Fat‐water separated delayed hyperenhanced myocardial infarct imaging

Fat deposition associated with myocardial infarction (MI) has been reported as a commonly occurring phenomenon. Magnetic resonance imaging (MRI) has the ability to efficiently detect MI using T₁‐sensitive contrast‐enhanced sequences and fat via its resonant frequency shift. In this work, the feasibility of fat‐water separation applied to the conventional delayed hyperenhanced (DHE) MI imaging technique is demonstrated. A three‐point Dixon acquisition and reconstruction was combined with an inversion recovery gradient‐echo pulse sequence. This allowed fat‐water separation along with T₁ sensitive imaging after injection of a gadolinium contrast agent. The technique is demonstrated in phantom experiments and three subjects with chronic MI. Areas of infarction were well defined as conventional hyperenhancement in water images. In two cases, fatty deposition was detected in fat images and confirmed by precontrast opposed‐phase imaging. Magn Reson Med 60:503–509, 2008. © 2008 Wiley‐Liss, Inc.     

Assessment of right ventricular lipomatosis by histomorphometry in control adult autopsy cases

A histomorphometry study was carried out to assess the degree of right ventricular lipomatosis in control autopsy cases and to evaluate if this was correlated with parameters such as sex, age, body mass index (BMI) and heart weight. A total of 70 adult cases were selected from cases of violent death between 1991 and 1999 and where autopsies were carried out in the Department of Pathology and Forensic Medicine in Garches. All cases with heart pathology, abnormal BMI or putrefaction were excluded. Cases with lung or liver pathology were also excluded. Furthermore, 10 adult autopsy cases who died suddenly of arrhythmogenic right ventricular cardiomyopathy (ARVC) were compared with 10 age and sex-matched control cases. Details on sex, age, BMI and heart weight were obtained from the post-mortem records. For each case one sample of the right front ventricular wall was fixed in 10% neutral saline-buffered formalin and one 5-μm-section was stained with haematoxylin and eosin. The Leica Quantimet 500 analysis system was used for the histomorphometrical study. The mean degree of lipomatosis was measured under blind conditions in the ventricular wall and epicardial fat was excluded. Covariance analysis and the Wilcoxon test were used for statistics. The mean age of the control population was 37.5 years, the sex ratio was 1.9:1 (male:female). The mean degree of lipomatosis was 17.03% and the degree of lipomatosis was significantly correlated with age (p = 0.0029) but not with sex, BMI and heart weight. There was a statistically significant increase in fat in ARVC cases compared with age and sex-matched controls (p < 0.001). Fat infiltration of the right ventricle could be an adipose involution due to an ageing process and heavy fat infiltration can be difficult to distinguish from ARVC. Our study suggests that fat infiltration is not essential for the post-mortem diagnosis of ARVC which also requires fibrosis and degenerating myocytes trapped within areas of fibrosis. Received: 6 October 2000 / Accepted: 20 March 2001     

Value of fat suppression in the MRI evaluation of suspected arrhythmogenic right ventricular dysplasia

OBJECTIVE: Arrhythmogenic right ventricular dysplasia (ARVD) is characterized by intramyocardial fibrofatty change. Fat suppression performed during conventional spin-echo imaging has been used to confirm fatty infiltration. The utility of fat suppression for enhancing the interpretation of studies of suspected ARVD has not previously been formally tested. We investigated the value of fat suppression for enhancing the interpretation of intramyocardial fatty infiltration. MATERIALS AND METHODS: Twenty-six consecutive patients clinically referred for evaluation of possible ARVD underwent cardiac MRI. Two independent observers reviewed the images retrospectively. Intramyocardial areas (n = 101) that had increased signal intensity relative to normal surrounding myocardium on T1-weighted conventional spin-echo images ("index areas") were identified. The index areas were interpreted for presence of fatty infiltration using two sets of images: The first set was obtained without fat suppression, and the second set was obtained with fat suppression. Agreement between reviewers and confidence of interpretation were determined and compared. RESULTS: Interobserver agreement was measured using a 5-point scale: 1, definitely not fat; 2, probably not fat; 3, equivocal; 4, probably fat; and 5, definitely fat. The resulting kappa values were 0.35 for non-fat-suppressed images and 0.55 for fat-suppressed images. Interobserver kappa increased from 0.67 without fat suppression to 0.90 with fat suppression using a 3-point scale: 1, not fat; 2, equivocal; and 3, fat. Confidence in the diagnosis increased from 7.2 without fat suppression to 8.8 with fat suppression (p < 0.0001) on a 10-point scale ranging from 1, not confident, to 10, very confident. CONCLUSION: The use of fat-suppressed in addition to non-fat-suppressed conventional T1-weighted spin-echo imaging increased interobserver agreement and confidence in diagnosis and evaluation of intramyocardial fatty infiltration in patients who were suspected to have ARVD.     

