Determination of tissue type surrounding a needle tip by electrical bioimpedance.

A novel method for determining needle position based on local tissue impedance and electrode polarization data, is presented. Measurements of electrical impedance in a small volume around a needle tip can aid in determining if the needle is in the desired tissue. There are many possible applications for this technique, such as needle positioning when administering drugs in blood vessels or muscle tissue, for epidural analgesia or needle EMG exams.