Details

Autor(en) / Beteiligte

• Skinner, Matthew G
• Kolind, Shannon H
• MacKay, Alex L

Titel

The effect of varying echo spacing within a multiecho acquisition: better characterization of long T sub(2) components

Ist Teil von

• Magnetic resonance imaging, 2007-06, Vol.25 (6), p.840-847

Erscheinungsjahr

2007

Quelle

Elsevier ScienceDirect Journals

Beschreibungen/Notizen

• A 48-echo pulse sequence with five different echo-spacing combinations was examined to determine how one can most effectively measure the T sub(2) relaxation characteristics of cerebral tissue containing a long T sub(2) component. For each scan, the first 32 echoes had an echo spacing of 10 ms, while the spacing for Echoes 33-48 ( Delta TE2) was 10, 20, 30, 40 or 50 ms. In an in vivo study using 10 normal volunteers, it was found that the resolution of T sub(2) distribution peaks for both myelin water ([not, vert, similar]20 ms) and intracellular/extracellular (IE) water ([not, vert, similar]80 ms) improved as Delta TE2 increased. The geometric mean T sub(2) values of the main peak agreed within the error for all Delta TE2 values. A phantom study simulated T sub(2) relaxation distributions that are expected in the brains of patients with demyelinating diseases. For phantoms in which the T sub(2) values of the IE and lesion (200-500 ms) water compartments were separated by at least a factor of 3, each compartment in the distribution was better resolved when Delta TE2=40 or 50 ms. On the basis of these results, we recommend the use of extended Delta TE2 values for imaging patients with lesions, without the risk of losing valuable short T sub(2) information.