Special report: MEG and MSI for the purpose of presurgical localization of epileptic lesions--a challenge for technology evaluation.

Authors' objectives The objective of this Special Report is to present the particular challenges that this diagnostic technology presents in terms of evaluating the evidence to determine its potential benefit. Without a thorough presentation of the manner in which MEG is used in the evaluation of patients, it is difficult to determine whether the technology is beneficial. Various problems such as ascertainment biases, patient dropouts, and imperfect reference standards crop up in the published studies evaluating MEG, making it more difficult to assess them. To some extent, these difficulties may be inherent in the clinical setting in which MEG is used.