PISCOM: a new procedure for epilepsy combining ictal SPECT and interictal PET

Area of Science:

• Neuroimaging
• Epileptology
• Nuclear Medicine

Background:

• Accurate localization of the seizure onset zone (SOZ) is critical for successful epilepsy surgery.
• Current techniques like SISCOM (subtracted ictal and interictal) SPECT Co-registered with MRI have limitations.
• Exploring alternative imaging modalities for improved SOZ identification is essential.

Purpose of the Study:

• To introduce and evaluate a novel nuclear imaging technique, PISCOM (PET interictal subtracted ictal SPECT coregistered with MRI).
• To compare the efficacy of PISCOM with the traditional SISCOM procedure for SOZ localization.
• To assess the correlation between cerebral perfusion and glucose metabolism in epilepsy.

Main Methods:

• Retrospective analysis of 23 medically refractory epilepsy patients who achieved seizure freedom post-surgery.
• Reprocessing of interictal FDG PET (rFDG PET) to match SPECT features for image subtraction.
• Comparison of PISCOM and SISCOM using visual and automated volume of interest (VOI)-based analyses, validated against surgical resection sites.

Main Results:

• Statistical Parametric Mapping (SPM) revealed no significant cortical activity differences between SPECT and rFDG PET.
• PISCOM and SISCOM yielded equivalent results in 74% of patients.
• PISCOM successfully identified the SOZ in 83% of patients, outperforming SISCOM (74%), with reduced indeterminate activity.

Conclusions:

• Preliminary findings suggest PISCOM is a valid technique for SOZ identification, correlating perfusion and glucose metabolism.
• PISCOM demonstrates potential for improved accuracy and reduced ambiguity in SOZ localization.
• Further research is warranted to validate PISCOM's clinical utility in epilepsy management.