A new method to improve RF safety of implantable medical devices using inductive coupling at 3.0 T MRI.

Objective: To enhance RF safety when implantable medical devices are located within the body coil but outside the imaging region by using a secondary resonator (SR) to reduce electric fields, the corresponding specific absorption rate (SAR), and temperature change during MRI.

Materials And Methods: This study was conducted using numerical simulations with an American Society for Testing and Materials (ASTM) phantom and adult human models of Ella and Duke from Virtual Family Models, along with corresponding experimental results of temperature change obtained using the ASTM phantom. The circular SR was designed with an inner diameter of 150 mm and a width of 6 mm.

A Multi-Frequency 3D Printed Hand Phantom for Electromagnetic Measurements.

It has been shown that the presence of a hand holding a wireless handset (cell phone) can influence antenna efficiency and the measurement of specific absorption rate (SAR) and electromagnetic compatibility. Head phantoms, used in handset compliance testing to estimate SAR in the head, have achieved low cost and multi-frequency use. Head phantoms typically consist of a thin plastic shell, open on the top, holding a tissue simulating fluid.

Comparison of SAR distribution of hip and knee implantable devices in 1.5T conventional cylindrical-bore and 1.2T open-bore vertical MRI systems.

Purpose: There is increasing use of open-bore vertical MR systems that consist of two planar RF coils. A recent study showed that the RF-induced heating of a neuromodulation device was much lower in the open-bore system at the brain and the chest imaging landmarks. This study focused on the hip and knee implants and compared the specific absorption rate (SAR) distribution in human models in a 1.

Static magnetic field measurements of smart phones and watches and applicability to triggering magnet modes in implantable pacemakers and implantable cardioverter-defibrillators.

Background: Implantable pacemakers and implantable cardioverter-defibrillators (ICDs) are designed to include a "magnet mode" feature that can be activated from magnets stronger than 10 G. This feature is designed to be used when a patient is undergoing a procedure where electromagnetic interference is possible, or anytime suspension of tachycardia detection and therapy is needed. A publication in Heart Rhythm demonstrates an iPhone 12 triggering the magnet mode of a Medtronic ICD.

A Case Study of Medical Device Wireless Coexistence Evaluation.

This article aims to provide a narrative for addressing wireless coexistence in medical devices to help medical device developers, test engineers, and regulatory affairs personnel throughout the device life cycle. Accordingly, we present a case-study covering the coexistence evaluation process including the risk analysis of the wireless functionality of a hypothetical medical device, determining the corresponding risk category, specification of the device functional wireless performance (FWP), wireless coexistence testing, and measurement of the intended/untended signal ratio. Also, we propose a simple method for translating the test outcome into user recommendations for minimum/maximum separation distances between the device, its intended companion, and the source of unintended signals.

An outlook on wireless coexistence with focus on medical devices.

The use of shared and unlicensed radio spectrum has been the impetus of innovative and widely used technologies (e.g., Wi-Fi, Bluetooth, and others)-driving the scene of ubiquitous connectivity for devices, sensors, and peripherals in an encompassing Internet of Things (IoT).

Personal medical electronic devices and walk-through metal detector security systems: assessing electromagnetic interference effects.

Background: There have been concerns that Electromagnetic security systems such as walk-through metal detectors (WTMDs) can potentially cause electromagnetic interference (EMI) in certain active medical devices including implantable cardiac pacemakers and implantable neurostimulators. Incidents of EMI between WTMDs and active medical devices also known as personal medical electronic devices (PMED) continue to be reported. This paper reports on emission measurements of sample WTMDs and testing of 20 PMEDs in a WTMD simulation system.

A novel method to decrease electric field and SAR using an external high dielectric sleeve at 3 T head MRI: numerical and experimental results.

Materials with high dielectric constant (HDC) have been used in high field MRI to decrease specific absorption rate (SAR), increase magnetic field intensity, and increase signal-to-noise ratio. In previous studies, the HDC materials were placed inside the RF coil decreasing the space available. This study describes an alternative approach that considers an HDC-based sleeve placed outside the RF coil.

Feasibility results of an electromagnetic compatibility test protocol to evaluate medical devices to radio frequency identification exposure.

Background: The use of radio frequency identification (RFID) systems in healthcare is increasing, and concerns for electromagnetic compatibility (EMC) pose one of the biggest obstacles for widespread adoption. Numerous studies have demonstrated that RFID systems can interfere with medical devices; however, the majority of past studies relied on time-consuming and burdensome test schemes based on ad hoc test methods applied to individual RFID systems.

Methods: This paper presents the results of using an RFID simulator that allows for faster evaluation of RFID-medical device EMC against a library of RFID test signals at various field strengths.

Adhoc electromagnetic compatibility testing of non-implantable medical devices and radio frequency identification.

Background: The use of radiofrequency identification (RFID) in healthcare is increasing and concerns for electromagnetic compatibility (EMC) pose one of the biggest obstacles for widespread adoption. Numerous studies have documented that RFID can interfere with medical devices. The majority of past studies have concentrated on implantable medical devices such as implantable pacemakers and implantable cardioverter defibrillators (ICDs).

Analysis of induced electrical currents from magnetic field coupling inside implantable neurostimulator leads.

Background: Over the last decade, the number of neurostimulator systems implanted in patients has been rapidly growing. Nearly 50, 000 neurostimulators are implanted worldwide annually. The most common type of implantable neurostimulators is indicated for pain relief.

Electromagnetic compatibility of implantable neurostimulators to RFID emitters.

Background: The objective of this study is to investigate electromagnetic compatibility (EMC) of implantable neurostimulators with the emissions from radio frequency identification (RFID) emitters.

Methods: Six active implantable neurostimulators with lead systems were tested for susceptibility to electromagnetic fields generated by 22 RFID emitters. These medical devices have been approved for marketing in the U.

In vitro tests reveal sample radiofrequency identification readers inducing clinically significant electromagnetic interference to implantable pacemakers and implantable cardioverter-defibrillators.

Background: The use of radiofrequency identification (RFID) systems is expanding and highlights the need to address electromagnetic interference (EMI) to implantable pacemakers and implantable cardioverter-defibrillators (ICDs).

Objective: This study sought to examine the electromagnetic compatibility (EMC) between RFID readers and implantable pacemakers or ICDs.

Methods: During in vitro testing, 15 implantable pacemakers and 15 ICDs were exposed to 13 passive RFID readers in 3 frequency bands: 134 kHz (low frequency [LF]), 13.

The Virtual Family--development of surface-based anatomical models of two adults and two children for dosimetric simulations.

The objective of this study was to develop anatomically correct whole body human models of an adult male (34 years old), an adult female (26 years old) and two children (an 11-year-old girl and a six-year-old boy) for the optimized evaluation of electromagnetic exposure. These four models are referred to as the Virtual Family. They are based on high resolution magnetic resonance (MR) images of healthy volunteers.