Dixon Technique Research Articles

Lower-extremity magnetic resonance imaging in patients with hyperkalemic periodic paralysis carrying the SCN4A mutation T704M: 30-month follow-up of seven patients

Hyperkalemic periodic paralysis (hyperKPP) is a muscle channelopathy characterized by recurrent paralytic attacks. Our previous study, in which we conducted whole-body muscle magnetic resonance imaging (MRI) in patients with hyperKPP, revealed muscle atrophy and fatty change in the lower extremity, especially in older persons. The aim of current study was to identify the progression of myopathy in hyperKPP patients had been assessed in the previous study. We performed lower-extremity muscle MRI in seven hyperKPP patients carrying the T704M mutation in the SCN4A gene at an interval of 30 months. Muscle atrophy, edematous change, fatty change, and fat fraction quantified using the Dixon technique were compared with the previous MRI findings. The lower-extremity MRI scan showed progressive muscle pathologic findings when compared with the previous study. Muscle atrophy, edematous change, and fatty change were prominent in the superficial posterior compartment of the lower leg. The follow-up lower-extremity muscle MRI findings provide evidence for chronic progressive myopathy and suggest the usefulness of MRI for assessing disease progression in patients with hyperKPP. This study is meaningful in terms of providing data showing the longitudinal changes of muscles in patients with periodic paralysis.

Fracture of ankle: MRI using opposed-phase imaging obtained from turbo spinecho modified Dixon image shows improved sensitivity.

To evaluate if opposed-phase (OP) imaging obtained from the turbo spin echo (TSE) modified Dixon (mDixon) technique can increase the sensitivity of MRI for diagnosing ankle fractures. This study included 95 CT-confirmed ankle fractures with additional MRI of the ankle using a TSE modified Dixon (mDixon) technique. Two groups of images were analyzed independently: Group 1-imaging group without OP imaging; Group 2-imaging group with OP imaging. Readers assessed the images using a 4-point confidence score to detect fractures. During the first review session, the fracture site was blinded. For the second review session, the fracture site was provided. Sensitivity and positive-predictive value were calculated. In both sessions, the sensitivity for Group2 was significantly greater than that for Group 1 (Session 1: 76.3% vs 62.6%, p < 0.0001; Session 2: 80.5% vs 65.3%, p < 0.0001). The positive-predictive value of Group2 was significantly lower in both sessions 1 and 2 (Session 1: 85.8% vs 97.5%, p < 0.0001; Session 2: 90.5% vs 96.9%, p = 0.0068). Among the 28 false-negative fractures missed in Group 1 (Session 1), 12 (9 minimal displaced and 4 small diameter fractures) were identified in Group 2 (Session 1). While 8.9% showed lower movement, 33.6% showed upper movement in Group2 compared with Group 1. Possible causes of false-positive lesions were subcutaneous fat, bone marrow edema, and intraosseous vessel mimic fractures. OP imaging obtained using the modified Dixon technique provided better sensitivity and improved descriptions of fractures, especially for minimal displaced fractures and small diameter fractures. However, caution is required when diagnosing fractures with OP imaging because pseudofractures can appear as a result of adjacent bone marrow edema, vascular structures, or subcutaneous fat lobules. Advances in knowledge: In MRI, minimal displaced or small chip bone fracture maybe missed, OP imaging obtained using the mDixon technique provided better sensitivity and improved descriptions of fractures using the black boundary artifact.

Fat suppression in magnetic resonance imaging of the head and neck region: is the two-point DIXON technique superior to spectral fat suppression?

The aim of our study was to systematically compare two-point Dixon fat suppression (FS) and spectral FS techniques in contrast enhanced imaging of the head and neck region. Three independent readers analysed coronal T1 weighted images recorded after contrast medium injection with Dixon and spectral FS techniques with regard to FS homogeneity, motion artefacts, lesion contrast, image sharpness and overall image quality. 85 patients were prospectively enrolled in the study. Images generated with Dixon-FS technique were of higher overall image quality and had a more homogenous FS over the whole field of view compared with the standard spectral fat-suppressed images (p < 0.001). Concerning motion artefacts, flow artefacts, lesion contrast and image sharpness no statistically significant difference was observed. The Dixon-FS technique is superior to the spectral technique due to improved homogeneity of FS and overall image quality while maintaining lesion contrast. Advances in knowledge: T1 with Dixon FS technique offers, compared to spectral FS, significantly improved FS homogeneity and over all image quality in imaging of the head and neck region.

