Flow-Related Artifacts in MR Imaging and MR Angiography of the Central Nervous System
We include the following artifacts: 1) Ghosting artifacts replicate a “mobile” structure in the phase direction due to spatial misregistration that results from rhythmic motion. 2) Paradoxical or flow-related enhancement seen on the first or last image of a sequence is due to signal intensity from unsaturated protons moving into the interrogated field. 3) Vascular and CSF flow can create artifacts due to the change in the location of excited and/or unexcited hydrogen protons. 4) Intermediate signal intensity often arises in an area of slow flow and may be misinterpreted as thrombus or tumor. 5) Artifacts on 2D TOF imaging are common and may be caused by susceptibility artifacts, shinethrough, and reversed flow in loops and subclavian steal. 6) “Venetian blind” artifacts occur in 3D TOF imaging secondary to loss of flow-related enhancement as protons traverse the MOTSA volume and can be minimized by modifying the flip angle throughout the acquisition.
Knowledge of the mechanism, appearance, and correction of these artifacts is essential for the accurate analysis of MR imaging/MRA of the central nervous system.
Keywords: FE = frequency encoding; FLAIR = fluid-attenuated inversion recovery; FRE = flow-related enhancement; GRE = gradient-recalled echo; MIP = maximum intensity projection; MOTSA = multiple overlapping thin-slab acquisition; MRA = MR angiography; PE = phase-encoding; RF = radio-frequency; SE = spin-echo; TOF = time-of-flight; true FISP = true fast imaging with steady-state precession
Document Type: Research Article
Publication date: 01 December 2012
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