Acute responses of hepatic fat content to consuming fat, glucose and fructose alone and in combination in non-obese non-diabetic individuals with non-alcoholic fatty liver disease.

We have recently demonstrated that a high-fat load can induce immediate increase in hepatic fat content (HFC) and that such an effect can be modified differently by co-administration of fructose or glucose in healthy subjects. Therefore, we addressed the question how consumption of these nutrients affects changes in HFC in subjects with non-alcoholic fatty liver disease (NAFLD). Eight male non-obese non-diabetic patients with NAFLD underwent 6 experiments each lasting 8 hours: 1. fasting, 2. high-fat load (150 g of fat (dairy cream) at time 0), 3. glucose (three doses of 50 g at 0, 2, and 4 hours), 4. high-fat load with three doses of 50 g of glucose, 5. fructose (three doses of 50 g at 0, 2, and 4 hours), 6. high-fat load with three doses of 50 g of fructose. HFC was measured using magnetic resonance spectroscopy prior to meal administration and 3 and 6 hours later. Plasma triglycerides, non-esterified fatty acids, glucose and insulin were monitored throughout each experiment. HFC increased by 10.4 ± 6.9% six hours after a high-fat load and by 15.2 ± 12.5% after high-fat load with fructose. When co-administering glucose with fat, HFC rose only transiently to return to baseline at 6 hours. Importantly, NAFLD subjects accumulated almost five times more fat in their livers than healthy subjects with normal HFC. Consumption of a high-fat load results in fat accumulation in the liver of NAFLD patients. Fat accumulation after a fat load is diminished by glucose but not fructose co-administration.

Clinical and (31)P magnetic resonance spectroscopy characterization of patients with critical limb ischemia before and after autologous cell therapy.

Autologous cell therapy (ACT) is a new treatment method for diabetic patients with critical limb ischemia (CLI) not eligible for standard revascularization. After intramuscular injection of bone marrow-derived mononuclear cells local arteriogenesis in the ischemic tissue occurs. Studies assessing visualization of this therapeutic vasculogenesis after ACT by novel imaging techniques are lacking. The aim of our study was to assess the effect of ACT on possible metabolic changes and perfusion of critically ischemic limbs using (31)P magnetic resonance spectroscopy ( (31)P MRS) and its possible correlation with changes of transcutaneous oxygen pressure (TcPO(2)). Twenty-one patients with diabetes and no-option CLI treated by ACT in our foot clinic over 8 years were included in the study. TcPO(2) as well as rest (phosphocreatine, adenosine triphosphate and inorganic phosphate) and dynamic (mitochondrial capacity and phosphocreatine recovery time) (31)P-MRS parameters were evaluated at baseline and 3 months after cell treatment. TcPO(2) increased significantly after 3 months compared with baseline (from 22.4±8.2 to 37.6±13.3 mm Hg, p=0.0002). Rest and dynamic (31)P MRS parameters were not significantly different after ACT in comparison with baseline values. Our study showed a significant increase of TcPO(2) on the dorsum of the foot after ACT. We did not observe any changes of rest or dynamic (31)P MRS parameters in the area of the proximal calf where the cell suspension has been injected into.

Differences in muscle metabolism in patients with type I diabetes - influence of gender and nephropathy studied by (31)P MR spectroscopy.

Type I diabetes mellitus (DM1) is a complex disease with adverse effects on organs and tissues despite compensation by insulin treatment. The goal of our study was to study how kidney diseases change (31)P MR parameters of muscle metabolism in DM1 patients with respect to gender. 51 DM1 patients (19 m/14 f without and 13 m/5 f with nephropathy) and 26 (14 m/12 f) healthy volunteers were examined using (31)P magnetic resonance spectroscopy at 3T tomograph at rest, and during and after a calf muscle exercise. The exercise consisted of a six-minute plantar flexion using a pedal ergometer followed by a six-minute recovery. It is reflected by reduced relative beta-ATP and increased Pi and phosphodiester signals to phosphocreatine (PCr) at rest and prolongation of the PCr recovery time after the exercise. Measurement on healthy volunteers indicated differences between males and females in pH at the rest and after the exercise only. These differences between patients groups were not significant. We have proven that nephropathy affects the metabolism in diabetic patients and our results confirm significant difference between patients with and without nephropathy. Gender differences in pH were observed only between male and female healthy volunteers.

