Neuroimaging for patient selection for medial temporal lobe epilepsy surgery: Part 1 Structural neuroimaging

• Many imaging methods are routinely applied in clinical practice, while others are still under investigation.
• Structural MRI is continuously improving, leading to more detailed elucidation of temporal lobe structures and anomalies that are responsible for temporal lobe epilepsy (TLE).
• Diffusion-weighted imaging and tractography also play an important role for surgical planning and the improvement of postsurgical prognosis.
• Magnetoencephalography can be a very useful and complementary tool that, in combination with the other methods, can increase the reliability of the presurgical evaluation of TLE patients.
• There is still room for improvement with regards to the imaging methods used to investigate TLE and evaluate TLE patients prior to surgery, which can be achieved with additional studies of larger patient cohorts.

The objective of part one of this review is to present the structural neuroimaging techniques that are currently used to evaluate patients with temporal lobe epilepsy (TLE), and to discuss their potential to define patient eligibility for medial temporal lobe surgery. A PubMed query, using Medline and Embase, and subsequent review, was performed for all English language studies published after 1990, reporting neuroimaging methods for the evaluation of patients with TLE. The extracted data included demographic variables, population and study design, imaging methods, gold standard methods, imaging findings, surgical outcomes and conclusions. Overall, 56 papers were reviewed, including a total of 1517 patients. This review highlights the following structural neuroimaging techniques: MRI, diffusion-weighted imaging, tractography, electroencephalography and magnetoencephalography. The developments in neuroimaging during the last decades have led to remarkable improvements in surgical precision, postsurgical outcome, prognosis, and the rate of seizure control in patients with TLE. The use of multiple imaging methods provides improved outcomes, and further improvements will be possible with future studies of larger patient cohorts.