The case for global quantitative analysis in the assessment of temporal lobe epilepsy

• Published in: The Journal of nuclear medicine (1978) Vol. 58; p. 975
• Main Authors: Peter, Jonah, Werner, Thomas, Alavi, Abass
• Format: Journal Article
• Language: English
• Published: New York Society of Nuclear Medicine 01-05-2017
• Subjects: Abnormalities; Acetylcholine receptors (nicotinic); Atrophy; Butyric acid; Clinical trials; Computed tomography; Control methods; Correlation analysis; Correlation coefficients; Diagnosis; Diagnostic software; Diagnostic systems; EEG; Electrodes; Electroencephalography; Epilepsy; Health risks; Hemispheric laterality; Magnetic resonance imaging; Medical imaging; Mental disorders; Metabolism; Neuroimaging; Neurology; Opioid receptors; Patients; Photon emission; Positron emission; Positron emission tomography; Quantitative analysis; Radioactive tracers; Receptors; Seizing; Seizures; Serotonin receptors; Single photon emission computed tomography; Surgery; Surgical instruments; Temporal lobe; Uncertainty
• ISSN: 0161-5505; 1535-5667

Objectives: 1. Review of commonly used modalities for assessing temporal lobe epilepsy. 2. Description of a novel method of global quantitative analysis for more accurate metabolic assessment. 3. Demonstration of the efficacy of global quantitative analysis for use in healthy control subjects. Traditional methods of evaluating temporal lobe epilepsy (TLE) rely on electroencephalography (EEG) to aid in diagnosis, treatment, and surgical planning. Although generally accepted as the "gold standard" for TLE diagnosis, the use of depth electrodes is an invasive procedure and puts the patient at risk for infection and cerebral hemorrhaging. Surface electrode EEG can be informative in severe cases, but fails to locate a specific lateralization of seizure focus in many instances. Noninvasive neuroimaging provides an attractive alternative for evaluating TLE, although many modalities remain ineffective. Quantification of temporal lobe volume using volumetric magnetic resonance imaging (MRI) can accurately assess asymmetrical atrophy in patients with severe TLE. However, structural abnormalities that appear on MRI may take years to develop. Molecular imaging modalities such as single photon emission computed tomography (SPECT) and positron emission tomography (PET) have the potential to detect seizure lateralization far earlier. Ictal imaging using (99m)Tc-hexamethylpropyleneamine oxime (HMPAO) is an effective diagnostic tool, however ictal scans are difficult and complicated to perform. A variety of novel interictal radiotracers have been recently developed including those binding to gamma-amino-butyric acid(A) receptors, opioid receptors, 5-HT(1A) serotonin receptors, and nicotinic acetylcholine receptors, but the reliability of these tracers remains to be proven. By contrast, quantification of global standardized uptake value (SUV) using 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) has been shown to accurately diagnose seizure lateralization other methods of visual assessment failed to do so. A study conducted in our lab showed that diagnoses made using the global quantitative assessment on FDG-PET were in agreement with clinical evaluations for 91% of patients on consecutive trials, with single measure intraclass correlation coefficients (ICC) of 0.97 and 0.92 for metabolic ratios and lateralization indices respectively. We are currently performing a study to assess the efficacy of the global quantitative technique in observing cerebral metabolism in healthy control subjects. An analysis of the precision of this technique on healthy control subjects is necessary to determine the limits of uncertainty associated with the technique. The results of this study will help determine whether global quantitative analysis using FDG-PET should be adopted for diagnosis of neuropsychiatric disorders such as TLE. 1. Current modalities used to assess TLE: a. depth electrode and surface EEG b. volumetric MRI c. molecular imaging using PET and SPECT 2. Demonstration of global quantitative assessment using FDG-PET: a. results from global quantitative analysis b. comparison to traditional ROI techniques d. comparison to visual assessments on FDG-PET and MRI 3. Applications of global quantitative analysis for use in healthy control subjects a. analysis of intraobserver and interobserver variability