Development and evaluation of TWIST Dixon for dynamic contrast-enhanced (DCE) MRI with improved acquisition efficiency and fat suppression

Purpose:

To develop a new pulse sequence called time‐resolved angiography with stochastic trajectories (TWIST) Dixon for dynamic contrast enhanced magnetic resonance imaging (DCE‐MRI).

Materials and Methods:

The method combines dual‐echo Dixon to generate separated water and fat images with a k‐space view‐sharing scheme developed for 3D TWIST. The performance of TWIST Dixon was compared with a volume interpolated breathhold examination (VIBE) sequence paired with spectrally selective adiabatic inversion Recovery (SPAIR) and quick fat‐sat (QFS) fat‐suppression techniques at 3.0T using quantitative measurements of fat‐suppression accuracy and signal‐to‐noise ratio (SNR) efficiency, as well as qualitative breast image evaluations.

Results:

The water fraction of a uniform phantom was calculated from the following images: 0.66 ± 0.03 for TWIST Dixon; 0.56 ± 0.23 for VIBE‐SPAIR, and 0.53 ± 0.14 for VIBE‐QFS, while the reference value is 0.70 measured by spectroscopy. For phantoms with contrast (Gd‐BOPTA) concentration ranging from 0–6 mM, TWIST Dixon also provides consistently higher SNR efficiency (3.2–18.9) compared with VIBE‐SPAIR (2.8–16.8) and VIBE‐QFS (2.4–12.5). Breast images acquired with TWIST Dixon at 3.0T show more robust and uniform fat suppression and superior overall image quality compared with VIBE‐SPAIR.

Conclusion:

The results from phantom and volunteer evaluation suggest that TWIST Dixon outperforms conventional methods in almost every aspect and it is a promising method for DCE‐MRI and contrast‐enhanced perfusion MRI, especially at higher field strength where fat suppression is challenging. J. Magn. Reson. Imaging 2012;36:483–491. © 2012 Wiley Periodicals, Inc.     

T1 independent,T2* corrected MRI with accurate spectral modeling for quantification of fat: Validation in a fat‐water‐SPIO phantom

Purpose:

To validate a T₁‐independent, T₂*‐corrected fat quantification technique that uses accurate spectral modeling of fat using a homogeneous fat‐water‐SPIO phantom over physiologically expected ranges of fat percentage and T₂* decay in the presence of iron overload.

Materials and Methods:

A homogeneous gel phantom consisting of vials with known fat‐fractions and iron concentrations is described. Fat‐fraction imaging was performed using a multiecho chemical shift‐based fat‐water separation method (IDEAL), and various reconstructions were performed to determine the impact of T₂* correction and accurate spectral modeling. Conventional two‐point Dixon (in‐phase/out‐of‐phase) imaging and MR spectroscopy were performed for comparison with known fat‐fractions.

Results:

The best agreement with known fat‐fractions over the full range of iron concentrations was found when T₂* correction and accurate spectral modeling were used. Conventional two‐point Dixon imaging grossly underestimated fat‐fraction for all T₂* values, but particularly at higher iron concentrations.

