Quantification of hepatic steatosis with MRI: The effects of accurate fat spectral modeling

Abstract

Purpose: To develop a chemical-shift-based imaging method for fat quantification that accounts for the complex spectrum of fat, and to compare this method with MR spectroscopy (MRS). Quantitative noninvasive biomarkers of hepatic steatosis are urgently needed for the diagnosis and management of nonalcoholic fatty liver disease (NAFLD). Materials and Methods:Hepatic steatosis was measured with "fat-fraction" images in 31 patients using a multiecho chemical-shift-based water-fat separation method at 1.5T. Fat-fraction images were reconstructed using a conventional signal model that considers fat as a single peak at -210 Hz relative to water ("single peak" reconstruction). Fat-fraction images were also reconstructed from the same source images using two methods that account for the complex spectrum of fat; precalibrated and self-calibrated "multipeak" reconstruction. Single-voxel MRS that was coregistered with imaging was performed for comparison.Results: Imaging and MRS demonstrated excellent correlation with single peak reconstruction (r 2 ϭ 0.91), precalibrated multipeak reconstruction (r 2 ϭ 0.94), and self-calibrated multipeak reconstruction (r 2 ϭ 0.91). However, precalibrated multipeak reconstruction demonstrated the best agreement with MRS, with a slope statistically equivalent to 1 (0.96 Ϯ 0.04; P ϭ 0.4), compared to self-calibrated multipeak reconstruction (0.83 Ϯ 0.05, P ϭ 0.001) and single-peak reconstruction (0.67 Ϯ 0.04, P Ͻ 0.001). Conclusion:Accurate spectral modeling is necessary for accurate quantification of hepatic steatosis with MRI.

NMR imaging estimates of muscle volume and intramuscular fat infiltration in the thigh: variations with muscle, gender, and age

“…In fact, this technique underestimates the fat signal because it accounts only for the methylene component in the triglyceride molecules that account for most of body fat. In the studies that introduced more accurate fat spectral models Reeder et al 2009), the authors showed linear relationship between multi-and single peaks fat models using in vivo data and phantoms. Using simulations, it was also shown that a linear relation exists between actual fat signal and the estimated one using three-point Dixon technique (Azzabou et al 2015).…”

Hepatic steatosis in overweight/obese females: Newscreening method for those at risk

“…Ultrasound (US) is widely used to detect HS, without exposing subjects to ionizing radiations. Indeed, more specific imaging techniques [19] are costly and not always useful in close follow-up. Tsushima et al [20] first identified the so-called liver-spleen axis in NAFLD patients.…”

Focal iron sparing and focal fat sparing of liver in patients with hemosiderosis: diagnosis by combination of r2* relaxometry and fat fraction calculation by mri.

“…The IDEAL-IQ sequence takes T2* and field homogeneity variations into consideration for fat fraction calculations. The details of the IDEAL-IQ sequence have been described elsewhere (13). The parameters of the IDEAL-IQ sequence were TR, 12.9 ms; FOV, 35-40 cm; matrix, 224×160; 125-kHz bandwidth; and slice thickness, 5 mm.…”

“…Hemosiderosis, most commonly seen in thalassemia patients, leads to an increased R2* value in the liver, which directly correlates with hepatic iron concentration (7). Recent advances in quantitative magnetic resonance imaging (MRI) methods have allowed for the separate and combined evaluation of liver fat and iron content (8)(9)(10)(11)(12)(13). We used an investigative version of the chemical shift-based water-fat separation method, which addresses all known confounding factors, specifically those involving T1, T2*, spectral complexity of fat, noise bias, and eddy currents (14,15).…”