Resting-State Functional MRI/PET Profile as a Potential Alternative to Tri-Modality EEG-MR/PET Imaging: An Exploratory Study in Drug-Refractory Epilepsy

Sandhya Mangalore; Sameer Peer; Sunil Kumar Khokhar; Rose Dawn Bharath; Karthik Kulanthaivelu; Jitender Saini; Sanjib Sinha; Vyasaraj Kalya Kishore; Ravindranadh Chowdary Mundlamuri; Ajay Asranna; Vishwanath Lakshminarayanapuram Gopal; Raghavendra Kenchaiah; Arivazhagan Arimappamagan; Nishanth Sadashiva; Malla Bhaskara Rao; Anita Mahadevan; Jamuna Rajeswaran; Keshav Kumar; Kandavel Thennarasu

doi:10.1055/s-0043-1760852

Resting-State Functional MRI/PET Profile as a Potential Alternative to Tri-Modality EEG-MR/PET Imaging: An Exploratory Study in Drug-Refractory Epilepsy

Asian J Neurosurg. 2023 Mar 27;18(1):53-61. doi: 10.1055/s-0043-1760852. eCollection 2023 Mar.

Authors

Sandhya Mangalore¹, Sameer Peer¹, Sunil Kumar Khokhar¹, Rose Dawn Bharath¹, Karthik Kulanthaivelu¹, Jitender Saini¹, Sanjib Sinha², Vyasaraj Kalya Kishore², Ravindranadh Chowdary Mundlamuri², Ajay Asranna², Vishwanath Lakshminarayanapuram Gopal², Raghavendra Kenchaiah², Arivazhagan Arimappamagan³, Nishanth Sadashiva³, Malla Bhaskara Rao³, Anita Mahadevan⁴, Jamuna Rajeswaran⁵, Keshav Kumar⁵, Kandavel Thennarasu⁶

Affiliations

¹ Department of Neuroimaging and Interventional Radiology, National Institute of Mental Health and Neurosciences (NIMHANS), Bengaluru, Karnataka, India.
² Department of Neurology, National Institute of Mental Health and Neurosciences (NIMHANS), Bengaluru, Karnataka, India.
³ Department of Neurosurgery, National Institute of Mental Health and Neurosciences (NIMHANS), Bengaluru, Karnataka, India.
⁴ Department of Neuropathology, National Institute of Mental Health and Neurosciences (NIMHANS), Bengaluru, Karnataka, India.
⁵ Department of Clinical Psychology, National Institute of Mental Health and Neurosciences (NIMHANS), Bengaluru, Karnataka, India.
⁶ Department of Biostatistics, National Institute of Mental Health and Neurosciences (NIMHANS), Bengaluru, Karnataka, India.

Abstract

Objective The study explores whether the epileptic networks associate with predetermined seizure onset zone (SOZ) identified from other modalities such as electroencephalogram/video electroencephalogram/structural MRI (EEG/VEEG/sMRI) and with the degree of resting-state functional MRI/positron emission tomography (RS-fMRI/PET) coupling. Here, we have analyzed the subgroup of patients who reported having a seizure on the day of scan as postictal cases and compared the findings with interictal cases (seizure-free interval). Methods We performed independent component analysis (ICA) on RS-fMRI and 20 ICA were hand-labeled as large scale, noise, downstream, and epilepsy networks (Epinets) based on their profile in spatial, time series, and power spectrum domains. We had a total of 43 cases, with 4 cases in the postictal group (100%). Of 39 cases, 14 cases did not yield any Epinet and 25 cases (61%) were analyzed for the final study. The analysis was done patient-wise and correlated with predetermined SOZ. Results The yield of finding Epinets on RS-fMRI is more during the postictal period than in the interictal period, although PET and RS-fMRI spatial, time series, and power spectral patterns were similar in both these subgroups. Overlaps between large-scale and downstream networks were noted, indicating that epilepsy propagation can involve large-scale cognition networks. Lateralization to SOZ was noted as blood oxygen level-dependent activation and correlated with sMRI/PET findings. Postoperative surgical failure cases showed residual Epinet profile. Conclusion RS-fMRI may be a viable option for trimodality imaging to obtain simultaneous physiological information at the functional network and metabolic level.

Keywords: epilepsy; epileptic network; fluorodeoxyglucose; positron emission tomography; resting-state functional MRI; temporal lobe epilepsy.

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