Conclusion:

This work demonstrates the necessity of T₂* correction and accurate spectral modeling of fat to accurately quantify fat using MRI. J. Magn. Reson. Imaging 2009;30:1215–1222. © 2009 Wiley‐Liss, Inc.     

Chemical shift encoding‐based water–fat separation methods

The suppression of signal from fat constitutes a basic requirement in many applications of magnetic resonance imaging. To date, this is predominantly achieved during data acquisition, using fat saturation, inversion recovery, or water excitation methods. Postponing the separation of signal from water and fat until image reconstruction holds the promise of resolving some of the problems associated with these methods, such as failure in the presence of field inhomogeneities or contrast agents. In this article, methods are reviewed that rely on the difference in chemical shift between the hydrogen atoms in water and fat to perform such a retrospective separation. The basic principle underlying these so‐called Dixon methods is introduced, and some fundamental implementations of the required chemical shift encoding in the acquisition and the subsequent water–fat separation in the reconstruction are described. Practical issues, such as the selection of key parameters and the appearance of typical artifacts, are illustrated, and a broad range of applications is demonstrated, including abdominal, cardiovascular, and musculoskeletal imaging. Finally, advantages and disadvantages of these Dixon methods are summarized, and emerging opportunities arising from the availability of information on the amount and distribution of fat are discussed. J. Magn. Reson. Imaging 2014;40:251–268 . © 2014 Wiley Periodicals, Inc .     

Diagnosis of fatty liver with MR imaging.

The diagnosis of fatty liver with magnetic resonance (MR) imaging was evaluated in experimental rat models of simple fatty infiltration and fatty liver with hepatocellular injury. T1 and T2 were measured ex vivo and correlated with the histologic degree of fatty infiltration. Enhancement of fatty liver with four different cells-specific contrast agents was studied with ex vivo relaxometry and in vivo MR imaging. Quantitative analysis of conventional and chemical shift MR images was correlated with biochemically determined fat content of the liver. Diet-induced simple fatty infiltration of the liver caused a decrease in T1 of 15%, whereas the T1 of L-ethionine-induced fatty liver with hepatocellular injury increased by 12%. T2 showed a positive correlation with the degree of fatty infiltration in both models. Cell-specific hepatobiliary contrast agents showed the same liver uptake and relaxation enhancement in fatty livers as in normal livers. Conventional T1-weighted images and chemical shift images showed good correlation (r = .83 and .80, respectively) between signal intensity and the degree of fatty infiltration. However, only chemical shift imaging was reliable in the diagnosis of fatty liver.     

Multiecho time‐resolved acquisition (META): A high spatiotemporal resolution dixon imaging sequence for dynamic contrast‐enhanced MRI

Purpose

To evaluate a new dynamic contrast‐enhanced (DCE) imaging technique called multiecho time‐resolved acquisition (META) for abdominal/pelvic imaging. META combines an elliptical centric time‐resolved three‐dimensional (3D) spoiled gradient‐recalled echo (SPGR) imaging scheme with a Dixon‐based fat‐water separation algorithm to generate high spatiotemporal resolution volumes.

Materials and Methods

Twenty‐three patients referred for hepatic metastases or renal masses were imaged using the new META sequence and a conventional fat‐suppressed 3D SPGR sequence on a 3T scanner. In 12 patients, equilibrium‐phase 3D SPGR images acquired immediately after META were used for comparing the degree and homogeneity of fat suppression, artifacts, and overall image quality. In the remaining 11 of 23 patients, DCE 3D SPGR images acquired in a previous or subsequent examination were used for comparing the efficiency of arterial phase capture in addition to the qualitative analysis for the degree and homogeneity of fat suppression, artifacts, and overall image quality.

Results

META images were determined to be significantly better than conventional 3D SPGR images for degree and uniformity of fat suppression and ability to visualize the arterial phase. There were no significant differences in artifact levels or overall image quality.

Conclusion

META is a promising high spatiotemporal resolution imaging sequence for capturing the fast dynamics of hyperenhancing hepatic lesions and provides robust fat suppression even at 3T. J. Magn. Reson. Imaging 2009. © 2009 Wiley‐Liss, Inc.     

