Patent ID: 8195269

Claim:
A method of detecting malacia in airways, comprising the steps of: receiving, by a computer system, a plurality of 3-dimensional (3D) digital lung images acquired over an inhalation/exhalation cycle from a same subject, each said image comprising a set of intensities on a 3-dimensional grid of points; registering, by the computer system, a successive pair of images, wherein a registration mapping of the point grid of one image is calculated; calculating, by the computer system, a quality factor of said registration mapping, wherein the quality factor is indicative of rigidity of the registration mapping; locating, by the computer system, airways in each of said pair of images; and if the quality factor indicates that the registration mapping is sufficiently rigid, collecting, by the computer system, points between volumes of the airways in each of said pair of images, wherein the points are used to obtain a volume difference that is a measure of an extent of malacia in said airways; wherein if said quality factor is greater than a predetermined threshold, accepting the registration, otherwise repeating said steps of registering the pair of images and calculating a quality factor until the quality factor exceeds the predetermined threshold; wherein said quality factor Q is defined as Q = 1 2 ⁢ ∑ i = 1 2 ⁢ w i ⁡ ( α i ) , and wherein w 1 (α 1 ) and w 2 (α 2 ) are weighting functions that monotonically increase from 0 to 1 to penalize abnormal local deformations, and are defined as w 1 ⁡ ( α 1 ) = exp ⁡ ( - A ⁡ ( 1 - α 1 ) E 1 ) , ⁢ and w 2 ⁡ ( α 2 ) = exp ⁡ ( - B ⁡ ( 1 - α 2 ) E 2 ) .