Sequential 123I-iododexetimide scans in temporal lobe epilepsy: comparison with neuroimaging scans (MR imaging and 18F-FDG PET imaging)

  • Armin Mohamed
  • Stefan Eberl
  • Michael J. Fulham
  • Michael Kassiou
  • Aysha Zaman
  • David Henderson
  • Scott Beveridge
  • Chris Constable
  • Sing Kai Lo
Original Article

DOI: 10.1007/s00259-004-1654-2

Cite this article as:
Mohamed, A., Eberl, S., Fulham, M.J. et al. Eur J Nucl Med Mol Imaging (2005) 32: 180. doi:10.1007/s00259-004-1654-2

Abstract

Purpose

Muscarinic acetylcholine receptors (mAChRs) play an important role in the generation of seizures. Single-photon emission computed tomography (SPECT) with 123I-iododexetimide (IDEX) depicts tracer uptake by mAChRs. Our aims were to: (a) determine the optimum time for interictal IDEX SPECT imaging; (b) determine the accuracy of IDEX scans in the localisation of seizure foci when compared with video EEG and MR imaging in patients with temporal lobe epilepsy (TLE); (c) characterise the distribution of IDEX binding in the temporal lobes and (d) compare IDEX SPECT and 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) in identifying seizure foci.

Methods

We performed sequential scans using IDEX SPECT imaging at 0, 3, 6 and 24 h in 12 consecutive patients with refractory TLE undergoing assessment for epilepsy surgery. Visual and region of interest analyses of the mesial, lateral and polar regions of the temporal lobes were used to compare IDEX SPECT, FDG PET and MR imaging in seizure onset localisation.

Results

The 6-h IDEX scan (92%; κ=0.83, p=0.003) was superior to the 0-h (36%; κ=0.01, p>0.05), 3-h (55%; κ=0.13, p>0.05) and 24-h IDEX scans in identifying the temporal lobe of seizure origin. The 6-h IDEX scan correctly predicted the temporal lobe of seizure origin in two patients who required intracranial EEG recordings to define the seizure onset. Reduced ligand binding was most marked at the temporal pole and mesial temporal structures. IDEX SPECT was superior to interictal FDG PET (75%; κ=0.66, p=0.023) in seizure onset localisation. MR imaging was non-localising in two patients in whom it was normal and in another patient in whom there was bilateral symmetrical hippocampal atrophy.

Conclusion

The 6-h IDEX SPECT scan is a viable alternative to FDG PET imaging in seizure onset localisation in TLE.

Keywords

Temporal lobe epilepsy Radionuclide imaging Muscarinic acetylcholine receptors Iododexetimide SPECT 

Copyright information

© Springer-Verlag 2004

Authors and Affiliations

  • Armin Mohamed
    • 1
    • 2
    • 3
  • Stefan Eberl
    • 1
  • Michael J. Fulham
    • 1
    • 3
  • Michael Kassiou
    • 1
    • 4
  • Aysha Zaman
    • 3
  • David Henderson
    • 1
  • Scott Beveridge
    • 1
  • Chris Constable
    • 1
  • Sing Kai Lo
    • 5
  1. 1.Department of PET and Nuclear MedicineRoyal Prince Alfred HospitalCamperdownAustralia
  2. 2.Comprehensive Epilepsy ServiceRoyal Prince Alfred HospitalCamperdownAustralia
  3. 3.Faculty of MedicineUniversity of SydneySydneyAustralia
  4. 4.Department of PharmacologyUniversity of SydneySydneyAustralia
  5. 5.Institute of International HealthUniversity of SydneySydneyAustralia