The value of resting-state functional magnetic resonance imaging for detecting epileptogenic zones in patients with focal epilepsy.

Zhijuan Chen,Hongyan Ni,Weidong Yang,Bofeng Zhao,Qing Yu,Yang An,Li Cai,Jianzhong Yin,Satoru Hayasaka

doi:10.1371/journal.pone.0172094

Abstract

ObjectiveTo determine the value of resting-state functional magnetic resonance imaging (RS-fMRI) based on the local analysis methods regional homogeneity (ReHo), amplitude of low-frequency fluctuations (ALFF), and fractional ALFF (fALFF), for detecting epileptogenic zones (EZs).MethodsA total of 42 consecutive patients with focal epilepsy were enrolled. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of visually assessed RS-fMRI, MRI, magnetic resonance spectroscopy (MRS), video electroencephalography (VEEG), and positron-emission tomography computed tomography (PET-CT) in EZ localization were evaluated to assess their diagnostic abilities. ReHo, ALFF, and fALFF were also compared for their diagnostic values.ResultsRS-fMRI showed comparable sensitivity to PET (83.3%) and specificity to VEEG (66.7%), respectively, for EZ localization in patients with focal epilepsy. There were no significant differences between RS-fMRI and the other localization techniques in terms of sensitivity, specificity, PPV, and NPV. The sensitivities of ReHo, ALFF, and fALFF were 69.4%, 52.8%, and 38.9%, respectively, and for specificities of 66.7%, 83.3%, and 66.7%, respectively. There were no significant differences among ReHo, ALFF, and fALFF, except that ReHo was more sensitive than fALFF.ConclusionsRS-fMRI may be an efficient tool for detecting EZs in focal epilepsy patients.

Highlights

Focal epilepsy accounts for approximately 60% of all epilepsy cases [1]
There were no significant differences between resting-state functional magnetic resonance imaging (RS-functional MRI (fMRI)) and the other localization techniques in terms of sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV)
There were no significant differences among regional homogeneity (ReHo), amplitude of low-frequency fluctuations (ALFF), and fractional ALFF (fALFF), except that ReHo was more sensitive than fALFF

Summary

Introduction

Focal epilepsy accounts for approximately 60% of all epilepsy cases [1]. A selected subset of focal epilepsy patients may benefit from complete resection or total disconnection of the epileptogenic zone (EZ), which is defined as an area of the cortex indispensable for the generation of clinical seizures [2]. Structural magnetic resonance imaging (MRI) has the best spatial resolution but is not sensitive enough to detect subtle structural lesions such as cortical dysplasia [3,4]. Magnetic resonance spectroscopy (MRS) can elucidate the neurochemical substrates of epilepsy and has important diagnostic value in patients with no overt morphological abnormalities but only metabolic and functional defects. Positron-emission tomography (PET) and single-photon emission computed tomography (SPECT) have improved the detection rate of inconspicuous lesions [5,6]. These methods expose the patient to radioactivity, and tend to reveal regional rather than local abnormalities. A combination of these techniques could improve the accuracy of localization, there is still a need for more precise, noninvasive techniques for preoperative EZ identification

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Conclusion