Accuracy and precision

Destroying tumors with image-guided therapy
Ablated Zone Elastic Modulus Image
Elastic modulus imaging shows a significantly enhanced visualization of the ablated zone.

An alternative to risky surgery, thermal ablation is used to treat tumors in the liver, kidneys, and lungs. Thermal ablation uses very high temperatures to destroy a small area of cells. The high heat kills cancer cells by coagulating their proteins and destroying nearby blood vessels—in effect “cooking” them.

Radio-frequency waves, microwaves, ultrasound waves, and other forms of energy can be used to heat the area. Heat can be applied by insertion of a small applicator (such as a needle or a microwave antenna) into a cancer or by focusing acoustic/laser energy on a tumor in a touchless fashion.

Early results are promising, but thermal ablation has its challenges. Failure to ablate the entire tumor, which is particularly difficult at the edges, can result in regrowth of the residual tumor. In radiofrequency ablation (RFA), using too much heat can destroy healthy surrounding tissues. For instance, renal tissues could be accidently damaged during a liver ablation procedure conducted without effective image monitoring.

Jingfeng Jiang is developing ultrasound-based image guidance algorithms for thermal ablation to ensure a complete denaturation while sparing surrounding tissue. Jiang’s Biocomplexity and Mechanics Lab at Michigan Tech is partnering with an interdisciplinary team at the University of Wisconsin–Madison to investigate real-time ultrasonic monitoring of thermal ablation therapy. Jiang’s novel computer algorithms will monitor the tissue stiffness changes associated with thermal ablation, and these algorithms will be used for (Phase I) clinical trials in human patients at the University of Wisconsin Hospitals and Comprehensive Cancer Center.

Ablated Zone Ultrasound

B-mode ultrasound shows ablated zone.

Jiang uses ultrasound-based elastic modulus imaging (EMI) to better view thermal ablation zones. “Elastic modulus is a physics term for hardness. The elastic modulus image represents spatial (hardness) distributions of the tissue. EMI is created based on ultrasound-based measurements such as displacements. After all, the stiffer spring deforms less. Ablated tissue is stiffer,” he explains.

“Our goal is to help surgeons gain better control during the procedure. It can be difficult to accurately measure the temperature inside a tumor. Nearby tissues can be negatively affected. By monitoring temperature and tissue stiffness during treatment and adjusting heat levels accordingly, thermal ablation can be more precise and offer patients better results. The initial answer is yes. Surgeons like what they see so far.”