Eung-Yeop Kim MD, Presenter: Nothing to Disclose

Jae-Wook Lee MD, Abstract Co-Author: Nothing to Disclose

Eunhye Yoo MD, Abstract Co-Author: Nothing to Disclose

Byung Hoon Lee MD, Abstract Co-Author: Nothing to Disclose

Double inversion-recovery (DIR) imaging suppresses the signals from both white matter and cerebrospinal fluid, selectively depicting cortex with bright signal intensity. The primary motor cortex (PMC) contains prominent myelin in its layers 3 and 5 (more in layer 3), which may be seen as triple-layer appearance on thin-section DIR (outer hyperintense, middle hypointense, and inner mildly hyperintense layers). The purpose of this study was to investigate whether the PMC can be differentiated from other cortices by thin-section DIR.

We enrolled 90 patients (female, 41; age, 5-80 years; mean, 35.9 years) without neurological abnormalities who underwent 2-mm DIR at 3.0 T. The presence or absence of the triple-layer appearance within the cortices at the level of the centrum semiovale was graded independently by two neuroradiologists as definitely present (grade 2), probably present (grade 1), or definitely absent (grade 0). Differences in grades between the two sexes and among age groups were analyzed by Mann-Whitney test and Kruskal-Wallis one-way ANOVA test, respectively. According to the previously defined criteria, the central sulcus was found by another neuroradiologist who was not involved in evaluation of the PMC.

The triple-layer appearance of grade 1 and 2 was found only in the PMC on both sides in 75 (83.3%) and 10 (11.1%) of 90 patients, respectively. Grade 0 was determined in 4 patients younger than 10 years of age. Grades were significantly lower in patients younger than 10 years of age than those in the others (p .0001), but not different among age groups older than 10 years (p > .05). Interobserver agreement was excellent (weighted κ = .915). No significant difference was present in grades between age-matched female and male patients (p > .05).

The PMC can be differentiated from other cortices by showing triple-layer appearance on thin-section DIR over 10 years of age.

The triple-layer appearance on thin-section DIR is a new marker of the primary motor cortex, and may be useful for presurgical identification of this crucial cortex.

Kim, E, Lee, J, Yoo, E, Lee, B, Primary Motor Cortex of the Normal Brain: Triple-layer Appearance on Thin-section Double Inversion-recovery Imaging.  Radiological Society of North America 2007 Scientific Assembly and Annual Meeting, November 25 - November 30, 2007 ,Chicago IL. http://archive.rsna.org/2007/5014253.html