Estimation of hepatic fat fraction using modified Dixon magnetic resonance imaging techniques: effect of liver cirrhosis

PurposeTo evaluate modified Dixon MRI techniques in hepatic fat estimation and to assess the effect of cirrhosis. Methods235 patients who underwent liver MRI were included. Correlation between modified Dixon techniques with MRS was assessed. Accuracy of MR techniques in hepatic fat estimation was calculated, and the result was compared between patients with/without liver cirrhosis. ResultsCorrelation between modified Dixon and MRS was better in group without liver cirrhosis, and accuracy of modified Dixon method was higher in group without liver cirrhosis. ConclusionsModified Dixon techniques estimate hepatic fat fraction noninvasively, but the result can be influenced by the presence of liver cirrhosis.

Fat status detection and histotypes differentiation in solid renal masses using Dixon technique

PurposeTo detect fat status and differentiate histotypes of renal masses by using Dixon technique. Materials and methodsThis study included 134 solid renal masses. Signal intensity index (SII) and fat fraction (FF) in different histotypes were compared. ResultsOnly angiomyolipoma (AML), clear cell renal cell carcinoma (RCC), and papillary RCC were confirmed to contain fat. The FF of 16.8% can effectively differentiate AML from clear cell RCC, so did the SII of 9.2% can differentiate clear cell RCC from non-clear cell RCC and rare benign histotypes. ConclusionDixon technique successfully evaluated the fat status and histotypes of renal masses.

Optimal Fat Suppression in Head and Neck MRI: Comparison of Multipoint Dixon with 2 Different Fat-Suppression Techniques, Spectral Presaturation and Inversion Recovery, and STIR

Uniform complete fat suppression is essential for identification and characterization of most head and pathology. Our aim was to compare the multipoint Dixon turbo spin-echo fat-suppression technique with 2 different fat-suppression techniques, including a hybrid spectral presaturation with inversion recovery technique and an inversion recovery STIR technique, in head and neck fat-suppression MR imaging. Head and neck MR imaging datasets of 72 consecutive patients were retrospectively reviewed. All patients were divided into 2 groups based on the type of fat-suppression techniques used (group A: STIR and spectral presaturation with inversion recovery gadolinium-T1WI; group B: multipoint Dixon T2 TSE and multipoint Dixon gadolinium-T1WI TSE). Objective and subjective image quality and scan acquisition times were assessed and compared between multipoint Dixon T2 TSE versus STIR and multipoint Dixon gadolinium-T1WI TSE versus spectral presaturation with inversion recovery gadolinium-T1WI using the Mann-Whitney U test. A total of 64 patients were enrolled in the study (group A, n = 33 and group B, n = 31). Signal intensity ratios were significantly higher for multipoint Dixon T2 and gadolinium-T1WI techniques compared with STIR (P < .001) and spectral presaturation with inversion recovery gadolinium-T1WI (P < .001), respectively. Two independent blinded readers revealed that multipoint Dixon T2 and gadolinium-T1WI techniques had significantly higher overall image quality (P = .022 and P < .001) and fat-suppression grades (P < .013 and P < .001 across 3 different regions) than STIR and spectral presaturation with inversion recovery gadolinium-T1WI, respectively. The scan acquisition time was relatively short for the multipoint Dixon technique (2 minutes versus 4 minutes 56 seconds for the T2-weighted sequence and 2 minutes versus 3 minutes for the gadolinium-T1WI sequence). The multipoint Dixon technique offers better image quality and uniform fat suppression at a shorter scan time compared with STIR and spectral presaturation with inversion recovery gadolinium-T1WI techniques.

