Adiabatic localized correlation spectroscopy (AL-COSY): application in muscle and brain

Purpose:

To describe an enhanced version of a localized correlation spectroscopy (L‐COSY) by introducing adiabatic radiofrequency (RF) pulses for localization in two dimensions. Adiabatic pulses will improve slice selection profile and reduce chemical shift artifacts. Optimized Mao and adiabatic hyperbolic secant pulses are tested in vivo.

Materials and Methods:

Region of interest is localized by a 90° nonselective adiabatic RF pulse followed by two pairs of adiabatic RF pulses and a terminal 90° RF sinc pulse. Slice profiles for both refocusing pulses and chemical shift artifacts are measured in a water–oil phantom for L‐COSY and AL‐COSY. In vivo results of both COSY sequences are shown from muscle and brain on a 3 Tesla (T) scanner.

Results:

Chemical shift artifacts were reduced with AL‐COSY compared with L‐COSY. Slice profiles of adiabatic pulses were found to be sharper and more symmetrical than those of traditional Mao pulses. One‐dimensional (1D) phantom studies showed longer T2 values using AL‐COSY sequence. Comparison of 2D spectra obtained revealed spectroscopic peak volume improvements in AL‐COSY and less residual water. In vivo 1D comparison showed more inphase and sharper peaks in AL‐COSY spectrum.

Conclusion:

The AL‐COSY sequence is an improved sequence due to sharper slice selection profiles, reduction of chemical shift artifacts, peak volume improvements in 2D techniques, and less J‐modulation. J. Magn. Reson. Imaging 2011;33:1447–1455. © 2011 Wiley‐Liss, Inc.     

Real-time magnetic resonance imaging of normal swallowing

Purpose:

To evaluate the use of a novel real‐time magnetic resonance imaging (MRI) technique for the assessment of normal swallowing dynamics.

Materials and Methods:

In a cohort of 10 healthy subjects, real‐time MRI movies at 24.3 frames per second were obtained in sagittal, coronal, and axial orientation during self‐controlled swallows of 5 mL pineapple juice as oral contrast bolus. All studies were performed with the use of a commercial MRI system at 3 T combining two sets of radiofrequency receiver coils. Real‐time movies relied on a fast low‐angle shot (FLASH) MRI sequence with radial undersampling and image reconstruction by nonlinear inversion yielding 41.23 msec acquisition time for an in‐plane resolution of 1.5 mm. Evaluations focused on clinical image quality as well as visualization and temporal quantification of distinct swallowing functions.

Results:

Throughout the entire process, the swallowing dynamics were well depicted and characterized with almost no visible image artifacts in all subjects. The mid‐sagittal plane turned out to be most valuable. The movies allowed for a quantitative determination of the temporal pattern of all swallowing events.

Conclusion:

The proposed real‐time MRI technique yields noninvasive, robust, and quantitative access to the physiology of normal swallowing in healthy subjects at high temporal resolution and image quality. J. Magn. Reson. Imaging 2012;35:1372–1379. © 2012 Wiley Periodicals, Inc.     

Multiband accelerated spin‐echo echo planar imaging with reduced peak RF power using time‐shifted RF pulses

Purpose:

To evaluate an alternative method for generating multibanded radiofrequency (RF) pulses for use in multiband slice‐accelerated imaging with slice‐GRAPPA unaliasing, substantially reducing the required peak power without bandwidth compromises. This allows much higher accelerations for spin‐echo methods such as SE‐fMRI and diffusion‐weighted MRI where multibanded slice acceleration has been limited by available peak power.

Theory and Methods:

Multibanded “time‐shifted” RF pulses were generated by inserting temporal shifts between the applications of RF energy for individual bands, avoiding worst‐case constructive interferences. Slice profiles and images in phantoms and human subjects were acquired at 3 T.

Results:

For typical sinc pulses, time‐shifted multibanded RF pulses were generated with little increase in required peak power compared to single‐banded pulses. Slice profile quality was improved by allowing for higher pulse bandwidths, and image quality was improved by allowing for optimum flip angles to be achieved.

Conclusion:

A simple approach has been demonstrated that significantly alleviates the restrictions imposed on achievable slice acceleration factors in multiband spin‐echo imaging due to the power requirements of multibanded RF pulses. This solution will allow for increased accelerations in diffusion‐weighted MRI applications where data acquisition times are normally very long and the ability to accelerate is extremely valuable. Magn Reson Med 69:1261–1267, 2013 Wiley Periodicals, Inc.     

