Non-invasive measurement of liver iron concentration by magnetic resonance imaging and its clinical usefulness.

Determination of liver iron concentration by magnetic resonance imaging (MRI) is becoming the new technique of choice for the diagnosis of iron overload in hereditary haemochromatosis and other liver iron surcharge diseases. Determination of hepatic iron concentration obtained by liver biopsy has been the gold standard for years. The development of MRI techniques, via signal intensity ratio methods or relaxometry, has provided a non-invasive and more accurate approach to the diagnosis of liver iron overload. This article reviews the available MRI methods for the determination of liver iron concentration and also evaluates the technique for the diagnosis and quantification of iron overload in different clinical practice scenarios.

Adiponectin, Leptin, and IGF-1 Are Useful Diagnostic and Stratification Biomarkers of NAFLD.

Background: Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease where liver biopsy remains the gold standard for diagnosis. Here we aimed to evaluate the role of circulating adiponectin, leptin, and insulin-like growth factor 1 (IGF-1) levels as non-invasive NAFLD biomarkers and assess their correlation with the metabolome. Materials and Methods: Leptin, adiponectin, and IGF-1 serum levels were measured by ELISA in two independent cohorts of biopsy-proven obese NAFLD patients and healthy-liver controls (discovery: 38 NAFLD, 13 controls; validation: 194 NAFLD, 31 controls) and correlated with clinical data, histology, genetic parameters, and serum metabolomics. Results: In both cohorts, leptin increased in NAFLD vs. controls (discovery: AUROC 0.88; validation: AUROC 0.83; p < 0.0001). The leptin levels were similar between obese and non-obese healthy controls, suggesting that obesity is not a confounding factor. In the discovery cohort, adiponectin was lower in non-alcoholic steatohepatitis (NASH) vs. non-alcoholic fatty liver (AUROC 0.87; p < 0.0001). For the validation cohort, significance was attained for homozygous for PNPLA3 allele c.444C (AUROC 0.63; p < 0.05). Combining adiponectin with specific serum lipids improved the assay performance (AUROC 0.80; p < 0.0001). For the validation cohort, IGF-1 was lower with advanced fibrosis (AUROC 0.67, p < 0.05), but combination with international normalized ratio (INR) and ferritin increased the assay performance (AUROC 0.81; p < 0.01). Conclusion: Serum leptin discriminates NAFLD, and adiponectin combined with specific lipids stratifies NASH. IGF-1, INR, and ferritin distinguish advanced fibrosis.

Liver iron concentration in dysmetabolic hyperferritinemia: Results from a prospective cohort of 276 patients.

INTRODUCTION AND OBJECTIVES: We aimed to study the liver iron concentration in patients referred for hyperferritinemia to six hospitals in the Basque Country and to determine if there were differences between patients with or without metabolic syndrome. PATIENTS AND METHODS: Metabolic syndrome was defined by accepted criteria. Liver iron concentration was determined by magnetic resonance imaging. RESULTS: We obtained the data needed to diagnose metabolic syndrome in 276 patients; a total of 135 patients (49%), 115/240 men (48%), and 20/36 women (55.6%) presented metabolic syndrome. In all 276 patients, an MRI for the determination of liver iron concentration (mean±SD) was performed. The mean liver iron concentration was 30.83±19.38 for women with metabolic syndrome, 38.84±25.50 for men with metabolic syndrome, and 37.66±24.79 (CI 95%; 33.44-41.88) for the whole metabolic syndrome group. In 141 patients (51%), metabolic syndrome was not diagnosed: 125/240 were men (52%) and 16/36 were women (44.4%). The mean liver iron concentration was 34.88±16.18 for women without metabolic syndrome, 44.48±38.16 for men without metabolic syndrome, and 43.39±36.43 (CI 95%, 37.32-49.46) for the whole non-metabolic syndrome group. Comparison of the mean liver iron concentration from both groups (metabolic syndrome vs non-metabolic syndrome) revealed no significant differences (p=0.12). CONCLUSIONS: Patients with hyperferritinemia and metabolic syndrome presented a mildly increased mean liver iron concentration that was not significantly different to that of patients with hyperferritinemia and non-metabolic syndrome.

PNPLA3 p.I148M variant is associated with greater reduction of liver fat content after bariatric surgery.

