R.C. Conceicao

University of Lisbon | UL · Instituto de Biofísica e Engenharia Biomédica (IBEB)

We assess the application of microwave tomography (MWT) for the detection of axillary lymph nodes (ALNs) in breast cancer patients. We numerically study the effects of limiting angular view in axillary MWT, as probes can only be placed on a limited arc around the axillary region. We also numerically study the possibility of increasing the amount of...

Dental caries is a major oral health issue which compromises oral health, as it is the main cause of oral pain and tooth loss. Early caries detection is essential for effective clinical intervention. However, methods commonly employed for its diagnosis often fail to detect early caries lesions, which motivates the research for more effective diagno...

Breast cancer is the most common and the fifth deadliest cancer worldwide. In more advanced stages of cancer, cancer cells metastasize through lymphatic and blood vessels. Currently there is no satisfactory neoadjuvant (i.e., preoperative) diagnosis to assess whether cancer has spread to neighboring Axillary Lymph Nodes (ALN). This paper addresses...

In the last decades, researchers have shown the potential of using Electrocardiogram (ECG) as a biometric trait due to its uniqueness and hidden nature. However, despite the great number of approaches found in the literature, no agreement exists on the most appropriate methodology. This paper presents a systematic review of data acquisition methods...

Purpose Patient-specific information on the depth of Axillary Lymph Nodes (ALNs) is important for the development of new diagnostic imaging technologies, e.g. Microwave Imaging (MWI), aiming to assess the diagnosis of ALNs during breast cancer staging. Studies about ALNs depth have been presented for treatment planning, but they lack information on...

Recently, several studies have demonstrated the potential of electrocardiogram (ECG) to be used as a physiological signature for biometric systems (BS). We investigated the potential of ECG as a biometric trait for the identification and authentication of individuals. We used data from a public database, CYBHi, containing two off-the-person records...

Breast cancer diagnosis using radar-based medical MicroWave Imaging (MWI) has been studied in recent years. Realistic numerical and physical models of the breast are needed for simulation and experimental testing of MWI prototypes. We aim to provide the scientific community with an online repository of multiple accurate realistic breast tissue mode...

In this paper we revisited a database with measurements of the dielectric properties of rat muscles. Measurements were performed both in vivo and ex vivo; the latter were performed in tissues with varying levels of hydration. Dielectric property measurements were performed with an open-ended coaxial probe between the frequencies of 500 MHz and 50 G...

We study the effect of freezing and defrosting on the dielectric properties of biological tissues. The electromagnetic characterization of tissues at microwave frequencies is crucial for the development of microwave-based biomedical devices. These measurements are often not practical, as tissue degradation restricts the time available between tissu...

Purpose: Microwave Imaging (MWI) has been studied as a complementary imaging modality to improve sensitivity and specificity of diagnosis of Axillary Lymph Nodes (ALNs), which can be metastasised by breast cancer. The feasibility of such a system is based on the dielectric contrast between healthy and metastasised ALNs. However, reliable informati...

The number of metastasised Axillary Lymph Nodes (ALNs) is a key indicator for breast cancer staging. Its correct assessment affects subsequent therapeutic decisions. Common ALN screening modalities lack high enough sensitivity and specificity. Level I ALNs produce detectable backscattering of microwaves, opening the way for Microwave Imaging (MWI)...

Dry Microwave Imaging (MWI) systems are more practical, hygienic and fast to operate since they do not require immersion liquid. However, the dielectric contrast between air and the part of the body under examination is larger, causing larger refraction effects. Including refraction in the image reconstruction algorithm significantly increases the...

We produced an anatomically and dielectrically realistic phantom of the axillary region to enable the experimental assessment of Axillary Lymph Node (ALN) imaging using microwave imaging technology. We segmented a thoracic Computed Tomography (CT) scan and created a computer-aided designed file containing the anatomical configuration of the axillar...

Medical Microwave Imaging (MWI) has been studied as a technique to aid breast cancer diagnosis. Several different prototypes have been proposed but most of them require the use of a coupling medium between the antennas and the breast, in order to reduce skin backscattering and avoid refraction effects. The use of dry setups has been addressed and r...

Electromagnetic-based hyperthermic therapies induce a controlled increase of temperature in a specific tissue target in order to increase the tissue perfusion or metabolism, or even to induce cell necrosis. These therapies require accurate knowledge of dielectric and thermal properties to optimise treatment plans. While dielectric properties have b...

The development of 3D anthropomorphic head and neck phantoms is of crucial and timely importance to explore novel imaging techniques, such as radar-based MicroWave Imaging (MWI), which have the potential to accurately diagnose Cervical Lymph Nodes (CLNs) in a neoadjuvant and non-invasive manner. We are motivated by a significant diagnostic blind-sp...

In electromagnetic hyperthermic applications, the thermal properties of the biological tissue under treatment, as well as its dielectric properties, influence the deposition of the electromagnetic energy and the heat distribution into the tissue. Thus, their knowledge can allow to accurately model the therapeutic results. The induced heat distribut...

