Abstract
In this prospective study, we postulate that there is a difference between clearance of [99mTc]Tc- ethyl cysteinate dimer (ECD) in the seizure onset zone (SOZ) and other brain areas and thus SOZ localization by clearance patterns might become a potential novel method for SOZ localization in epilepsy. The parametric images of brain ECD clearance were generated by linear regression model analysis from serial brain SPECT scans from 30 to 240min after ECD injection (7-times point) in 7 patients with drug-resistant epilepsy and 3 normal volunteers. Clearance patterns of the SOZ confirmed by good surgical outcome or consensus with other investigations were analyzed quantitatively and semi-quantitatively by visual grading (slower or faster washout than contralateral brain regions). The average [99mTc]Tc-ECD clearance rates of SOZs were + 1.08% ± 2.57%/hr (wash in), -7.02% ± 2.56%/hr (washout), and -5.37% ± 1.71%/hr (washout) in ictal, aura and interictal states, respectively. Paired t-tests between the SOZ and contralateral regions showed statistically significant difference (p = 0.039 in interictal state). Clearance patterns that can define the SOZs were 1) wash in and slow washout on ictal slope, 2) fast washout on aura slope and interictal slope with 100% (6/6), 100% (2/2) and 75% (6/8) localization using ictal, aura, and interictal slope maps, respectively. Our study provided the evidence that clearance pattern methods are potential additive diagnostic tools for SOZ localization when routine one-time point SPECT are unable to define the SOZ.
Highlights
Almost 50 million patients were diagnosed with active epilepsy (Collaborators, 2019)
single photon emission computed tomography (SPECT) in epilepsy is performed at one-time point for ictal and interictal states
We postulate that there is a difference between clearance of [99mTc]Tc-ECD in the seizure onset zone (SOZ) and other brain areas and seizure focus localization by clearance patterns might become a potential non-invasive method for better pre-surgical SOZ localization
Summary
Almost 50 million patients were diagnosed with active epilepsy (Collaborators, 2019). 20–40% of epilepsy becomes drug-resistant epilepsy (DRE) (French, 2007). DRE or long-term epilepsy increases mortality and decreases quality of life (Kanchanatawan & Kasalak, 2012; Sillanpaa & Shinnar, 2010). Surgical treatment with correct localization of epileptogenic zone (EZ) in DRE shows better outcome than continued medical treatment (Ramey et al, 2013). There are generally 2 types of EZ localization, invasive and noninvasive methods. Intracranial electroencephalography (iEEG), an invasive method, is considered a gold standard for pre-surgical localization (Shah & Mittal, 2014). Scalp EEG and single photon emission computed tomography (SPECT) are examples of non-invasive methods. SPECT in epilepsy is performed at one-time point for ictal and interictal states.
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