Associated Particle Neutron Elemental Imaging (APNEI) for in vivo and in vitro diagnostic analysis is a potential technology to measure elemental disease signatures. APNEI can produce elemental images with spatial resolution as small as ~ 1 mm. The use of APNEI technology for disease diagnoses is based on measured concentrations of many signature elements having large differences between normal and diseased tissues ranging up to more than 10 times. For cancer, anomalous elemental concentrations have been observed for breast, liver, colon, kidney, lung and prostate. In principle, in vivo observation of these anomalies would provide a diagnostic tool for disease presence. In vitro measurements may be useful in margin measurements for immediate surgical response. In addition, investigation into the pathways underlying these anomalous elemental concentrations may provide new understanding and possible novel therapeutic targets. To this end possible elemental concentration sensitivity and spatial resolution of APNEI technology for in vivo and in vitro disease diagnosis is presented.