Diffusion Weighted ZOOM Imaging in the Lumbar Spine Based on Single-Shot STEAM

Abstract

A magnetic resonance imaging (MRI) technique for diffusion weighted imaging (DWI) is described which is, in contrast to echo-planar imaging (EPI), insensitive to offresonances, due to tissue susceptibility differences, magnetic field inhomogeneities or chemical shifts. The sequence combines a diffusion weighted (DW) spin-echo preparation and a single-shot stimulated echo acquisition mode (STEAM) module. The application of an inner-volume excitation by the ZOOM imaging technique allows a reduced rectangular fieldof- view (FOV) in PE direction, but suppresses aliasing artifacts which are usually the consequence of too small FOVs. Sagittal single-shot images of the lumbar spine were acquired at 3.0 T with 2.34 × 2.34 mm² in-plane resolution and 7 mm slice thickness. For the calculation of the apparent diffusion coefficient (ADC) and to determine the diffusibility of water in lumbar intervertebral disks (IVDs) the DW gradients were applied in orthogonal gradient orientations with b = 100 sec/mm², b = 150 sec/mm² and b = 250 sec/mm².