FIG 4. a, Ratios of ¹H MR signal intensities (double spin-echo sequence 1500/135/200–300) of total choline and total creatine (I_tCho/I_tCr) versus ratios of intensities of total choline and NAA (I_tCho/I_NAA) observed in lesions classified as progressive tumor (, n = 35), radiation injury (, n = 17), and stable disease (, n = 15). The straight lines: (I_tCho/I_tCr) = 2.5–0.5 x (I_tCho/I_NAA) (line 1) and (I_tCho/I_tCr) = 4.2–1.35 x (I_tCho/I_NAA) (line 2) obtained from linear discriminant analysis and 7-point neighbor method, respectively, differentiate neoplastic and nonneoplastic lesions.

b, Detail of (a) with ratios 5.0 together with I_tCho/I_tCr and I_tCho/I_NAA values of normal brain (x, n = 33, voxel in the contralateral unaffected side). Parallel lines obtained from linear discriminant analysis are labeled with the probability of PT.