Table 3.
Study population, primary outcome and diagnostic properties of included studies.
| Reference | Patients N |
Controls N |
Follow-up Months |
Primary endpoint outcome* | Surgery N (%) and type of surgery | Conventional MRI negative N (%) | UHF MRI negative N (%) | Conventional MRI negative, 7T positive N (%) |
|---|---|---|---|---|---|---|---|---|
| De Ciantis et al (De Ciantis et al., 2016) 2016 | 21 | – | 12 | In 6/21 (29%) 7T MRI showed structural abnormalities not detected on conventional MRI. | 8 (38) Lesionectomy 6x ATL + AH 2x |
21 (100) | 15 (71) | 6 (29) |
| Veersema et al (Veersema et al., 2016) 2016 | 6 | 8 | 3 – 36 | In 2/6 (33%) 7T MRI T2* showed structural abnormalities not detected on 3T MRI. | 6 (100) Lesionectomy 4x ATL + AH 2x |
4 (67) | 2 (33) | 2 (33) |
| Kwan et al (Kwan et al., 2016) 2016 | 13 | – | 7 – 39 | 7T MRI can consistently detect HS. 7T MRI findings had high concordance with histopathology, highest for SWI, followed by T2*. | 10 (77) ATL with AH 10x |
4 (31) | 1 (8) | 3 (23) |
| Santyr et al (Santyr et al., 2016) 2016 | 13 | 20 | 7 – 39 | Abnormal atrophy patterns were identified in the ipsilateral CA1 and CA4 + DG subfields. No significant correlation between surgical outcomes and qualitative assessment of hippocampal abnormality. | 10 (77) ATL with AH 10x |
4 (31) | 1 (8) | 3 (23) |
| Colon et al (Colon et al., 2016) 2016 | 10 | – | NS | No additional abnormalities found at 7T compared to 3T. For FCD characteristics 7T scored significantly better than 3T. In 1 patient diagnosis changed due to 7T MRI. | 5 (50) Lesionectomy 5x |
0 (0) | 0 (0) | 0 |
| O’Halloran et al (O’Halloran et al., 2017) 2017 | 8 | 8 | NS | Epilepsy patients had significantly lower raw and normalized mean u-fiber count across all u-fiber groups, suggesting that short-range network connections are compromised in epilepsy. | NS | 8 (100) | NS | NS |
| Stefanits et al (Stefanits et al., 2017) 2017 | 13 | – | NS | Presence or absence of HS correctly detected by 4 investigators on 7T MRI with sensitivity 75–100%, specificity 80–100%: 11/13 (85%) correct prediction of type of HS. | 13 (100) AH 5x ATL + AH 8x |
NS | 5 (38) | NS |
| Voets et al (Voets et al., 2017) 2017 | 12 | 12 | 6 – ≥12 | 9/12 (75%) TLE patients had significant hippocampal subfield atrophy, commonly affecting CA3. TLE patients showed reduced total NAA levels in both hippocampi. Atrophy of hippocampal subfield correlated with clinical TLE variables. | 5 (42) | 7 (58) | 1 (8) | 6 (50) |
| Veersema et al (Veersema et al., 2017) 2017 | 40 | – | 1 – 60 | In 9/40 (23%) 7T MRI showed a lesion not detected on conventional MRI, guiding further surgical decision making. | 13 (30) Lesionectomy 11x ATL + AH 2x |
38 (95) | 31 (77) | 7 (18) |
| Feldman et al (Feldman et al., 2018) 2018 | 21 | 17 | ≥12 | PVS distribution may be strongly liked to effects of epilepsy on the brain. An apparent reduction of PVSs is causing the asymmetry in the brains of epilepsy patients when compared to controls. | 3 (14) | 21 (100) | 11 (52) | 10 (48) |
| Pittau et al (Pittau et al., 2018) 2018 | 7 | – | NS | 7T MRI MP2RAGE and SWI improve the detection rate of epileptogenic lesions and characterization of already known lesions. | 7 (100) | NS | 0 (0) | NS |
| Colon et al (Colon et al., 2018) 2018 | 19 | – | 15 – 46 | In 3/19 (16%) 7T MRI showed a lesion representing an epileptogenic focus, in an additional 3/19 an abnormality was detected after MEG-guidance. | 5 (26) | 19 (100) | 13 (68) | 6 (32) |
| Shah et al (Shah et al., 2019) 2019 | 13 | 24 | NS | Significant differences in volumetric asymmetries between TLE-MTS and TLE-NL in CA1, CA2, CA3, DG, and subiculum, as well as the whole hippocampus were found. | NS | NS | 9 (69) | NS |
| Feldman et al (Feldman et al., 2019) 2019 | 37 | 21 | NS | In 25/37 (67%) 7T MRI showed abnormalities of epileptogenic potential (5x definitely; 3x likely; 7x possibly; 10x uncertain) in focal epilepsy not detected on conventional MRI. | 10 (27) | 37 (100) | 12 (33) | 25 (67) |
| Bartolini et al (Bartolini et al., 2019) 2019 | 12 | – | 12–48 | 7T MRI disclosed FCD type II not seen on conventional MRI in 1 patient. The T2*WI sequence provided the highest added value, disclosing a peculiar intracortical hypointense band, surgical removal was associated with good outcome. | 12 (100) | 3 (25) | 2 (17) | 1 (8) |
| Wang et al (Wang et al., 2020) 2020 | 67 | 50 | 12–60 | Visual review of 7T showed lesions in 22% (15/67), when aided with 7T MAP total yield was 43% (29/67). | 25 (37) | 67 (100) | 38 (57) | 29 (43) |
| After removing duplicates: Total N (%) | 117 (43) | 205 (75) | 128 (47) | 84 (31) | ||||
*See for the primary outcome and primary outcome measurement Table 1.
NS = not specified. MRI = magnetic resonance imaging. HA = hippocampal atrophy/abnormalities. FCD = focal cortical dysplasia. CA = cornu ammonis. DG = dentate gyrus. HS = hippocampal sclerosis. SWI = susceptibility weighted imaging. ATL = anterior temporal lobectomy. AH = amygdalohippocampectomy. TLE =Temporal lobe epilepsy. NAA = N-acetyl-aspartate. PVS = perivascular spaces. MTS = mesial temporal sclerosis. NL = nonlesional. MAP = morphometric analysis program.