Table 1.
Study design parameters of included studies.
| Reference | Type | Inclusion criteria | Exclusion criteria | Timeframe | Primary endpoint | Measurement of primary endpoint |
|---|---|---|---|---|---|---|
| De Ciantis et al (De Ciantis et al., 2016) 2016 | P | Age ≥ 8 years; intractable focal epilepsy; unrevealing MRI at 1.5T or 3T | Any contraindications to MRI; need for sedation during MRI; lack of consent. | NS | Diagnostic gain of 7T MRI over conventional MRI | 7T MRI interpretation by 3 experts with knowledge of suspected SOZ |
| Veersema et al (Veersema et al., 2016) 2016 | R | Refractory epilepsy due to histopathologically-confirmed FCD | NS | Nov 2008-Nov 2014 | Diagnostic yield of T2* MRI sequence at 7T | 7T MRI abnormalities co-localizing with epileptogenic zones |
| Kwan et al (Kwan et al., 2016) 2016 | P | History of drug-resistant TLE aged 16–65 years old | Severe coexisting or terminal systemic disease and those unsuitable for MRI evaluation | NS | Ability of 7T MRI (particularly SWI) to detect hippocampal and mesial temporal lobe abnormalities; concordance of 7T MR with postoperative histopathology | 7T MRI lesion detection and location of lesion; 7T MRI concordant or disconcordant correlation with histopathology |
| Santyr et al (Santyr et al., 2016) 2016 | P | Drug-resistant TLE; had continuous video-EEG monitoring followed by ATL | Severe coexisting medical conditions; unsuitable for MRI evaluation. | NS | Using 7T MRI for volumetric assessment of hippocampal subfields, to predict surgical outcomes | 7T MRI normal or abnormal mesial temporal internal architecture; manual hippocampal subfield delineation protocol (Mueller et al., 2007) |
| Colon et al (Colon et al., 2016) 2016 | R | Localization related epilepsy and diagnosed FCD on 1.5T or 3T MRI | Standard MRI exclusion criteria | NS | To study the presentation on 7T MRI of FCDs previously described on conventional MRI | Findings on conventional MRI were compared to the appearance at 7T MRI; features of FCD rated for visibility using Likert scale |
| O’Halloran et al (O’Halloran et al., 2017) 2017 | R | Focal non-lesional epilepsy; healthy controls | NS | NS | u-fiber quantification; u-fiber counts | Difference of u-fiber counts between patients with epilepsy and healthy controls |
| Stefanits et al (Stefanits et al., 2017) 2017 | P | Scheduled for epilepsy surgery due to TLE | NS | NS | Correlation between 7T MRI and histopathological slides | 7T MRI concordant or disconcordant correlation with histopathology |
| Voets et al (Voets et al., 2017) 2017 | P | Pre-surgical patients with TLE, all considered for selective AH; age-matched healthy controls | NS | NS | Whether quantification of hippocampal subfield volumes aids in lateralizing hippocampal dysfunction | 7T MRI SWI manual segmentation of hippocampal subfields |
| Veersema et al (Veersema et al., 2017) 2017 | P | Presurgical evaluation for epilepsy surgery; lesional focal epilepsy suspected; negative 1.5T or 3T MRI | NS | Mar 2009-Feb 2016 | Diagnostic gain of 7T MRI in clinical practice over conventional MRI; influence on surgical decision making | 7T MRI lesion detection, interpreted by dedicated epilepsy radiologist |
| Feldman et al (Feldman et al., 2018) 2018 | P | Focal epilepsy; between 18 and 65 years of age; conventional MRI-negative; healthy controls | Contra-indications to 7T MRI; traumatic brain injury; brain infection | Jul 2014- Oct 2016 | Quantitative evaluation of PVS distribution in epilepsy patients and healthy controls | Marked PVS with diameter ≥ 0.5 mm; PVS quantification in right or left hemisphere and location into one of seven regions |
| Pittau et al (Pittau et al., 2018) 2018 | P | Patients with drug-resistant lesional epilepsy; absence of contra-indications for MRI | NS | Jul 2014-Dec 2016 | Characterize features found in MP2RAGE and SWI sequences at 7T MRI | Qualitative analysis of 7T MRI MP2RAGE and SWI sequences |
| Colon et al (Colon et al., 2018) 2018 | P | Previously diagnosed focal epilepsy; MEG results showing epileptiform abnormalities concordant with semiology; 3T MRI negative; age ≥ 18 years | Pregnancy; incapacitated to sign informed consent | NS | Diagnostic gain of 7T MRI over 3T MRI and estimated added value of MEG-guidance | 7 TMRI lesion detection; levels of convergence between clinical data, MEG, and 7T MRI localization of suspected epileptogenic foci |
| Shah et al (Shah et al., 2019) 2019 | P | Medically refractory unilateral TLE; presurgical evaluation; healthy controls | Neocortical rather than mesial temporal onset; dual pathology; extra-temporal lesions; bilateral disease or ambiguous laterality; neoplasms; other neurological co-morbidities | NS | 7T MRI volumetric assessment of subregions of the hippocampus; characterize differences between TLE-NL and TLE-MTS. | Automated multi-atlas segmented delineation of 10 MTL subregions per hemisphere per subject |
| Feldman et al (Feldman et al., 2019) 2019 | P | Definite focal epilepsy (based on clinical history and EEG); non-lesional conventional MRI; healthy controls | No definite focal epilepsy; generalized epilepsy; lesional clinical MRI; traumatic brain injury; other CNS disease | Jul 2014- Oct 2016 | Correlation between clinical SOZ and abnormalities seen on 7T MRI. | Relationship of clinical SOZ and MRI results in 5 categories; presence or absence of 4 radiological findings |
| Bartolini et al (Bartolini et al., 2019)2019 | R | Focal, single, SOZ. Ablative brain surgery with diagnosis of FCD. Postoperative clinical 1.5/3T MRI. | NS | 2013–2019 | Correlation FCD 7T MRI findings with histopathology and postoperative epilepsy outcome. | 7T MRI signs of FCD: abnormal sulcal/gyral contouring; increased cortical thickness; increased T2W intracortical signal; blurring of GM/WM junction; transmantle sign; T2 WM subcortical hyperintensity; T1 WM subcortical hypointensity. Histopathology: ILAE class Epilepsy surgery: Engel |
| Wang et al. (Wang et al., 2020) 2020 |
P | Negative 3T MRI and suggested focal epilepsy | Contra-indications to MRI, unable to lie still in scanner, claustrophobia, psychiatric conditions, <30 kg, <10 years | 2014–2019 | Diagnostic yield of unaided visual review of 7T and increased yield with 7T MAP | 7T MRI and 7T MAP interpretation by an experienced epilepsy radiologist |
P = prospective. R = retrospective. NS = not specified. NA = not applicable. SOZ = seizure-onset zone. FCD = focal cortical dysplasia. EEG = electroencephalography. ATL = anterior temporal lobectomy. SWI = susceptibility weighted images. PVS = perivascular spaces. MEG = magnetoencephalography. MTL = medial temporal lobe. CNS = central nervous system. GM = gray matter. WM = white matter. ILAE = International League Against Epilepsy. MAP = morphometric analysis program.