Artifacts and signal loss due to flow in the presence of Bo inhomogeneity

✍ Scribed by Maria Drangova; Norbert J. Pelc

• Book ID: 102953636
• Publisher: John Wiley and Sons
• Year: 1996
• Tongue: English
• Weight: 510 KB
• Volume: 35
• Category: Article
• ISSN: 0740-3194
• DOI: 10.1002/mrm.1910350116

✦ Synopsis

Abstract

An in vitro study was performed to investigate the effects of B~o~ inhomogeneity on magnetic resonance images of flow. Controlled inhomogeneity gradients (G~1~) were applied and the magnitude of the artifacts produced was quantified for different echo delay times (TE). Both steady and pulsatile flows were examined. In the presence of an inhomogeneity gradient, signal loss is apparent if the flow is pulsatile and/or if the slice thickness is large. The signal loss increases with increasing TE and G~1~. With pulsatile flow, ghosting artifacts are also generated. These increase in intensity with increasing TE and G~1~. In vivo, field inhomogeneity due to susceptibility variations is large enough to produce these effects. Representative time‐of‐flight images obtained of a normal volunteer with two different TEs demonstrate the effect in vivo. Flow‐related signal loss and artifacts, therefore, increase with increasing TE independent of the moments of the applied gradients.