Magnetic field strength dependence of chemical shift artifacts

Lufkin, Robert B.; Anselmo, M.; Crues, John V.; Smoker, Wendy R. K.; Hanafee, William N.

doi:10.1016/0895-6111(88)90002-x

Cited by 9 publications

(3 citation statements)

References 14 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The in vitro and in vivo studies were conducted at 3‐T field strength. The spatial shift of chemically shifted perivascular fat at 1.5 T is half of that at 3 T because δf 1.5T ≈ ½δf 3T (38), which leads to ∼1/2 the spatial shift and half the off‐resonance phase accumulation for fat at 1.5 T. Therefore, the chemical shift induced phase error is lower at 1.5 T when spatial resolution and SNR effects are not considered (Fig. 4d,e).…”

Section: Discussionmentioning

confidence: 97%

Chemical shift‐induced phase errors in phase‐contrast MRI

Middione

Ennis

2012

Magnetic Resonance in Med

View full text Add to dashboard Cite

Phase contrast magnetic resonance imaging (PC-MRI) is subject to numerous sources of error, which decrease clinical confidence in the reported measures. This work outlines how stationary perivascular fat can impart a significant chemical shift induced PC-MRI measurement error using computational simulations, in vitro, and in vivo experiments. This chemical shift error does not subtract in phase difference processing, but can be minimized with proper parameter selection. The chemical shift induced phase errors largely depend on both the receiver bandwidth (BW) and the TE. Both theory and an in vivo comparison of the maximum difference in net forward flow between vessels with and without perivascular fat indicated that the effects of chemically shifted perivascular fat are minimized by the use of high BW (814 Hz/px) and an in-phase TE (HBW-TEIN). In healthy volunteers (N=10) HBW-TEIN significantly improves intrapatient net forward flow agreement compared to low BW (401 Hz/px) and a mid-phase TE as indicated by significantly decreased measurement biases and limits of agreement for the ascending aorta (1.8±0.5 mL vs. 6.4±2.8 mL, P=0.01), main pulmonary artery (2.0±0.9 mL vs. 11.9±5.8 mL, P=0.04), the left pulmonary artery (1.3±0.9 mL vs. 5.4±2.5 mL, P=0.003), and all vessels (1.7±0.8 mL vs. 7.2±4.4 mL, P=0.001).

show abstract

Section: Discussionmentioning

confidence: 97%

Chemical shift‐induced phase errors in phase‐contrast MRI

Middione

Ennis

2012

Magnetic Resonance in Med

View full text Add to dashboard Cite

show abstract

“…CSA is caused by the differences in precessional frequency of adjacent proton‐containing substances and increases as field strength increases and gradient steepness and BW decrease (18, 19). It is usually recognized clinically in the frequency‐encoding direction, but occurs in the slice‐selection direction as well (20).…”

Section: Discussionmentioning

confidence: 99%

Correlation of single‐lumen silicone implant integrity with chemical shift artifact on T2‐weighted magnetic resonance images

Murphy¹,

Piccoli²,

Mitchell³

2002

Magnetic Resonance Imaging

View full text Add to dashboard Cite

Purpose:To correlate the integrity of single-lumen silicone gel implants with chemical shift artifact (CSA) associated with infolding of the elastomer shell. Materials and Methods:The T2-weighted images of presurgical MRI examinations of 54 implants were retrospectively reviewed by two breast radiologists blinded to the operative and pathologic findings. CSA associated with intraluminal membranes was quantified by determining the fraction of membranes with it and categorized as minimal (0 - ), and marked ( 2 3 to all). CSA was qualified by noting whether CSA intensity of the membranes was less than or similar to that of blood vessels. The CSA was correlated with the surgical or pathology findings to judge integrity of the implant.Results: Nineteen implants were intact, 35 were dysfunctional (gel leakage or rupture). Twenty-eight of 29 (97%) with a minimal fraction of membranes with CSA were dysfunctional; 17/21 (81%) with CSA associated with a marked fraction of membranes were intact (P Ͻ 0.001). All 28 implants with CSA intensity less than vessels were dysfunctional, 19/26 (73%) with CSA equal to vessels were intact (P Ͻ 0.001). All 25 implants with minimal CSA and intensity less than vessels were dysfunctional. Seventeen of 19 (89%) implants with CSA associated with a marked fraction of membranes and intensity equal to vessels were intact (P ϭ 0.02). The magnetic resonance imaging (MRI) signs were combined with strong CSA as a predictor of integrity, and 22 of 26 (85%) implants were correctly diagnosed, 4 dysfunctional and 18 intact (P Ͻ 0.0001). Conclusion:CSA correlates with integrity of silicone gel implants on T2-weighted images and can be used with other MRI signs to improve diagnosis.

show abstract

“…These non‐EPI trajectories have the advantage that data acquisition time within any one excitation is short relative to the signal decay constant T2* and relative to the time it takes for chemical shift, magnetic susceptibility, and other field distortion artifacts (14–19) to evolve to an easily noticed level. Such artifacts, typically seen as distortions and blurring, are most readily seen across the image space dimension corresponding to the k‐space axis that was most slowly traversed, which in non‐EPI rectilinear trajectories is the readout (x) direction.…”

Section: K‐space Trajectoriesmentioning

confidence: 99%

K‐space in the clinic

Paschal

Morris

2004

Magnetic Resonance Imaging

View full text Add to dashboard Cite

Magnetic resonance imaging (MRI) sequences are characterized by both radio frequency (RF) pulses and time-varying gradient magnetic fields. The RF pulses manipulate the alignment of the resonant nuclei and thereby generate a measurable signal. The gradient fields spatially encode the signals so that those arising from one location in an excited slice of tissue may be distinguished from those arising in another location. These signals are collected and mapped into an array called k-space that represents the spatial frequency content of the imaged object. Spatial frequencies indicate how rapidly an image feature changes over a given distance. It is the action of the gradient fields that determines where in the k-space array each data point is located, with the order in which k-space points are acquired being described by the k-space trajectory. How signals are mapped into k-space determines much of the spatial, temporal, and contrast resolution of the resulting images and scan duration. The objective of this article is to provide an understanding of k-space as is needed to better understand basic research in MRI and to make well-informed decisions about clinical protocols. Four major classes of trajectories-echo planar imaging (EPI), standard (non-EPI) rectilinear, radial, and spiral-are explained. Parallel imaging techniques SMASH (simultaneous acquisition of spatial harmonics) and SENSE (sensitivity encoding) are also described.

show abstract

Magnetic field strength dependence of chemical shift artifacts

Cited by 9 publications

References 14 publications

Chemical shift‐induced phase errors in phase‐contrast MRI

Chemical shift‐induced phase errors in phase‐contrast MRI

Correlation of single‐lumen silicone implant integrity with chemical shift artifact on T2‐weighted magnetic resonance images

K‐space in the clinic

Contact Info

Product

Resources

About