A method of identifying nodules in radiological images, said method comprising: (a) obtaining a radiological image; (b) selecting a sub-image centered around a candidate location; (c) dividing the sub-image into a rectangular array of cells; (d) calculating absolute values of Intensity Differences id(k) according to a Fractional Brownian Motion (FBM) calculation equation: id ( k ) = [ ∑ x = 0 N - 1  ∑ y = 0 N - k - 1   I  ( x , y ) - I  ( x , y + k )  4  N  ( N - k ) + ∑ y = 0 N - 1  ∑ x = 0 N - k - 1   I  ( x , y ) - I  ( x + k , y )  4  N  ( N - k ) + ∑ x = 0 N - 1 - k  ∑ y = 0 N - k - 1   I  ( x , y ) - I  ( x + k , y + k )  4  ( N - k ) 2 + ∑ x = 0 N - 1 - k  ∑ y = 0 N - k - 1   I  ( x , N - y ) - I  ( x + k , N - ( y + k ) )  4  ( N - k ) 2 ] , for k=1 to s; (e) calculating a NFBM feature, f(k), for each id(k): f(k)=log(id(k))−log(id(1); (f) integrating f(k), over k=1 to s; (i) classifying the cells into intensity contrast classes, according to intensity contrast between each cell and its neighbors, and the integration result; (k) remapping each cell of the sub-image according to its contrast class, and (m) determining the shape of the region of high-contrast cells in the sub-image, wherein an annular shape identifies a nodule.