The role of malignant tissue on the thermal distribution of cancerous breast

The present work focuses on the integration of analytical and numerical strategies to investigate the thermal distribution of cancerous breasts. Coupled stationary bioheat transfer equations are considered for the glandular and heterogeneous tumor regions, which are characterized by different thermophysical properties. The cross-section of the cancerous breast is identified by a homogeneous glandular tissue that surrounds the heterogeneous tumor tissue, which is assumed to be a two-phase periodic composite with non-overlapping circular inclusions and a square lattice distribution, wherein the constituents exhibit isotropic thermal conductivity behavior. Asymptotic periodic homogenization method is used to find the effective properties in the heterogeneous region. The tissue effective thermal conductivities are computed analytically and then used in the homogenized model, which is solved numerically. Results are compared with appropriate experimental data reported in the literature. In particular, the tissue scale temperature profile agrees with experimental observations. Moreover, as a novelty result we find that the tumor volume fraction in the heterogeneous zone influences the breast surface temperature

A Patient-Specific Approach for Breast Cancer Detection and Tumor Localization Using Infrared Imaging

Breast cancer (BC) is the most common cancer among women in the United States; approximately one out of every 24 women die of related causes. BC screening is a critical factor for improving patient prognosis and survival rate. Infrared (IR) thermography is an accurate, inexpensive and operator independent modality that is not affected by tissue density as it captures surface temperature variations induced by the presence of tumors. A novel patient-specific approach for IR imaging and simulation is proposed. In this work, multi-view IR images of isolated breasts are obtained in the prone position (face down), which allows access to the entire breast surface because the breasts hang freely. The challenge of accurately determining size and location of tumors within the breasts is addressed through numerical simulations of a patient-specific digital breast model. The digital breast models for individual patients are created from clinical images of the breast, such as IR imaging, digital photographs or magnetic resonance images. The numerical simulations of the digital breast model are conducted using ANSYS Fluent, where computed temperature images are generated in the same corresponding views as clinical IRI images. The computed and clinical IRI images are aligned and compared to measure their match. The determination of tumor size and location was conducted through the Levenberg-Marquardt algorithm, which iteratively minimized the mean squared error. The methodology was tested on the breasts of seven patients with biopsy-proven breast cancer with tumor diameters ranging from 8 mm to 27 mm. The method successfully predicted the equivalent tumor diameter within 2 mm and the location was predicted within 6.3 mm in all cases. The time required for the estimation is 48 minutes using a 10-core, 3.41 GHz workstation. The method presented is accurate, fast and has potential to be used as an adjunct modality to mammography in BC screening, especially for dense breasts

Experimental verification of heat source parameter stimation from 3D thermograms

Major amount of thermal radiation emitted by objects is located in a small part of the infrared spectrum of electromagnetic radiation, called the thermal infrared spectrum, and can be observed and measured using thermal infrared measurement cameras. Measuring heat transfer by radiation has proven to be very valuable inmedicine. One such medical application is the early detection and monitoring of breast cancers. Since tumors cause the rise in local tissue temperature, they can be observed as small embedded heat sources. The focus of this paper is the construction of new artificial test sets for heat source parameter estimation (such as the source depth, volume and intensity/size), to be used before clinical trials. Amixture of ballistic gelatin was used as a heat conductance medium, while a resistor grid (consisting of nine resistors) was used as a heat source, embedded inside the gelatin. Simulation procedure was conducted, resulting in a rank list of parameter configurations for every heat source of the grid. The expected values of parameters were found to be high on the configuration list,with about the first 20% of configurations present in the search space. This paper shows a convenient and effective way of testing parameter estimation methods. On the other hand, although ballistic gelatin presents a homogeneous mixture for heat transfer, with similar density and elastic properties as the living tissue, it does not necessarily have the same thermal conductance. Therfore the possibilities for future development of new materials for comparing parameter estimation methods on artificial test sets should be considered, as well as development ofmore complex materials consisting ofmultiple layers and thus more accurately emulating the heat dispersion in human bodies

