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PURPOSE: To evaluate repeatability of ROI sampling strategies for quantifying hepatic proton density fat fraction (PDFF) and to assess error relative to the 9-ROI PDFF. METHODS: This was a secondary analysis in subjects with known or suspected nonalcoholic fatty liver disease who underwent MRI for magnitude-based hepatic PDFF quantification. Each subject underwent three exams, each including three acquisitions (nine acquisitions total). An ROI was placed in each hepatic segment on the first acquisition of the first exam and propagated to other acquisitions. PDFF was calculated for each of 511 sampling strategies using every combination of 1, 2, …, all 9 ROIs. Intra- and inter-exam intraclass correlation coefficients (ICCs) and repeatability coefficients (RCs) were estimated for each sampling strategy. Mean absolute error (MAE) was estimated relative to the 9-ROI PDFF. Strategies that sampled both lobes evenly (“balanced”) were compared with those that did not (“unbalanced”) using two-sample t-tests. RESULTS: The 29 enrolled subjects (23 male, mean age 24 years) had mean 9-ROI PDFF 11.8% (1.1–36.3%). With more ROIs, ICCs increased, RCs decreased, and MAE decreased. Of the 60 balanced strategies with 4 ROIs, all (100%) achieved inter- and intra-exam ICCs>0.998, 55 (92%) achieved intra-exam RC

PurposeTo assess feasibility and accuracy of point-of-care (POC) NMR-proton density fat fraction (PDFF) in phantoms and in a human pilot study in a POC setting.MethodsPOC NMR (LiverScope, Livivos, San Diego CA) PDFF measurements were obtained of certified phantoms with known PDFF values (0%-40%). In an institutional review board-approved, Health Insurance Portability and Accountability Act-compliant prospective human study, a convenience sample of participants from an obesity clinic was enrolled (November 2020 to June 2021). The inclusion criteria required body mass index (BMI)=27-40 kg/m2 and willingness to undergo POC NMR and MRI-PDFF measurements. Liver PDFF was measured by POC NMR and, within 35 days after, by a confounder corrected CSE MRI PDFF acquisition and reconstruction method. The adverse events were documented and linear regression analyses were performed.ResultsPOC NMR-PDFF measurements agreed with known phantom PDFF values (R2 =0.99). Fourteen participants were enrolled in the pilot human study. MRI-PDFF could not be obtained in 4 participants (claustrophobia reaction, n=3, exceeded size of MR scanner bore, n=1). POC NMR was unevaluable in 2 participants (insufficient signal penetration depth, n=1, failure to comply with instructions, n=1). Technical success was 11 of 13 (85%) for POC NMR PDFF. In 7 participants (4 female; 31-74 years old; median BMI 35 kg/m2 ), MRI-PDFF (range, 2.8%-18.1%), and POC NMR-PDFF (range, 3%-25.2%), agreed with R2 =0.94. POC NMR had no adverse events.ConclusionPOC NMR measures PDFF accurately in phantoms and, in a first-in-human pilot study, is feasible and accurate in adults with obesity. Further testing to determine precision and accuracy across larger and more diverse cohorts is needed.

Abstract Objectives To assess reproducibility and fibrosis classification accuracy of magnetic resonance elastography (MRE)–determined liver stiffness measured manually at two different centers, and by automated analysis software in adults with nonalcoholic fatty liver disease (NAFLD), using histopathology as a reference standard. Methods This retrospective, cross-sectional study included 91 adults with NAFLD who underwent liver MRE and biopsy. MRE-determined liver stiffness was measured independently for this analysis by an image analyst at each of two centers using standardized manual analysis methodology, and separately by an automated analysis. Reproducibility was assessed pairwise by intraclass correlation coefficient (ICC) and Bland-Altman analysis. Diagnostic accuracy was assessed by receiver operating characteristic (ROC) analyses. Results ICC of liver stiffness measurements was 0.95 (95% CI: 0.93, 0.97) between center 1 and center 2 analysts, 0.96 (95% CI: 0.94, 0.97) between the center 1 analyst and automated analysis, and 0.94 (95% CI: 0.91, 0.96) between the center 2 analyst and automated analysis. Mean bias and 95% limits of agreement were 0.06 ± 0.38 kPa between center 1 and center 2 analysts, 0.05 ± 0.32 kPa between the center 1 analyst and automated analysis, and 0.11 ± 0.41 kPa between the center 2 analyst and automated analysis. The area under the ROC curves for the center 1 analyst, center 2 analyst, and automated analysis were 0.834, 0.833, and 0.847 for distinguishing fibrosis stage 0 vs. ≥ 1, and 0.939, 0.947, and 0.940 for distinguishing fibrosis stage ≤ 2 vs. ≥ 3. Conclusion MRE-determined liver stiffness can be measured with high reproducibility and fibrosis classification accuracy at different centers and by an automated analysis. Key Points • Reproducibility of MRE liver stiffness measurements in adults with nonalcoholic fatty liver disease is high between two experienced centers and between manual and automated analysis methods. • Analysts at two centers had similar high diagnostic accuracy for distinguishing dichotomized fibrosis stages. • Automated analysis provides similar diagnostic accuracy as manual analysis for advanced fibrosis.

Objectives To compare the diagnostic accuracy of US shear wave elastography (SWE) and magnetic resonance elastography (MRE) for classifying fibrosis stage in patients with nonalcoholic fatty liver disease (NAFLD). Methods Patients from a prospective single-center cohort with clinical liver biopsy for known or suspected NAFLD underwent contemporaneous SWE and MRE. AUCs for classifying biopsy-determined liver fibrosis stages ≥ 1, ≥ 2, ≥ 3, and = 4, and their respective performance parameters at cutoffs providing ≥ 90% sensitivity or specificity were compared between SWE and MRE. Results In total, 100 patients (mean age, 51.8 ± 12.9 years; 46% males; mean BMI 31.6 ± 4.7 kg/m2) with fibrosis stage distribution (stage 0/1/2/3/4) of 43, 36, 5, 10, and 6%, respectively, were included. AUCs (and 95% CIs) for SWE and MRE were 0.65 (0.54–0.76) and 0.81 (0.72–0.89), 0.81 (0.71–0.91) and 0.94 (0.89–1.00), 0.85 (0.74–0.96) and 0.95 (0.89–1.00), and 0.91 (0.79–1.00) and 0.92 (0.83–1.00), for detecting fibrosis stage ≥ 1, ≥ 2, ≥ 3, and = 4, respectively. The differences were significant for detecting fibrosis stage ≥ 1 and ≥ 2 (p Conclusions In adults with NAFLD, MRE was more accurate than SWE in diagnosing stage ≥ 1 and ≥ 2 fibrosis, but not stage ≥ 3 or 4 fibrosis. Key Points • For detecting any fibrosis or mild fibrosis, MR elastography was significantly more accurate than shear wave elastography. • For detecting advanced fibrosis and cirrhosis, MRE and SWE did not differ significantly in accuracy. • For excluding advanced fibrosis and potentially ruling out the need for biopsy, SWE and MRE did not differ significantly in negative predictive value. • Neither SWE nor MRE had sufficiently high positive predictive value to rule in advanced fibrosis.

To compare longitudinal hepatic proton density fat fraction (PDFF) changes estimated by magnitude- vs. complex-based chemical-shift-encoded MRI during a weight loss surgery (WLS) program in severely obese adults with biopsy-proven nonalcoholic fatty liver disease (NAFLD). This was a secondary analysis of a prospective dual-center longitudinal study of 54 adults (44 women; mean age 52 years; range 27–70 years) with obesity, biopsy-proven NAFLD, and baseline PDFF ≥ 5%, enrolled in a WLS program. PDFF was estimated by confounder-corrected chemical-shift-encoded MRI using magnitude (MRI-M)- and complex (MRI-C)-based techniques at baseline (visit 1), after a 2- to 4-week very low–calorie diet (visit 2), and at 1, 3, and 6 months (visits 3 to 5) after surgery. At each visit, PDFF values estimated by MRI-M and MRI-C were compared by a paired t test. Rates of PDFF change estimated by MRI-M and MRI-C for visits 1 to 3, and for visits 3 to 5 were assessed by Bland-Altman analysis and intraclass correlation coefficients (ICCs). MRI-M PDFF estimates were lower by 0.5–0.7% compared with those of MRI-C at all visits (p

To investigate if size measurements of liver observations is more variable in the arterial phase as suggested by LI-RADS and assess potential higher instability in categorization in this particular phase. Secondarily, to assess inter- and intra-reader agreement for size across phases. Patients with liver cirrhosis who underwent multi-arterial phase MRI between 2017 and 2018 were retrospectively selected. Three radiologists measured liver observations in each phase, independently, in a random order. Mean size between early and late arterial phases (AP), 2, 3 and 10 min delay and the number of observations crossing the LI-RADS size thresholds (10 and 20 mm) per phase were compared using McNemar’s test. Reader agreement was evaluated using intraclass correlation coefficient (ICC) and bootstrap-based comparisons. Bonferroni’s correction was applied to pairwise comparisons. 94 observations (LR-3, LR-4, LR-5, and LR-M) were included. Mean sizes (mm) were late AP: 19.9 (95% CI 17.2, 24.2), 2 min delay: 19.8 (95% CI 17.1, 24.0), 3 min delay: 19.8 (95% CI 17.2, 24.0), 10 min delay: 20.2 (95% CI 17.5, 24.5) (p = 0.10–0.88). There was no difference between phases in number of observations that could have changed category due to variability in size (p = 0.546–1.000). Inter- and intra-reader agreement was excellent (ICC = 0.952–0.981). Measurements of focal liver observations were consistent across all post-contrast imaging phases and we found no higher instability in LI-RADS category in any particular phase. Inter- and intra-reader agreement for size was excellent for each phase. Based on these findings, size measurement could be allowed on any post-contrast phase, including the arterial phase, if deemed appropriate by the radiologist.

