Elastographie

Elastography is a medical imaging modality that assesses the elastic properties of soft tissues, most commonly tissue stiffness, by measuring how tissues deform in response to an applied mechanical stimulus. The resulting maps or images reflect variations in mechanical properties that can aid in characterizing normal versus diseased tissue.

There are several elastography techniques. Ultrasound-based elastography includes strain elastography, which analyzes tissue displacement under manual or physiological compression, and shear wave elastography, which uses focused acoustic pulses to generate shear waves and measures their propagation speed to estimate stiffness. Transient elastography (FibroScan) is a widely used ultrasound method for liver stiffness. Magnetic resonance elastography (MRE) uses MRI to visualize propagating mechanical waves and derives quantitative stiffness maps. Other approaches include vibroelastography and newer ARFI-based methods (acoustic radiation force impulse).

Principles center on the relationship between tissue stiffness and pathology. Many diseases increase stiffness, such as liver fibrosis, malignant tumors, or inflammatory processes, while others may alter viscoelastic properties. Elastography provides qualitative images and, in most modern systems, quantitative values expressed in kilopascals (kPa) or meters per second for wave speed, aiding assessment and monitoring.

Applications span several organ systems. Liver fibrosis staging is a common indication, supporting the need for biopsy in selected cases. Other uses include characterization of breast lesions, pancreatic masses, thyroid nodules, prostate conditions, and musculoskeletal disorders. Benefits include noninvasiveness, repeatability, and real-time feedback; limitations involve operator dependence (especially for ultrasound methods), depth and motion artifacts, obesity, and lack of universal standardization across platforms.

Ongoing developments aim at improving accuracy, standardization, and integration with other imaging data and clinical workflows.