<unk> , or EIM, is a non-invasive technique for the assessment of muscle health that is based on the measurement of the<unk>  impedance characteristics of individual muscles or groups of muscles. The technique has been used for the purpose of evaluating neuromuscular diseases both for their diagnosis and for their ongoing assessment of progression or with therapeutic intervention. Muscle composition and microscopic structure change with disease, and EIM measures alterations in impedance that occur as a result of disease pathology. EIM has been specifically recognized for its potential as an ALS biomarker (also known as a biological correlate or surrogate endpoint) by Prize4Life, a 501(c)(3) nonprofit organization dedicated to accelerating the discovery of treatments and cures for ALS. The $1M ALS Biomarker Challenge focused on identifying a biomarker precise and reliable enough to cut Phase II drug trials in half. The prize was awarded to Dr. Seward Rutkove, chief, Division of Neuromuscular Disease, in the Department of Neurology at Beth Israel Deaconess Medical Center and Professor of Neurology at Harvard Medical School, for his work in developing the technique of EIM and its specific application to ALS. It is hoped that EIM as a biomarker will result in the more rapid and efficient identification of new treatments for ALS. EIM has shown sensitivity to disease status in a variety of neuromuscular conditions, including radiculopathy, inflammatory myopathy, Duchenne muscular dystrophy, and spinal muscular atrophy. In addition to the assessment of neuromuscular disease, EIM also has the prospect of serving as a convenient and sensitive measure of muscle condition. Work in aging populations and individuals with orthopedic injuries indicates that EIM is very sensitive to muscle atrophy and disuse and is conversely likely sensitive to muscle conditioning and hypertrophy. Work on mouse and rats models, including a study of mice on board the final Space Shuttle mission (STS-135), has helped to confirm this potential value.
Electrical impedance myography
Magnetocardiography
Spectral imaging 
Vectorcardiography
Electrical impedance tomography
Mechanomyogram
Capnography
Sphygmograph