Feasibility of and agreement between MR imaging and spectroscopic estimation of hepatic proton density fat fraction in children with known or suspected nonalcoholic fatty liver disease.

PURPOSE: To assess feasibility of and agreement between magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS) for estimating hepatic proton density fat fraction (PDFF) in children with known or suspected nonalcoholic fatty liver disease (NAFLD). MATERIALS AND METHODS: Children were included in this study from two previous research studies in each of which three MRI and three MRS acquisitions were obtained. Sequence acceptability, and MRI- and MRS-estimated PDFF were evaluated. Agreement of MRI- with MRS-estimated hepatic PDFF was assessed by linear regression and Bland-Altman analysis. Age, sex, BMI-Z score, acquisition time, and artifact score effects on MRI- and MRS-estimated PDFF agreement were assessed by multiple linear regression. RESULTS: Eighty-six children (61 boys and 25 girls) were included in this study. Slope and intercept from regressing MRS-PDFF on MRI-PDFF were 0.969 and 1.591%, respectively, and the Bland-Altman bias and 95% limits of agreement were 1.17% ± 2.61%. MRI motion artifact score was higher in boys than girls (by 0.21, p = 0.021). Higher BMI-Z score was associated with lower agreement between MRS and MRI (p = 0.045). CONCLUSION: Hepatic PDFF estimation by both MRI and MRS is feasible, and MRI- and MRS-estimated PDFF agree closely in children with known or suspected NAFLD.

Effect of echo-sampling strategy on the accuracy of out-of-phase and in-phase multiecho gradient-echo MRI hepatic fat fraction estimation.

PURPOSE: To assess the effect of echo-sampling strategy on the accuracy of out-of-phase (OP) and in-phase (IP) multiecho gradient-echo magnetic resonance imaging (MRI) hepatic fat fraction (FF) estimation, using MR spectroscopy (MRS) proton density FF (PDFF) as a reference standard. MATERIALS AND METHODS: In this Institutional Review Board (IRB)-approved, Health Insurance Portability and Accountability Act (HIPAA)-compliant prospective study, 84 subjects underwent proton MRS and non-T1 -weighted gradient-echo imaging of the liver at 3T. Imaging data were collected at 16 nominally OP and IP echo times (TEs). MRI-FF was estimated while varying two echo-sampling parameters (number of consecutive echoes, starting echo number). For each combination of these parameters, MRI-FF estimation accuracy was assessed with slope, intercept, average bias, and R2 from a linear regression of MRS-PDFF on MRI-FF. The relationship between accuracy metrics and echo-sampling parameters was assessed by Spearman rank correlation. RESULTS: For FF calculations using 3-16 echoes and a starting echo number of 1, the intercept ranged from 0.0046 to 0.0124, slope from 0.941 to 0.96, average bias from 0.0034 to 0.0078, and R2 from 0.968 to 0.976. All four accuracy metrics were the best with the 3- and 4-echo calculations and worsened progressively with an increasing number of echoes. For a given number of echoes, there was an overall trend toward decreasing accuracy as starting echo number increased. Spearman correlation coefficients between starting echo number and intercept, slope, average bias, and R2 were 0.911, -0.64, -0.889, and -0.954, respectively, indicating progressive loss of accuracy in each case. CONCLUSION: Multiecho OP and IP imaging provided high FF estimation accuracy. Accuracy was highest using the earliest 3 or 4 echoes. Incorporation of additional echoes or delaying the starting echo number progressively reduced accuracy.

Amphicrine carcinoma of the liver.

Amphicrine tumors are defined by evidence of both glandular and neuroendocrine differentiation in the same cell. These are extremely rare tumors, with only scattered case reports in the pancreas and stomach. We here report a case of amphicrine carcinoma occurring in apparent isolation in the liver. The tumor was characterized by signet ring cell morphology, mucicarmine, and periodic acid Schiff with diastase (PASD) positivity, and expression of chromogranin, synaptophysin, villin, and CDX2. No other tumor was identified by radiological or endoscopic examination of the gastrointestinal tract. The patient is disease-free 22 months after the resection. We speculate that this represents the first reported occurrence of primary amphicrine carcinoma of the liver.