1. A method for characterizing a region of interest (ROI) comprising: positioning a tool within a region of interest (ROI), wherein the tool includes an electromagnetic sensor; measuring one or more position data and orientation data as the electromagnetic sensor travels within the ROI; generating a geometric data set of the ROI based on the measured one or more position data and orientation data, wherein the geometric data set includes one or more of the following: length, bifurcation location, angle and curvature characteristics of the ROI; and determining at least one of a size of a lead for permanent placement within the ROI, or a location within the ROI for permanent placement of the lead.