MRI measurement of pancreatic fat fraction based on Dixon method and correlation analysis with clinical factors

Objective To analyze the pancreatic fat fraction based on magnetic resonance Dixon sequence and correlation with clinical factors. Methods A total of 95 cases of adult physical examinees who had underwent abdominal MRI were retrospectively studied. Age, blood pressure, height and weight were recorded for every subject, and BMI was then calculated. The venous blood sample were analyzed for fasting plasma glucose (FPC), total cholesterol (TC), triglycerides (TG), low density lipoprotein-cholesterol (LDL-c) and high density lipoprotein-cholesterol (HDL-c). All cases underwent water-fat separation T1WI, fat inhibition T2WI, DWI, and coronal T2WI scans. We measured PFF of all the examinees, subcutaneous fat area (SA), visceral fat area (VA), and total abdominal fat area (TA) on the images above 8 centimeter of L4 to L5 were also measured, subcutaneous fat percentage (SFP) and visceral fat percentage (VFP) were further calculated. PFF of the 95 cases ranged from 2.1% to 35.0%, and the median PFF was 8.9%. This cohort was divided into low-fat pancreas groups (PFF≤8.9%, n=51) and high-fat pancreas group (PFF>8.9%, n=44) according to the median PFF. Independent sample t test was used to test for differences in clinical index between the two groups, Pearson correlation coefficient was used to measure the strength of a linear association between clinical indexes and PFF. Results Excellent water only, fat only, in phase and out of phase images of all the 95 adults were obtained. Signals of MRI images of all pancreas were homogeneous, the anatomic structures of all images were sharp and clear, and all the images had no motion artifact. The levels of BMI, systolic blood pressure, TG, LDL-c, FPC, VA, TA, VFP of high-fat pancreas group were significantly higher than those of low-fat pancreas group, and SFP was lower (P 0.05). PFF was weakly to moderately positively correlated with age, BMI, systolic blood pressure, diastolic blood pressure, TG, LDL-c, FPG, SA, VA, TA and VFP (r=0.219 to 0.515, P<0.05), SFP was moderately negatively correlated with PFF(r=-0.434, P<0.01). Conclusions It's feasible and accurate to measure the PFF with Dixon technique. PFF have a certain correlation with age, BMI, blood pressure, abdominal fat area and blood lipid metabolism. Key words: Pancreas; Magnetic resonance imaging; Fat fraction

Comparison of fat suppression capability for chest MR imaging with Dixon, SPAIR and STIR techniques at 3 Tesla MR system

PurposeTo directly compare fat suppression efficacy of Dixon, spectral attenuated inversion recovery (SPAIR) and short tau inversion recovery (STIR) techniques for a 3T MR system. Materials and methodsNineteen consecutive patients (11 men, 8 women; mean age 67.9years) underwent chest MR imaging. Contrast-noise ratio (CNR) between muscle and fat (CNRFat) was calculated by ROI measurement. Then, two radiologists used a five-point scale for visual assessment of image quality, fat suppression capability and lesion detection. Next, the quantitative calculations obtained with all three techniques were compared by means of Tukey's honest significant difference (HSD) test. Inter-observer agreements were assessed by kappa statistics and χ2 test. Fisher's least significant difference (LSD) test was used for comparison among all scores. ResultsCNRFat of SPAIR were significantly higher than those of Dixon and STIR (p<0.001). Inter-observer agreements were assessed as significantly moderate, substantial or almost perfect (0.51<κ<0.89, p<0.0001). Total image quality and fat suppression capability of Dixon and STIR were significantly higher than those of SPAIR (p<0.001). ConclusionDixon technique has better fat suppression capability on T2-weighted turbo SE imaging than SPAIR technique on chest MR imaging examined with a 3T MR system, although it can't substitute STIR technique on fat suppression and lesion visualization.