BACKGROUND: Obesity is the major trigger of nonalcoholic fatty liver disease (NAFLD). NAFLD is further favored by the patatin-like phospholipase domain-containing 3 (PNPLA3) p.I148M, transmembrane 6 superfamily member 2 (TM6SF2) p.E167K, and membrane-bound O-acyltransferase domain containing 7 (MBOAT7) rs641738 variants. OBJECTIVES: To investigate the relationship between the PNPLA3, TM6SF2, and MBOAT7 genotypes and the outcomes of bariatric surgery. SETTING: University hospital. METHODS: Prospectively we monitored 84 obese individuals (body mass index 35-64 kg/m2) scheduled for bariatric surgery. The PNPLA3 p.I148M, TM6SF2 p.E167K, and MBOAT7 rs641738 variants were genotyped using restriction fragment length polymorphism analysis and TaqMan assays. Hepatic steatosis was determined before surgery using analysis of liver biopsy samples and a novel magnetic resonance imaging-based equation. One year later, steatosis was reevaluated by magnetic resonance imaging. RESULTS: The presence of the PNPLA3 allle [M] was associated with increased hepatic triglyceride content (P = .03), steatosis detected by magnetic resonance imaging (P = 0.04), and decreased serum glucose concentrations (P = .04). Neither variant TM6SF2 nor MBOAT7 increased hepatic steatosis (all P>.05); however, the MBOAT7 polymorphism was associated with increased triglyceride, total cholesterol, low density lipoprotein, and serum glucose levels (all P<.05). Patients carrying the prosteatotic PNPLA3 allele [M] lost more weight (P<.01) and liver fat (P = .04) one year after surgery, as compared to individuals having the common genotype. The PNPLA3 genotype and initial grade of steatosis, but not the TM6SF2 or MBOAT7 variants, were independent predictors of NAFLD improvement (P = .03 and P<.01, respectively). CONCLUSION: In obese patients, the presence of the PNPLA3 p.I148M allele might be associated with greater improvement of hepatic steatosis after bariatric surgery in comparison to carriers of PNPLA3 wild-type alleles.

Liver iron concentration is not raised in patients with dysmetabolic hyperferritinemia.

Background &amp;amp;amp; aims. Hyperferritinemia (HF) is frequently present in patients with metabolic syndrome (MS). MS associated with HF is named dysmetabolic hyperferritinemia (DH). There are some publications that propose that DH is associated with a raised liveriron concentration (LIC). We studied the LIC in patients referred for HF to a secondary hospital to determine if there are differences between patients with or without MS. MATERIAL AND METHODS: We conducted a prospective study of 132 consecutive patients with HF from January to December 2010. The MS was defined by the International Diabetes Federation criteria (2005). LIC was determined by Magnetic resonance imaging (MRI). RESULTS: The number of patients for which there was enough data to determine MS was 97, out of which 54 had MS and 43 had no MS (NMS). In 54/97 patients, MRI for LIC determination was performed. From the MS group, 44 were men (27 underwent MRI) and 10 women (9 MRI). The mean LIC was 27.83 ± 20.90 ?mol/g for the MS group. In the NMS group, 36 were men (13 MRI), and 7 women (5 MRI). In 18 patients from the NMS group, LIC was determined by MRI. The mean LIC was 33.16 ± 19.61 ?mol/g in the NMS group. We compared the mean values of LIC from both groups (MS vs. NMS) and no significant differences were found (p = 0.067). CONCLUSION: Patients with DH present a mean LIC within normal values and their values do not differ from those of patients with HF but without MS.

Novel equation to determine the hepatic triglyceride concentration in humans by MRI: diagnosis and monitoring of NAFLD in obese patients before and after bariatric surgery.