Purpose: The assessment of the size and shape of breast tumours is of utter importance to the correct diagnosis and staging of breast cancer. In this paper, we classify breast tumour models of varying sizes and shapes using signals collected with a monostatic ultra-wideband radar microwave imaging prototype system with machine learning algorithms...

Microwave Imaging is an emerging technique to aid breast cancer diagnosis. Current multistatic setups involve complex and heavy signal processing techniques, such as to remove the energy coupling between adjacent sensors, which masks the response from inner tissues. We investigate a novel approach using a dielectric lens in order to reduce the coup...

Diffusion kurtosis imaging (DKI) is a diffusion-weighted MRI technique that probes the non-Gaussian diffusion of water molecules within biological tissues. The purpose of this study was to investigate the DKI model optimal b-values combinations in invasive ductal carcinoma (IDC) versus ductal carcinoma in situ (DCIS) breast lesions. The study inclu...

Background The gamma distribution (GD) model is based on the statistical distribution of the apparent diffusion coefficient (ADC) parameter. The GD model is expected to reflect the probability of the distribution of water molecule mobility in different regions of tissue, but also the intra‐ and extracellular diffusion and perfusion components (f1,...

Currently, breast cancer often requires invasive biopsies for diagnosis, motivating researchers to design and develop non-invasive and automated diagnosis systems. Recent microwave breast imaging studies have shown how backscattered signals carry relevant information about the shape of a tumour, and tumour shape is often used with current imaging m...

This paper addresses the process of extracting features from multistatic signals collected during the simulation (or operation) of a radar multistatic microwave imaging system for breast cancer detection. These features are then useful for classification purposes, for example classifying between benign and malignant tumours, or to build a classific...

This book highlights one of the most recent advances in the field of microwave imaging. The framework presented offers an innovative and effective way to address the difficulties that arise in microwave imaging, namely the non-linearity and the ill-posedness of the underlying inverse problem. The book provides a comprehensive treatment of this new...

Radar breast imaging (RBI) involves the illumination of the breast with a microwave pulse. If a tumour is present, backscattered radar signals are generated due to the dielectric contrast between normal and tumour tissue at microwave frequencies. These backscattered signals are processed by an RBI beamformer to identify the presence and location of...

In this chapter, the anatomy of the breast is presented first. The anatomy of the breast is described primarily from the perspective of microwave imaging, with a focus on the various layers and structure of the breast with differing dielectric properties. Next, the disease of breast cancer is discussed, including the cellular origins of the disease...

Recent breast tissue dielectric spectroscopy measurements in [35] suggest that the malignant-to-benign dielectric contrast may not be sufficiently high to allow for tumour classification based on backscatter intensity. Alternatively, it is well known that the architectural distortion in breast parenchyma can aid in distinguishing malignant tumours...

This book collates past and current research on one of the most promising emerging modalities for breast cancer detection. Readers will discover how, as a standalone technology or in conjunction with another modality, microwave imaging has the potential to provide reliable, safe and comfortable breast exams at low cost. Current breast imaging modal...

In this paper, the authors propose the use of spectral beamforming for the reconstruction of a breast energy profile for cancer detection. Experiments were performed on three different breast phantoms and different spectral beamformers were implemented and tested.

This talk addresses the development of imaging techniques for the early detection of breast cancer, based on Ultra Wideband (UWB) radar, a promising emerging technology that exploits the dielectric contrast between normal and tumour tissues at microwave frequencies. Of particular interest in this work are issues related to techniques for classifica...

In this letter, a novel method for the generation of numerical 3-D clinically informed breast tumor models for microwave imaging applications is proposed, which greatly enhances flexibility in creating clinically realistic models. The proposed method was clinically validated through collaboration with breast cancer clinicians and conforms to the BI...

This paper presents results from the development and evaluation of a dedicated Computer-Aided Detection and Diagnosis (CAD) system for Microwave Imaging (MWI) of the breast. CAD systems play a very important role in aiding breast cancer detection, since they help minimising the number of false positives usually associated with most breast imaging t...

By using anatomically accurate models, the potential to improve microwave imaging as a detection and classification technique for breast cancer is very promising. This paper proposes a novel, clinically-informed approach to 3D modelling of breast tumours that significantly enhances flexibility in setting tumour parameters compared to existing...

In this paper we present a method for creating a numerical phantom of the underarm region which captures the heterogeneous anatomical structure and the differences in the electric properties between the constituent tissues of the underarm region. Specifically, the model is intended to identify and segment the sentinel nodes, which are axillary lymp...

Across all biomedical imaging applications, there is a growing emphasis placed on reducing data acquisition and imaging times. This research explores the use of a technique, known as compressive sampling or compressed sensing (CS), as an efficient technique to minimise the data acquisition time for time critical microwave imaging (MWI) applications...

This study presents the first experimental results using a pre-clinical UWB prototype imaging system for tumour classification based on the shape of tumours. A database of 13 benign and 13 malignant tumours with average diameters between 13 and 40 mm was created using dielectrically-representative tissue-mimicking material. Classification of benign...

