video or image-based quiz on artifact identification.
- Create flashcards for names, causes, and clinical importance.
📌 Final Thoughts:
Artifacts aren’t just test questions — they’re powerful tools in clinical sonography. Knowing what’s real and what’s an artifact helps you avoid diagnostic errors and improve image interpretation.
Coming Up on Day 12:
Understanding Doppler Basics – Frequencies, Flow, and the Magic of Shifts