Freehand Elastography – a Hybrid 3D Strain Image Acquisition Technique

C Uff, L Garcia, JC Bamber, G Fromageu, JR Symonds-Tayler; in collaboration with N Dorward, Royal Free & University College Hospital Medical School, and with RJ Housden, A Gee, G Treece and R Prager, University of Cambridge.

Source of funding: EPSRC, Royal Free Hospital

3D strain imaging is potentially useful for producing a complete picture of mechanical anatomy and accurately measuring the volume of stiff or soft structures. There have been two approaches to producing such images: a 2D probe is swept by hand while applying a continuous axial oscillatory motion, or a 3D (mechanically swept) probe is moved axially between two positions, at each of which it is held stationary while a 3D echo volume is acquired. The latter method is often more practical, but the strain images suffer loss of quality because it is difficult to apply a single freehand compression. 

With A Gee et al, at the University of Cambridge, a new method was developed in which, as the 3D probe sweeps out a volume, a continuous axial oscillatory probe motion is used and several frames are recorded for each palpation cycle. Although the volume pair method occasionally produces very high quality elastograms, the new technique is easier, and it more consistently produces images of useful quality. It is currently being evaluated for assisting brain tumour resection.