Timed function tests, motor function measure, and quantitative thigh muscle MRI in ambulant children with Duchenne muscular dystrophy: A cross-sectional analysis

The development of new therapeutic agents for the treatment of Duchenne muscular dystrophy has put a focus on defining outcome measures most sensitive to capture treatment effects. This cross-sectional analysis investigates the relation between validated clinical assessments such as the 6-minute walk test, motor function measure and quantitative muscle MRI of thigh muscles in ambulant Duchenne muscular dystrophy patients, aged 6.5 to 10.8 years (mean 8.2, SD 1.1). Quantitative muscle MRI included the mean fat fraction using a 2-point Dixon technique, and transverse relaxation time (T2) measurements. All clinical assessments were highly significantly inter-correlated with p < 0.001. The strongest correlation with the motor function measure and its D1-subscore was shown by the 6-minute walk test. Clinical assessments showed no correlation with age. Importantly, quantitative muscle MRI values significantly correlated with all clinical assessments with the extensors showing the strongest correlation. In contrast to the clinical assessments, quantitative muscle MRI values were highly significantly correlated with age. In conclusion, the motor function measure and timed function tests measure disease severity in a highly comparable fashion and all tests correlated with quantitative muscle MRI values quantifying fatty muscle degeneration.

Agreement between manual relaxometry and semi-automated scanner-based multi-echo Dixon technique for measuring liver T2* in a pediatric and young adult population.

Commercially available 3D multi-echo Dixon (mDixon) sequences provide parametric maps of liver T2*, obviating manual curve fitting that is often required with conventional gradient recalled echo (GRE)-based multi-echo relaxometry, potentially simplifying clinical work flow. The purpose of our study was to compare T2* values generated by a 3D mDixon sequence to values generated by GRE-based T2* relaxometry with manual curve fitting in a pediatric and young adult population. We reviewed clinical MRI exams performed at 1.5T for liver iron content estimation between February 2015 and June 2016 that included both mDixon and multi-echo GRE pulse sequences. We obtained mean T2* measurements based on each sequence by drawing regions of interest on each of four axial slices through the mid-liver. We compared mDixon-based and GRE-based T2* measurements using paired t-tests and assessed agreement using single-measure intra-class correlation coefficients and Bland-Altman difference plots. One hundred nine patients met inclusion criteria (site 1=82; site 2=27). Mean age was 12.4±5.8years, and 42 subjects (39%) were female. There was no statistically significant difference in mean T2* values for the two sequences (pooled means: 11.7±11.0 [GRE] vs. 11.7±10.9ms [mDixon]; P=0.93). There was excellent absolute agreement between sequences (intraclass correlation coefficient [ICC]=0.98 for patients at both sites, confidence interval [CI]: 0.97-0.98 with mean bias of 0.0ms [-4.2ms to +4.2ms]). 3D mDixon is accurate for measuring liver T2* and can likely replace 2D GRE-based relaxometry.

Comparison of the Dixon and CTDI dose quantification techniques

Quantification of radiation dose in computed tomography(CT) is an ongoing area of research due to the continual evolution of CT technology both physical and software based. CT contributes to nearly 70% of the total dose given to patients during examinations [1] . As the number CT examinations are grown in the world, the radiation dose delivered from CT scanners to patient must be quantified precisely. Current dose measurement from CT is based on Computed Tomography Dose Index(CTDI) which was developed in 1981 [2] . The CTDI method utilizes a 10-cm long pencil ionization chamber placed in a 14-cm long PMMA phantom at 5 independent sites. The CT dose measurement is of a single rotation for each reference site. Modern CT scanners with helical scanning modes, auto exposure control, array detectors and multiple slice planes go beyond the efficacy of the CTDI technique. CTDI excludes the contribution of radiation scattered beyond the 100-mm range along the z axis. Dixon et al. [3] developed a new method to measure the dose from CT scan which is more accurate than the conventional CTDI. By scanning the length of a long phantom containing a small volume farmer chamber we were able to directly measure the cumulative dose D(x) at any point allowing the measurement of a dose equilibrium at the centre of the dose profile. This presentation will compare both techniques (i.e. the dose profiles and output obtained from Dixon and CTDI method in a Clinical CT.