A multimodal medical imaging technique is proposed to improve breast cancer diagnosis. Initial studies are being pursued in order to optimise breast cancer detection and classification when combining Positron Emission Mammography (PEM) with Ultra Wideband (UWB) radar imaging. In this study, the same numerical breast phantom is simulated for both PE...

Purpose: The optimization of the collimator design is essential to obtain the best possible sensitivity in single photon emission computed tomography imaging. The aim of this work is to present a methodology for maximizing the sensitivity of convergent collimators, specifically designed to match the pitch of pixelated detectors, for a fixed spatia...

A novel multimodal imaging approach for breast cancer detection is studied in terms of its detection and classification capabilities in a simple homogeneous breast model. The study comprises three stages: i) realistic breast and tumour numerical models are adapted so that they can be simultaneously used in both Positron Emission Mammography (PEM) a...

This paper presents an initial study towards the development of a multimodal breast imaging technique that combines Positron Emission Mammography (PEM) and Ultra WideBand (UWB) radar which has the potential to be complementary in breast cancer detection and classification due to the different types of information provided by the two modalities. The...

Microwave Imaging (MI) has been extensively investigated for a number of years to develop a technique to detect breast cancer at the earliest stages of development. MI for this application is based on exploiting the dielectric contrast between normal breast tissue and cancerous tissue at microwave frequencies. Recent findings have reported overlapp...

Breast cancer detection using Ultra Wideband Radar has been thoroughly investigated over the last decade. This breast imaging modality is based on the dielectric properties of normal and cancerous breast tissue at microwave frequencies. However, the dielectric properties of benign and malignant tumours are very similar, so tumour classification bas...

Several studies have investigated the possibility of using the Radar Target Signature (RTS) of a tumour to classify the tumour as either benign or malignant, since the RTS has been shown to be influenced by the size, shape and surface texture of tumours. The Evolved-Topology Spiking Neural Neural (SNN) presented here extends the use of evolutionary...

Over the past ten years, Ultra Wideband (UWB) Radar has been widely investigated as a biomedical imaging modality, used to detect early-stage breast cancer and to continuously monitor vital signs using both wearable and contactless devices. The advantages of the technology in terms of low-power requirements and non-ionising radiation are well recog...

The considerable overlap in the dielectric properties of benign and malignant tissue at microwave frequencies means that breast tumour classification using traditional UWB Radar imaging algorithms could be very problematic. Several studies have examined the possibility of using the Radar Target Signature (RTS) of a tumour to classify the tumour as...

Microwave Imaging is one of the most promising emerging imaging technologies for breast cancer detection, and exploits the dielectric contrast between normal and malignant breast tissue at microwave frequencies. The development of many UWB Radar imaging approaches requires the use of accurate numerical models for the propagation and scattering of m...

Recent studies have shown that the dielectric properties of normal breast tissue vary considerably. This dielectric heterogeneity may mean that the identification of tumours using Ultra Wideband Radar imaging alone may be quite difficult. Significantly, since the dielectric properties of benign tissue were shown to overlap with those of malignant,...

Ultra Wideband (UWB) radar has been extensively investigated as a means of detecting early-stage breast cancer. The basis for this imaging modality is the dielectric contrast between normal and cancerous breast tissue at microwave frequencies. However, based on the dielectric similarities between a malignant and a benign tumour within the breast, d...

Microwave Imaging (MI) has been widely investigated as a method to detect early stage breast cancer based on the dielectric contrast between normal and cancerous breast tissue at microwave frequencies. Furthermore, classiflcation methods have been developed to difierentiate between malignant and benign tumours. To successfully classify tumours usin...

The use of Ultra Wideband (UWB) radar to detect early-stage breast cancer has been extensively investigated. The basis for this imaging modality is the significant dielectric contrast between normal and cancerous breast tissue at microwave frequencies. However, based on the recently-established dielectric similarities between malignant, benign and...

Ultra Wide Band (UWB) radar is a promising emerging technology for breast cancer detection that makes use of the dielectric contrast between normal and tumour tissues at microwave frequencies. An important consideration in UWB imaging system design is the configuration of the antenna array. Two antenna configurations have been previously proposed t...

Microwave imaging is one of the most promising emerging imaging technologies for breast cancer detection. Microwave imaging exploits the dielectric contrast between normal and malignant breast tissue at microwave frequencies. Many UWB radar imaging techniques require the development of accurate numerical phantoms to model the propagation and scatte...

Ultra Wideband (UWB) radar is a promising emerging technology for breast cancer detection based on the dielectric contrast between normal and tumor tissues at microwave frequencies. One of the most important considerations in developing a UWB imaging system is the configuration of the antenna array. Two specific configurations are currently under i...

Ultrawideband (UWB) radar is one of the most promising emerging technologies for breast imaging. Several algorithms have already been developed which exploit dielectric contrasts between normal and malignant tissue. These algorithms have been tested on anatomically accurate models of the breast. However, the recently established similarities in die...

Motility assays are the tools of choice for the studies regarding the motility of protein molecular motors in vitro. Despite their wide usage, some simple, but fundamental issues still need to be specifically addressed in order to achieve the best and the most meaningful motility analyses. Several tracking methods used for the study of motility hav...