To determine whether LI-RADS ancillary features predict longitudinal LR-3 observation category changes. This exploratory, retrospective, single-center study with an independent reading center included patients who underwent two or more multiphase CT or MRI examinations for hepatocellular carcinoma assessment between 2011 and 2015. Three readers independently evaluated each observation using CT/MRI LI-RADS v2017, and observations categorized LR-3 using major features only were included in the analysis. Prevalence of major and ancillary features was calculated. After excluding low-frequency (

Non-alcoholic steatohepatitis (NASH) is prevalent in adults with obesity and can progress to cirrhosis. In a secondary analysis of prospectively acquired data from the multicenter, randomized, placebo-controlled FLINT trial, we investigated the relationship between reduction in adipose tissue compartment volumes and hepatic histologic improvement.Adult participants in the FLINT trial with paired liver biopsies and abdominal MRI exams at baseline and end-of-treatment (72 weeks) were included (n = 76). Adipose tissue compartment volumes were obtained using MRI.Treatment and placebo groups did not differ in baseline adipose tissue volumes, or in change in adipose tissue volumes longitudinally (p = 0.107 to 0.745). Deep subcutaneous adipose tissue (dSAT) and visceral adipose tissue volume reductions were associated with histologic improvement in NASH (i.e., NAS [non-alcoholic fatty liver disease activity score] reductions of ≥2 points, at least 1 point from lobular inflammation and hepatocellular ballooning, and no worsening of fibrosis) (p = 0.031, and 0.030, respectively). In a stepwise logistic regression procedure, which included demographics, treatment group, baseline histology, baseline and changes in adipose tissue volumes, MRI hepatic proton density fat fraction (PDFF), and serum aminotransferases as potential predictors, reductions in dSAT and PDFF were associated with histologic improvement in NASH (regression coefficient = -2.001 and -0.083, p = 0.044 and 0.033, respectively).In adults with NASH in the FLINT trial, those with greater longitudinal reductions in dSAT and potentially visceral adipose tissue volumes showed greater hepatic histologic improvements, independent of reductions in hepatic PDFF.NCT01265498.Although central obesity has been identified as a risk factor for obesity-related disorders including insulin resistance and cardiovascular disease, the role of central obesity in non-alcoholic steatohepatitis (NASH) warrants further clarification. Our results highlight that a reduction in central obesity, specifically deep subcutaneous adipose tissue and visceral adipose tissue, may be related to histologic improvement in NASH. The findings from this analysis should increase awareness of the importance of lifestyle intervention in NASH for clinical researchers and clinicians. Future studies and clinical practice may design interventions that assess the reduction of deep subcutaneous adipose tissue and visceral adipose tissue as outcome measures, rather than simply weight reduction.

To investigate associations between histology and hepatic mechanical properties measured using multiparametric magnetic resonance elastography (MRE) in adults with known or suspected nonalcoholic fatty liver disease (NAFLD) without histologic fibrosis. This was a retrospective analysis of 88 adults who underwent 3T MR exams including hepatic MRE and MR imaging to estimate proton density fat fraction (MRI-PDFF) within 180 days of liver biopsy. Associations between MRE mechanical properties (mean shear stiffness (|G*|) by 2D and 3D MRE, and storage modulus (G′), loss modulus (G″), wave attenuation (α), and damping ratio (ζ) by 3D MRE) and histologic, demographic and anthropometric data were assessed. In univariate analyses, patients with lobular inflammation grade ≥ 2 had higher 2D |G*| and 3D G″ than those with grade ≤ 1 (p = 0.04). |G*| (both 2D and 3D), G′, and G″ increased with age (rho = 0.25 to 0.31; p ≤ 0.03). In multivariable regression analyses, the association between inflammation grade ≥ 2 remained significant for 2D |G*| (p = 0.01) but not for 3D G″ (p = 0.06); age, sex, or BMI did not affect the MRE-inflammation relationship (p > 0.20). 2D |G*| and 3D G″ were weakly associated with moderate or severe lobular inflammation in patients with known or suspected NAFLD without fibrosis. With further validation and refinement, these properties might become useful biomarkers of inflammation. Age adjustment may help MRE interpretation, at least in patients with early-stage disease. • Moderate to severe lobular inflammation was associated with hepatic elevated shear stiffness and elevated loss modulus (p =0.04) in patients with known or suspected NAFLD without liver fibrosis; this suggests that with further technical refinement these MRE-assessed mechanical properties may permit detection of inflammation before the onset of fibrosis in NAFLD. • Increasing age is associated with higher hepatic shear stiffness, and storage and loss moduli (rho = 0.25 to 0.31; p ≤ 0.03); this suggests that age adjustment may help interpret MRE results, at least in patients with early-stage NAFLD.

PURPOSE: MRI proton density fat fraction (PDFF) can be calculated using magnitude (MRI-M) or complex (MRI-C) MRI data. The purpose of this study was to identify, assess and compare the accuracy of common PDFF thresholds for MRI-M and MRI-C for assessing hepatic steatosis in patients with obesity, using histology as reference. METHODS: This two-center prospective study included patients undergoing MRI-C- and MRI-M-PDFF estimations within 3 days before weight-loss surgery. Liver biopsy was performed, and histology-determined steatosis grades used as reference standard. Using receiver operating characteristics (ROC) analysis on data pooled from both methods, single common thresholds for diagnosing and for differentiating none or mild (0–1) from moderate to severe steatosis (2–3) were selected as the ones achieving the highest sensitivity while providing at least 90% specificity. Selection methods were cross-validated. Performances were compared using McNemar’s tests. RESULTS: Of 81 included patients, 54 (67%) had steatosis. The common PDFF threshold for diagnosing steatosis was 5.4%, which provided cross-validated 0.88 (95% CI, 0.77–0.95) sensitivity and 0.92 (0.75–0.99) specificity for MRI-M and 0.87 sensitivity (0.75–0.94) with 0.81 (0.61–0.93) specificity for MRI-C. The common PDFF threshold to differentiate steatosis grades 0–1 from 2–3 was 14.7%, which provided cross-validated 0.86 (95% CI, 0.59–0.98) sensitivity and 0.95 (0.87–0.99) specificity for MRI-M and 0.93 sensitivity (0.68–0.99) with 0.97(0.89–0.99) specificity for MRI-C. CONCLUSION: If independently validated, diagnostic thresholds of 5.4% and 14.7% could be adopted for both techniques for detecting and for differentiating none to mild from moderate to severe steatosis, respectively, with high diagnostic accuracy.

ObjectivesThis study assesses the risk of progression of Liver Imaging Reporting and Data System (LI-RADS) categories, and the effects of inter-exam changes in modality or radiologist on LI-RADS categorization.MethodsClinical LI-RADS v2014 CT and MRI exams at our institution between January 2014 and September 2017 were retrospectively identified. Untreated LR-1, LR-2, LR-3, and LR-4 observations with at least one follow-up exam were included. Three hundred and seventy-two observations in 214 patients (149 male, 65 female, mean age 61 ± 10years) were included during the study period (715 exams total). Cumulative incidence curves for progression to malignant LI-RADS categories (LR-5 or LR-M) and to LR-4 or higher were generated for each index category and compared using log-rank tests with a resampling extension. Relationships between inter-exam changes in LI-RADS category and modality or radiologist, adjusted for inter-exam time intervals, were modeled using mixed effect logistic regressions.ResultsMedian inter-exam follow-up interval and total follow-up duration were 123 and 227 days, respectively. Index LR-1, LR-2, LR-3, and LR-4 differed significantly in their cumulative incidences of progression to malignant categories (p&nbsp

The purpose of this study was to (1) evaluate proton density fat fraction (PDFF) distribution across liver segments at baseline and (2) compare longitudinal segmental PDFF changes across time points in adult patients undergoing a very low-calorie diet (VLCD) and subsequent bariatric weight loss surgery (WLS). We performed a secondary analysis of data from 118 morbidly obese adult patients enrolled in a VLCD-WLS program. PDFF was estimated using magnitude-based confounder-corrected chemical-shift-encoded (CSE) MRI in each hepatic segment and lobe at baseline (visit 1), after completion of VLCD (visit 2), and at 1, 3, and 6 months (visits 3–5) following WLS. Linear regressions were used to estimate the rate of PDFF change across visits. Lobar and segmental rates of change were compared pairwise. Baseline PDFF was significantly higher in the right lobe compared to the left lobe (p

To assess reproducibility and fibrosis classification accuracy of magnetic resonance elastography (MRE)-determined liver stiffness measured manually at two different centers, and by automated analysis software in adults with nonalcoholic fatty liver disease (NAFLD), using histopathology as a reference standard.This retrospective, cross-sectional study included 91 adults with NAFLD who underwent liver MRE and biopsy. MRE-determined liver stiffness was measured independently for this analysis by an image analyst at each of two centers using standardized manual analysis methodology, and separately by an automated analysis. Reproducibility was assessed pairwise by intraclass correlation coefficient (ICC) and Bland-Altman analysis. Diagnostic accuracy was assessed by receiver operating characteristic (ROC) analyses.ICC of liver stiffness measurements was 0.95 (95% CI: 0.93, 0.97) between center 1 and center 2 analysts, 0.96 (95% CI: 0.94, 0.97) between the center 1 analyst and automated analysis, and 0.94 (95% CI: 0.91, 0.96) between the center 2 analyst and automated analysis. Mean bias and 95% limits of agreement were 0.06 ± 0.38 kPa between center 1 and center 2 analysts, 0.05 ± 0.32 kPa between the center 1 analyst and automated analysis, and 0.11 ± 0.41 kPa between the center 2 analyst and automated analysis. The area under the ROC curves for the center 1 analyst, center 2 analyst, and automated analysis were 0.834, 0.833, and 0.847 for distinguishing fibrosis stage 0 vs. ≥ 1, and 0.939, 0.947, and 0.940 for distinguishing fibrosis stage ≤ 2 vs. ≥ 3.MRE-determined liver stiffness can be measured with high reproducibility and fibrosis classification accuracy at different centers and by an automated analysis.• Reproducibility of MRE liver stiffness measurements in adults with nonalcoholic fatty liver disease is high between two experienced centers and between manual and automated analysis methods. • Analysts at two centers had similar high diagnostic accuracy for distinguishing dichotomized fibrosis stages. • Automated analysis provides similar diagnostic accuracy as manual analysis for advanced fibrosis.

