Given a single PivotGrid cell (as PivotCell), is there a quick way to find the items in the FlatDataSource that contributes to that cell?

If one or more dimensions of the FlatDataSource is omitted from the grid, then each cell is the sum of multiple items from the data source. I can from the cell find column and row, and from there the levelnames and values that is agregated into the cell, and finally loop through the item source and check each item for match.

However, with several hundred thousands of items in the source this is time consuming. Is there some place the cell has stored pointers/indexes to the data source items that are accumulated into the cell?