Nuclear Magnetic Resonant Imaging (also called Magnetic Resonant Imaging or “MRI”) devices which are implantable, internal or insertable are provided. The disclosure describes ways to miniaturize, simplify, calibrate, cool, and increase the utility of MRI systems for structural investigative purposes, and for biological investigation and potential treatment. It teaches use of target objects of fixed size, shape and position for calibration and comparison to obtain accurate images. It further teaches cooling of objects under test by electrically conductive leads or electrically isolated leads; varying the magnetic field of the probe to move chemicals or ferrous metallic objects within the subject. The invention also teaches comparison of objects using review of the frequency components of a received signal rather than by a pictorial representation.