To compare the diagnostic accuracy of US shear wave elastography (SWE) and magnetic resonance elastography (MRE) for classifying fibrosis stage in patients with nonalcoholic fatty liver disease (NAFLD).Patients from a prospective single-center cohort with clinical liver biopsy for known or suspected NAFLD underwent contemporaneous SWE and MRE. AUCs for classifying biopsy-determined liver fibrosis stages ≥ 1, ≥ 2, ≥ 3, and = 4, and their respective performance parameters at cutoffs providing ≥ 90% sensitivity or specificity were compared between SWE and MRE.In total, 100 patients (mean age, 51.8 ± 12.9 years; 46% males; mean BMI 31.6 ± 4.7 kg/mIn adults with NAFLD, MRE was more accurate than SWE in diagnosing stage ≥ 1 and ≥ 2 fibrosis, but not stage ≥ 3 or 4 fibrosis.• For detecting any fibrosis or mild fibrosis, MR elastography was significantly more accurate than shear wave elastography. • For detecting advanced fibrosis and cirrhosis, MRE and SWE did not differ significantly in accuracy. • For excluding advanced fibrosis and potentially ruling out the need for biopsy, SWE and MRE did not differ significantly in negative predictive value. • Neither SWE nor MRE had sufficiently high positive predictive value to rule in advanced fibrosis.

Purpose: The purpose of the study is to assess the reader agreement and accuracy of eight ultrasound imaging features for classifying hepatic steatosis in adults with known or suspected hepatic steatosis. Methods: This was an IRB-approved, HIPAA-compliant prospective study of adult patients with known or suspected hepatic steatosis. All patients signed written informed consent. Ultrasound images (Siemens S3000, 6C1HD, and 4C1 transducers) were acquired by experienced sonographers following a standard protocol. Eight readers independently graded eight features and their overall impression of hepatic steatosis on ordinal scales using an electronic case report form. Duplicated images from the 6C1HD transducer were read twice to assess intra-reader agreement. Intra-reader, inter-transducer, and inter-reader agreement were assessed using intraclass correlation coefficients (ICC). Features with the highest intra-reader agreement were selected as predictors for dichotomized histological steatosis using Classification and Regression Tree (CART) analysis, and the accuracy of the decision rule was compared to the accuracy of the radiologists’ overall impression. Results: 45 patients (18 males, 27 females; mean age 56 ± 12 years) scanned from September 2015 to July 2016 were included. Mean intra-reader ICCs ranged from 0.430 to 0.777, inter-transducer ICCs ranged from 0.228 to 0.640, and inter-reader ICCs ranged from 0.014 to 0.561. The CART decision rule selected only large hepatic vein blurring and achieved similar accuracy to the overall impression (74% to 75% and 68% to 72%, respectively). Conclusions: Large hepatic vein blurring, liver–kidney contrast, and overall impression provided the highest reader agreement. Large hepatic vein blurring may provide the highest classification accuracy for dichotomized grading of hepatic steatosis.

This protocol is withdrawn because of changed interests and lack of time of the review authors. A new review entitled 'Magnetic resonance imaging for the diagnosis of hepatocellular carcinoma in people with chronic liver disease' is now planned.

To investigate if size measurements of liver observations is more variable in the arterial phase as suggested by LI-RADS and assess potential higher instability in categorization in this particular phase. Secondarily, to assess inter- and intra-reader agreement for size across phases.Patients with liver cirrhosis who underwent multi-arterial phase MRI between 2017 and 2018 were retrospectively selected. Three radiologists measured liver observations in each phase, independently, in a random order. Mean size between early and late arterial phases (AP), 2, 3 and 10 min delay and the number of observations crossing the LI-RADS size thresholds (10 and 20 mm) per phase were compared using McNemar's test. Reader agreement was evaluated using intraclass correlation coefficient (ICC) and bootstrap-based comparisons. Bonferroni's correction was applied to pairwise comparisons.94 observations (LR-3, LR-4, LR-5, and LR-M) were included. Mean sizes (mm) were late AP: 19.9 (95% CI 17.2, 24.2), 2 min delay: 19.8 (95% CI 17.1, 24.0), 3 min delay: 19.8 (95% CI 17.2, 24.0), 10 min delay: 20.2 (95% CI 17.5, 24.5) (p = 0.10-0.88). There was no difference between phases in number of observations that could have changed category due to variability in size (p = 0.546-1.000). Inter- and intra-reader agreement was excellent (ICC = 0.952-0.981).Measurements of focal liver observations were consistent across all post-contrast imaging phases and we found no higher instability in LI-RADS category in any particular phase. Inter- and intra-reader agreement for size was excellent for each phase. Based on these findings, size measurement could be allowed on any post-contrast phase, including the arterial phase, if deemed appropriate by the radiologist.

The aim of this study was to estimate parameters determining liver triglyceride composition (TC) using 1 H MRS and to assess how TC estimability is affected by proton density fat fraction (PDFF) in adults with nonalcoholic fatty liver disease (NAFLD). In this prospective single-site study, 199 adults with known or suspected NAFLD in whom other causes of liver disease were excluded underwent two 1 H MRS STimulated Echo Acquisition Method (STEAM) sequences at 3 T. A respiratory-gated water-suppressed free breathing sequence (TE 10 ms, 16 signal averages) was used to assess TC in terms of the number of double bonds (ndb) and methylene-interrupted double bonds (nmidb), and a single breath-hold-long TR, multi-TE sequence (TR 3500 ms), which acquired five single average spectra over TE 10-30 ms, was used to estimate liver PDFF. Ndb and nmidb estimability was qualitatively assessed for each case and summarized descriptively. The consistency of ndb and nmidb estimation was examined using ROC analysis. The relationship between ndb and nmidb values and PDFF was presented graphically. Quality-of-fit of ndb and nmidb versus PDFF was evaluated by Pearson-r correlation. A significance level of 0.05 was used. In 263 1 H MRS examinations performed on 199 adult participants, ndb and nmidb were successfully estimated in 7/53 (13.2%) examinations with PDFF 10% (maximum PDFF 38.1%). Liver TC could be estimated consistently for PDFF > 6.7%. Both ndb and nmidb decreased with increasing PDFF (ndb = 2.83-0.0160·PDFF, r = -0.449, P < 0.0001); nmidb = 0.75-0.0088·PDFF, r = -0.350, P < 0.0001). In a cohort of adults with known or suspected NAFLD, liver TC becomes more saturated as PDFF increases.

To determine whether LI-RADS ancillary features predict longitudinal LR-3 observation category changes.This exploratory, retrospective, single-center study with an independent reading center included patients who underwent two or more multiphase CT or MRI examinations for hepatocellular carcinoma assessment between 2011 and 2015. Three readers independently evaluated each observation using CT/MRI LI-RADS v2017, and observations categorized LR-3 using major features only were included in the analysis. Prevalence of major and ancillary features was calculated. After excluding low-frequency ( 5%) features, inter-reader agreement was assessed using intraclass correlation coefficient (ICC). Major and ancillary feature prediction of observation upgrade (to LR-4 or higher) or downgrade (to LR-1 or LR-2) on follow-up imaging was assessed using logistic regression.141 LR-3 observations in 79 patients were included. Arterial phase hyperenhancement, washout, restricted diffusion, mild-moderate T2 hyperintensity, and hepatobiliary phase hypointensity were frequent enough for further analysis (consensus prevalence 5.0-66.0%). ICCs for inter-reader agreement ranged from 0.18 for restricted diffusion to 0.48 for hepatobiliary phase hypointensity. On follow-up, 40% (57/141) of baseline LR-3 observations remained LR-3. 8% (11/141) were downgraded to LR-2, and 42% (59/141) were downgraded to LR-1. A small number were ultimately upgraded to LR-4 (2%, 3/141) or LR-5 (8%, 11/141). None of the assessed major or ancillary features was significantly associated with observation category change. Longer follow-up time was significantly associated with both observation upgrade and downgrade.While numerous ancillary features are described in LI-RADS, most are rarely present and are not useful predictors of LR-3 observation category changes.

Author(s): Bashir, Mustafa R; Wolfson, Tanya; Gamst, Anthony C; Fowler, Kathryn J; Ohliger, Michael; Shah, Shetal N; Alazraki, Adina; Trout, Andrew T; Behling, Cynthia; Allende, Daniela S; Loomba, Rohit; Sanyal, Arun; Schwimmer, Jeffrey; Lavine, Joel E; Shen, Wei; Tonascia, James; Van Natta, Mark L; Mamidipalli, Adrija; Hooker, Jonathan; Kowdley, Kris V; Middleton, Michael S; Sirlin, Claude B; NASH Clinical Research Network (NASH CRN) | Abstract: BackgroundThe liver R2* value is widely used as a measure of liver iron but may be confounded by the presence of hepatic steatosis and other covariates.PurposeTo identify the most influential covariates for liver R2* values in patients with nonalcoholic fatty liver disease (NAFLD).Study typeRetrospective analysis of prospectively acquired data.PopulationBaseline data from 204 subjects enrolled in NAFLD/NASH (nonalcoholic steatohepatitis) treatment trials.Field strength1.5T and 3T; chemical-shift encoded multiecho gradient echo.AssessmentCorrelation between liver proton density fat fraction and R2*; assessment for demographic, metabolic, laboratory, MRI-derived, and histological covariates of liver R2*.Statistical testsPearson's and Spearman's correlations; univariate analysis; gradient boosting machines (GBM) multivariable machine-learning method.ResultsHepatic proton density fat fraction (PDFF) was the most strongly correlated covariate for R2* at both 1.5T (r = 0.652, P l 0.0001) and at 3T (r = 0.586, P l 0.0001). In the GBM analysis, hepatic PDFF was the most influential covariate for hepatic R2*, with relative influences (RIs) of 61.3% at 1.5T and 47.5% at 3T; less influential covariates had RIs of up to 11.5% at 1.5T and 16.7% at 3T. Nonhepatocellular iron was weakly associated with R2* at 3T only (RI 6.7%), and hepatocellular iron was not associated with R2* at either field strength.Data conclusionHepatic PDFF is the most influential covariate for R2* at both 1.5T and 3T; nonhepatocellular iron deposition is weakly associated with liver R2* at 3T only.Level of evidence4 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019;49:1456-1466.