Image artifacts in concurrent transcranial magnetic stimulation (TMS) and fMRI caused by leakage currents: Modeling and compensation

Purpose

To characterize and eliminate a new type of image artifact in concurrent transcranial magnetic stimulation and functional MRI (TMS‐fMRI) caused by small leakage currents originating from the high‐voltage capacitors in the TMS stimulator system.

Materials and Methods

The artifacts in echo‐planar images (EPI) caused by leakage currents were characterized and quantified in numerical simulations and phantom studies with different phantom‐coil geometries. A relay‐diode combination was devised and inserted in the TMS circuit that shorts the leakage current. Its effectiveness for artifact reduction was assessed in a phantom scan resembling a realistic TMS‐fMRI experiment.

Results

The leakage‐current‐induced signal changes exhibited a multipolar spatial pattern and the maxima exceeded 1% at realistic coil‐cortex distances. The relay‐diode combination effectively reduced the artifact to a negligible level.

Conclusion

The leakage‐current artifacts potentially obscure effects of interest or lead to false‐positives. Since the artifact depends on the experimental setup and design (eg, amplitude of the leakage current, coil orientation, paradigm, EPI parameters), we recommend its assessment for each experiment. The relay‐diode combination can eliminate the artifacts if necessary. J. Magn. Reson. Imaging 2009;29:1211–1217. © 2009 Wiley‐Liss, Inc.     

Magnetization spoiling in radial FLASH contrast-enhanced MR digital subtraction angiography

Purpose:

To increase the in‐plane spatial resolution and image update rates of 2D magnetic resonance (MR) digital subtraction angiography (DSA) pulse sequences to 0.57 × 0.57 mm and 6 frames/sec, respectively, for intracranial vascular disease applications by developing a radial FLASH protocol and to characterize a new artifact, not previously described in the literature, which arises in the presence of such pulse sequences.

Materials and Methods:

The pulse sequence was optimized and artifacts were characterized using simulation and phantom studies. With Institutional Review Board (IRB) approval, the pulse sequence was used to acquire time‐resolved images from healthy human volunteers and patients with x‐ray DSA‐confirmed intracranial vascular disease.

Results:

Artifacts were shown to derive from inhomogeneous spoiling due to the nature of radial waveforms. Gradient spoiling strategies were proposed to eliminate the observed artifact by balancing gradient moments across TR intervals. The resulting radial 2D MR DSA sequence (2.6 sec temporal footprint, 6 frames/sec with sliding window factor 16, 0.57 × 0.57 mm in‐plane) demonstrated small vessel detail and corroborated x‐ray DSA findings in intracranial vascular imaging studies.

Conclusion:

Appropriate gradient spoiling in radial 2D MR DSA pulse sequences improves intracranial vascular depiction by eliminating circular banding artifacts. The proposed pulse sequence may provide a useful addition to clinically applied 2D MR DSA scans. J. Magn. Reson. Imaging 2012;36:249–258. © 2012 Wiley Periodicals, Inc.     

Optimum fuzzy filters for phase‐contrast magnetic resonance imaging segmentation

Purpose

To develop and validate a multidimensional segmentation and filtering methodology for accurate blood flow velocity field reconstruction from phase‐contrast magnetic resonance imaging (PC MRI).

Materials and Methods

The proposed technique consists of two steps: (1) the boundary of the vessel is automatically segmented using the active contour approach; and (2) the noise embedded within the segmented vector field is selectively removed using a novel fuzzy adaptive vector median filtering (FAVMF) technique. This two‐step segmentation process was tested and validated on 111 synthetically generated PC MRI slices and on 10 patients with congenital heart disease.

Results

The active contour technique was effective for segmenting blood vessels having a sensitivity and specificity of 93.1% and 92.1% using manual segmentation as a reference standard. FAVMF was the superior technique in filtering out noise vectors, when compared with other commonly used filters in PC MRI (P < 0.05). The peak wall shear rate calculated from the PC MRI data (248 ± 39 sec^?1), was significantly decreased to (146 ± 26 sec^?1) after the filtering process.

Conclusion

The proposed two‐step segmentation and filtering methodology is more accurate compared to a single‐step segmentation process for post‐processing of PC MRI data. J. Magn. Reson. Imaging 2009;29:155–165. © 2008 Wiley‐Liss, Inc.

