Fast 3-D Tomographic Microwave Imaging for Breast Cancer Detection

Abstract

Microwave breast imaging (using electromagnetic waves of frequencies around 1 GHz) has mostly remained at the research level for the past decade, gaining little clinical acceptance. The major hurdles limiting patient use are both at the hardware level (challenges in collecting accurate and noncorrupted data) and software level (often plagued by unrealistic reconstruction times in the tens of hours). In this paper we report improvements that address both issues. First, the hardware is able to measure signals down to levels compatible with sub-centimeter image resolution while keeping an exam time under 2 min. Second, the software overcomes the enormous time burden and produces similarly accurate images in less than 20 min. The combination of the new hardware and software allows us to produce and report here the first clinical 3-D microwave tomographic images of the breast. Two clinical examples are selected out of 400+ exams conducted at the Dartmouth Hitchcock Medical Center (Lebanon, NH). The first example demonstrates the potential usefulness of our system for breast cancer screening while the second example focuses on therapy monitoring.

An Overview of Uwb Antennas for Microwave Imaging Systems for Cancer Detection Purposes

“…The interaction of electromagnetic waves and matter depends on dielectric properties which can be directly related to various types of biological constituents due to their varying degree of water content: bone, fat, muscle, etc. [14]. Imaging systems that employ microwave radar techniques are a promising tool due to the high contrast obtained between normal tissue and tumors [11], non-ionizing, low-cost system, reduced safety concerns, potential to detect small tumors [15] and may be a tool suitable for frequent screening [16].…”

“…These diagnosis systems will get data from highly directive microwave sensors, which are basically designed to detect the changes on permittivity of the biological tissues, to be processed by imaging reconstruction techniques. The permittivity is normally high at lower frequencies due to an insulating effect of cell membranes and decreases over higher frequencies due to scattering [14].…”

“…One of the main challenges in the design of these antennas is related to the physical size in order to allow a greater number of antennas to collect more information of the scattered signal for a successful image reconstruction, as well as to achieve a wider bandwidth to get a high-resolution image [20] and reduce the distortion in transmission of short-duration pulses [21]. Several antennas were proposed for cancer detection as monopole antennas [14,22], fractal antennas [23][24][25][26], antipodal Vivaldi antennas [27], slot antenna [28,29], and patch antenna [30], as will be described below.…”

Time-Domain Microwave Radar Applied to Breast Imaging: Measurement Reliability in a Clinical Setting

“…In the published studies on microwave breast imaging, only a few research groups report on systems that have undergone clinical trials [5][6][7][8]. Our system is the first microwave-radar time-domain system to reach the clinical trial stage.…”

Three-Dimensional Far-Field Holographic Microwave Imaging: An Experimental Investigation of Dielectric Object

“…Tomography [13][14][15][16][17] reconstructs a map of the electrical properties in the breast using measurements of energy transmitted through the breast. Microwave holographic based techniques [18][19][20][21] do not require expensive ultra-high speed electronics as narrow-band signals can be converted to the baseband for digitization at a slower rate, thereby enabling imaging at significantly lower cost [22].…”