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Fig. 2 | EJNMMI Research

Fig. 2

From: Evaluation of [ 13 N]ammonia positron emission tomography as a potential method for quantifying glutamine synthetase activity in the human brain

Fig. 2

Representative ammonia TAC data and fit examples. Symbols show example time activity curves (TACs) from ammonia PET scans and lines show model fits. Top row (ac): data from test scan; bottom row (df) data from retest scan. 1st column (a, d): Subject 1, fits to grey matter TAC: blue line: irreversible 1TCM (K1 plus blood volume, Vb); green line: reversible 1TCM (K1, k2, Vb); red line: irreversible 2TCM (K1, k2, k3, Vb) and magenta line: reversible 2TCM (K1, k2, k3, k4, Vb). The most complex three models appear to fit equally well and appear as superimposed on the graph. 2nd column (b, e): TAC (point) and irreversible 2TCM model fits (lines) from subject 1 for grey matter (blue), white matter (green), left hippocampus (red), left lingual gyrus (magenta), left posterior cingulate gyrus (cyan), left putamen (black), left thalamus (grey) and left cerebellum (dark red). c TACs (points) and irreversible 2TCM model fits (lines) for grey matter in all subjects. Coloured circles and lines (blue, green, red, magenta and cyan, for subjects 1–5, respectively) and grey symbols and lines (triangle/solid, square/dashed, diamond/dotted for subjects 6–8, respectively). All fits for all subjects are shown in Additional file 1: Figure S5

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