A computer-implemented method comprising: generating, based on a voxel distance map, a signal indicative of a quantification of a characteristic of a lumen of a tubular structure of interest over a pre-determined volume of the tubular structure of interest represented in volumetric imaging data, wherein the tubular structure is a blood vessel or the colon, wherein the characteristic includes a radius or diameter of the tubular structure of interest at one or more points along the tubular structure of interest determined by moving an elastic ball through the tubular structure of interest between a selected start point and end point and determining the radius or diameter of the ball at the one or more points, wherein the ball is grown as large as possible at a point while being enclosed by the tubular structure of interest; and determining a state metric from the quantification that indicates a percentage of occlusion of the tubular structure of interest between the selected start point and end point, wherein the percentage of occlusion is based on an average diameter and a minimum diameter between the selected start point and end point, wherein the average diameter includes at least one of: an average of all diameters between the selected start point and end point, a largest diameter of all diameters between the selected start point and end point, or an average diameter over a predetermined range along a path of the lumen and wherein the minimum diameter includes at least one of: a smallest diameter of all diameters between the selected start point and end point, an average of a range of smallest diameters of all diameters between the selected start point and end point, or a diameter at a user selected or predetermined location along a path of the lumen. generating, based on a voxel distance map, a signal indicative of a quantification of a characteristic of a lumen of a tubular structure of interest over a pre-determined volume of the tubular structure of interest represented in volumetric imaging data, wherein the tubular structure is a blood vessel or the colon, wherein the characteristic includes a radius or diameter of the tubular structure of interest at one or more points along the tubular structure of interest determined by moving an elastic ball through the tubular structure of interest between a selected start point and end point and determining the radius or diameter of the ball at the one or more points, wherein the ball is grown as large as possible at a point while being enclosed by the tubular structure of interest; and determining a state metric from the quantification that indicates a percentage of occlusion of the tubular structure of interest between the selected start point and end point, wherein the percentage of occlusion is based on an average diameter and a minimum diameter between the selected start point and end point, wherein the average diameter includes at least one of: an average of all diameters between the selected start point and end point, a largest diameter of all diameters between the selected start point and end point, or an average diameter over a predetermined range along a path of the lumen and wherein the minimum diameter includes at least one of: a smallest diameter of all diameters between the selected start point and end point, an average of a range of smallest diameters of all diameters between the selected start point and end point, or a diameter at a user selected or predetermined location along a path of the lumen.