Influence of Gd-EOB-DTPA on proton density fat fraction using the six-echo Dixon method in 3 Tesla magnetic resonance imaging

The purpose of this study was to evaluate whether disodium gadoxetate (Gd-EOB-DTPA) affects proton density fat fractions (PDFFs) during use of the multiecho Dixon (meDixon) method in phantom and simulation magnetic resonance imaging (MRI) studies at 3 T. Fat–water phantoms comprising vegetable fat–water emulsions with varying fat volume percentages (0, 5, 10, 15, 20, 30, 40, and 50) and Gd-EOB-DTPA concentrations (0 and 0.4 mM) were prepared. Phantoms without Gd-EOB-DTPA were defined as precontrast, and those with Gd-EOB-DTPA were defined as postcontrast. All phantoms were scanned with a 3 T MRI system using the meDixon method, and precontrast and postcontrast PDFFs were calculated. Simulated pre and postcontrast PDFFs in the liver were calculated using a theoretical formula. The relationship between PDFFs measured in the pre and postcontrast phantoms was evaluated using linear regression and Bland–Altman analysis. The regression analysis comparing the pre and postcontrast PDFFs yielded a slope of 0.77 (P < 0.001). The PDFFs on the postcontrast phantom were smaller than those on the precontrast phantom. The mean difference between the PDFFs on the pre and postcontrast phantoms was 6.12% (95% confidence interval 3.13 to 9.10%; limits of agreement ?0.88 to 13.11%). The simulated PDFF on the postcontrast phantom was smaller than that on the precontrast phantom. We demonstrated that the PDFF measured using the meDixon was smaller on postcontrast than on precontrast at 3 T, if a low flip angle was used. This tendency was also seen in the simulation study results.     

Fast three‐dimensional dual echo dixon technique improves fat suppression in breast MRI

Purpose:

To compare qualitative and quantitative measures of the contrast‐enhanced dual‐echo Dixon technique with the commonly used standard three‐dimensional (3D) gradient echo (spectrally selective fat suppression) technique (SS‐FS) in breast MRI exams (bMRI).

Materials and Methods:

A total of 19 women, with prescheduled bMRI exam, were recruited to our study between 2006 and 2008. Dixon and standard SS‐SF techniques were used on both breasts of each patient. Image quality was rated in five categories: fat suppression quality, fat suppression uniformity, lesion margin clarity, lesion visibility, and axillary visibility. For quantitative assessment, we calculated the signal‐to‐noise ratio (SNR) and contrast‐to‐noise ratio (CNR) of lesion to breast, SNR efficiency, and CNR efficiency.

Results:

Of 19 patients evaluated, 13 had a primary breast malignancy and 6 had benign lesions or negative exams. Dixon images were rated higher in four of five qualitative categories (P < 0.0001) and required a shorter scan time. Dixon images yielded significantly higher SNR (43.8) and CNR (40.1) values than did 3DGRE images (SNR = 34.8, CNR = 25.3; P < 0.05). SNR efficiency (36.30) and CNR efficiency (33.79) values for Dixon images were also higher than were 3DGRE images (SNR efficiency =25.7, CNR efficiency = 19.1; P < 0.05).

Conclusion:

Dixon images were superior to the standard SS‐SF images in both qualitative and quantitative assessment of 19 bMRI exams. The Dixon technique could replace standard SS‐SF technique in bMRI exam, after our findings have been confirmed in future studies with a larger sample size. J. Magn. Reson. Imaging 2010;31:889–894. ©2010 Wiley‐Liss, Inc.     

ECG-gated multiecho Dixon fat-water separation in cardiac MRI: advantages over conventional fat-saturated imaging

OBJECTIVE: The purpose of this pictorial essay is to explore the advantages of multiecho Dixon fat-water separation techniques in cardiac MRI. The clinical indications, potential artifacts, and imaging findings with this technique are reviewed. CONCLUSION: Multiecho Dixon fat-water separation can be used to help characterize cardiac masses, evaluate for myocardial lipomatous infiltration, and diagnose pericarditis. Advantages over conventional fat-saturation techniques include fewer artifacts from background inhomogeneity, improved contrast of microscopic fat, and capability for use in combination with cine and contrast-enhanced imaging.     

