In vivo¹H-MRS hepatic lipid profiling in nonalcoholic fatty liver disease: An animal study at 9.4 T

Abstract

The applicability of the in vivo proton magnetic resonance spectroscopy hepatic lipid profiling (MR-HLP) technique in nonalcoholic fatty liver disease was investigated. Using magnetic resonance spectroscopy, the relative fractions of diunsaturated (fdi), monounsaturated (fmono), and saturated (fsat) fatty acids as well as total hepatic lipid content were estimated in the livers of 8 control and 23 CCl4-treated rats at 9.4 T. The mean steatosis, necrosis, inflammation, and fibrosis scores of the treated group were all significantly higher than those of the control group (P < 0.01). There was a strong correlation between the histopathologic parameters and the MR-HLP parameters (r = 0.775, P < 0.01) where both steatosis and fibrosis are positively correlated with fmono and negatively correlated with fdi. Both necrosis and inflammation, however, were not correlated with any of the MR-HLP parameters. Hepatic lipid composition appears to be changed in association with the severity of steatosis and fibrosis in nonalcoholic fatty liver disease, and these changes can be depicted in vivo by using the MR-HLP method at 9.4 T. Thus, while it may not likely be that MR-HLP helps differentiate between steatohepatitis in its early stages and simple steatosis, these findings altogether are in support of potential applicability of in vivo MR-HLP at high field in nonalcoholic fatty liver disease.

Ultrashort-TE stimulated echo acquisition mode (STEAM) improves the quantification of lipids and fatty acid chain unsaturation in the human liver at 7 T

“…In the first session, in addition to HCL measurements, T 2 measurements were performed with the GUSTEAU sequence using eight TEs (6,10,15,20,30,40,50 and 70 ms). The TEs were optimized for fast measurement of the monoexponential decay of the hepatic lipids.…”

“…Although MRI can cover the entire liver tissue, MRS is currently the most accurate non‐invasive method for the assessment of hepatic steatosis . In vivo MRS measurements of HCL have already been validated against the histological analysis of tissue specimens from animals at 9.4 T and in humans at clinical field strengths (≤3 T) . As a result of the water signal and motion, FA profiling in the liver is more complicated than in adipose tissue or bone marrow .…”

Long TE PRESS and STEAM for measuring the triglyceride glycerol CH2 protons at 3 T

“…Proton MRS studies have shown levels and composition of fat to be relevant to the study of a number of diseases such as cancer, obesity, osteoporosis and liver disease . The fat olefinic (≈5.4 parts per million, ppm) resonance yields a measure of fat unsaturation, and olefinic levels normalized to methylene (≈1.3 ppm) or methyl (≈0.9 ppm) signals have been used to estimate measures of fat unsaturation in humans in vivo .…”

A fully automatic reference deconvolution strategy to increase the accuracy of in vivo lipid signal quantification

“…Using magnetic resonance spectroscopy (MRS) for this analysis, highly accurate quantification of the occurring signal parts is of great importance to get reliable information about the composition of body fat. Especially, precise assessment of monounsaturated and polyunsaturated fatty acids has become an important task for metabolic studies on obesity and type 2 diabetes (3)(4)(5)(6).…”

“…. ; yðl þ L À 1Þ T at the time instants 0 l N À L. If q k ðnÞ from Eq [6]. only changes slowly in an interval of the length L it can be replaced in each measurement vector with its Taylor-series approximation.…”