Research Interest

Quantitative elasticity imaging – slip elastography

L Garcia, C Uff, J Fromageau, JC Bamber; in collaboration with A Chakraborty, N Dorward, Royal Free & University College Hospital Medical School
Source of funding: EPSRC, Royal Free Hospital

Tissue may be mechanically nonlinear, viscous, compressible, porous, anisotropic and discontinuous. With respect to the last of these, information extracted from elastograms concerning the degree of bonding between one tissue region and another may provide information that is useful for diagnosis, prognosis or guiding surgery. Knowledge of whether and where a slippery boundary separates tumour from surrounding tissue may indicate degree of invasiveness and may provide useful information concerning beneficial planes for surgical dissection. 

We have extended our understanding of strain image appearance in the presence of slippery inclusion boundaries showing, both in simulation and in phantom experiments, that (a) slip-induced strain at the inclusion boundary, (b) a stiffening effect and (c) heterogeneous deformation strain within the inclusion (Figure 5), are additional to any pre-existing Young’s modulus contrast.

Fig.5.  Finite element modelling results showing the Young’s modulus (YM) contrast dependence of the contrast transfer efficiency (CTE) for inclusions with a boundary that is either slippery or adhered to the surrounding medium. CTE is a measure of the efficiency of transferring YM contrast into strain image contrast; when expressed in decibels, 0 dB represents perfect transfer. A CTE > 0 indicates the introduction of a new contrast mechanism. Note the stiffening effect (CTE increases for stiff inclusions and decreases for soft inclusions), and the heterogeneity of internal strain, when the boundary is slippery. These curves, and similar effects, have also been observed in phantoms.