PURPOSE:To determine the inter-reader agreement of magnetic resonance imaging proton density fat fraction (PDFF) and its longitudinal change in a clinical trial of adults with nonalcoholic steatohepatitis (NASH). STUDY TYPE:We performed a secondary analysis of a placebo-controlled randomized clinical trial of a bile acid sequestrant in 45 adults with NASH. A six-echo spoiled gradient-recalled-echo magnitude-based fat quantification technique was performed at 3T. Three independent readers measured MRI-PDFF by placing one primary and two additional regions of interest (ROIs) in each segment at both time points. Cross-sectional agreement between the three readers was evaluated using intra-class correlation coefficients (ICCs) and coefficients of variation (CV). Additionally, we used Bland-Altman analyses to examine pairwise agreement between the three readers at baseline, end of treatment (EOT), and for longitudinal change. RESULTS:Using all ROIs by all readers, mean PDFF at baseline, at EOT, and mean change in PDFF was 16.1%, 16.0%, and 0.07%, respectively. The 27-ROI PDFF measurements had 0.998 ICC and 1.8% CV at baseline, 0.998 ICC and 1.8% CV at EOT, and 0.997 ICC for longitudinal change. The 9-ROI PDFF measurements had corresponding values of 0.997 and 2.6%, 0.996 and 2.4%, and 0.994. Using 27 ROIs, the magnitude of the bias between readers for whole-liver PDFF measurement ranged from 0.03% to 0.06% points at baseline, 0.01% to 0.07% points at EOT, and 0.01% to 0.02% points for longitudinal change. CONCLUSION:Inter-reader agreement for measuring whole-liver PDFF and its longitudinal change is high. 9-ROI measurements have only slightly lower agreement than 27-ROI measurements.

Author(s): Park, Charlie C; Hooker, Catherine; Hooker, Jonathan C; Bass, Emily; Haufe, William; Schlein, Alexandra; Covarrubias, Yesenia; Heba, Elhamy; Bydder, Mark; Wolfson, Tanya; Gamst, Anthony; Loomba, Rohit; Schwimmer, Jeffrey; Hernando, Diego; Reeder, Scott B; Middleton, Michael; Sirlin, Claude B; Hamilton, Gavin | Abstract: BACKGROUND:Improving the signal-to-noise ratio (SNR) of chemical-shift-encoded MRI acquisition with complex reconstruction (MRI-C) may improve the accuracy and precision of noninvasive proton density fat fraction (PDFF) quantification in patients with hepatic steatosis. PURPOSE:To assess the accuracy of high SNR (Hi-SNR) MRI-C versus standard MRI-C acquisition to estimate hepatic PDFF in adult and pediatric nonalcoholic fatty liver disease (NAFLD) using an MR spectroscopy (MRS) sequence as the reference standard. STUDY TYPE:Prospective. POPULATION/SUBJECTS:In all, 231 adult and pediatric patients with known or suspected NAFLD. FIELD STRENGTH/SEQUENCE:PDFF estimated at 3T by three MR techniques: standard MRI-C; a Hi-SNR MRI-C variant with increased slice thickness, decreased matrix size, and no parallel imaging; and MRS (reference standard). ASSESSMENT:MRI-PDFF was measured by image analysts using a region of interest coregistered with the MRS-PDFF voxel. STATISTICAL TESTS:Linear regression analyses were used to assess accuracy and precision of MRI-estimated PDFF for MRS-PDFF as a function of MRI-PDFF using the standard and Hi-SNR MRI-C for all patients and for patients with MRS-PDFF l10%. RESULTS:In all, 271 exams from 231 patients were included (mean MRS-PDFF: 12.6% [SD: 10.4]; range: 0.9-41.9). High agreement between MRI-PDFF and MRS-PDFF was demonstrated across the overall range of PDFF, with a regression slope of 1.035 for the standard MRI-C and 1.008 for Hi-SNR MRI-C. Hi-SNR MRI-C, compared to standard MRI-C, provided small but statistically significant improvements in the slope (respectively, 1.008 vs. 1.035, P = 0.004) and mean bias (0.412 vs. 0.673, P l 0.0001) overall. In the low-fat patients only, Hi-SNR MRI-C provided improvements in the slope (1.058 vs. 1.190, P = 0.002), mean bias (0.168 vs. 0.368, P = 0.007), intercept (-0.153 vs. -0.796, P l 0.0001), and borderline improvement in the R2 (0.888 vs. 0.813, P = 0.01). DATA CONCLUSION:Compared to standard MRI-C, Hi-SNR MRI-C provides slightly higher MRI-PDFF estimation accuracy across the overall range of PDFF and improves both accuracy and precision in the low PDFF range. LEVEL OF EVIDENCE:1 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019;49:229-238.

Author(s): Mamidipalli, Adrija; Hamilton, Gavin; Manning, Paul; Hong, Cheng William; Park, Charlie C; Wolfson, Tanya; Hooker, Jonathan; Heba, Elhamy; Schlein, Alexandra; Gamst, Anthony; Durelle, Janis; Paiz, Melissa; Middleton, Michael S; Schwimmer, Jeffrey B; Sirlin, Claude B | Abstract: PURPOSE:To determine the relationship between hepatic proton density fat fraction (PDFF) and R2* in vivo. MATERIALS AND METHODS:In this Health Insurance Portability and Accountability Act (HIPAA)-compliant, Institutional Review Board (IRB)-approved, cross-sectional study, we conducted a secondary analysis of 3T magnetic resonance imaging (MRI) exams performed as part of prospective research studies in children in whom conditions associated with iron overload were excluded clinically. Each exam included low-flip-angle, multiecho magnitude (-M) and complex (-C) based chemical-shift-encoded MRI techniques with spectral modeling of fat to generate hepatic PDFF and R2* parametric maps. For each technique and each patient, regions of interest were placed on the maps in each of the nine Couinaud segments, and composite whole-liver PDFF and R2* values were calculated. Pearson's correlation coefficients between PDFF and R2* were computed for each MRI technique. Correlations were compared using Steiger's test. RESULTS:In all, 184 children (123 boys, 61 girls) were included in this analysis. PDFF estimated by MRI-M and MRI-C ranged from 1.1-35.4% (9.44 ± 8.76) and 2.1-38.1% (10.1 ± 8.7), respectively. R2* estimated by MRI-M and MRI-C ranged from 32.6-78.7 s-1 (48.4 ± 9.8) and 27.2-71.5 s-1 (42.2 ± 8.6), respectively. There were strong and significant correlations between hepatic PDFF and R2* values estimated by MRI-M (r = 0.874; P l 0.0001) and MRI-C (r = 0.853; P l 0.0001). The correlation coefficients (0.874 vs. 0.853) were not significantly different (P = 0.15). CONCLUSION:Hepatic PDFF and R2* are strongly correlated with each other in vivo. This relationship was observed using two different MRI techniques. LEVEL OF EVIDENCE:2 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2018;47:418-424.

Author(s): Haufe, William M; Wolfson, Tanya; Hooker, Catherine A; Hooker, Jonathan C; Covarrubias, Yesenia; Schlein, Alex N; Hamilton, Gavin; Middleton, Michael S; Angeles, Jorge E; Hernando, Diego; Reeder, Scott B; Schwimmer, Jeffrey B; Sirlin, Claude B | Abstract: PurposeTo assess and compare the accuracy of magnitude-based magnetic resonance imaging (MRI-M) and complex-based MRI (MRI-C) for estimating hepatic proton density fat fraction (PDFF) in children, using MR spectroscopy (MRS) as the reference standard. A secondary aim was to assess the agreement between MRI-M and MRI-C.Materials and methodsThis was a HIPAA-compliant, retrospective analysis of data collected in children enrolled in prospective, Institutional Review Board (IRB)-approved studies between 2012 and 2014. Informed consent was obtained from 200 children (ages 8-19 years) who subsequently underwent 3T MR exams that included MRI-M, MRI-C, and T1 -independent, T2 -corrected, single-voxel stimulated echo acquisition mode (STEAM) MRS. Both MRI methods acquired six echoes at low flip angles. T2*-corrected PDFF parametric maps were generated. PDFF values were recorded from regions of interest (ROIs) drawn on the maps in each of the nine Couinaud segments and three ROIs colocalized to the MRS voxel location. Regression analyses assessing agreement with MRS were performed to evaluate the accuracy of each MRI method, and Bland-Altman and intraclass correlation coefficient (ICC) analyses were performed to assess agreement between the MRI methods.ResultsMRI-M and MRI-C PDFF were accurate relative to the colocalized MRS reference standard, with regression intercepts of 0.63% and -0.07%, slopes of 0.998 and 0.975, and proportion-of-explained-variance values (R2 ) of 0.982 and 0.979, respectively. For individual Couinaud segments and for the whole liver averages, Bland-Altman biases between MRI-M and MRI-C were small (ranging from 0.04 to 1.11%) and ICCs were high (≥0.978).ConclusionBoth MRI-M and MRI-C accurately estimated hepatic PDFF in children, and high intermethod agreement was observed.Level of evidence1 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2017;46:1641-1647.

