Acoustical imaging of internal spheroid structures for a series of frequencies

We have previously measured the speed of sound in individual cells and cell pellets. Spheroids can be used to more accurately model nonvascularized tumors due to their three-dimensional growth pattern, cell-cell interaction, disorganized growth, and development of a necrotic core when grown to sufficiently large sizes. To examine cell death in spheroids due to necrosis or chemotherapy, quantitative ultrasound methods were used on the ultrasound backscatter power spectrum throughout the spheroid. MCF7 spheroids were probed at 55 MHz using a VEVO770 high frequency ultrasound machine, and at 80 and a scanning acoustic microscope. Changes in spheroid structure as the necrotic core develops were recorded and analysed. This work furthers our understanding of non-invasively identifying the viability of cancerous tumours.