     

A fast,effective filtering method for improving clinical pulsed arterial spin labeling MRI

Purpose

To evaluate the effectiveness of a fully automated postprocessing filter algorithm in pulsed arterial spin labeling (PASL) MRI perfusion images in a large clinical population.

Materials and Methods

A mean and standard deviation‐based filter was implemented to remove outliers in the set of perfusion‐weighted images (control – label) before being averaged and scaled to quantitative cerebral blood flow (CBF) maps. Filtered and unfiltered CBF maps from 200 randomly selected clinical cases were assessed by four blinded raters to evaluate the effectiveness of the filter.

Results

The filter salvaged many studies deemed uninterpretable as a result of motion artifacts, transient gradient, and/or radiofrequency instabilities, and unexpected disruption of data acquisition by the technologist to communicate with the patient. The filtered CBF maps contained significantly (P < 0.05) fewer artifacts and were more interpretable than unfiltered CBF maps as determined by one‐tail paired t‐test.

Conclusion

Variations in MR perfusion signal related to patient motion, system instability, or disruption of the steady state can introduce artifacts in the CBF maps that can be significantly reduced by postprocessing filtering. Diagnostic quality of the clinical perfusion images can be improved by performing selective averaging without a significant loss in perfusion signal‐to‐noise ratio. J. Magn. Reson. Imaging 2009;29:1134–1139. © 2009 Wiley‐Liss, Inc.     

MR venography of the brain with enhanced vessel contrast using image-domain high-pass filtering of the susceptibility phase shift

Purpose:

To develop a postprocessing algorithm that enhances the visibility of intracranial venous vasculature and reduces the artifacts in the display of susceptibility‐weighted images (SWI).

Materials and Methods:

Image‐domain high‐pass filters based on second‐order phase difference were applied to the complex 3D SWI data to enhance the susceptibility phase shift of the veins and suppress background signal in SWI. A multivariant statistical parameter was used to suppress the noise in air.

Results:

Magnetic resonance (MR) venography with enhanced susceptibility phase shift and reduced off‐resonance artifacts was obtained using the proposed filters. The background signal in the 3D MR venography data was well suppressed. Venous vasculature in the peripheral regions of the brain was well depicted and the adverse effect of noise in air in the maximum‐intensity projection display of the 3D SWI data was well suppressed.

Conclusion:

Image‐domain high‐pass filtering with second‐order phase difference provides an alternative display of 3D SWI data with enhanced visibility of the venous vasculature and effective suppression of artifacts. J. Magn. Reson. Imaging 2011;. © 2011 Wiley Periodicals, Inc.     

Pyrolytic graphite foam: A passive magnetic susceptibility matching material

Purpose:

To evaluate a novel soft, lightweight cushion that can match the magnetic susceptibility of human tissue. The magnetic susceptibility difference between air and tissue produces field inhomogeneities in the B₀ field, which leads to susceptibility artifacts in magnetic resonance imaging (MRI) studies.

Materials and Methods:

Pyrolytic graphite (PG) microparticles were uniformly embedded into a foam cushion to reduce or eliminate field inhomogeneities at accessible air and tissue interfaces. 3T MR images and field maps of an air/water/PG foam phantom were acquired. Q measurements on a 4T tuned head coil and pulse sequence heating tests at 3T were also performed.

Results:

The PG foam improved susceptibility matching, reduced the field perturbations in phantoms, does not heat, and is nonconductive.

Conclusion:

The susceptibility matched PG foam is lightweight, safe for patient use, adds no noise or MRI artifacts, is compatible with radiofrequency coil arrays, and improves B₀ homogeneity, which enables more robust MR studies. J. Magn. Reson. Imaging 2010;32:684–691. © 2010 Wiley‐Liss, Inc.     

Suppression of vascular enhancement artifacts through the use of a multiband, selectively spoiled radiofrequency excitation pulse

Purpose:

To test the ability of a multi‐band RF pulse to reduce flow enhancement artifacts for steady state imaging without compromising temporal resolution or spatial coverage.

Materials and Methods:

Selectively spoiled composite RF pulses that provide simultaneous excitation and flow preparation were designed and tested by means of simulation, phantom, and in vivo measurements under varying conditions of flow.

Results:

Suppression of flow enhancement was found to depend on flow velocity and spatial extent of spoiled regions. By determining necessary pulse characteristics for a given experimental geometry, flow enhancement was reduced and sensitivity to T₁‐reducing contrast agent was dramatically increased.

