elastogram

An elastogram is a diagnostic image produced by elastography that visualizes tissue stiffness by mapping mechanical properties onto a color-coded map. Elastography derives stiffness from tissue response to an applied mechanical stimulus, and elastograms are used to assess tissue characteristics noninvasively.

There are two main elastography approaches. Strain elastography estimates relative deformation (strain) under external compression, producing a qualitative or semi-quantitative elastogram that highlights relative stiffness. Shear wave elastography uses focused acoustic radiation force to generate shear waves and measures their speed to calculate absolute tissue stiffness, typically displayed as a quantitative elastogram with stiffness values in kilopascals (kPa) or equivalent units.

Elastograms are usually overlaid on B-mode ultrasound images, with color scales indicating soft to hard tissue. The specific color palette and numerical ranges vary by vendor and technique. Interpretation relies on the pattern and magnitude of stiffness: areas of increased stiffness may suggest fibrosis, scarring, or neoplasm, but elastography is an adjunct to conventional imaging and clinical data; stiffness alone does not provide a definitive diagnosis.

Applications of elastograms include evaluation of liver fibrosis, characterization of breast and thyroid nodules, prostate assessment, and investigation of musculoskeletal and other soft tissues. Limitations include variability between platforms, operator dependence for strain-based methods, depth-related attenuation, patient motion, obesity, calcifications, and artifacts near interfaces. Proper interpretation requires consideration of the overall clinical context and, when indicated, corroborating histology or additional imaging.