A Bilateral Constrained Image Reconstruction Method Using Electrical Impedance Tomography and Ultrasonic Measurement

Electrical Impedance Tomography (EIT) reconstructs the conductivity distribution in a sensing area through an array of boundary electrodes and has received increasing attention in bio-impedance measurement. To provide accurate image reconstruction of irregular conductivity distribution in large sensing area, we propose an efficient and accurate bilateral constrained dual modality reconstruction algorithm using EIT and ultrasonic measurement, where the EIT pre-reconstruction helps to select the time of flight (TOF) time window and the ultrasound reflection information of boundary points contributes to joint iterative reconstruction. In the simulations and phantom experiments selecting abdomen tumor as the object of interest, the proposed method successfully reconstructed the small inclusions. Quantitatively, the proposed bilateral constrained method has improved the reconstruction performance in terms of boundary preservation and robustness compared with single modality EIT and ultrasonic algorithms.

I. Introduction

Electrical Impedance Tomography (EIT) is a non-invasive technology imaging the impedance distribution within the observation domain. Compared with Computed Tomography (CT) [1], Magnetic Resonance Imaging (MRI) [2] and ultrasound imaging [3], EIT is a promising modality due to its safety, portable device and continuous monitoring ability [4]–[6]. Fundamentally, EIT can show the electrical impedance difference between lesion and healthy tissue, making itself an good tool to realize early diagnosis of malignant tumors since the conductivity changes are much earlier than physical physique [7], [8]. There are many researches of EIT on biological impedance detection and reconstruction. Yang et al. reconstructed the breast cancer cell development with a specially designed EIT sensor [9]. Yao et al. realized real-time measurement of vascular and biological microfluidics [10]. Furthermore, EIT has also achieved progress in human disease diagnosis and body monitoring. Huang et al. reconstructed three-dimensional lung cancerous tissues [11] based on the EIT measurement system [12]. Boveman et al. carried out the brain hemorrhage detection on a human subject using absolute EIT reconstruction [13]. EIT is also widely applied in the detection of abdominal tissues. Yamaguchi and Okamoto proposed a high-fidelity EIT reconstruction method to evaluate the visceral fat area [14] and Luo conducted human experiment for multi-scale liver fat content reconstruction [15].