Conclusion:

These pulses provide an effective means of suppressing flow enhancement without sacrificing temporal resolution or spatial coverage. J. Magn. Reson. Imaging 2011;33:1256–1261. © 2011 Wiley‐Liss, Inc.     

New look at renal vasculature: 7 tesla nonenhanced T1-weighted FLASH imaging

Purpose:

To investigate the feasibility of 7 Tesla (T) nonenhanced high field MR imaging of the renal vasculature and to evaluate the diagnostic potential of various nonenhanced T1‐weighted (T1w) sequences.

Materials and Methods:

Twelve healthy volunteers were examined on a 7T whole‐body MR system (Magnetom 7T, Siemens Healthcare Sector) using a custom‐built eight‐channel radiofrequency (RF) transmit/receive body coil. Subsequent to RF shimming, the following sequences were acquired (i) fat‐saturated two‐dimensional (2D) FLASH, (ii) fat‐saturated 3D FLASH, and a (iii) fat‐saturated 2D time‐of‐flight MR angiography (TOF MRA). SNR and CNR were measured in the aorta and both renal arteries. Qualitative analysis was performed with regard to vessel delineation (5‐point scale: 5 = excellent to 1 = nondiagnostic) and presence of artifacts (5‐point scale: 5 = no artifact present to 1 = strong impairment).

Results:

The inherently high signal intensity of the renal arterial vasculature in T1w imaging enabled moderate to excellent vessel delineation in all sequences. Qualitative (mean, 4.7) and quantitative analysis (SNR_mean: 53.9; CNR_mean: 28.0) demonstrated the superiority of TOF MRA, whereas 2D FLASH imaging provided poorest vessel delineation and was most strongly impaired by artifacts (overall impairment 3.7). The 3D FLASH MRI demonstrated its potential for fast high quality imaging of the nonenhanced arterial vasculature, providing homogeneous hyperintense vessel signal.

Conclusion:

Nonenhanced T1w imaging in general and, TOF MRA in particular, appear to be promising techniques for good quality nonenhanced renal artery assessment at 7 Tesla. J. Magn. Reson. Imaging 2012;36:714–721. © 2012 Wiley Periodicals, Inc.     

New MR imaging methods for metallic implants in the knee: artifact correction and clinical impact

Purpose:

To evaluate two magnetic resonance imaging (MRI) techniques, slice encoding for metal artifact correction (SEMAC) and multiacquisition variable‐resonance image combination (MAVRIC), for their ability to correct for artifacts in postoperative knees with metal.

Materials and Methods:

A total of 25 knees were imaged in this study. Fourteen total knee replacements (TKRs) in volunteers were scanned with SEMAC, MAVRIC, and 2D fast spin‐echo (FSE) to measure artifact extent and implant rotation. The ability of the sequences to measure implant rotation and dimensions was compared in a TKR knee model. Eleven patients with a variety of metallic hardware were imaged with SEMAC and FSE to compare artifact extent and subsequent patient management was recorded.

Results:

SEMAC and MAVRIC significantly reduced artifact extent compared to FSE (P < 0.0001) and were similar to each other (P = 0.58), allowing accurate measurement of implant dimensions and rotation. The TKRs were properly aligned in the volunteers. Clinical imaging with SEMAC in symptomatic knees significantly reduced artifact (P < 0.05) and showed findings that were on the majority confirmed by subsequent noninvasive or invasive patient studies.

Conclusion:

SEMAC and MAVRIC correct for metal artifact, noninvasively providing high‐resolution images with superb bone and soft tissue contrast. J. Magn. Reson. Imaging 2011;33:1121–1127. © 2011 Wiley‐Liss, Inc.     

Artifact‐reduced two‐dimensional cine steady state free precession for myocardial blood‐ oxygen‐level‐dependent imaging

Purpose:

To minimize image artifacts in long TR cardiac phase‐resolved steady state free precession (SSFP) based blood‐oxygen‐level‐dependent (BOLD) imaging.

