The present disclosure relates to cannula systems for delivery of a therapeutic agent to parenchymal tissue of a target subject. In certain embodiments, the cannula system is for delivery of a therapeutic agent to parenchymal tissue in the spine of a target subject. In certain embodiments, the cannula system includes a cannula positioning guide (CPG) useful in the delivery of a therapeutic agent to a localized target tissue of a subject. The guide may be used in a surgical suite or during a surgical procedure.