Master File Table in NT

Recently I ran Executive Software’s Diskeeper 4.0 on an PIII workstation. When I ran the analyzer it flaged me with a prompt stating that the application was unable to defrag the drive properly due to the 20% disk space limitation. After examinig the chart further I noticed that the MFT Space has nearly doubled in size. I later discovered that this MFT space was reserved for NTFS to record file locations,size, and other information. Also the data within this space could be deleted but the MFT table would not reduce in size.
My question is:
How can the MFT table be reduced and original diskspace be restored?