Comparison of Ictal SPECT with 99mTc-HMPAO versus MRI for the Epileptic Seizure Onset Zone Detection in Saudi Patients

Abstract

Background: In the presurgical evaluation of patients with drug-resistant epilepsy, magnetic resonance imaging (MRI) and ictal brain perfusion SPECT with the chemical microspheres 99mTc-HMPAO are widely used for diagnosing the seizure onset zone (SOZ). For both modalities, there is theoretical controversy over favoring one over the other. This study aimed to compare the performance of 99mTc-HMPAO SPECT with MRI for SOZ identification in EEG-proved epileptic Saudi patients. Methods and Results: For this observational retrospective study, the database of the nuclear medicine departments at the Prince Sultan Military Medical City (PSMMC) and King Abdullah bin Abdulaziz University Hospital (KAAUH) were searched for male and female patients with suspected unifocal epilepsy in whom ictal brain perfusion SPECT and MRI had been performed for presurgical evaluation. A total of 14 adult epileptic patients above 18 years were included who have undergone SPECT scans using 99mTc-HMPAO and MRI between Jan 2014 and Dec 2021. 99mTc-HMPAO SPECT and MRI scans were performed simultaneously for each patient, and there was almost general agreement that 99mTc-HMPAO SPECT accurately localized and detected the SOZ in 12/14 patients (sensitivity 85.71%). It was superior to MRI, which detected and localized the SOZ in only 7/14 patients (sensitivity 50.0%). Unfortunately, the specificity of ictal brain perfusion SPECT, by using 99mTc-HMPAO in seizure localization in epileptic patients, was not detected due to the shortage of data that led to all the EEG findings being 100% positive. Conclusion: This study reported that ictal SPECT using 99mTc-HMPAO provides more valuable information about SOZ localization than MRI. However, future studies with a larger sample size are needed to assess the specificity of 99mTc-HMPAO SPECT in detecting the SOZ.