M. Guardiola

UWB high-contrast robust tomographic imaging for medical applications

In this paper a complete UWB Circular Tomographic System robust to high contrast or large objects, applied to Breast Tumor Detection, is presented. The main contribution of this paper is to focus on the implementation of a two degrees of freedom imaging setup in order to deal with non-symmetric objects and to demonstrate its functionality with realistic breast phantoms.

3-D Microwave Magnitude Combined Tomography for Breast Cancer Detection Using Realistic Breast Models

Microwave imaging (MWI) is a feasible tool for medical imaging driven by its capability to discriminate between different types of tissues and abnormalities. Nowadays, a variety of reconstruction algorithms are investigated, mainly based on complex and time-consuming iterative schemes. Considering a future patient use, an algorithm requiring tens of hours seems unrealistic. In this letter, a 3-D quasi real-time algorithm, inspired in a computationally efficient modified-Born method, is assessed for early-stage breast cancer detection using 3-D anthropomorphic breast phantoms. The algorithm uses multifrequency information over a portion of the UWB range to produce robust images with a fair tradeoff between resolution and penetration.

3D UWB tomography for medical imaging applications

Biomedical applications have been an active research field for the development of microwave imaging due to the non-ionizing character of this radiation and its comfortable application. In particular, stroke detection, constitute a challenging application due to the high contrast between the mediums involved [1]. Ischemic strokes occur due to a loss of blood supply to a part of the brain caused by a blood clot, possibly leading to death of the tissue. Nowadays, stroke affects 795,000 people in US every year, meaning that, on average, every 40 seconds someone in the US has a stroke [2]. Moreover, it accounted for about one of every 17 deaths, representing 150,000 deceases per year in US. Currently, they are usually treated with thrombolytics (clot buster). However to ensure its effectiveness, it has to be given within 3 hours of the onset of symptoms and requires a firm diagnosis of an ischemic stroke. Currently, this diagnosis relies on imaging methods including CT, PET and MRI, which cannot be widely available at all medical centers due to its high cost. Hence, many times the diagnosis is delayed or not very accurate. Microwaves experiment highly sensitive interactions with dielectric properties of tissues, which can be used to identify them. This turns to be useful in stroke detection to distinguish between ischemic and hemorrhagic strokes, which present similar symptoms, but radically different treatment. Thus, by using microwave imaging, we will have enough specificity to distinguish vessels of blood in the brain (hemorrhagic stroke) and in this case, identify the injury as an ischemic stroke in a cost-effective way.

3D arrayed microwave tomographic system for medical imaging

A 3D cylindrical microwave tomographic system for medical imaging applications has been proposed. The cylindrical sampling has been accomplished rotating a multiplexed column array for the transmitting and receiving ends with the aim to reduce the acquistion time. The array has been designed to obtain a broad bandwith in a compact size and a vertical electric filed and a radiation pattern directed to the body under test.

UWB MST MEMS-based near-field imaging system

This paper has discussed and characterized a complete system for UWB imaging. The system has utilized conformed Vivaldi geometries for the illuminator and collector antennas, and a MEMS switched disc dipole as the probe. An imaging algorithm has been presented for a linear transmission imaging architecture. A complete experimental validation has been done for the Vivaldi antennas, probe antenna and switching MST technique. Preliminary results have been obtained for a point-like object, which has shown good results in accordance with UWB resolution capabilities.

UWB magnitude combined realistic breast model imaging capabilities

Breast cancer is the leading cancer killer among women. Early stage detection has been recognized to be best solution to reduce mortality rates. A non-ionizing, economical screening system based on microwave imaging is being investigated, but it is still a long way towards clinical ready system. In this paper, the validation of UWB-MC tomographic algorithm is performed using realistic breast models.