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Definition of a Stereotactic 3-Dimensional Magnetic Resonance Imaging Template of the Human Insula

Afif, Afif MD, PhD*,‡,§; Becq, Guillaume PhD; Mertens, Patrick MD, PhD*,‡

doi: 10.1227/NEU.0b013e31826cdc57
Technique Assessment

BACKGROUND: This study proposes a 3-dimensional (3-D) template of the insula in the bicommissural reference system with posterior commissure (PC) as the center of coordinates.

OBJECTIVE: Using the bicommissural anterior commissure (AC)–PC reference system, this study aimed to define a template and design a method for the 3-D reconstruction of the human insula that may be used at an individual level during stereotactic surgery.

METHODS: Magnetic resonance imaging (MRI)–based morphometric analysis was performed on 100 cerebral cortices with normal insulae based on a 3-step procedure: Step 1: AC-PC reference system–based reconstruction of the insula from the 1-mm thick 3-D T1-weighted MRI slices. Step 2: Digitalization and superposition of the data obtained in the 3 spatial planes. Step 3: Representation of pixels as colors on a scale corresponding to the probability of localization of each insular anatomic component.

RESULTS: The morphometric analysis of the insula confirmed our previously reported findings of a more complex shape delimited by 4 peri-insular sulci. A very significant correlation between the coordinates of the main insular structures and the length of AC-PC was demonstrated. This close correlation allowed us to develop a method that allows the 3-D reconstruction of the insula from MRI slices and only requires the localization of AC and PC. This process defines an area deemed to contain insula with 100% probability.

CONCLUSION: This 3-D reconstruction of the insula should be useful to improve its localization and other cortical areas and allow the differentiation of insular cortex from opercular cortex.

ABBREVIATIONS: AC, anterior commissure

CI, confidence interval

CIS, central insular sulcus

PC, posterior commissure

VPC, the perpendicular plane on AC-PC plane passes by the posterior commissural

*Department of Neurosurgery, Neurological Hospital, Hospices civils de Lyon, Lyon, France

Department of Anatomy, Lyon-1 University, Inserm U 879, Lyon 1 University, Lyon, France

§Department of Neurosurgery, Al Mowasat Hospital, Damascus University, Damascus, Syria

Laboratory of Gipsa, Domaine Universitaire, Saint Martin d'Hères cedex, France

Correspondence: Afif Afif, MD, PhD, Department of Anatomy, Lyon 1 University, 8 avenue Rockefeller, 69003 Lyon, France. E-mail:

Received December 17, 2011

Accepted July 17, 2012

Copyright © by the Congress of Neurological Surgeons