No Evidence to Favor 99mTc-HMPAO or 99mTc-ECD for Ictal Brain Perfusion SPECT for Identification of the Seizure Onset Zone

Purpose: Ictal brain perfusion SPECT with the tracer Tc-99m-HIVIPAO or Tc-99m-ECD is widely used for identification of the epileptic seizure onset zone (SOZ) in presurgical evaluation if standard pointers are uncertain or inconsistent. For both tracers, there are theoretical arguments to favor it over the other for this task. The aim of this study was to compare the performance of ictal brain perfusion SPECT between study and Tc-99m-ECD in a rather large patient sample. Patients and Methods: The study retrospectively included 196 patients from clinical routine in whom ictal perfusion SPECT had been performed with stabilized Tc-99m-HMPAO (n = 110) or Tc-99m-ECD (n = 86). Lateralization and localization of the SOZ were obtained by the consensus of 2 independent readers based on visual inspection of the SPECT images. Results: The Tc-99m-HNIPAO group and the Tc-99m-ECD group were well matched with respect to age, sex, age at first seizure, duration of disease, seizure frequency, history of previous brain surgery, and findings of presurgical MRI. The proportion of lateializing ictal SPECT did not differ significantly between Tc-99m-HMPAO and Tc-99m-ECD (65.5% vs 72.1%, P= 0.36). Sensitivity of ictal perfusion SPECT (independent of the tracer) for correct localization of the SOZ in 62 patients with temporal lobe epilepsy and at least worthwhile improvement (Engel scale <= III) 12 months after temporal epilepsy surgery was 63%. Conclusions: This study does not provide evidence to favor Tc-99m-HMPAO or Tc-99m-ECD for identification of the SOZ by ictal perfusion SPECT.

Automated summary

The study compared the performance of two tracers in ictal brain perfusion SPECT and found no significant difference in identifying the seizure onset zone (SOZ) between Tc-99m-HMPAO and Tc-99m-ECD. The results did not provide evidence to favor one tracer over the other for this purpose.