Reduced metallic artefacts in 3 T knee MRI using fast spin-echo multi-point Dixon compared to fast spin-echo T2-weighted sequences

To compare multi-point Dixon magnetic resonance imaging (MRI) and fast spin-echo (FSE) T2-weighted imaging (WI) with regard to the size of metallic artefacts when imaging the knee joint. A total of 42 patients who underwent anterior cruciate ligament (ACL) reconstruction and follow-up imaging with 3T MRI using the multi-point Dixon technique was included in this retrospective study. The maximal distance of the image distortion area around the metallic artefact was measured (interference screw of femoral tunnel area) on sagittal images of both FSE T2WI (T2WI and fat-suppressed [FS] T2WI) and multi-point Dixon (water only image and in-phase image) sequences. The maximal distance of the image distortion were compared using paired t-tests across the image sequences (multi-point Dixon water only image versus FS T2WI and multi-point Dixon in-phase image versus T2WI). The mean distance of the image distortion from metallic artefacts regardless of the image sequence ranged from 16.6mm to 24.5mm (Table2). The mean distances measured by two readers on multi-point Dixon (water only image) sequences were significantly shorter than those in FS T2WI sequences (p<0.001). In contrast, the mean distances measured by two readers on multi-point Dixon (in-phase image) sequences did not differ from those of T2WI (p>0.05) sequences. The water-only image of multi-point Dixon technique reduces the amount of metallic artefacts compared to that in FS FSE T2WI sequences; however, the metallic artefacts were not significantly different between in-phase images of multi-point Dixon and FSE T2WI.

Reliability of MR Quantification of Rotator Cuff Muscle Fatty Degeneration Using a 2-point Dixon Technique in Comparison with the Goutallier Classification: Validation Study by Multiple Readers

Presurgical assessment of fatty degeneration is important in the management of patients with rotator cuff tears. The Goutallier classification is widely accepted as a qualitative scoring system, although it is highly observer-dependent and has poor reproducibility. The objective of this study was to quantify fatty degeneration of the supraspinatus muscle using a 2-point Dixon technique in patients with rotator cuff tears by multiple readers, and to evaluate the reproducibility compared to Goutallier classification. Two hundred patients with rotator cuff tears who underwent magnetic resonance imaging (MRI), including 2-point Dixon sequence at 3.0-T, were selected retrospectively. Qualitative and quantitative analyses of fatty degeneration were performed by two radiologists and three orthopedic surgeons independently. The fat quantification was performed by measuring signal intensity values of in phase (S(In)) and fat image (S(Fat)), and calculating fat fraction as S(Fat)/S(In). The reproducibility of MR quantification was analyzed by the intra- and interclass correlation coefficients and Bland-Altman plots. The interobserver agreement of the Goutallier classification among five readers was moderate (k = 0.51), whereas the interclass correlation coefficient regarding fat fraction value quantified in 2-point Dixon sequence was excellent (0.893). The mean differences in fat fraction values from the individual segmentation results were from -0.072 to 0.081. Proposed fat fraction grading and Goutallier grading showed similar frequency and distribution in severity of rotator cuff tears. Fat quantification in the rotator cuff muscles using a 2-point Dixon technique at 3.0-T MRI is highly reproducible and clinically feasible in comparison to the qualitative evaluation using Goutallier classification.

Using MRI to non-invasively and accurately quantify preoperative hepatic steatosis