Purpose To determine potential associations between histologic features of pediatric nonalcoholic fatty liver disease (NAFLD) and estimated quantitative magnetic resonance diffusion-weighted imaging (DWI) parameters. Materials and Methods This prospective, cross-sectional study was performed as part of the Magnetic Resonance Assessment Guiding NAFLD Evaluation and Treatment (MAGNET) ancillary study to the Nonalcoholic Steatohepatitis Clinical Research Network (NASH CRN). Sixty-four children underwent a 3T DWI scan (b-values: 0, 100, and 500 s/mm2) within 180 days of a clinical liver biopsy of the right hepatic lobe. Three parameters were estimated in the right hepatic lobe: apparent diffusion coefficient (ADC), diffusivity (D), and perfusion fraction (F); the first assuming exponential decay and the latter two assuming biexponential intravoxel incoherent motion. Grading and staging of liver histology were done using the NASH CRN scoring system. Associations between histologic scores and DWI-estimated parameters were tested using multivariate linear regression. Results Estimated means ± standard deviations were: ADC: 1.3 (0.94–1.8) × 10−3 mm2/s; D: 0.82 (0.56–1.0) × 10−3 mm2/s; and F: 17 (6.0–28)%. Multivariate analyses showed ADC and D decreased with steatosis and F decreased with fibrosis (P < 0.05). Associations between DWI-estimated parameters and other histologic features were not significant: ADC: fibrosis (P = 0.12), lobular inflammation (P = 0.20), portal inflammation (P = 0.27), hepatocellular inflammation (P = 0.29), NASH (P = 0.30); D: fibrosis (P = 0.34), lobular inflammation (P = 0.84), portal inflammation (P = 0.76), hepatocellular inflammation (P = 0.38), NASH (P = 0.81); F: steatosis (P = 0.57), lobular inflammation (P = 0.22), portal inflammation (P = 0.42), hepatocellular inflammation (P = 0.59), NASH (P = 0.07). Conclusion In children with NAFLD, steatosis and fibrosis have independent effects on DWI-estimated parameters ADC, D, and F. Further research is needed to determine the underlying mechanisms and clinical implications of these effects. Level of Evidence: 1 J. Magn. Reson. Imaging 2017.

BACKGROUND AND AIMS Emerging data from a single-center study suggests that a 30% relative reduction in liver fat content as assessed by magnetic resonance imaging-proton density fat fraction (MRI-PDFF) from baseline may be associated with histologic improvement in nonalcoholic steatohepatitis (NASH). There are limited multicenter data comparing an active drug versus placebo on the association between the quantity of liver fat reduction assessed by MRI-PDFF and histologic response in NASH. This study aims to examine the association between 30% relative reduction in MRI-PDFF and histologic response in obeticholic acid (OCA) versus placebo-treated patients in the FLINT (farnesoid X receptor ligand obeticholic acid in NASH trial). APPROACH AND RESULTS This is a secondary analysis of the FLINT trial including 78 patients with MRI-PDFF measured before and after treatment along with paired liver histology assessment. Histologic response was defined as a 2-point improvement in nonalcoholic fatty liver disease activity score without worsening of fibrosis. OCA (25 mg orally once daily) was better than placebo in improving MRI-PDFF by an absolute difference of -3.4% (95% confidence interval [CI], -6.5 to -0.2%, P value = 0.04) and relative difference of -17% (95% CI, -34 to 0%, P value = 0.05). The optimal cutoff point for relative decline in MRI-PDFF for histologic response was 30% (using Youden's index). The rate of histologic response in those who achieved less than 30% decline in MRI-PDFF versus those who achieved a 30% or greater decline in MRI-PDFF (MRI-PDFF responders) relative to baseline was 19% versus 50%, respectively. Compared with MRI-PDFF nonresponders, MRI-PDFF responders demonstrated both a statistically and clinically significant higher odds 4.86 (95% CI, 1.4-12.8, P value

PURPOSE: To estimate parameters determining liver triglyceride composition (TC) using (1)H MRS and to assess how TC estimability is affected by proton density fat fraction (PDFF) in adults with nonalcoholic fatty liver disease (NAFLD). MATERIAL AND METHODS: In this prospective single-site study, 199 adults with known or suspected NAFLD in whom other causes of liver disease were excluded underwent two (1)H MRS STimulated Echo Acquisition Method (STEAM) sequences at 3T. A respiratory-gated water-suppressed free breathing sequence (TE 10 ms, 16 signal averages) was used to assess triglyceride composition in terms of number of double bonds (ndb) and methylene-interrupted double bonds (nmidb), and a single breath-hold long-TR, multi-TE sequence (TR 3500 ms) which acquired 5 single average spectra over TE 10–30 ms was used to estimate liver PDFF. Ndb and nmidb estimability was qualitatively assessed for each case and summarized descriptively. Consistency of ndb and nmidb estimation was examined using ROC analysis. Relationship between ndb and nmidb values and PDFF was presented graphically. Quality-of-fit of ndb and nmidb vs. PDFF was evaluated by Pearson-r correlation. A significance level of 0.05 was used. RESULTS: In 263 (1)H MRS exams performed on 199 adult participants, ndb and nmidb were successfully estimated in 7/53 (13.2%) exams with PDFF < 4%, 13/30 (43.3%) exams with PDFF between 4% and 7%, 33/41 (80.5%) exams with PDFF between 7% and 10%, and 124/139 (89.2%) exams with PDFF > 10% (max PDFF 38.1%). Liver TC could be estimated consistently for PDFF > 6.7 %. Both ndb and nmidb decreased with increasing PDFF (ndb = 2.83 - 0.0160·PDFF, r = −0.449 p < 0.0001); nmidb = 0.75 −0.0088·PDFF, r = −0.350, p < 0.0001). CONCLUSION: In a cohort of adults with known or suspected NAFLD, liver triglyceride composition becomes more saturated as PDFF increases.

PURPOSE: To describe a single-center preliminary experience with gadoxetate disodium–enhanced abbreviated MRI for hepatocellular carcinoma (HCC) screening and surveillance in patients with cirrhosis or chronic hepatitis B virus (cHBV). MATERIALS AND METHODS: This was a retrospective study of consecutive patients aged 18 years and older with cirrhosis or cHBV who underwent at least one gadoxetate-enhanced abbreviated MRI examination for HCC surveillance from 2014 through 2016. Examinations were interpreted prospectively by one of six abdominal radiologists for clinical care. Clinical, imaging, and other data were extracted from electronic medical records. Diagnostic adequacy was assessed in all patients. Diagnostic accuracy was assessed in the subset of patients who could be classified as having HCC or not having HCC on the basis of a composite reference standard. RESULTS: In this study, 330 patients (93% with cirrhosis; 45% women; mean age, 59 years) underwent gadoxetate-enhanced abbreviated MRI. In the 330 patients, 311 (94.2%) baseline gadoxetate-enhanced abbreviated MRI examinations were diagnostically adequate. Of 141 (43%) of the 330 patients, 91.4% (129 of 141) could be classified as not having HCC and 8.6% (12 of 141) could be classified as having HCC. Baseline gadoxetate-enhanced abbreviated MRI had 0.92 sensitivity (95% confidence interval [CI]: 0.62, 1.00) and 0.91 specificity (95% CI: 0.84, 0.95) for detection of HCC. Of the 330 patients who underwent baseline gadoxetate-enhanced abbreviated MRI, 187 (57%) were lost to follow-up. CONCLUSION: Gadoxetate-enhanced abbreviated MRI is feasible clinically, has a high diagnostic adequacy rate, and, on the basis of our preliminary experience, accurately depicts HCC in high-risk patients. Strategies to enhance follow-up compliance are needed. © RSNA, 2019 Keywords: Abdomen/GI, Cirrhosis, Liver, MR-Imaging, Oncology, Screening Supplemental material is available for this article.

PURPOSE: To longitudinally monitor liver fat before and after bariatric surgery by using quantitative chemical shift-encoded (CSE) MRI and to compare with changes in body mass index (BMI), weight, and waist circumference (WC). MATERIALS AND METHODS: For this prospective study, which was approved by the internal review board, a total of 126 participants with obesity who were undergoing evaluation for bariatric surgery with preoperative very low calorie diet (VLCD) were recruited from June 27, 2010, through May 5, 2015. Written informed consent was obtained from all participants. Participants underwent CSE MRI measuring liver proton density fat fraction (PDFF) before VLCD (2–3 weeks before surgery), after VLCD (1–3 days before surgery), and 1, 3, and 6–10 months following surgery. Linear regression was used to estimate rates of change of PDFF (ΔPDFF) and body anthropometrics. Initial PDFF (PDFF(0)), initial anthropometrics, and anthropometric rates of change were evaluated as predictors of ΔPDFF. Mixed-effects regression was used to estimate time to normalization of PDFF. RESULTS: Fifty participants (mean age, 51.0 years; age range, 27–70 years), including 43 women (mean age, 50.8 years; age range, 27–70 years) and seven men (mean age, 51.7 years; age range, 36–62 years), with mean PDFF(0) ± standard deviation of 18.1% ± 8.6 and mean BMI(0) of 44.9 kg/m(2) ± 6.5 completed the study. By 6–10 months following surgery, mean PDFF decreased to 4.9% ± 3.4 and mean BMI decreased to 34.5 kg/m(2) ± 5.4. Mean estimated time to PDFF normalization was 22.5 weeks ± 11.5. PDFF(0) was the only strong predictor for both ΔPDFF and time to PDFF normalization. No body anthropometric correlated with either outcome. CONCLUSION: Average liver proton density fat fraction (PDFF) decreased to normal (< 5%) by 6–10 months following surgery, with mean time to normalization of approximately 5 months. Initial PDFF was a strong predictor of both rate of change of PDFF and time to normalization. Body anthropometrics did not predict either outcome. Online supplemental material is available for this article. © RSNA, 2018

Background: E-cigarettes are purchased through multiple channels, including general retail, online, and specialty smoke and vape shops. We examine how e-cigarette users&rsquo, primary purchase place relates to e-cigarette use and smoking cessation behaviors. Methods: Probability-based samples of the U.S. population who were current e-cigarette users were surveyed in 2014 (N = 879) and 2016 (N = 743), with responses combined for most analyses. E-cigarette use and smoking cessation behaviors were compared across users&rsquo, primary purchase place. Results: Higher percentages of vape shop (59.1%) and internet (42.9%) customers were current daily users of e-cigarettes compared to retail (19.7%) and smoke shop (23.2%) customers (p-values &lt, 0.001). Higher percentages of vape shop (40.2%) and internet (35.1%) customers were also former smokers, compared to 17.7% of retail and 19.3% of smoke shop customers (p&rsquo, s &lt, 0.001). Among those smoking 12 months prior to survey, smoking cessation rates were higher for vape shop (22.2%) and internet customers (22.5%) than for retail customers (10.7%, p = 0.010 and p = 0.022, respectively), even though retail customers were more likely to use FDA-approved smoking cessation aids. The percentage of customers purchasing from vape shops increased from 20.4% in 2014 to 37.6% in 2016, surpassing general retail (27.7%) as the most likely channel in 2016. Conclusions: E-cigarette customers differed in significant ways by channels of purchase, most notably in their smoking cessation behaviors. Previous population studies have relied mostly on retail channel data, which accounted for less than 30% of all products sold by 2016. Future studies of e-cigarette use should consider a broader set of channels.