Four-dimensional flow MRI using spiral acquisition

Fat suppression is an essential part of routine MRI scanning. Multiecho chemical‐shift based water‐fat separation methods estimate and correct for Bo field inhomogeneity. However, they must contend with the intrinsic challenge of water‐fat ambiguity that can result in water‐fat swapping. This problem arises because the signals from two chemical species, when both are modeled as a single discrete spectral peak, may appear indistinguishable in the presence of Bo off‐resonance. In conventional methods, the water‐fat ambiguity is typically removed by enforcing field map smoothness using region growing based algorithms. In reality, the fat spectrum has multiple spectral peaks. Using this spectral complexity, we introduce a novel concept that identifies water and fat for multiecho acquisitions by exploiting the spectral differences between water and fat. A fat likelihood map is produced to indicate if a pixel is likely to be water‐dominant or fat‐dominant by comparing the fitting residuals of two different signal models. The fat likelihood analysis and field map smoothness provide complementary information, and we designed an algorithm (Fat Likelihood Analysis for Multiecho Signals) to exploit both mechanisms. It is demonstrated in a wide variety of data that the Fat Likelihood Analysis for Multiecho Signals algorithm offers highly robust water‐fat separation for 6‐echo acquisitions, particularly in some previously challenging applications. Magn Reson Med, 2011. © 2011 Wiley‐Liss, Inc.     

Three‐point dixon method enables whole‐body water and fat imaging of obese subjects

Dixon imaging techniques derive chemical shift‐separated water and fat images, enabling the quantification of fat content and forming an alternative to fat suppression. Whole‐body Dixon imaging is of interest in studies of obesity and the metabolic syndrome, and possibly in oncology. A three‐point Dixon method is proposed where two solutions are found analytically in each voxel. The true solution is identified by a multiseed three‐dimensional region‐growing scheme with a dynamic path, allowing confident regions to be solved before unconfident regions, such as background noise. 2π‐Phase unwrapping is not required. Whole‐body datasets (256 × 184 × 252 voxels) were collected from 39 subjects (body mass index 19.8‐45.4 kg/m²), in a mean scan time of 5 min 15 sec. Water and fat images were reconstructed offline, using the proposed method and two reference methods. The resulting images were subjectively graded on a four‐grade scale by two radiologists, blinded to the method used. The proposed method was found superior to the reference methods. It exclusively received the two highest grades, implying that only mild reconstruction failures were found. The computation time for a whole‐body dataset was 1 min 51.5 sec ± 3.0 sec. It was concluded that whole‐body water and fat imaging is feasible even for obese subjects, using the proposed method. Magn Reson Med 63:1659–1668, 2010. © 2010 Wiley‐Liss, Inc.     

致心律不齐性右室心肌病的MRI诊断

目的：用心脏MR新技术评价致心律不齐性右室心肌病（ARVC）的MRI征象，探讨MR扫描技术。方法：对15例临床、超声诊断或疑为ARVC的病人进行RM检查，使用GE Signa1.5TCV/iMR扫描系统，扫描序列包括黑血技术：双反转恢复快速自旋回波(double-IR FSE)和三反转自旋回波（triple-IR FSE）序列；白血技术：快速电影成像（fastcine）序列。扫描平面有短轴面、四腔面和长轴面。结果：10例诊断为ARVC，ARVC的主要MRI表现有：右室壁脂肪信号3例，右室壁变薄9例，右心室扩大6例，室壁瘤形成2例，右心腔内慢血流信号9例，右室射血分数降低6例，右房扩大3例。右室乳状肌和左室心尖部、室间隔前部累及2例。黑血技术可显示心脏解剖、形态及组织特性，白血技术主要了解心脏功能及心肌壁的运动，短轴面和四腔面显示病变较满意。结论：ARVC的RMI表现具有一定的特征，多序列、多平面成像的MR新技术对该病的诊断更准确、更可靠。     

