James Enrico Sabatini

Multi-channel electrical impedance tomography for regional tissue hydration monitoring

Poor assessment of hydration status during hemodialysis can lead to under- or over-hydration in patients with consequences of increased morbidity and mortality. In current practice, fluid management is largely based on clinical assessments to estimate dry weight (normal hydration body weight). However, hemodialysis patients usually have co-morbidities that can make the signs of fluid status ambiguous. Therefore, achieving normal hydration status remains a major challenge for hemodialysis therapy. Electrical impedance technology has emerged as a promising method for hydration monitoring due to its non-invasive nature, low cost and ease-of-use. Conventional electrical impedance-based hydration monitoring systems employ single-channel current excitation (either 2-electrode or 4-electrode methods) to perturb and extract averaged impedance from bulk tissue and use generalized models from large populations to derive hydration estimates. In the present study, a prototype, single-frequency electrical impedance tomography (EIT) system with simultaneous multi-channel current excitation was used to enable regional hydration change detection. We demonstrated the capability to detect a difference in daily impedance change between left leg and right leg in healthy human subjects, who wore a compression sock only on one leg to reduce daily gravitational fluid accumulation. The impedance difference corresponded well with the difference of lower leg volume change between left leg and right leg measured by volumetry, which on average is ~35 ml, accounting for 0.7% of the lower leg volume. We have demonstrated the feasibility of using multi-channel EIT to extract hydration information in different tissue layers with minimal skin interference. Our simultaneous, multi-channel current excitation approach provides an effective method to separate electrode contact impedance and skin condition artifacts from hydration signals. The prototype system has the potential to be used in clinical settings for helping optimize patient fluid management during hemodialysis as well as for home monitoring of patients with congestive heart failure, chronic kidney disease, diabetes and other diseases with peripheral edema symptoms.

Real-time 3D electrical impedance imaging for ventilation monitoring of the lung: Pilot study.

We report an Electrical Impedance Tomography device capable of detecting gravity-induced regional ventilation changes in real-time without averaging or using a contrast medium. Changes in lung ventilation are demonstrated in right and left lateral decubitus position and compared to those seen in an upright and supine normal subject.

A magnetic resonance compatible E4D ultrasound probe for motion management of radiation therapy

There is recent interest in the use of ultrasound (US) and magnetic resonance (MR) imaging modalities for motion management during radiation therapy treatments. These imaging modalities aim to improve clinical outcomes by tracking tumor motion in order to increase the therapeutic ratio. The objective of this research is to develop an MR-compatible, real-time, three-dimensional ultrasound probe (E4D) for simultaneous MR and US imaging. The probe will be used in a system which leverages the real-time capabilities of ultrasound imaging and the soft-tissue image quality of MR for image guided radiation therapy (IgRT) of moving tumors.

Design and development of a 3D folded slot antenna for body-worn wireless devices

A new 3D foldable flexible slot antenna is proposed to be embedded in body-worn devices. It can accommodate skin-thin wearable devices while maintaining a radiation efficiency as high as 75%. The antenna is designed for on-body applications to be operated in 2.36-2.48 GHz frequency range, which covers both the medical body area network (MBAN) and the industrial, scientific and medical (ISM) frequencies. It also has a large bandwidth of 120 MHz that can facilitate high data rate wireless channels, suitable for many critical medical applications.

Real-time 3D electrical impedance imaging for ventilation and perfusion of the lung in lateral decubitus position

We report a prototype Electrical Impedance Imaging System. It is able to detect the gravity-induced changes in the distributions of perfusion and ventilation in the lung between supine and lateral decubitus positions. Impedance data were collected on healthy volunteer subjects and 3D reconstructed images were produced in real-time, 20 frames per second on site, without using averaging or a contrast agent. Imaging data also can be reconstructed offline for further analysis.