Author(s): Covarrubias, Yesenia; Fowler, Kathryn J; Mamidipalli, Adrija; Hamilton, Gavin; Wolfson, Tanya; Leinhard, Olof Dahlqvist; Jacobsen, Garth; Horgan, Santiago; Schwimmer, Jeffrey B; Reeder, Scott B; Sirlin, Claude B | Abstract: BACKGROUND:Quantitative-chemical-shift-encoded (CSE)-MRI methods have been applied to the liver. The feasibility and potential utility CSE-MRI in monitoring changes in pancreatic proton density fat fraction (PDFF) have not yet been demonstrated. PURPOSE:To use quantitative CSE-MRI to estimate pancreatic fat changes during a weight-loss program in adults with severe obesity and nonalcoholic fatty liver disease (NAFLD). To explore the relationship of reduction in pancreatic PDFF with reductions in anthropometric indices. STUDY TYPE:Prospective/longitudinal. POPULATION:Nine adults with severe obesity and NAFLD enrolled in a weight-loss program. FIELD STRENGTH/SEQUENCE:CSE-MRI fat quantification techniques and multistation-volumetric fat/water separation techniques were performed at 3 T. ASSESSMENT:PDFF values were recorded from parametric maps colocalized across timepoints. STATISTICAL TESTS:Rates of change of log-transformed variables across time were determined (linear-regression), and their significance assessed compared with no change (Wilcoxon test). Rates of change were correlated pairwise (Spearman's correlation). RESULTS:Mean pancreatic PDFF decreased by 5.7% (range 0.7-17.7%) from 14.3 to 8.6%, hepatic PDFF by 11.4% (2.6-22.0%) from 14.8 to 3.4%, weight by 30.9 kg (17.3-64.2 kg) from 119.0 to 88.1 kg, body mass index by 11.0 kg/m2 (6.3-19.1 kg/m2 ) from 44.1 to 32.9 kg/m2 , waist circumference (WC) by 25.2 cm (4.0-41.0 cm) from 133.1 to 107.9 cm, HC by 23.5 cm (4.5-47.0 cm) from 135.8 to 112.3 cm, visceral adipose tissue (VAT) by 2.9 L (1.7-5.7 L) from 7.1 to 4.2 L, subcutaneous adipose tissue (SCAT) by 4.0 L (2.9-7.4 L) from 15.0 to 11.0 L. Log-transformed rate of change for pancreatic PDFF was moderately correlated with log-transformed rates for hepatic PDFF, VAT, SCAT, and WC (ρ = 0.5, 0.47, 0.45, and 0.48, respectively), although not statistically significant. DATA CONCLUSION:Changes in pancreatic PDFF can be estimated by quantitative CSE-MRI in adults undergoing a weight-loss surgery program. Pancreatic and hepatic PDFF and anthropometric indices decreased significantly. LEVEL OF EVIDENCE:2 Technical Efficacy Stage: 1 J. Magn. Reson. Imaging 2019;50:1092-1102.

Purpose To investigate the regional variability of adipose tissue triglyceride composition in vivo using 1H MRS, examining potential confounders and corrections for artifacts, to allow for adipose tissue spectrum estimation. Materials and Methods 1H magnetic resonance (MR) stimulated echo acquisition mode (STEAM) spectra were acquired in vivo at 3T from 340 adult patients (mean age 48.9 years, range 21–79 years; 172 males, 168 females; mean body mass index [BMI] 34.0, range 22–49 kg/m2) with known or suspected nonalcoholic fatty liver disease (NAFLD) in deep (dSCAT), surface (sSCAT) subcutaneous adipose tissue, and visceral adipose tissue (VAT). Triglyceride composition was characterized by the number of double bonds (ndb) and number of methylene-interrupted double bonds (nmidb). A subset of patients (dSCAT n = 80, sSCAT n = 55, VAT n = 194) had the acquisition repeated three times to examine the repeatability of ndb and nmidb estimation. Results Mean ndb and nmidb showed significant (P < 0.0001) differences between depots except for dSCAT and sSCAT nmidb (dSCAT ndb 2.797, nmidb 0.745; sSCAT ndb 2.826, nmidb 0.737; VAT ndb 2.723, nmidb 0.687). All ndb and nmidb estimates were highly repeatable (VAT ndb ICC = 0.888, nmidb ICC = 0.853; sSCAT: ndb ICC = 0.974, nmidb ICC = 0.964; dSCAT: ndb ICC = 0.959, nmidb ICC = 0.948). Conclusion Adipose tissue composition can be estimated repeatably using 1H MRS and different fat depots have different triglyceride compositions. Level of Evidence 2 J. Magn. Reson. Imaging 2016.

The current study aimed to measure perioperative changes in driving performance following arthroscopic shoulder surgery using a validated driving simulator.21 patients who underwent arthroscopic surgery for rotator cuff or labral pathology were tested on a driving simulator preoperatively, and 6 and 12 weeks postoperatively. An additional 21 subjects were tested to establish driving data in a control cohort. The number of collisions, centerline crossings, and off-road excursions were recorded for each trial. VAS and SPADI scores were obtained at each visit.The mean number of collisions in the study group significantly increased from 2.05 preoperatively to 3.75 at 6 weeks (p0.001), and significantly decreased to 1.95 at 12 weeks (p0.001). Centerline crossings and off-road excursions did not significantly change from preoperative through 12 weeks, although centerline crossings were statistically different from the controls at each time point (p0.001). Surgery on the dominant driving arm resulted in greater collisions at 6 weeks than surgery on the non-dominant driving arm (p0.001).Preliminary data shows that driving performance is impaired for at least 6 weeks postoperatively, with a return to normal driving by 12 weeks. Driving is more profoundly affected in conditions that require avoiding a collision and when the dominant driving arm is involved.

ObjectivesRecent studies show two-dimensional (2D)-magnetic resonance elastography (MRE) is accurate in diagnosing advanced fibrosis (stages 3 and 4) in nonalcoholic fatty liver disease (NAFLD) patients. Three-dimensional (3D)-MRE is a more advanced version of the technology that can image shear-wave fields in 3D of the entire liver. The aim of this study was to prospectively compare the diagnostic accuracy of 3D-MRE and 2D-MRE for diagnosing advanced fibrosis in patients with biopsy-proven NAFLD.MethodsThis cross-sectional analysis of a prospective study included 100 consecutive patients (56% women) with biopsy-proven NAFLD who also underwent MRE. Area under the receiver operating characteristic (AUROC) analysis was performed to assess the accuracy of 2D- and 3D-MRE in diagnosing advanced fibrosis.ResultsThe mean (±s.d.) of age and body mass index were 50.2 (±13.6) years and 32.1 (±5.0) kg/m(2), respectively. The AUROC for diagnosing advanced fibrosis was 0.981 for 3D-MRE at 40 Hz, 0.927 for 3D-MRE at 60 Hz (standard shear-wave frequency), and 0.921 for 2D-MRE at 60 Hz (standard shear-wave frequency). At a threshold of 2.43 kPa, 3D-MRE at 40 Hz had sensitivity 1.0, specificity 0.94, positive predictive value 0.72, and negative predictive value 1.0 for diagnosing advanced fibrosis. 3D-MRE at 40 Hz had significantly higher AUROC (P

A recent paper by Chatterjee, Rose, and Sinha (2013) reported impressively large “money priming” effects: incidental exposure to concepts relating to cash or credit cards made participants much less generous with their time and money (after cash primes) or much more generous (after credit card primes ). Primes also altered participants’ choices in a word-stem completion task. To explore these effects, we carried out re-analyses of the raw data. A number of strange oddities were brought to light, including a dramatic similarity of the filler word-stem completion responses produced by the 20 subjects who contributed most to the priming effects. We suggest that these oddities undermine the credibility of the paper and require further investigation.

In our reanalysis of Chatterjee, Rose, and Sinha (2012), which appears earlier in this issue (Pashler, Rohrer, Abramson, Wolfson, & Harris, 2016/this issue), we brought to light two strange and (in...

