Patients with focal epilepsy often have diagnostic difficulties as their culprit for seizures are difficult to be picked up using conventional imaging. The current study is to investigate the utility of advanced MRI sequences on detection of subtle lesions accountable for focal epilepsy.

Focal epilepsy refers to having seizures arising from a specific part of the brain. In these patients, workup in magnetic resonance imaging is often necessary as patients with structural lesions have a much higher rate of seizures, ranging from 10% to 26% at 1 year and from 29% to 48% at 5 years. However, there is also a subgroup of patients who has epilepsy not adequately controlled by anti-epileptics with unrevealing first MRI study, a dedicated MRI protocol may reveal positive lesion in 30-65% of the cases. In these patients, several tricks can be applied to increase the detection rate. First, the used of a high-resolution MRI on a high-field scanner could be helpful, which can be increased the sensitivity up to 90%. The use of 7T-MRI in further picking up subtle lesions in patients presenting with epilepsy has been investigated, further affirming the role of high resolution MRI imaging. Secondly, the use of dedicated sequences, such as T1-weighted inversion recovery sequences which allow better distinction of grey and white matter, could also reveal subtle lesions such as polymicrogyria or Type 1 focal cortical dysplasia.

This study is therefore aimed to apply the findings to the local settings, and specifically to investigate if T1-weighted inversion recovery sequences provides additional benefit in picking up more subtle lesions in patients who had an initial first negative MRI.

Inclusion Criteria:

• Consecutive patients with drug-resistant focal epilepsy fulfilling the following criteria -

  1. Diagnosis of focal epilepsy with a probable site identified, as defined by concordant results from any TWO of the following:

• Clinical seminology compatible with focal epilepsy.

• Electroencephalography pointing towards a specific site for focal epilepsy.

• Positive ictal brain scintigraphy with SPECT-CT correlation. AND 2. Previous MRI (at least one study with protocol tailored for epilepsy) which did not reveal accountable focal lesion.

AND 3. Able to consent for MRI examination (if patient under age of 18, consent for MRI will be obtained from guardian). Patients will be provided information leaflets to read on, and written consent before taking part in this study and MRI examination.

Exclusion Criteria:

• Patients who are contraindicated to magnetic resonance imaging (such as due to underlying MRI incompatible metallic implants)
• Patients who cannot cooperate for MRI scanning.
• Patients show are unable to provide informed consent.

The image data and outcome measures of the participants can be provided in an anonymized manner upon reasonable request by email to the principal investigator.

No masking is performed during the study