An MRI-based approach for the measurement of the dorsolateral prefrontal cortex in humans

Abstract

The dorsolateral prefrontal cortex (DLPFC) has been implicated in the pathophysiology of mental disorders. Previous region-of-interest MRI studies that attempted to delineate this region adopted various landmarks and measurement techniques, with inconsistent results. We developed a new region-of-interest measurement method to obtain morphometric data of this region from structural MRI scans, taking into account knowledge from cytoarchitectonic postmortem studies and the large inter-individual variability of this region. MRI scans of 10 subjects were obtained, and DLPFC tracing was performed in the coronal plane by two independent raters using the semi-automated software Brains2. The intra-class correlation coefficients between two independent raters were 0.94 for the left DLPFC and 0.93 for the right DLPFC. The mean +/- S.D. DLPFC volumes were 9.23 +/- 2.35 ml for the left hemisphere and 8.20 +/- 2.08 ml for the right hemisphere. Our proposed method has high inter-rater reliability and is easy to implement, permitting the standardized measurement of this region for clinical research applications

Figure 1. DLPFC tracing

Tracing started on the slice immediately anterior to the most rostral one where corpus callosum could be seen as a bridge and was performed from posterior to anterior. Medial and lateral portions of area 9 were delineated through a line traced from the tip of the superior frontal gyrus to the bottom of the superior frontal sulcus.

Figure 2. Anatomical landmarks for the DPFC tracing

The DPFC was delimited medially by the cingulate sulcus (CS) and inferiorly by the inferior frontal sulcus (IFS). Medial and lateral portions of DPFC were delineated through a line traced from the tip of the superior frontal gyrus to the bottom of the superior frontal sulcus (SFS).

Figure 3. A three plane view of the dorsal prefrontal cortex

Figure 4. 3D rendering of the lateral surface of the DPFC