BACKGROUND: Non-alcoholic fatty liver disease (NAFLD) is caused by abnormal accumulation of lipids within liver cells. Its prevalence is increasing in developed countries in association with obesity, and it represents a risk factor for non-alcoholic steatohepatitis (NASH), cirrhosis and hepatocellular carcinoma. Since NAFLD is usually asymptomatic at diagnosis, new non-invasive approaches are needed to determine the hepatic lipid content in terms of diagnosis, treatment and control of disease progression. Here, we investigated the potential of magnetic resonance imaging (MRI) to quantitate and monitor the hepatic triglyceride concentration in humans. METHODS: A prospective study of diagnostic accuracy was conducted among 129 consecutive adult patients (97 obesity and 32 non-obese) to compare multi-echo MRI fat fraction, grade of steatosis estimated by histopathology, and biochemical measurement of hepatic triglyceride concentration (that is, Folch value). RESULTS: MRI fat fraction positively correlates with the grade of steatosis estimated on a 0 to 3 scale by histopathology. However, this correlation value was stronger when MRI fat fraction was linked to the Folch value, resulting in a novel equation to predict the hepatic triglyceride concentration (mg of triglycerides/g of liver tissue = 5.082 + (432.104 * multi-echo MRI fat fraction)). Validation of this formula in 31 additional patients (24 obese and 7 controls) resulted in robust correlation between the measured and estimated Folch values. Multivariate analysis showed that none of the variables investigated improves the Folch prediction capacity of the equation. Obese patients show increased steatosis compared to controls using MRI fat fraction and Folch value. Bariatric surgery improved MRI fat fraction values and the Folch value estimated in obese patients one year after surgery. CONCLUSIONS: Multi-echo MRI is an accurate approach to determine the hepatic lipid concentration by using our novel equation, representing an economic non-invasive method to diagnose and monitor steatosis in humans.

Effect of neoadjuvant chemotherapy in hepatic steatosis.

UNLABELLED: Chemotherapy drugs often produce side effects in the liver. In recent years, there has been speculation about the ability to produce hepatic steatosis in patients treated with 5-fluorouracil and oxaliplatin. This prospective study examines whether these drugs can produce steatosis in patients with neoadjuvant treatment who were operated on for liver tumors. PURPOSE: Our objective was to assess the effect of neoadjuvant chemotherapy (NAC) on the development of hepatic steatosis in the healthy liver. PATIENTS AND METHODS: This was a prospective study based on 32 patients divided into two groups. The presence of steatosis was assessed using a histological score (Kleiner classification) and a biochemical method (Folch method) for patients from both groups. RESULTS: A total of 14 patients (44%) had hepatic steatosis and half of these were in each group. The steatosis was moderate to severe (grades 2-3) in 4 patients (13%), 2 in each group. The mean levels of triglycerides in the liver were 33.38 and 29.94 mg/g in group I and group II, respectively, with the difference not being statistically significant. CONCLUSIONS: Almost half of the patients treated with NAC for liver neoplasia developed steatosis. Nevertheless, NAC does not seem to increase the risk of hepatic steatosis.

Accurate fat fraction quantification by multiecho gradient-recalled-echo magnetic resonance at 1.5T in rats with nonalcoholic fatty liver disease.

AIM: To assess the diagnostic accuracy of a new reconstruction technique for gradient-recalled-echo magnetic resonance (MR) sequences that provides a full decomposition of the water and fat content inside a voxel for nonalcoholic fatty liver disease (NAFLD) in rats. MATERIAL AND METHODS: Rats were randomized into two groups. A control group (n = 10) was given free access to regular dry rat chow for 4 weeks. The steatosis (n = 40) group was given free access to feed and water 4 days per week, and fasted for the remaining 3 days for 4 weeks. All rats were killed at 4 weeks and assessed for fatty infiltration and biochemical method. RESULTS: The average fat content using the gold standard method was 2.65 g (2.20-3.05) of fat/100g liver for the control group and 4.14 g (1.95-8.60) of fat/100g of liver for the overfed group (p<0.05). The average fat-fraction obtained from the MR was 0.016 (0.01-0.02) for the control group and 0.057 (0.00-0.18) for the overfed group. The Pearson correlation coefficient between the samples was r(2) = 0.87. CONCLUSION: Multi-echo MR is a good technique to quantify liver fat in rats.

Liver iron concentration quantification by MRI: are recommended protocols accurate enough for clinical practice?