BackgroundThe obesity epidemic has significantly increased the incidence and severity of hepatic steatosis in liver surgery patients and liver donors, potentially impacting postoperative liver regeneration and function. Development of a non-invasive means to quantify hepatic steatosis would facilitate selection of candidates for liver resection and transplant donation. MethodsAn IRB-approved protocol prospectively enrolled 28 patients with liver tumors requiring hepatic resection. In all patients, fast dual-echo gradient-echo MR images were acquired using 2-Point Dixon technique in 2D and 3D. The degree of steatosis was quantified by percent fat fraction (%FF) from in- and out-of-phase, and water-only and fat-only images. The technique-specific %FFs were compared to intraoperative and histopathological findings. ResultsFor patients with >30% steatosis by histology, the mean %FF was 22% (SD ± 5.2%) compared to a mean %FF of 5.0% (SD ± 2.1%, p = 0.0001) in patients with <30% steatosis. Using scaled values for the MR-calculated %FF, all patients with >30% pathologic steatosis could be identified preoperatively. ConclusionsQuantitative MRI identified patients with clinically-relevant steatosis with 100% accuracy. These findings could have significant impact on the management of liver resection patients and transplant donors.

The international clinical outcome study in dysferlinopathy

Objectives The Jain Clinical Outcome Study (COS) is the largest international natural history study in patients with genetically confirmed dysferlinopathy. We recruited 203 participants across 15 sites in 8 countries. The aim of the study was to analyse longitudinal clinical data over the first year of the study, describe the muscle MRI pattern and longitudinal changes in quantitative muscle MRI. Methods An adapted North Star Ambulatory Assessment (aNSAA), MFM-20 and timed tests (rise from floor, 10 metre walk/run, four stair climb and descend, Timed Up and Go (TUG) and 6MWD) were completed at baseline, six months and year 1. A semi-quantitative MRI analysis was performed on T1-weighted axial sequences at baseline in 182 patients using the Mercuri scale modified by Fisher. Hierarchical analysis was performed to define the selective pattern of involvement. Results of the T1-weighted were correlated with appropriate functional tests. Quantitative muscle MRI is made annually based on fat/water separation (Dixon techniques) and muscle water T2 mapping (Multi-Slice Multi-Echo, MSME). Results aNSAA, MFM-20, 10m walk test, and TUG demonstrated consistent deterioration in scores or time taken over each 6 months window, although variation in the change scores was wide. The rise from floor, stair climb and stair descend detected significant change over one year. On muscle MRI scans, gastrocnemius medialis and soleus were most frequently affected. A similar pattern of involvement was identified regardless of clinical phenotype. The increase of fat replacement on MRI correlated positively with disease duration and functional tests. MRI fat fraction showed significant change over a year. However water T2 did not change significantly. Conclusions Functional tests showed changes at 6 months and 1 year. Semi-quantitative MRI can help define the muscle pattern of fat replacement. We detected significant changes in thigh and calf muscles using muscle MRI quantitative Dixon sequences.

Breast fat volume measurement using wide-bore 3 T MRI: comparison of traditional mammographic density evaluation with MRI density measurements using automatic segmentation

To compare magnetic resonance imaging (MRI)-derived breast density measurements using automatic segmentation algorithms with radiologist estimations using the Breast Imaging Reporting and Data Systems (BI-RADS) density classification. Forty women undergoing mammography and dynamic breast MRI as part of their clinical management were recruited. Fat-water separated MRI images derived from a two-point Dixon technique, phase-sensitive reconstruction, and atlas-based segmentation were obtained before and after intravenous contrast medium administration. Breast density was assessed using software from Advanced MR Analytics (AMRA), Linköping, Sweden, with results compared to the widely used four-quartile quantitative BI-RADS scale. The proportion of glandular tissue in the breast on MRI was derived from the AMRA sequence. The mean unenhanced breast density was 0.31±0.22 (mean±SD; left) and 0.29±0.21 (right). Mean breast density on post-contrast images was 0.32±0.19 (left) and 0.32±0.2 (right). There was "almost perfect" correlation between pre- and post-contrast breast density quantification: Spearman's correlation rho=0.98 (95% confidence intervals [CI]: 0.97-0.99; left) and rho=0.99 (95% CI: 0.98-0.99; right). The 95% limits of agreement were -0.11-0.08 (left) and -0.08-0.03 (right). Interobserver reliability for BI-RADS was "substantial": weighted Kappa k=0.8 (95% CI: 0.74-0.87). The Spearman correlation coefficient between BI-RADS and MRI breast density was rho=0.73 (95% CI: 0.60-0.82; left) and rho=0.75 (95% CI: 0.63-0.83; right) which was also "substantial". The AMRA sequence provides a fully automated, reproducible, objective assessment of fibroglandular breast tissue proportion that correlates well with mammographic assessment of breast density with the added advantage of avoidance of ionising radiation.

