title: Diffusion tensor imaging tractography of Meyer's loop in planning resective surgery for drug-resistant temporal lobe epilepsy.
abstract: OBJECTIVE
  Whether Meyer's loop (ML) tracking using diffusion tensor imaging tractography (DTIT) can be utilized to avoid post-operative visual field deficits (VFD) after anterior temporal lobectomy (ATL) for drug-resistant temporal lobe epilepsy (TLE) using a large cohort of controls and patients. Also, we wanted to create a normative atlas of ML in normal population.
  
  
  METHODS
  DTIT was used to study ML in 75 healthy subjects and 25 patients with and without VFD following ATL. 1.5T MRI echo-planar DTI sequences with DTI data were processed in Nordic ICE using a probabilistic method; a multiple region of interest technique was used for reconstruction of optic radiation trajectory. Visual fields were assessed in patients pre- and post-operatively.
  
  
  RESULTS
  Results of ANOVA showed that the left ML-TP distance was less than right across all groups (p = 0.01). The average distance of ML from left temporal pole was 37.44 ± 4.7 mm (range: 32.2-46.6 mm) and from right temporal pole 39.08 ± 4.9 mm (range: 34.3-49.7 mm). Average distance of left and right temporal pole to tip of temporal horn was 28.32 ± 2.03 mm (range: 26.4-32.8 mm) and was 28.92 ± 2.09 mm, respectively (range: 25.9-33.3 mm). If the anterior limit of the Meyer's loop was ≤38 mm on the right and ≤35 mm on the left from the temporal pole, they are at a greater risk of developing VFDs.
  
  
  CONCLUSIONS
  DTIT is a novel technique to delineate ML and plays an important role in planning surgical resection in TLE to predict post-operative visual performance and disability.
authors.affiliation: Department of Imaging and Interventional Radiology, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Trivandrum 695011, India.
authors.forename: Jija S
authors.initials: JS
authors.lastname: James
authors.affiliation: R Madhavan Nayar Centre for Comprehensive Epilepsy Care, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Trivandrum 695011, India. Electronic address: drashalatha@sctimst.ac.in.
authors.forename: Ashalatha
authors.initials: A
authors.lastname: Radhakrishnan
authors.affiliation: Department of Imaging and Interventional Radiology, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Trivandrum 695011, India.
authors.forename: Bejoy
authors.initials: B
authors.lastname: Thomas
authors.affiliation: R Madhavan Nayar Centre for Comprehensive Epilepsy Care, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Trivandrum 695011, India.
authors.forename: Mini
authors.initials: M
authors.lastname: Madhusoodanan
authors.affiliation: Department of Imaging and Interventional Radiology, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Trivandrum 695011, India.
authors.forename: Chandrashekharan
authors.initials: C
authors.lastname: Kesavadas
authors.affiliation: R Madhavan Nayar Centre for Comprehensive Epilepsy Care, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Trivandrum 695011, India.
authors.forename: Mathew
authors.initials: M
authors.lastname: Abraham
authors.affiliation: R Madhavan Nayar Centre for Comprehensive Epilepsy Care, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Trivandrum 695011, India.
authors.forename: Ramshekhar
authors.initials: R
authors.lastname: Menon
authors.affiliation: R Madhavan Nayar Centre for Comprehensive Epilepsy Care, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Trivandrum 695011, India.
authors.forename: Chaturbhuj
authors.initials: C
authors.lastname: Rathore
authors.affiliation: R Madhavan Nayar Centre for Comprehensive Epilepsy Care, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Trivandrum 695011, India.
authors.forename: George
authors.initials: G
authors.lastname: Vilanilam
mesh_terms: D000328:Adult; D038481:Anterior Temporal Lobectomy / Q000379:methods*; D001271:Atlases as Topic; D015331:Cohort Studies; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D056324:Diffusion Tensor Imaging / Q000379:methods*; D004833:Epilepsy, Temporal Lobe / Q000473:pathology* / Q000601:surgery; D005260:Female; D007839:Functional Laterality; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D021621:Imaging, Three-Dimensional / Q000379:methods; D008297:Male; D009929:Organ Size; D025321:Surgery, Computer-Assisted / Q000379:methods*; D013702:Temporal Lobe / Q000033:anatomy & histology / Q000473:pathology / Q000601:surgery; D014786:Vision Disorders / Q000517:prevention & control; D058609:Visual Field Tests; D014794:Visual Fields; D014795:Visual Pathways / Q000033:anatomy & histology / Q000473:pathology* / Q000601:surgery; D055815:Young Adult
keywords: Anterior temporal lobectomy; DTIT; Meyer's loop; Optic radiation; Temporal lobe epilepsy; Visual field defect