sp_spaceused display huge index size eveb though index was dropped

Sybase version: Adaptive Server Enterprise/12.5.4/EBF 15446 ESD#8/P/Solaris AMD64/OS 5.10/ase1254/2105/64-bit/OPT/Sat Mar 22 04:05:46 2008

Good afternoon,

I have a question about sp_spaceused information.

For a table, sp_spaceused returns

                                      rowcount    reserved           data               index               unused

REPOSITORY_SPACE    2875956    11855104 KB    140596 KB    11710208 KB    4300 KB

The table has an index on a NUMERIC field.

This table has a field of type IMAGE

I don't understand why the space used by my index is so huge compared to the data size.

I even drop the index, run reorg rebuild, delete statistics, sp_flushstats but the values don't change.

Could anyone explain me the figures and why my index size is still present.

Thank you

Simon