Non-uniform muscle fat replacement along the proximodistal axis in Duchenne muscular dystrophy

The progressive replacement of muscle tissue by fat in Duchenne muscular dystrophy (DMD) has been studied using quantitative MRI between, but not within, individual muscles. We studied fat replacement along the proximodistal muscle axis using the Dixon technique on a 3T MR scanner in 22 DMD patients and 12 healthy controls. Mean fat fractions per muscle per slice for seven lower and upper leg muscles were compared between and within groups assuming a parabolic distribution. Average fat fraction for a small central slice stack and a large coverage slice stack were compared to the value when the stack was shifted one slice (15 mm) up or down. Higher fat fractions were observed in distal and proximal muscle segments compared to the muscle belly in all muscles of the DMD subjects (p < 0.001). A shift of 15 mm resulted in a difference in mean fat fraction which was on average 1–2% ranging up to 12% (p < 0.01). The muscle end regions are exposed to higher mechanical strain, which points towards mechanical disruption of the sarcolemma as one of the key factors in the pathophysiology. Overall, this non-uniformity in fat replacement needs to be taken into account to prevent sample bias when applying quantitative MRI as biomarker in clinical trials for DMD.

Proton Density Fat Fraction Measurements at 1.5- and 3-T Hepatic MR Imaging: Same-Day Agreement among Readers and across Two Imager Manufacturers.

Purpose To determine the agreement of proton density fat fraction (PDFF) measurements obtained with hepatic magnetic resonance (MR) imaging among readers, imager manufacturers, and field strengths. Materials and Methods This HIPAA-compliant study was approved by the institutional review board. After providing informed consent, 24 adult volunteers underwent imaging with one 1.5-T MR unit (Ingenia; Philips Healthcare, Best, the Netherlands) and two different 3.0-T units (750 W [GE Healthcare, Waukesha, Wis] and Ingenia) on the same day to estimate hepatic PDFF. A single-breath-hold multipoint Dixon-based acquisition was performed with commercially available pulse sequences provided by the MR imager manufacturers (mDIXON Quant [Philips Healthcare], IDEAL IQ [GE Healthcare]). Five readers placed one large region of interest, inclusive of as much liver parenchyma as possible in the right lobe while avoiding large vessels, on imager-generated parametric maps to measure hepatic PDFF. Two-way single-measure intraclass correlation coefficients (ICCs) were used to assess interreader agreement and agreement across the three imaging platforms. Results Excellent interreader agreement for hepatic PDFF measurements was obtained with mDIXON Quant and the Philips 1.5-T unit (ICC, 0.995; 95% confidence interval [CI]: 0.991, 0.998), mDIXON Quant and the Philips 3.0-T unit (ICC, 0.992; 95% CI: 0.986, 0.996), and IDEAL IQ and the GE 3.0-T unit (ICC, 0.966; 95% CI: 0.939, 0.984). Individual reader ICCs for hepatic PDFF measurements across all three imager manufacturer-field strength combinations also showed excellent interimager agreement, ranging from 0.914 to 0.954. Conclusion Estimation of PDFF with hepatic MR imaging by using multipoint Dixon techniques is highly reproducible across readers, field strengths, and imaging platforms. © RSNA, 2017.

Skull Base Dermoid Cyst in the Right Infratemporal Fossa Diagnosed Using the Dixon Technique: a Case Report and Review of Literature

Skull Base Dermoid Cyst in the Right Infratemporal Fossa Diagnosed Using the Dixon Technique: a Case Report and Review of Literature

Effect of Gd-EOB-DTPA on Hepatic Fat Quantification using Two-point Dixon Technique

Effect of Gd-EOB-DTPA on Hepatic Fat Quantification using Two-point Dixon Technique