Method and Apparatus for Imaging and Spectroscopy of Tumors and Determination of the Efficacy of Anti-tumor Drug Therapies
Cancerous tumor growth is dependent on a process called angiogenesis wherein factors secreted by a tumor cause surrounding normal tissue to produce new blood vessels that enter the tumor and support its growth. This so-called neovascular growth is essential to tumor survival and growth. They also represent an internal energy source that heats the tumor and causes it to emit infrared radiation at rates different than surrounding tissue. The net emission and its wavelength response depends on the depth and lateral spatial distribution of the vascular growth within the tumor, associated metabolic activity and optical properties of the tumor and surrounding tissue including tissue located between the tumor and the skin surface. The process of angiogenesis may be an avenue for anti-cancer therapy if biochemical agents, which inhibit it, can be developed. Such agents would destroy tumors on a systemic basis including sub-clinical lesions. This prospect has led to a research effort at many institutions seeking to develop agents that block angiogenesis. However, progress is limited by the current lengthy process needed to establish efficacy that is based on administration of a prospective agent to a panel of patients monitoring their condition with time. Tumor response times can be long when using standard imaging methods, hence slowing drug evaluation and impeding development. A more rapid assay is needed both for research and clinical purposes.
Researchers at The Johns Hopkins Applied Physics Laboratory have concluded preliminary studies showing that infrared imaging can provide rapid assays of tumor condition with significant new information not present in the current visible and radiographic image data. These studies suggest that metabolic processes are being imaged including processes directly linked to invasive growth.
In utilizing a method to image metabolic processes of tumors, doctors would have the ability to distinguish active tumors from inactive ones. They would be able to easily and quickly identify invasive tumors. Doctors would have a method of mapping the lateral, spatial distribution of blood vessels throughout the depth of the tumor. An apparatus and software to acquire and analyze passive and active infrared images can also be developed through use of this tumor imaging technology.
The technological advancement of assessing tumor activity and determining the efficacy of anti-tumor drugs in reducing tumor angiogenes is based on passive and active radiometric thermal imaging. These categories of thermal imaging use an infrared camera to determine the spatial and wavelength dependence of the infrared response of tumors as a function of depth in the tumor. They provide information on the distribution of blood vessels within the tumor and at its periphery and on metabolic processes associated with blood vessel and tumor growth including neovascular growth of the blood vessels associated with invasive cancers. Preliminary measurements on some cancers indicate that the level of activity of various tumors on a single individual varies and hence the method may provide an approach to a diagnostic method for targeted therapy.
The Method and Apparatus for Imaging and Spectroscopy of Tumors & Determination of the Efficacy of Anti-Tumor Drugs has specific applications to breast imaging. Current methods have limitations including cost and convenience, radiation risk and poor results due to low contrast of the images. The early detection of small tumors against the background of dense, glandular breast tissue is difficult. This new screening method would be rapid, easy to use and low cost. Use in the evaluation and development of tumor reducing drugs is also promising.