Diffusion-weighted imaging for the head-neck region and spinal cord: echo planar and non-echo planar imaging technique

Gonzalo Araya-Rojas, Departamento de Imágenes, Clínica Alemana de Santiago, Santiago, Chile
Rodrigo Araya-Rojas, Facultad de Medicina, Universidad Católica del Norte, Antofagasta; Servicio de Imagenología, Hospital San Pablo de Coquimbo, Coquimbo; Chile
Pablo Maturana-Quijada, Escuela de Tecnología Médica, Facultad de Medicina y Ciencias de la Salud, Universidad Mayor, Santiago, Chile

In the last decade, diffusion imaging has gained ground in applications for head, neck, and spinal cord imaging; however, it remains a tool with limitations. The technique is susceptible to certain artifacts, such as geometric distortion, wrapping artifacts, magnetic susceptibility effects, incomplete fat saturation, and artifacts due to patient movement, in addition to having lower spatial resolution and signal-to-noise ratio compared to conventional T1- and T2-weighted sequences. This sometimes makes precise anatomical localization of pathology a challenge. These limitations have led many radiologists to consider that routine implementation in head and neck imaging still lacks development to obtain a good image. In recent years, the methods for acquiring the technique have been improved, which has allowed for the enhancement of the artifacts present in the early images. The aim of this paper is to present a review of the new commercially available techniques based on non-echo planar acquisitions, defining their image acquisition methods, applications, advantages, and disadvantages.

Keywords: Magnetic resonance imaging. Diffusion-weighted imaging. Echo-planar imaging. Apparent diffusion coefficient.