Exploring MRI and RF Safety in Medical Device Development

In the world of medical device safety, the intersection of hardware engineering and electromagnetics is crucial. We had the privilege of interviewing Krishna Singhal, Ph.D, an expert in the field of MRI/RF Safety for medical devices. With a background in Electrical Engineering and extensive experience at TÜV SÜD, Krishna sheds light on the intricacies of MRI safety, the challenges of testing implantable medical devices, and the importance of a multidisciplinary approach for patient well-being. 

Q: Can you give us a brief overview of your role and expertise in the field of MRI/RF Safety for medical devices? 

Krishna: Certainly! I am a Technical Lead for MR Safety at TÜV SÜD, where I oversee all aspects of medical device characterization in MRI environment. My journey in this field started during my formal education at Purdue University, where I spent more than 5 years designing MRI conditional implantable shielded leads. This laid the foundation for my specialization in implantable medical devices safety, especially in the context of MRI environments. After that, I worked at a large medical device manufacturer as one of their early employees establishing their MRI lab and developing the team, where I worked on designing Class III medical devices, specifically neurostimulators and leads. 

Q: Could you elaborate on the significance of MRI safety testing in medical device development? 

Krishna: For patients with implantable devices, there is a significant clinical need to undergo an MRI scan. However, due to safety concerns, patients carrying metallic implantable devices may potentially be denied an MRI scan. For some patients that require multiple MRI scans, let us say a cancer patient, for example, no therapy is possible for this patient, due to MRI safety concerns. The other option available to patients with implantable devices is computed tomography (CT) scans or X-rays, i.e., instead of an MRI, these patients can undergo a CT scan. However, this is not an ideal option, as it possesses ionizing radiation. The third option would be the removal of the implantable device, receiving an MRI and then reimplantation of the device. This option results in exposing patients to multiple surgeries, which is not practical. 

It should be noted that medical professionals prefer MRI scans over other imaging modalities as they provide higher contrast and excellent resolution of images of various soft tissues. However, there are other hazards associated with MRI. The magnetic fields in the MR environments can present serious hazards to patients with implantable metallic devices. These interactions between MRI coils and the metallic components of medical devices can cause force, torque, device vibrations, RF-induced heating etc. The lead wires which are inside your body can act as antennas causing heat dissipation. This is critical to patient safety. Thus, the compatibility and safety of such devices within MRI environments becomes crucial to prevent adverse effects on patients. It is important to characterize how the electromagnetic fields affect the devices, develop methods to mitigate any risks and provide proper conditions under which a patient with an implantable device can undergo an MRI scan. 

Q: Could you walk us through the challenges of characterization of implantable medical devices with a focus on MR/RF safety? 

Krishna: Evaluating implantable medical devices for MR/RF safety is a complex process. Devices, such as cardiovascular stents, neurostimulators or pacemakers, need to function as intended while being exposed to strong electromagnetic fields. Challenges include characterization of RF-induced heating, magnetic force, device malfunction, image artifacts in MRI scans, etc. and that the device's therapeutic effectiveness remains unaffected. Additionally, strict regulatory standards including ASTM 2182 and ISO 10974 must be adhered to. This requires a deeper understanding of electromagnetic theory, sophisticated testing methodologies, and collaboration across engineering disciplines. 

Q: Could you share an example of a breakthrough or solution you've contributed to in the field of MRI safety at TÜV SÜD? 

Krishna: One of the significant contributions I've been involved in is the establishment of a state-of-the-art Medical Device MR compatibility test lab at TÜV SÜD. This lab is one of very few in the world that is accredited to ISO 17025 standard. The lab enables us to perform comprehensive evaluations of medical devices in MRI environments, including temperature rise measurements, SAR measurements, E-field, H-field measurements, and more. This facility empowers us to validate the safety and compatibility of medical devices in an MRI environment effectively.

Q: How important is interdisciplinary collaboration when it comes to MRI safety in medical devices? 

Krishna: Interdisciplinary collaboration is paramount in this field. MRI safety involves a convergence of electrical engineering, electromagnetics, medical expertise, mechanical engineering and regulatory compliance. Engineers need to work alongside medical professionals to comprehend the clinical implications, and collaborate with regulatory bodies for compliance with safety standards. This approach is important for a holistic understanding of the challenges and solutions, ultimately safeguarding patient well-being. 

Q: What advice do you have for aspiring engineers interested in MRI/RF safety for medical devices? 

Krishna: Pursuing a career in MRI/RF safety for medical devices is both rewarding and challenging. It requires a strong foundation in electrical engineering, particularly in electromagnetics. Additionally, gaining insights into medical applications and regulatory standards is crucial. Engage in continuous learning, stay updated with industry advancements, and consider pursuing advanced degrees or certifications in relevant fields. But most importantly, be passionate about contributing to the well-being of patients so that patients with implantable devices can have expanded access to MRI diagnosis. 

Our conversation with Krishna Singhal, Ph.D, has provided a comprehensive understanding of the intricate world of MRI/RF safety for medical devices. His expertise and insights highlight the critical role of engineering in the compatibility and safety of implantable devices within MRI environments. As technology advances and medical device complexity grows, Krishna's work serves as a testament to the importance of interdisciplinary collaboration and continuous innovation in safeguarding patient health and well-being.