Medical diagnostic devices and related methods of use are described in which one or multiple coils in a sensor, each coil connected with an RLC circuit and frequency counter, are held against a patient's head at predetermined cranial locations. Frequencies of the RLC circuit are measured and compared against those taken from known, control heads, to determine whether there is a medical problem and what type of problem. In some instances, too high of frequencies can reveal pooled blood in the head, a sign of hemorrhagic stroke, while too low of frequencies imply lack of blood supply, a sign of ischemic stroke. A head-mountable frame can assist a first responder in securing and guiding the coils and, along with fiducials, allow for automatic comparison of frequencies with the correct control data.