3.0T ~1H-MRS联合梯度回波化学位移技术定量分析评估脂肪肝治疗效果

目的:探讨在3.0T MRI上联合运用氢质子波谱成像(1H-MRS)和梯度回波化学位移技术评估脂肪肝治疗效果的可行性。方法:搜集临床确诊的脂肪肝病例26例,于干预治疗前、干预治疗后3个月、6个月各行1次磁共振化学位移抑脂成像(梯度回波T1WI同/去相位双回波)和氢质子波谱成像(1 H-MRS),测得同/去相位序列的信号强度值(SIIP和SIOP),计算双回波脂变指数(FI)。测得1 H-MRS的水峰峰值(Pwater)和脂肪峰峰值(Plipid)、水峰峰下面积(Awater)、脂肪峰峰下面积(Alipid),计算肝细胞相对脂肪含量1(RLC1)及相对脂肪含量2(RLC2)。同期测量患者的血脂、谷氨酰转肽酶、腹围及身高体重指数(BMI),将其拟合成临床脂肪肝指数(FLI)。以FLI为参照标准,对不同时间点MRI所测得肝脏脂肪含量进行统计学分析。结果:FI、RLC1、RLC2与FLI进行秩相关性分析,呈正相关性(r>0,P<0.05)。干预治疗前后对照采用重复测量的方差分析,显示FI、RLC1、RLC2、FLI组间差异具有统计学意义(P=0.000),对时间(time)变化趋势的对比Polynomial检验显示time*type有统计学意义(P=0.000),提示FI、RLC1、RLC2在治疗前、治疗后3个月、治疗后6个月的变化是有差异的。可靠性分析显示,治疗前后组的FI和治疗前组的RLC1、RLC2的可重复性好,组内相关系数ICC≥0.75。结论:1H-MRS和梯度回波化学位移MRI可在一定程度上对脂肪肝进行定量测定,可作为脂肪肝动态监测、疗效评估和随访观察的有效手段。     

Two‐point dixon method with flexible echo times

The two‐point Dixon method is a proton chemical shift imaging technique that produces separated water‐only and fat‐only images from a dual‐echo acquisition. It is shown how this can be achieved without the usual constraints on the echo times. A signal model considering spectral broadening of the fat peak is proposed for improved water/fat separation. Phase errors, mostly due to static field inhomogeneity, must be removed prior to least‐squares estimation of water and fat. To resolve ambiguity of the phase errors, a corresponding global optimization problem is formulated and solved using a message‐passing algorithm. It is shown that the noise in the water and fat estimates matches the Cramér‐Rao bounds, and feasibility is demonstrated for in vivo abdominal breath‐hold imaging. The water‐only images were found to offer superior fat suppression compared with conventional spectrally fat suppressed images. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc.     

Subtle bone marrow edema assessed by frequency selective chemical shift MRI.

Subtle edema in yellow bone marrow from tumors (14 subjects) and osteomyelitis (9 subjects) were examined by selective nonexcitation (SENEX) water imaging using a short five pulse frequency selective excitation with lipid suppression greater than 96%. Standard spin-echo (SE) proton density-, T1- and T2-weighted images, and fat suppression methods such as short inversion time inversion recovery and also the chemical shift selective Dixon method are discussed in comparison with SENEX. Application of the SENEX method is described and images from four typical cases are demonstrated. Sensitivity to edema is obviously better using the SENEX chemical shift selective method than using other imaging techniques. Improved delineation of abnormal areas in yellow bone marrow is provided by SENEX water imaging in one slice after multislice standard imaging. After shimming, only one SE scan with frequency selective excitation is necessary to get a pure water image.     

