Create an Output checkpoint to store the displayed value in your DataTable. I'm assuming you'd want to use this value again, which can be done simply by calling the stored the DataTable cell value.
You may want to look up Output checkpoints and DataTable methods in QTP help. If you post a snipet of the script here, one of us may also be able to tell you what you need to change where. Though try using the help files first.
(I'm hiring Software Development Engineers in Test in Seattle, WA)