OBJECTIVE: To assess the accuracy of quantification of liver iron concentration (LIC) by MRI using the Rennes University (URennes) algorithm. METHODS: In the overall study period 1999-2006 the LIC in 171 patients was calculated with the URennes model and the results were compared with LIC measured by liver biopsy. RESULTS: The biopsy showed that 107 patients had no overload, 38 moderate overload and 26 high overload. The correlation between MRI and biopsy was r=0.86. MRI correctly classified 105 patients according to the various levels of LIC. Diagnostic accuracy was 61.4%, with a tendency to overestimate overload: 43% of patients with no overload were diagnosed as having overload, and 44.7% of patients with moderate overload were diagnosed as having high overload. The sensitivity of the URennes method for high overload was 92.3%, and the specificity for the absence of overload was 57.0%. MRI values greater than 170 µmol Fe/g revealed a positive predictive value (PPV) for haemochromatosis of 100% (n=18); concentrations below 60 µmol Fe/g had a negative predictive value (NPV) of 100% for haemochromatosis (n=101). The diagnosis in 44 patients with intermediate values remained uncertain. CONCLUSIONS: The assessment of LIC with the URennes method was useful in 74.3% of the patients to rule out or to diagnose high iron overload. The method has a tendency to overestimate overload, which limits its diagnostic performance.

Non-invasive methods for liver fibrosis prediction in hemochromatosis: One step beyond.

Advances in recent years in the understanding of, and the genetic diagnosis of hereditary hemochromatosis (HH) have changed the approach to iron overload hereditary diseases. The ability to use a radiologic tool (MRI) that accurately provides liver iron concentration determination, and the presence of non-invasive serologic markers for fibrosis prediction (serum ferritin, platelet count, transaminases, etc), have diminished the need for liver biopsy for diagnosis and prognosis of this disease. Consequently, the role of liver biopsy in iron metabolism disorders is changing. Furthermore, the irruption of transient elastography to assess liver stiffness, and, more recently, the ability to determine liver fibrosis by means of MRI elastography will change this role even more, with a potential drastic decline in hepatic biopsies in years to come. This review will provide a brief summary of the different non-invasive methods available nowadays for diagnosis and prognosis in HH, and point out potential new techniques that could come about in the next years for fibrosis prediction, thus avoiding the need for liver biopsy in a greater number of patients. It is possible that liver biopsy will remain useful for the diagnosis of associated diseases, where other non-invasive means are not possible, or for those rare cases displaying discrepancies between radiological and biochemical markers.

Iron overload in the liver diagnostic and quantification.

Hereditary Hemochromatosis is the most frequent modality of iron overload. Since 1996 genetic tests have facilitated significantly the non-invasive diagnosis of the disease. There are however many cases of negative genetic tests that require confirmation by hepatic iron quantification which is traditionally performed by hepatic biopsy. There are many studies that have demonstrated the possibility of performing hepatic iron quantification with Magnetic Resonance. However, a consensus has not been reached yet regarding the technique or the possibility to reproduce the same method of calculus in different machines. This article reviews the state of the art of the question and delineates possible future lines to standardise this non-invasive method of hepatic iron quantification.

MR quantification of hepatic iron concentration.

PURPOSE: To evaluate the accuracy of magnetic resonance (MR) imaging in the quantification of hepatic iron concentration. MATERIALS AND METHODS: Between April 1999 and June 2001, 112 patients were recruited prospectively. All had undergone liver biopsy and hepatic iron concentration quantification with spectrophotometry, followed by MR imaging. MR imaging involved use of four gradient-echo sequences and one spin-echo sequence. Signal intensity (SI) was measured on images obtained with each sequence by means of regions of interest placed in the liver and paraspinal muscle to obtain the liver-to-muscle SI ratio. The relationship between hepatic iron concentration and SI ratio for each sequence was analyzed with multiple linear regression. Receiver operating characteristic analysis was performed to find the diagnostic thresholds. RESULTS: Sixty-eight patients had normal hepatic iron levels (<36 micromol/g), 23 had hemosiderosis (36-80 micromol/g), and 21 had hemochromatosis (>80 micromol/g). With all sequences, an inverse linear relationship between iron concentration and SI ratio was apparent. The authors generated a mathematic model to estimate the iron concentrations from MR imaging data (r = 0.937). For estimated concentrations of more than 85 micromol/g, the positive predictive value for hemochromatosis was 100%; for those less than 40 micromol/g, the negative predictive value for hemochromatosis was 100%. For estimated concentrations of more than 58 micromol/g, the positive predictive value for iron overload was 100%; for those less than 20 micromol/g, the negative predictive value for iron overload was 100%. CONCLUSION: MR imaging is a useful and noninvasive diagnostic tool for quantification of hepatic iron concentration.