Fast three-point dixon MR imaging using low-resolution images for phase correction: a comparison with chemical shift selective fat suppression for pediatric musculoskeletal imaging

OBJECTIVE: The purpose of this study is to describe and to implement a new fast three-point Dixon MR imaging sequence with online image reconstruction, and to compare this sequence with conventional chemical shift selective (CHESS) suppression of fat in pediatric musculoskeletal imaging. SUBJECTS AND METHODS: A three-point Dixon technique using a fast spin-echo sequence with a new phase-correction algorithm providing online image reconstruction was implemented on a 1.5-T scanner. Twelve pediatric patients and young adults were imaged with both the new three-point Dixon and conventional CHESS sequences. Three radiologists un-aware of imaging parameters and clinical information independently scored the homogeneity of fat suppression and conspicuity of abnormality using a four-point system. An additional comparison between the two techniques was made using a phantom. RESULTS: The three-point Dixon method showed superior fat suppression and lesion conspicuity (p < 0.001), particularly in the hands and feet, where CHESS is prone to inconsistent fat suppression. The phantom study showed no significant difference in the ratio of suppressed fat signal to background noise and more homogeneous fat suppression using the three-point Dixon method. CONCLUSION: Compared with CHESS, the new fast three-point Dixon sequence with online image reconstruction provides superior fat suppression and lesion conspicuity and can be routinely used in pediatric musculoskeletal imaging.     

Two‐point dixon technique provides robust fat suppression for multi‐mouse imaging

Purpose:

To determine whether Dixon‐based fat separation techniques can provide more robust removal of lipid signals from multiple‐mouse magnetic resonance imaging (MRI)‐acquired images than conventional frequency selective chemical saturation techniques.

Materials and Methods:

A two‐point Dixon technique was implemented using a RARE‐based pulse sequence and techniques for multivolume fat suppression were evaluated using a 4‐element array of volume resonators at 4.7 T. Images were acquired of both phantoms and mice.

Results:

Fat saturation was achieved on all four channels of the multiple mouse acquisition with the Dixon technique, while failures of fat saturation were found with chemical saturation techniques.

Conclusion:

This proof of concept study found that Dixon fat separation provided more reliable and homogenous fat suppression than chemical saturation in phantoms and in vivo. J. Magn. Reson. Imaging 2010; 31:510–514. © 2010 Wiley‐Liss, Inc.     

Fast spin-echo triple echo dixon: Initial clinical experience with a novel pulse sequence for simultaneous fat-suppressed and nonfat-suppressed T2-weighted spine magnetic resonance imaging

Purpose

To evaluate a prototype fast spin‐echo (FSE) triple‐echo Dixon (FTED) technique for T2‐weighted spine imaging with and without fat suppression compared to conventional T2‐weighted fast recovery (FR) FSE and short‐tau inversion recovery (STIR) imaging.

Materials and Methods

Sixty‐one patients were referred for spine magnetic resonance imaging (MRI) including sagittal FTED (time 2:26), STIR (time 2:42), and T2 FRFSE (time 2:55). Two observers compared STIR and FTED water images and T2 FRFSE and FTED T2 images for overall image quality, fat suppression, anatomic sharpness, motion, cerebrospinal fluid (CSF) flow artifact, susceptibility, and disease depiction.

Results

On FTED images water and fat separation was perfect in 58 (.95) patients. Compared to STIR, the FTED water images demonstrated less motion in 57 (.93) of 61 patients (P < 0.05), better anatomic sharpness in 51 (.84) and patients (P < 0.05), and less CSF flow artifact in 7 (.11) P < 0.05) patients. There was no difference in fat suppression or chemical shift artifact. T2 FRFSE and FTED T2 images showed equivalent motion, CSF flow, and chemical shift artifact. Lesion depiction was equivalent on FTED water and STIR images and FTED T2 and T2 FRFSE images.

Conclusion

FTED efficiently provides both fat‐suppressed and nonfat‐suppressed T2‐weighted spine images with excellent image quality, equal disease depiction, and 56% reduction in scan time compared to conventional STIR and T2 FRFSE. J. Magn. Reson. Imaging 2011;33:390–400. © 2011 Wiley‐Liss, Inc.