The Edit Metabolites tab allows you define the scaling factor and the T₂ value of each simulated moiety. These values are important for a couple reasons:

1. The amplitudes of each moeity are scaled by the amplitude of the scaling factor. Although you can set the scaling factors to whatever you'd like, the scaling factors represent the ratio of a metabolite's concentration to that of NAA. For example, naa_acetyl and naa_aspartate have scaling factors of 1.0, while naag_acetyl, naag_aspartyl, and naag_glutamate have scaling factors of 0.16. This is because the average concentration of NAAG in the brain is 0.16 that of the average concentration of NAA in the brain.
   
   These scaling factors affect how the moeities are displayed in the Plot Metabolites Tab. If several moieties are defined as part of an "Amplitude Group" in the Generate Constraints Tab, the scaling factor also defines the relative amplitudes between moieties. For example, suppose you have an "Amplitude Group" such as this:
   
   ANaag, -inf, +inf, naag_acetyl, naag_aspartyl, naag_glutamate
   
   This means that the amplitudes of these three moieties are a function of a single parameter. The relative ratio of amplitudes between these three moieties will then be fixed and depend on the ratio between the scaling factors of these three moieties when a constraint file is generated. See here for more details.

2. The amplitudes of each moiety are also scaled by the amount of T₂ relaxation occurring by the echo-time. This is calculated using the specified T₂ relaxation rate in seconds. Like with scaling factors, this affects the display of the moieties, but also the way a constraint file is generated.
   
   It is possible that two moieties belonging to a single metabolite have different T₂ relaxation rates. This is the case for NAA, where naa_acetyl has a longer T₂ than naa_aspartate. In the above figure, you can see that naa_acetyl has a T₂ of 0.2943 sec, while naa_aspartate has a T₂ of 0.148 sec. When a constraint file is being generated, a single amplitude parameter is created for the entire metabolite, unless moieties belonging to the same metabolite have different T₂ values. In the case of NAA, two amplitude parameters are created, one for naa_acetyl (naa_0) and one for naa_aspartate (naa_1), as shown below.

The values may be changed directly by double-clicking a cell in the table and typing in a new value. DO NOT edit the names of the moieties in the "Metabolite" column.

Values may also be defined in an external *.metab file. Some default files are located in the pints/metabinfo folder. You can define a *.metab file using your favourite text editor.

These files are single tab-delimited files where each row should be the following:

METABOLITE  SCALING_FACTOR  T2_VALUE

An example file is given below.

You can load in a *.metab file by hitting hte Browse button. Select your file, hit "OK" and then hit the Confirm button. Finally, hit the Apply to Experiment button to load the values into the table.

alanine  0.0814814815  0.148
aspartate  0.2962962963  0.148
choline_1-CH2_2-CH2  0.1259259259  0.4413
choline_N(CH3)3_a  0.1259259259  0.4413
choline_N(CH3)3_b  0.1259259259  0.4413
creatine_N(CH3)  0.7037037037  0.1278
creatine_X  0.7037037037  0.148
d-glucose-alpha  0.2962962963  0.104
d-glucose-beta  0.2962962963  0.104
eth  0.2592592593  0.148
gaba  0.2222222222  0.105
glutamate  1.4444444444  0.089
glutamine  0.5555555556  0.116
glutathione_cysteine  0.2962962963  0.106
glutathione_glutamate  0.2962962963  0.106
glutathione_glycine  0.2962962963  0.106
glycine  0.0740740741  0.148
gpc_7-CH2_8-CH2  0.037037037  0.4413
gpc_N(CH3)3_a  0.037037037  0.4413
gpc_N(CH3)3_b  0.037037037  0.4413
gpc_glycerol  0.037037037  0.4413
lactate  0.2592592593  0.148
myoinositol  1.037037037  0.148
naa_acetyl  1  0.2943
naa_asparate  1  0.148
naag_acetyl  0.0518518519  0.2943
naag_aspartyl  0.0518518519  0.148
naag_glutamate  0.0518518519  0.148
pcho_N(CH3)3_a  0.0888888889  0.4413
pcho_N(CH3)3_b  0.0888888889  0.4413
pcho_X  0.0888888889  0.4413
pcr_N(CH3)  0.5925925926  0.1278
pcr_X  0.5925925926  0.148
peth  0.2222222222  0.096
scyllo-inositol  0.0148148148  0.148
taurine  0.5925925926  0.093