Welcome to Day 29!
Today we explore a modern advancement in ultrasound that adds functional insight to our structural images: Elastography — a technique that visualizes tissue stiffness. It helps differentiate benign from malignant lesions, assess fibrosis, and adds clinical value beyond grayscale imaging.
🧵 What is Elastography?
Elastography is a non-invasive ultrasound technique that evaluates tissue elasticity or stiffness by analyzing how tissue deforms under pressure.
In simple terms:
Soft tissue = deforms easily
Hard tissue = resists deformation
🧪 Why Tissue Stiffness Matters
- Malignant tumors are generally stiffer than benign ones
- Fibrotic livers (e.g., in chronic hepatitis) are less elastic
- Inflamed or scarred tissues show altered elasticity
By assessing stiffness, elastography provides functional data to support diagnostic decision-making.
🧰 Types of Elastography
1. Strain Elastography
- Applies manual compression to assess deformation.
- Color-coded map:
- Soft = red
- Hard = blue
- Semi-quantitative (uses strain ratios)
2. Shear Wave Elastography (SWE)
- Uses focused acoustic pulses to generate shear waves.
- Calculates tissue stiffness in kPa or m/s
- Quantitative and operator-independent
SPI Tip:
Shear wave elastography is more reproducible and less user-dependent than strain imaging.
🏥 Clinical Applications of Elastography
✅ Liver Fibrosis Staging
✅ Breast Mass Evaluation
✅ Thyroid Nodule Characterization
✅ Prostate and Musculoskeletal Imaging
✅ Lymph Node Assessment
🧠 Advantages of Elastography
- Non-invasive alternative to biopsy in some cases
- Adds diagnostic confidence in lesion evaluation
- Can detect early fibrosis or subtle stiffness changes
⚠️ Limitations
- Operator-dependent (especially in strain elastography)
- May be affected by motion, depth, or lesion location
- Not all machines or probes support elastography
📘 SPI Exam Essentials
✅ Elastography is based on tissue deformation under force
✅ Strain elastography is qualitative/semi-quantitative
✅ Shear wave elastography is quantitative and calculates velocity or stiffness
✅ Stiffer tissues = less displacement
✅ Expect image-based or concept MCQs
📝 Flashcard
Q: Which elastography method provides quantitative stiffness values in kPa or m/s?
A: Shear Wave Elastography
🧭 Conclusion
Elastography allows you to see what grayscale can’t — how tissue behaves under stress. It adds a new dimension to sonographic evaluation and will continue to grow in both clinical and registry settings. Get ready for Day 30, our final post — a complete SPI exam strategy and revision guide to bring it all together!