Length Scale Matters: Real-Time Elastography versus Nanomechanical Profiling by Atomic Force Microscopy for the Diagnosis of Breast Lesions

Figure 2

The spatial and mechanical sensitivity of real-time elastography and atomic force microscopy. (a) (Left) Real-time elastography provides a “strain image” or an elastogram based on the deformation of a breast lesion related to a compression force cyclically applied to the breast by a hand-held probe. (Right) Real-time elastography read-out from the Hitachi instrument used in this study. In the elastogram, tissue stiffness is color-coded and superimposed on the B-mode image. The example shows an invasive breast carcinoma (of 14.7mm diameter). (b) Top view image of an ultrasound-guided biopsy from a suspicious breast lesion immersed in a Ringer solution. Up to 20 stiffness maps (20 × 20 μm²; represented by black squares), each consisting of 1024 to 4096 indentation measurements, are recorded in a grid across the entire specimen. Subsequent analysis of the data provides a biopsy-wide stiffness distribution and individual areas can be visualized plotting color-coded stiffness maps. The choice of dimensions for both the AFM tip and the cantilever (drawn on the stiffness map) is critical for obtaining high-resolution topography and the nanomechanical properties. Post-AFM histology (bottom left) was used for spatial correlation of AFM maps and confirmation of AFM-based diagnostics.