Materials and Methods:

Nine healthy dogs (four male, five female, 20–25 kg) were studied in a clinical 1.5 Tesla MRI scanner to investigate the effect of temporal resolution, readout bandwidth, and motion compensation on long repetition time (TR) SSFP images. Breath‐held 2D SSFP cine sequences with various temporal resolutions (10–204 ms), bandwidths (239–930 Hz/pixel), with and without first‐order motion compensation were prescribed in the basal, mid‐ventricular, and apical along the short axis. Preliminary myocardial BOLD studies in dogs with controllable coronary stenosis were performed to assess the benefits of artifact‐reduction strategies.

Results:

Shortening the readout time by means of increasing readout bandwidth had no observable reduction in image artifacts. However, increasing the temporal resolution in the presence of first‐order motion compensation led to significant reduction in image artifacts. Preliminary studies demonstrated that BOLD signal changes can be reliably detected throughout the cardiac cycle.

Conclusion:

Artifact‐reduction methods used in this study provide significant improvement in image quality compared with conventional long TR SSFP BOLD MRI. It is envisioned that the methods proposed here may enable reliable detection of myocardial oxygenation changes throughout the cardiac cycle with long TR SSFP‐based myocardial BOLD MRI. J. Magn. Reson. Imaging 2010;31:863–871. ©2010 Wiley‐Liss, Inc.     

Magnetic resonance imaging in real time: Advances using radial FLASH

Purpose

To develop technical advances for real‐time magnetic resonance imaging (MRI) that allow for improved image quality and high frame rates.

Materials and Methods

The approach is based on a combination of fast low‐angle shot (FLASH) MRI sequences with radial data sampling and view sharing of successive acquisitions. Gridding reconstructions provide images free from streaking or motion artifacts and with a flexible trade‐off between spatial and temporal resolution. Immediate image reconstruction and online display is accomplished with the use of an unmodified 3 T MRI system. For receive coils with a large number of elements this process is supported by a user‐selectable channel compression that is based on a principal component analysis and performed during initial preparation scans.

Results

In preliminary applications to healthy volunteers, real‐time radial FLASH MRI visualized continuous movements of the temporomandibular joint during voluntary opening and closing of the mouth at high spatial resolution (0.75 mm in‐plane) and monitored cardiac functions at high temporal resolution (20 images per second) during free breathing and without synchronization to the electrocardiogram.

Conclusion

Real‐time radial FLASH MRI emerges as a simple and versatile tool for a large range of clinical applications. J. Magn. Reson. Imaging 2010. © 2009 Wiley‐Liss, Inc     

Simultaneous z‐shim method for reducing susceptibility artifacts with multiple transmitters

The signal loss susceptibility artifact is a major limitation in gradient‐echo MRI applications. Various methods, including z‐shim techniques and multidimensional tailored radio frequency (RF) pulses, have been proposed to mitigate the through‐plane signal loss artifact, which is dominant in axial slices above the sinus region. Unfortunately, z‐shim techniques require multiple steps and multidimensional RF methods are complex, with long pulse lengths. Parallel transmission methods were recently shown to be promising for improving B₁ inhomogeneity and reducing the specific absorption rate. In this work, a novel method using time‐shifted slice‐select RF pulses is presented for reducing the through‐plane signal loss artifact in parallel transmission applications. A simultaneous z‐shim is obtained by concurrently applying unique time‐shifted pulses on each transmitter. The method is shown to reduce the signal loss susceptibility artifact in gradient‐echo images using a four‐channel parallel transmission system at 3T. Magn Reson Med 61:255–259, 2009. © 2009 Wiley‐Liss, Inc.     

Cardiac motion in diffusion-weighted MRI of the liver: artifact and a method of correction

Purpose:

To characterize cardiac motion artifacts in the liver and assess the use of a postprocessing method to mitigate these artifacts in repeat measurements.

Materials and Methods:

Three subjects underwent breathhold diffusion‐weighted (DW) scans consisting of 25 repetitions for three b‐values (0, 500, 1000 sec/mm²). Statistical maps computed from these repetitions were used to assess the distribution and behavior of cardiac motion artifacts in the liver. An objective postprocessing method to reduce the artifacts was compared with radiologist‐defined gold standards.

Results:

Signal dropout is pronounced in areas proximal to the heart, such as the left lobe, but also present in the right lobe and in distal liver segments. The dropout worsens with b‐value and leads to overestimation of the diffusivity. By reference to a radiologist‐defined gold standard, a postprocessing correction method is shown to reduce cardiac motion artifact.

