Table 2. Information of the main methods for the mechanical strain measurement of tissues.

Technique	Dimension	Advantage	Disadvantage	Operation time	Image analysis
Strain gauge	2D 3D	Cheap; Few offline work	Invasive; Low anti-interference	Real-time	N/A
Strain transducers
Microscopy camera	2D 3D	Cheap; Easy operation	Transparent or translucent samples	Range from minutes to hours	Marker-tracking algorithm
Tissue Doppler imaging	1D 2D	Cheap; Easy clinical application	Simple structure	Minutes	Baseband speckle- tracking algorithm; Registration algorithm
US elastography	2D
Speckle tracking echocardiography
Tag tracking MRI	3D	Safe and no side effect	Expensive; Time-consuming	Range from minutes to hours	Registration algorithm
Elastography MRI
CT	3D	Relatively fast imaging; Relatively low cost	High contrast tissues needed; X-ray radiation	Range from seconds to hours	Registration algorithm

Notes.

^aMost of the image analysis methods are TC-based; please see example references from Table 1.