Technological and Clinical Challenges in Lead Placement for Cardiac Rhythm Management Devices.

Cardiac disease is a leading cause of death worldwide. Disturbance in the conduction system of the heart may trigger or aggravate heart dysfunction, affecting the efficiency of the heart, and lead to heart failure or cardiac arrest. Patients may require implantable cardiac rhythm management devices (ICRMDs) to maintain or restore the heart rhythm. ICRMDs have undergone important improvements, yet limitations still exist, presenting important technological challenges. Most ICRMDs consist of a subcutaneous control unit and intracardiac electrodes. The leads, which connect the electrodes to the control unit, are usually placed transvenously through the subclavian veins. Various locations inside the heart are used for placement of electrodes, depending on the specific condition. Some of the limitations to effective pacemaker therapy are associated with placement and location of the leads. Various approaches have been developed to overcome these challenges, such as multi-site pacing and leadless solutions. This paper aims to review the state of the art for the selection of placement sites for pacemakers, implantable cardioverter defibrillator (ICD) and cardiac resynchronization therapy devices (CRT) devices and discuss potential technological advancements to improve the results of ICRMD-therapy including development av leadless technology.

Edge density based automatic detection of inflammation in colonoscopy videos.

Colon cancer is one of the deadliest diseases where early detection can prolong life and can increase the survival rates. The early stage disease is typically associated with polyps and mucosa inflammation. The often used diagnostic tools rely on high quality videos obtained from colonoscopy or capsule endoscope. The state-of-the-art image processing techniques of video analysis for automatic detection of anomalies use statistical and neural network methods. In this paper, we investigated a simple alternative model-based approach using texture analysis. The method can easily be implemented in parallel processing mode for real-time applications. A characteristic texture of inflamed tissue is used to distinguish between inflammatory and healthy tissues, where an appropriate filter kernel was proposed and implemented to efficiently detect this specific texture. The basic method is further improved to eliminate the effect of blood vessels present in the lower part of the descending colon. Both approaches of the proposed method were described in detail and tested in two different computer experiments. Our results show that the inflammatory region can be detected in real-time with an accuracy of over 84%. Furthermore, the experimental study showed that it is possible to detect certain segments of video frames containing inflammations with the detection accuracy above 90%.

EEG based image encryption via quantum walks.

An electroencephalogram (EEG) based image encryption combined with Quantum walks (QW) is encoded in Fresnel domain. The computational version of EEG randomizes the original plaintext whereas QW can serve as an excellent key generator due to its inherent nonlinear chaotic dynamic behavior. First, a spatially coherent monochromatic laser beam passes through an SLM, which introduces an arbitrary EEG phase-only mask. The modified beam is collected by a CCD. Further, the intensity is multiply with the QW digitally. EEG shows high sensitivity to system parameters and capable of encrypting and transmitting the data whereas QW has unpredictability, stability and non-periodicity. Only applying the correct keys, the original image can be retrieved successfully. Simulations and comparisons show the proposed method to be secure enough for image encryption and outperforms prior works. The proposed method opens the door towards introducing EEG and quantum computation into image encryption and promotes the convergence between our approach and image processing.

Wireless communication link for capsule endoscope at 600 MHz.

Simulation of a wireless communication link for a capsule endoscopy is presented for monitoring of small intestine in humans. The realized communication link includes the transmitting capsule antenna, the outside body receiving antenna and the model of the human body. The capsule antenna is designed for operating at the frequency band of 600 MHz with an impedance bandwidth of 10 MHz and omnidirectional radiation pattern. The quality of the communication link is improved by using directive antenna outside body inside matching layer for electromagnetic wave tuning to the body. The outside body antenna has circular polarization that guaranteeing the communication link for different orientations of the capsule inside intestine. It is shown that the path loss for the capsule in 60 mm from the abdomen surface varies between 37-47 dB in relation to the antenna orientation. This link can establish high data rate wireless communications for capsule endoscopy.

An improved ultra wideband channel model including the frequency-dependent attenuation for in-body communications.

Ultra wideband (UWB) technology has big potential for applications in wireless body area networks (WBANs). The inherent characteristics of UWB signals make them suitable for the wireless interface of medical sensors. In particular, implanted medical wireless sensors for monitoring physiological parameters, automatic drug provision, etc. can benefit greatly from this ultra low power (ULP) interface. As with any other wireless technology, accurate knowledge of the channel is necessary for the proper design of communication systems. Only a few models that describe the radio propagation inside the human body have been published. Moreover, there is no comprehensive UWB in-body propagation model that includes the frequency-dependent attenuation. Hence, this paper extends a statistical model for UWB propagation channels inside the human chest in the 1-6 GHz frequency range by including the frequency-dependent attenuation. This is done by modeling the spectrum shape of distorted pulses at different depths inside the human chest. The distortion of the pulse was obtained through numerical simulations using a voxel representation of the human body. We propose a mathematical expression for the spectrum shape of the distorted pulses that act as a window function to reproduce the effects of frequency-dependent attenuation.

Intra-operative visualisation of 3D temperature maps and 3D navigation during tissue cryoablation.

Thermotherapeutic tools are increasingly used for tissue ablation, although the intra-operative monitoring is not adequate for such procedures. This is a main challenge for more extensive use of any ablative technique. The present work focuses on treatment of hepatic tumours by cryo therapy. For any thermotherapeutic tool there are specific thermal conditions that have to be met to ensure treatment adequacy. A software tool was made to calculate and visualise 3D temperature distributions during hepatic cryoablation combined with a 3D intra-operative navigation system. This system aids the user in placing the cryoprobe using an optical tracking system and 3D visualisation of the probe placement in relation to the target anatomy and the planned trajectory. 3D temperature distributions are calculated and visualized intra-operatively. The system is integrated with an interventional Magnetic Resonance 0.5T scanner. The system was tested in an animal experiment, exemplifying the usefulness of the navigation system and its ability to give intuitive feedback to the user on thermodynamic conditions induced in the target region. The system constitutes a novel tool for enhanced intra-operative control during cryoablative procedures, and motivates for studies using this tool to investigate predictors applied as indicators of treatment adequacy and patient outcome.