Experimental verification of heat source parameter stimation from 3D thermograms

Major amount of thermal radiation emitted by objects is located in a small part of the infrared spectrum of electromagnetic radiation, called the thermal infrared spectrum, and can be observed and measured using thermal infrared measurement cameras. Measuring heat transfer by radiation has proven to be very valuable inmedicine. One such medical application is the early detection and monitoring of breast cancers. Since tumors cause the rise in local tissue temperature, they can be observed as small embedded heat sources. The focus of this paper is the construction of new artificial test sets for heat source parameter estimation (such as the source depth, volume and intensity/size), to be used before clinical trials. Amixture of ballistic gelatin was used as a heat conductance medium, while a resistor grid (consisting of nine resistors) was used as a heat source, embedded inside the gelatin. Simulation procedure was conducted, resulting in a rank list of parameter configurations for every heat source of the grid. The expected values of parameters were found to be high on the configuration list,with about the first 20% of configurations present in the search space. This paper shows a convenient and effective way of testing parameter estimation methods. On the other hand, although ballistic gelatin presents a homogeneous mixture for heat transfer, with similar density and elastic properties as the living tissue, it does not necessarily have the same thermal conductance. Therfore the possibilities for future development of new materials for comparing parameter estimation methods on artificial test sets should be considered, as well as development ofmore complex materials consisting ofmultiple layers and thus more accurately emulating the heat dispersion in human bodies

Passive element enriched photoacoustic computed tomography (PER PACT) for simultaneous imaging of acoustic propagation properties and light absorption\ud

We present a ‘hybrid’ imaging approach which can image both light absorption properties and acoustic transmission properties of an object in a two-dimensional slice using a computed tomography (CT) photoacoustic imager. The ultrasound transmission measurement method uses a strong optical absorber of small cross-section placed in the path of the light illuminating the sample. This absorber, which we call a passive element acts as a source of ultrasound. The interaction of ultrasound with the sample can be measured in transmission, using the same ultrasound detector used for photoacoustics. Such measurements are made at various angles around the sample in a CT approach. Images of the ultrasound propagation parameters, attenuation and speed of sound, can be reconstructed by inversion of a measurement model. We validate the method on specially designed phantoms and biological specimens. The obtained images are quantitative in terms of the shape, size, location, and acoustic properties of the examined heterogeneitie

Parametric Study of Infrared Imaging Based Breast Cancer Detection Program

Breast cancer is one of the most common cancers among women and is responsible for over 41,000 lives every year in the US according to The American Cancer Society. Current screening and imaging methods such as mammography, breast magnetic resonance imaging, and breast ultrasound imaging have helped in improving survival rate when the cancer is detected at an early stage. The problems with these techniques include: low sensitivity, patient discomfort, invasiveness, and cost. Due to current advancements in infrared and computational technologies, infrared thermography has been utilized as a noninvasive adjunctive screening modality. A computerized approach using infrared imaging (IRI) has been recently developed at RIT in collaboration with Rochester General Hospital for breast cancer detection and image localization. The parameters used in this simulation have been selected based on limited information available in the literature. This study focuses on analyzing the effects of different tissue thermal parameters used in the simulation on the accuracy of prediction. Thermal conductivity and perfusion rate are systematically varied, and their effects are presented by comparing simulated images with the actual infrared images captured from a biopsy-proven breast cancer patient. The results indicate a strong influence of perfusion rate within the breast tissue surrounding the tumor on heat transfer within the breast. This study is expected to help in proper selection of thermal properties while conducting the simulations. Future directions for research are also presented

Challenges in the Design of Microwave Imaging Systems for Breast Cancer Detection

Among the various breast imaging modalities for breast cancer detection, microwave imaging is attractive due to the high contrast in dielectric properties between the cancerous and normal tissue. Due to this reason, this modality has received a significant interest and attention from the microwave community. This paper presents the survey of the ongoing research in the field of microwave imaging of biological tissues, with major focus on the breast tumor detection application. The existing microwave imaging systems are categorized on the basis of the employed measurement concepts. The advantages and disadvantages of the implemented imaging techniques are discussed. The fundamental tradeoffs between the various system requirements are indicated. Some strategies to overcome these limitations are outlined

Thermo-optic measurements and their inter-dependencies for delineating cancerous breast biopsy tissue from adjacent normal

The histopathological diagnosis of cancer is the current gold standard to differentiate normal from cancerous tissues. We propose a portable platform prototype to characterize the tissue's thermal and optical properties, and their inter-dependencies to potentially aid the pathologist in making an informed decision. The measurements were performed on 10 samples from five subjects, where the cancerous and adjacent normal were extracted from the same patient. It was observed that thermal conductivity (k) and reduced-scattering-coefficient (μ's) for both the cancerous and normal tissues reduced with the rise in tissue temperature. Comparing cancerous and adjacent normal tissue, the difference in k and μ's (at 940 nm) were statistically significant (p = 7.94e-3), while combining k and μ's achieved the highest statistical significance (6.74e-4). These preliminary results promise and support testing on a large number of samples for rapidly differentiating cancerous from adjacent normal tissues