Hi Nabeel,
A few things to consider,
Firstly you need to exclude a defect in the line alba which would represent a ventral hernia
Then use the panoramic mode with the patient relaxed and measure the width of the linea alba between the rectus abdomens muscles
Then ask the patient to do a small sit up and repeat the process measuring the width.
The length of the linea alba is not important here.
Then I would look at the rectus abdominus muscle bellies and comment on any atrophy or fibro-fatty replacement features.
I would have a look up and down the spigelian line and check out the lateral abdominal wall muscles ( TA, EO, IO ) again looking for hernia and muscle atrophy change.
that should about do it,
cheers
Steve