Background Treating women with gestational diabetes mellitus in the third trimester improves perinatal outcomes. It is unknown whether treating women with mild glucose intolerance earlier in pregnancy would be beneficial in the reduction of maternal and neonatal morbidities. Objective In women with hyperglycemia (hemoglobin A1c ≥5.7% and/or fasting glucose ≥92 mg/dL) in early pregnancy, we sought to determine whether immediate treatment improved maternal and neonatal outcomes. Study Design This unblinded randomized controlled trial enrolled women with hyperglycemia at ≤15+0 weeks gestation between 2013 and 2015. Participants were assigned randomly to early pregnancy or third-trimester treatment of hyperglycemia that included nutrition counseling, glucose monitoring, and medications as needed. Participants underwent a blinded 2-hour glucose tolerance test at 24–28 weeks gestation. Exclusion criteria were pregestational diabetes mellitus and multiple gestations. The primary outcome was the proportion of infants with neonatal umbilical cord C-peptide >1.77 nmoL (90th percentile). Secondary outcomes were neonatal fat mass, infant World Health Organization weight-for-length percentile at birth, maternal gestational weight gain, and diagnosis of gestational diabetes mellitus on glucose tolerance test. Mann-Whitney-Wilcoxon test and Fisher’s exact test were used, as appropriate. Results A total of 202 women were assigned randomly; 45 women dropped out before delivery, which left cases 157 for analysis (82 with early pregnancy and 75 with third-trimester treatment). The trial was terminated early because of low enrollment. Baseline characteristics were similar between groups. There was no difference in C-peptide >90th percentile between groups (1 [1.5%] vs 4 [6.7%]; P=.19) in the early pregnancy and third-trimester groups, respectively). There was also no difference in fat mass (0.37±0.16 vs 0.36±0.17 kg; P=.91), weight-for-length percentile at birth (25% vs 25%; P=.46), or macrosomia (1.5 vs 5.0%; P=.84). Maternal gestational weight gain was 22.6±12.9 lb and 23.9±11.2 lb in the early pregnancy and third-trimester groups, respectively (P=.88). Gestational diabetes mellitus was diagnosed in 19.0% of the cohort and did not differ between groups (14.2% vs 25.8%; P=.17). Conclusion In this population of women with hyperglycemia, treatment in early pregnancy did not appear to improve maternal or neonatal outcomes significantly. Given comparable results in both groups, caution should be used in the initiation of an intensive diabetes mellitus treatment protocol for women with the diagnosis of hyperglycemia in early gestation.

PURPOSE:Gadoxetate-disodium (Gd-EOB-DTPA)-enhanced 3D T1- weighted (T1w) MR cholangiography (MRC) is an efficient method to evaluate biliary anatomy due to T1 shortening of excreted contrast in the bile. A method that exploits both T1 shortening and T2* effects may produce even greater bile duct conspicuity. The aim of our study is to determine feasibility and compare the diagnostic performance of two-dimensional (2D) T1w multi-echo (ME) spoiled gradient-recalled-echo (SPGR) derived R2* maps against T1w MRC for bile duct visualization in living liver donor candidates. MATERIALS AND METHODS:Ten potential living liver donor candidates underwent pretransplant 3T MRI and were included in our study. Following injection of Gd-EOBDTPA and a 20-min delay, 3D T1w MRC and 2D T1w ME SPGR images were acquired. 2D R2* maps were generated inline by the scanner assuming exponential decay. The 3D T1w MRC and 2D R2* maps were retrospectively and independently reviewed in two separate sessions by three radiologists. Visualization of eight bile duct segments was scored using a 4-point ordinal scale. The scores were compared using mixed effects regression model. RESULTS:Imaging was tolerated by all donors and R2* maps were successfully generated in all cases. Visualization scores of 2D R2* maps were significantly higher than 3D T1w MRC for right anterior (p = 0.003) and posterior (p = 0.0001), segment 2 (p

The liver R2* value is widely used as a measure of liver iron but may be confounded by the presence of hepatic steatosis and other covariates.To identify the most influential covariates for liver R2* values in patients with nonalcoholic fatty liver disease (NAFLD).Retrospective analysis of prospectively acquired data.Baseline data from 204 subjects enrolled in NAFLD/NASH (nonalcoholic steatohepatitis) treatment trials.1.5T and 3T; chemical-shift encoded multiecho gradient echo.Correlation between liver proton density fat fraction and R2*; assessment for demographic, metabolic, laboratory, MRI-derived, and histological covariates of liver R2*.Pearson's and Spearman's correlations; univariate analysis; gradient boosting machines (GBM) multivariable machine-learning method.Hepatic proton density fat fraction (PDFF) was the most strongly correlated covariate for R2* at both 1.5T (r = 0.652, P 0.0001) and at 3T (r = 0.586, P 0.0001). In the GBM analysis, hepatic PDFF was the most influential covariate for hepatic R2*, with relative influences (RIs) of 61.3% at 1.5T and 47.5% at 3T; less influential covariates had RIs of up to 11.5% at 1.5T and 16.7% at 3T. Nonhepatocellular iron was weakly associated with R2* at 3T only (RI 6.7%), and hepatocellular iron was not associated with R2* at either field strength.Hepatic PDFF is the most influential covariate for R2* at both 1.5T and 3T; nonhepatocellular iron deposition is weakly associated with liver R2* at 3T only.4 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019;49:1456-1466.

BackgroundClinical trials utilizing proton density fat fraction (PDFF) as an imaging biomarker for hepatic steatosis have used a laborious region-of-interest (ROI) sampling strategy of placing an ROI in each hepatic segment.PurposeTo identify a strategy with the fewest ROIs that consistently achieves close agreement with the nine-ROI strategy.Study typeRetrospective secondary analysis of prospectively acquired clinical research data.PopulationA total of 391 adults (173 men, 218 women) with known or suspected NAFLD.Field strength/sequenceConfounder-corrected chemical-shift-encoded 3T MRI using a 2D multiecho gradient-recalled echo technique.AssessmentAn ROI was placed in each hepatic segment. Mean nine-ROI PDFF and segmental PDFF standard deviation were computed. Segmental and lobar PDFF were compared. PDFF was estimated using every combinatorial subset of ROIs and compared to the nine-ROI average.Statistical testingMean nine-ROI PDFF and segmental PDFF standard deviation were summarized descriptively. Segmental PDFF was compared using a one-way analysis of variance, and lobar PDFF was compared using a paired t-test and a Bland-Altman analysis. The PDFF estimated by every subset of ROIs was informally compared to the nine-ROI average using median intraclass correlation coefficients (ICCs) and Bland-Altman analyses.ResultsThe study population's mean whole-liver PDFF was 10.1 ± 8.9% (range: 1.1-44.1%). Although there was no significant difference in average segmental (P = 0.452) or lobar (P = 0.154) PDFF, left and right lobe PDFF differed by at least 1.5 percentage points in 25.1% (98/391) of patients. Any strategy with ≥4 ROIs had ICC >0.995. 115 of 126 four-ROI strategies (91%) had limits of agreement (LOA) 0.995, and 2/36 (6%) of two-ROI strategies and 46/84 (55%) of three-ROI strategies had LOA

Residual pulmonary vascular obstruction (RPVO) and chronic thromboembolic pulmonary hypertension (CTEPH) are both long-term complications of acute pulmonary embolism, but it is unknown whether RPVO can be predicted by variants of fibrinogen associated with CTEPH.We used the Akaike information criterion to select the best predictive models for RPVO in two prospectively followed cohorts of acute pulmonary embolism patients, using as candidate variables the extent of the initial obstruction, clinical characteristics and fibrinogen-related data. We measured the selected models’ goodness of fit by analysis of deviance and compared models using the Chi-squared test.RPVO occurred in 29 (28.4%) out of 102 subjects in the first cohort and 46 (25.3%) out of 182 subjects in the second. The best-fit predictive model derived in the first cohort (p=0.0002) and validated in the second cohort (p=0.0005) implicated fibrinogen Bβ-chain monosialylation in the development of RPVO. When the derivation procedure excluded clinical characteristics, fibrinogen Bβ-chain monosialylation remained a predictor of RPVO in the best-fit predictive model (p=0.00003). Excluding fibrinogen characteristics worsened the predictive model (p=0.03).Fibrinogen Bβ-chain monosialylation, a common structural attribute of fibrin, helped predict RPVO after acute pulmonary embolism. Fibrin structure may contribute to the risk of developing RPVO.

Purpose To determine in a large multicenter multireader setting the interreader reliability of Liver Imaging Reporting and Data System (LI-RADS) version 2014 categories, the major imaging features seen with computed tomography (CT) and magnetic resonance (MR) imaging, and the potential effect of reader demographics on agreement with a preselected nonconsecutive image set. Materials and Methods Institutional review board approval was obtained, and patient consent was waived for this retrospective study. Ten image sets, comprising 38-40 unique studies (equal number of CT and MR imaging studies, uniformly distributed LI-RADS categories), were randomly allocated to readers. Images were acquired in unenhanced and standard contrast material-enhanced phases, with observation diameter and growth data provided. Readers completed a demographic survey, assigned LI-RADS version 2014 categories, and assessed major features. Intraclass correlation coefficient (ICC) assessed with mixed-model regression analyses was the metric for interreader reliability of assigning categories and major features. Results A total of 113 readers evaluated 380 image sets. ICC of final LI-RADS category assignment was 0.67 (95% confidence interval [CI]: 0.61, 0.71) for CT and 0.73 (95% CI: 0.68, 0.77) for MR imaging. ICC was 0.87 (95% CI: 0.84, 0.90) for arterial phase hyperenhancement, 0.85 (95% CI: 0.81, 0.88) for washout appearance, and 0.84 (95% CI: 0.80, 0.87) for capsule appearance. ICC was not significantly affected by liver expertise, LI-RADS familiarity, or years of postresidency practice (ICC range, 0.69-0.70; ICC difference, 0.003-0.01 [95% CI: -0.003 to -0.01, 0.004-0.02]. ICC was borderline higher for private practice readers than for academic readers (ICC difference, 0.009; 95% CI: 0.000, 0.021). Conclusion ICC is good for final LI-RADS categorization and high for major feature characterization, with minimal reader demographic effect. Of note, our results using selected image sets from nonconsecutive examinations are not necessarily comparable with those of prior studies that used consecutive examination series. © RSNA, 2017.