Conclusion:

Cardiac motion leads to significant artifacts in liver DW imaging; we propose a postprocessing method that may be used to mitigate the artifact and is advantageous to standard signal averaging in acquisitions with multiple repetitions. J. Magn. Reson. Imaging 2012;318‐327. © 2011 Wiley Periodicals, Inc.     

Artifact reduction from metallic dental materials in T1‐weighted spin‐echo imaging at 3.0 tesla

Purpose:

To investigate and propose a method of artifact reduction arising from metallic dental materials by applying a slice‐encoding for metal artifact correction (SEMAC) technique on T1‐weighted spin‐echo (SE) imaging at 3 Tesla.

Materials and Methods:

The view angle tilting (VAT) technique was adapted to conventional T1‐weighted spin‐echo (SE) sequence to correct the in‐plane distortion, and the SEMAC technique was used for correcting the remaining through‐plane distortions. Fourier transform based B0 field simulations were performed to estimate the amount of field perturbation and a scout imaging method was developed which guide in selecting the number of slice‐encodings needed in SEMAC sequences. Phantoms of six different dental materials with various shapes and sizes that are used in practice (amalgam; titanium implant; gold and Ni‐Cr crowns; Ni‐Ti and stainless steel orthodontic wires) were imaged. In vivo images of two subjects were also acquired. The amounts of artifact reduction were quantified in phantom studies.

Results:

Compared with conventional SE imaging in phantom studies, in‐plane artifacts were reduced by up to 43% in the VAT SE images and 80% in the SEMAC images. Through‐plane artifacts were reduced by up to 65% in SEMAC images. In vivo SEMAC images also showed reduced artifacts.

Conclusion:

The SEMAC technique can mitigate artifact caused by metallic dental materials for T1w‐SE imaging. J. Magn. Reson. Imaging 2013;37:471–478. © 2012 Wiley Periodicals, Inc.     

Adaptive non‐local means denoising of MR images with spatially varying noise levels

Purpose:

To adapt the so‐called nonlocal means filter to deal with magnetic resonance (MR) images with spatially varying noise levels (for both Gaussian and Rician distributed noise).

Materials and Methods:

Most filtering techniques assume an equal noise distribution across the image. When this assumption is not met, the resulting filtering becomes suboptimal. This is the case of MR images with spatially varying noise levels, such as those obtained by parallel imaging (sensitivity‐encoded), intensity inhomogeneity‐corrected images, or surface coil‐based acquisitions. We propose a new method where information regarding the local image noise level is used to adjust the amount of denoising strength of the filter. Such information is automatically obtained from the images using a new local noise estimation method.

Results:

The proposed method was validated and compared with the standard nonlocal means filter on simulated and real MRI data showing an improved performance in all cases.

Conclusion:

The new noise‐adaptive method was demonstrated to outperform the standard filter when spatially varying noise is present in the images. J. Magn. Reson. Imaging 2010;31:192–203. © 2009 Wiley‐Liss, Inc.     

T1‐weighted 3D dynamic contrast‐enhanced MRI of the breast using a dual‐echo dixon technique at 3 T

Purpose:

To evaluate a single‐pass fast spoiled gradient echo (FSPGR) two‐point Dixon sequence and a gradient echo sequence with spectral fat suppression in their performance at 3 T for fat suppressed contrast‐enhanced bilateral breast imaging.

Materials and Methods:

Twenty patients were prospectively enrolled in an imaging protocol that included axial Dixon and 3D FSPGR with spectrally selective fat saturation sequences as part of patient care in this study. Qualitative analysis was performed retrospectively by two readers who scored the images for homogeneity and degree of fat saturation, severity of artifacts, and quality of normal anatomical structures. Enhancing lesions were scored according to the confidence with which American College of Radiology (ACR) BI‐RADS magnetic resonance imaging (MRI) features were identified.

Results:

The Dixon sequence showed superior fat saturation homogeneity, quality of posterior anatomical structures, and decreased artifact severity that were statistically significant (P < 0.0001). The degree of fat saturation was scored higher in the Dixon sequence, although the difference did not reach statistical significance. There were no significant differences between the 3D T1‐weighted FSPGR and Dixon groups for assessing lesion features.

Conclusion:

Our findings suggest that the Dixon technique is an effective fat suppression method for contrast‐enhanced breast MRI. The Dixon technique also seemed to provide better anatomical definition of posterior structures and improvement in severity of artifacts. J. Magn. Reson. Imaging 2011;. © 2011 Wiley‐Liss, Inc.