Grants support breast cancer diagnosis, management research
A two-year grant from the National Cancer Institute for $326,700 will support research to stage and monitor the treatment of lymphedema, the buildup of lymphatic fluid in interstitial tissues. “Lymphedema is common following treatment of several types of cancer, such as breast cancer and Hodgkin’s disease, due to the removal of lymph nodes,” Ophir said. “Limb problems can develop as can fibrosis, the thickening of tissues in the affected area.”
Using poroelastography, Ophir and his colleagues apply slight pressure to the affected tissue and measure the ratio of lateral and axial strain – Poisson’s ratio, which changes as the fluid leaves the tissue. (see video, produced in cooperation with R. Zahiri-Azar from the University of British Columbia)
“Our hypothesis is that lymphedema tissue is more akin to a sponge, and by measuring and imaging the distribution and time course of changes in this ratio, we can see where and how severely affected the tissues are – which will help determine treatment, and we can also measure the effectiveness of treatment,” he said. “Lymphedema tissue doesn’t behave like normal tissue, which is more like elastic Jell-O.”
The study on lymphedema patients will be done under a subcontract to the University of Vermont, under the direction of Dr. Brian Garra.
The second two-year grant was awarded two weeks ago from the U.S. Department of Health and Human Services and announced by Sen. Kay Bailey Hutchison, R-Dallas. Ophir was the only Medical School recipient of this new federal funding — $1.7 million for Texas — which is directed at cancer research.
Ophir’s project, “Imaging Shear Strains in Breast Tissues,” will bring $371,200 to study the difference between malignant and benign breast tumors using elastography to measure the shear strain at the boundaries between these tumors and the normal host tissues – or the sliding of the tumor tissue when slight external pressure is applied. This will be done on a database of images previously acquired by Garra.
“Malignant tumors appear to have tentacles surrounding them that aggressively hold on to the host tissue, tugging it when they move,” Ophir said. “The benign tumors, on the other hand, have smoother margins and move more freely within the host tissue, exhibiting very localized and distinct shearing patterns at the border of the tumor.” (see video produced in collaboration with R. Zahiri Azar (University of British Columbia).
Ophir pioneered elastography, the imaging of the elastic properties of soft tissues, and has been perfecting its use in clinical applications – primarily in breast and prostate cancers – over the last 17 years. Ophir and his research team discovered it was possible to noninvasively measure and image the local elastic changes inside soft objects, such as sponges and tissue. This technology has been patented by UTHSC and has since been licensed to several commercial manufacturers of medical ultrasound equipment.
Using the existing technology of diagnostic ultrasound, elastography involves a before and after picture – after a 1 percent compression – of the tissue in question. From these two images, a new image, an elastogram, is generated, which displays the hardness or softness of all tissue elements in the field of view. Since it is known that tissue hardness is related to the presence of pathology, the technique is able to image pathological changes, such as tumors, that may not be visible by other imaging methods.
“Most cancerous tissues are much harder than normal tissues, and malignant breast tumors are at least 5-10 times stiffer than other breast tissues. If you have a lump in your breast, it will be biopsied – yet only 1 in 10 will end up being cancer. These numbers mean that there are many unnecessary biopsies,” Ophir explained.
The research funded by these two grants aims to provide more weapons in the fight against breast cancer and its resulting problems.
Images from Ophir’s lab of shear strains will be the cover of the August 2008 issue of Institute of Electrical and Electronics Engineers Transactions on Ultrasonics, Ferroelectrics, and Frequency Control.