PurposeTo evaluate the repeatability and reproducibility of 2D and 3D hepatic MRE with rigid and flexible drivers at end-expiration and end-inspiration in healthy volunteers.Materials and methodsNine healthy volunteers underwent two same-day MRE exams separated by a 5- to 10-min break. In each exam, 2D and 3D MRE scans were performed, each under four conditions (2 driver types [rigid, flexible]×2 breath-hold phases [end-expiration, end-inspiration]). Repeatability (measurements under identical conditions) and reproducibility (measurements under different conditions) were analyzed by calculating bias, limit of agreement, repeatability coefficient (RC), reproducibility coefficient (RDC), intraclass correlation coefficient (ICC), and concordance correlation coefficient (CCC), as appropriate.ResultsFor 2D MRE, RCs and ICCs range between 0.29-0.49 and 0.71-0.91, respectively. For 3D MRE, RCs and ICCs range between 0.16-0.26 and 0.84-0.96, respectively. Stiffness values were biased by breath-hold phase, being higher at end-inspiration than end-expiration, and the differences were significant for 3D MRE (p&nbsp

Determine intra- and inter-examination repeatability of magnitude-based magnetic resonance imaging (MRI-M), complex-based magnetic resonance imaging (MRI-C), and magnetic resonance spectroscopy (MRS) at 3T for estimating hepatic proton density fat fraction (PDFF), and using MRS as a reference, confirm MRI-M and MRI-C accuracy.Twenty-nine overweight and obese pediatric (n = 20) and adult (n = 9) subjects (23 male, 6 female) underwent three same-day 3T MR examinations. In each examination MRI-M, MRI-C, and single-voxel MRS were acquired three times. For each MRI acquisition, hepatic PDFF was estimated at the MRS voxel location. Intra- and inter-examination repeatability were assessed by computing standard deviations (SDs) and intra-class correlation coefficients (ICCs). Aggregate SD was computed for each method as the square root of the average of first repeat variances. MRI-M and MRI-C PDFF estimation accuracy was assessed using linear regression with MRS as a reference.For MRI-M, MRI-C, and MRS acquisitions, respectively, mean intra-examination SDs were 0.25%, 0.42%, and 0.49%; mean intra-examination ICCs were 0.999, 0.997, and 0.995; mean inter-examination SDs were 0.42%, 0.45%, and 0.46%; and inter-examination ICCs were 0.995, 0.992, and 0.990. Aggregate SD for each method was0.9%. Using MRS as a reference, regression slope, intercept, average bias, and R (2), respectively, for MRI-M were 0.99%, 1.73%, 1.61%, and 0.986, and for MRI-C were 0.96%, 0.43%, 0.40%, and 0.991.MRI-M, MRI-C, and MRS showed high intra- and inter-examination hepatic PDFF estimation repeatability in overweight and obese subjects. Longitudinal hepatic PDFF change1.8% (twice the maximum aggregate SD) may represent real change rather than measurement imprecision. Further research is needed to assess whether examinations performed on different days or with different MR technologists affect repeatability of MRS voxel placement and MRS-based PDFF measurements.

To determine per-lesion sensitivity and positive predictive value (PPV) of gadoxetic acid-enhanced 3-T magnetic resonance (MR) imaging for the diagnosis of malignant lesions by using matched (spatially correlated) hepatectomy pathologic findings as the reference standard. Materials andIn this prospective, institutional review board-approved, HIPAA-compliant study, 20 patients (nine men, 11 women; mean age, 59 years) with malignant liver lesions who gave written informed consent underwent preoperative gadoxetic acid-enhanced 3-T MR imaging for surgical planning. Two image sets were independently analyzed by three readers to detect liver lesions (set 1 without and set 2 with hepatobiliary phase [HBP] images). Hepatectomy specimen ex vivo MR imaging assisted in matching gadoxetic acid-enhanced 3-T MR imaging findings with pathologic findings. Interreader agreement was assessed by using the Cohen κ coefficient. Per-lesion sensitivity and PPV were calculated.Cohen κ values were 0.64-0.76 and 0.57-0.84, and overall per-lesion sensitivity was 45% (42 of 94 lesions) to 56% (53 of 94 lesions) and 58% (55 of 94 lesions) to 64% (60 of 94 lesions) for sets 1 and 2, respectively. The addition of HBP imaging did not affect interreader agreement but significantly improved overall sensitivity for one reader (P.05) and almost for another (P = .05). Sensitivity for 0.2-0.5-cm lesions was 0% (0 of 26 lesions) to 8% (two of 26 lesions) for set 1 and 4% (one of 26 lesions) to 12% (three of 26 lesions) for set 2. Sensitivity for 0.6-1.0-cm lesions was 28% (nine of 32 lesions) to 59% (19 of 32 lesions) for set 1 and 66% (21 of 32 lesions) to 69% (22 of 32 lesions) for set 2. Sensitivity for lesions at least 1.0 cm in diameter was at least 81% (13 of 16 lesions) for set 1 and was not improved for set 2. PPV was 98% (56 of 57 lesions) to 100% (60 of 60 lesions) for all readers without differences between image sets or lesion size.Gadoxetic acid-enhanced 3-T MR imaging provides high per-lesion sensitivity and PPV for preoperative malignant liver lesion detection overall, although sensitivity for 0.2-0.5-cm malignant lesions is poor.

Author(s): Heba, Elhamy R; Desai, Ajinkya; Zand, Kevin A; Hamilton, Gavin; Wolfson, Tanya; Schlein, Alexandra N; Gamst, Anthony; Loomba, Rohit; Sirlin, Claude B; Middleton, Michael S | Abstract: PurposeTo determine the accuracy and the effect of possible subject-based confounders of magnitude-based magnetic resonance imaging (MRI) for estimating hepatic proton density fat fraction (PDFF) for different numbers of echoes in adults with known or suspected nonalcoholic fatty liver disease, using MR spectroscopy (MRS) as a reference.Materials and methodsIn this retrospective analysis of 506 adults, hepatic PDFF was estimated by unenhanced 3.0T MRI, using right-lobe MRS as reference. Regions of interest placed on source images and on six-echo parametric PDFF maps were colocalized to MRS voxel location. Accuracy using different numbers of echoes was assessed by regression and Bland-Altman analysis; slope, intercept, average bias, and R2 were calculated. The effect of age, sex, and body mass index (BMI) on hepatic PDFF accuracy was investigated using multivariate linear regression analyses.ResultsMRI closely agreed with MRS for all tested methods. For three- to six-echo methods, slope, regression intercept, average bias, and R2 were 1.01-0.99, 0.11-0.62%, 0.24-0.56%, and 0.981-0.982, respectively. Slope was closest to unity for the five-echo method. The two-echo method was least accurate, underestimating PDFF by an average of 2.93%, compared to an average of 0.23-0.69% for the other methods. Statistically significant but clinically nonmeaningful effects on PDFF error were found for subject BMI (P range: 0.0016 to 0.0783), male sex (P range: 0.015 to 0.037), and no statistically significant effect was found for subject age (P range: 0.18-0.24).ConclusionHepatic magnitude-based MRI PDFF estimates using three, four, five, and six echoes, and six-echo parametric maps are accurate compared to reference MRS values, and that accuracy is not meaningfully confounded by age, sex, or BMI.

Author(s): Zand, Kevin A; Shah, Amol; Heba, Elhamy; Wolfson, Tanya; Hamilton, Gavin; Lam, Jessica; Chen, Joshua; Hooker, Jonathan C; Gamst, Anthony C; Middleton, Michael S; Schwimmer, Jeffrey B; Sirlin, Claude B | Abstract: PurposeTo assess accuracy of magnitude-based magnetic resonance imaging (M-MRI) in children to estimate hepatic proton density fat fraction (PDFF) using two to six echoes, with magnetic resonance spectroscopy (MRS) -measured PDFF as a reference standard.MethodsThis was an IRB-approved, HIPAA-compliant, single-center, cross-sectional, retrospective analysis of data collected prospectively between 2008 and 2013 in children with known or suspected nonalcoholic fatty liver disease (NAFLD). Two hundred eighty-six children (8-20 [mean 14.2 ± 2.5] years; 182 boys) underwent same-day MRS and M-MRI. Unenhanced two-dimensional axial spoiled gradient-recalled-echo images at six echo times were obtained at 3T after a single low-flip-angle (10°) excitation with ≥ 120-ms recovery time. Hepatic PDFF was estimated using the first two, three, four, five, and all six echoes. For each number of echoes, accuracy of M-MRI to estimate PDFF was assessed by linear regression with MRS-PDFF as reference standard. Accuracy metrics were regression intercept, slope, average bias, and R(2) .ResultsMRS-PDFF ranged from 0.2-40.4% (mean 13.1 ± 9.8%). Using three to six echoes, regression intercept, slope, and average bias were 0.46-0.96%, 0.99-1.01, and 0.57-0.89%, respectively. Using two echoes, these values were 2.98%, 0.97, and 2.72%, respectively. R(2) ranged 0.98-0.99 for all methods.ConclusionUsing three to six echoes, M-MRI has high accuracy for hepatic PDFF estimation in children.

Objectives. We examined smoking cessation rate by education and determined how much of the difference can be attributed to the rate of quit attempts and how much to the success of these attempts. Methods. We analyzed data from the National Health Interview Survey (NHIS, 1991–2010) and the Tobacco Use Supplement to the Current Population Survey (TUS-CPS, 1992–2011). Smokers (≥ 25 years) were divided into lower- and higher-education groups (≤ 12 years and > 12 years). Results. A significant difference in cessation rate between the lower- and the higher-education groups persisted over the last 2 decades. On average, the annual cessation rate for the former was about two thirds that of the latter (3.5% vs 5.2%; P Conclusions. Smokers in the lower-education group have consistently lagged behind their higher-education counterparts in quitting. In addition to the usual concern about improving their success in quitting, tobacco control programs need to find ways to increase quit attempts in this group.