Tissue ablation

Thermal therapies as a tumor treatment method have seen significant growth in the last decade.  Predicting temperature, however, is extremely challenging, as blood flow and energy absorption ratea vary so widely between tissues.  Insufficient ablation may lead to recurrence of the cancer while excessive ablation may cause serious side effects by damaging healthy tissues.  The most successful current method is the use of magnetic resonance thermal imaging (MRTI) which is accurate but costly and time-consuming.  A more practical and cost effective solution being widely investigated is the use of ultrasound. 

Ablation monitoring testbed

Experimental setup for US B-mode and RF data  acquisition during ablation of a tissue sample. Actual picture of a  preliminary experiment (left) and the schematic diagram of the apparatus  (right).

In testing the applicability of US-based monitoring methods, the first step is ex-vivo validation based on spatial correlation between ultrasound, temperature measurements, histopathology images, and auxiliary imaging such as CT or MRI.  A test-bed apparatus (fig. 1) was developed consisting of a container box with integrated fiducial lines and tissue suspending in a stabilizing medium. Following US imaging, the gel block is sliced and pathology images are acquired. Tissue samples were contoured, reconstructed and registered in the common coordinate system of fiducials. There was agreement between the sample shapes.  Viability of concept has been achieved and further experimental work is required to optimize all materials and customize software.