Executive Leadership
Nathan Linstrom - CEO; Marathon Medical Imaging
Nathan Linstrom, MD is Chief Executive Officer of Marathon Medical Imaging and a proud US Air Force Veteran. Dr. Linstrom is a board-certified radiologist with expertise in physician leadership, imaging operations, and musculoskeletal radiology. Fellowship-trained at UCLA, Dr. Linstrom has built a career spanning academic medicine, hospital-based leadership, and radiology practice management, including prior roles as Director of Medical Imaging and Director of Operations. He also served as Clinical Assistant Professor of Radiology at the University of Arizona College of Medicine - Phoenix, bringing a leadership approach centered on clinical excellence, education, operational performance, and long-term growth.
Hannah Johnson-Hollingshead - COO; Marathon Medical Imaging
Hannah Johnson-Hollingshead is a seasoned radiology leader with extensive experience in radiology operations, level 1 trauma hospital imaging environments, and systems implementation. With a professional foundation in clinical imaging, she has advanced into leadership roles focused on building PACS platforms, improving workflow efficiency, and guiding radiology teams through operational growth and change. Hannah is widely recognized for her strength in organization, implementation, and team development, bringing a thoughtful and effective approach to imaging leadership.
Janelle Longobardi - Physician Integration Administrator; Marathon Medical ImagingÂ
Janelle Longobardi serves as Physician Integration Administrator for Marathon Medical Imaging, overseeing key operational functions including physician onboarding, credentialing, payroll coordination, and communication across contracted networks and affiliated sites. With a background in clinical imaging and imaging leadership, she is known for building effective systems, organizing complex workflows, and creating the structure needed to support seamless physician integration and operational excellence across the practice.
Benjamin Weigman, MD - Radiology Director
Benjamin Weigman, MD is a fellowship trained neuroradiologist and physician leader committed to providing exceptional patient care, supporting high-performing radiology teams, and bridging the gap between clinical staff and non-clinical administration. Dr. Weigman completed residency in diagnostic radiology at Creighton University Arizona and completed fellowship training in neuroradiology at Barrow Neurological Institute. With a focus in trauma and emergency imaging, he strives to provide precise, timely image interpretation to assist high-acuity clinical decision making.
Richard Wruble, DO– Radiology Director
Richard "RJ" Wruble, DO is a fellowship-trained neuroradiologist and emerging physician leader with a strong foundation in diagnostic radiology, acute care imaging, and academic medicine. He completed his diagnostic radiology residency at the University of Arizona, where he served as Chief Resident and earned multiple medical student teaching awards. Dr. Wruble went on to complete fellowship training in neuroradiology at Barrow Neurological Institute. Dr. Wruble brings a thoughtful, collaborative approach to clinical excellence, physician engagement, and high-quality patient care.
Erich Mussak, MD – Radiology Director
Erich Mussak, MD is an accomplished imaging leader with extensive experience in body and thoracic radiology. With more than a decade in practice, he has served in key leadership roles including Head of Operations and Medical Director, while contributing to broader imaging leadership initiatives. His expertise spans oncology imaging, lung cancer screening, advanced cross-sectional imaging, and general diagnostic radiology, supporting both clinical excellence and strategic growth in imaging services.