GABA spectra and remote distractor effect in progressive supranuclear palsy: A pilot study.

Disturbances of the gamma-aminobutyric-acid (GABA) system have been suspected of contributing to the pathophysiology of progressive supranuclear palsy (PSP). The ability to rapidly resolve competitive action decisions, such as shifting the gaze to one particular stimulus rather than another, can be predicted by the concentration of GABA in the region of the frontal cortex relevant to eye movements. For this reason, our study measured GABA levels in seven PSP patients and eight healthy controls, using proton magnetic resonance spectroscopy, and assessed the relationship of these measurements to the remote distractor effect (RDE), an eye-movement paradigm investigating competitive action decisions. No significant differences were found in either frontal-eye-field GABA levels or RDE between PSP patients and controls.

The age dependence of T2 relaxation times of N-acetyl aspartate, creatine and choline in the human brain at 3 and 4T.

Knowledge of the T2 age dependence is of importance for MRS clinical studies involving subject groups with a wide age range. A number of studies have focused on the age dependence of T2 values in the human brain, with rather conflicting results. The aim of this study was to analyze the age dependence of T2 values of N-acetyl aspartate (NAA), creatine (Cr) and choline (Cho) in the human brain using data acquired at 3T and 4T and to assess the influence of the macromolecule (MM) baseline handling on the obtained results. Two distinct groups of young and elderly controls have been measured at 3T (TE = 30-540 ms, 9 young and 11 elderly subjects) and 4T (TE = 10-180 ms, 18 young and 14 elderly subjects) using single-voxel spectroscopy. In addition, MM spectra were measured from two subjects using the inversion-recovery technique at 4T. All spectra were processed with LCModel using basis sets with different MM signals (measured or simulated) and also with MM signals included for a different TE range. Individual estimated T2 values were statistically analyzed using the R programming language for the age dependence of T2 values as well as the influence of the MM baseline handling. A significant decrease of T2 values of NAA and Cr in elderly subjects compared with young subjects was confirmed. The same trend was observed for Cho. Significantly higher T2 values calculated using the measured MM baseline for all studied metabolites at 4T were observed for both young and elderly subjects. To conclude, while the handling of MM and lipid signals may have a significant effect on estimated T2 values, we confirmed the age dependence of T2 values of NAA and Cr and the same trend for Cho in the human brain. Copyright © 2016 John Wiley & Sons, Ltd.

Minipig model of Huntington's disease: ¹H magnetic resonance spectroscopy of the brain.

Huntington's disease (HD) is an inherited autosomal neurodegenerative disorder affecting predominantly the brain, characterized by motor dysfunctions, behavioral and cognitive disturbances. The aim of this study was to determine changes in the brain of transgenic minipigs before HD onset using (1)H magnetic resonance (MR) spectroscopy. Measurements were performed on a 3 T MR scanner using a single voxel spectroscopy sequence for spectra acquisition in the white matter and chemical shift imaging sequence for measurement in the striatum, hippocampus and thalamus. A decrease of (phospho)creatine (tCr) concentration was found only in the thalamus (p=0.002) of transgenic minipigs, nevertheless we found significant changes in metabolite ratios. Increase of the ratio choline compounds (tCho)/tCr was found in all examined areas: striatum (p=0.010), thalamus (p=0.011) as well as hippocampus (p=0.027). The ratio N-acetylaspartate+N-acetylaspartylglutamate (tNAA)/tCr (p=0.043) and glutamate+glutamine (Glx)/tCr (p=0.039) was elevated in the thalamus, the ratio myo-inositol (Ins)/tCr (p=0.048) was significantly increased in the hippocampus. No significant differences were observed in the metabolite concentrations in the white matter, however we found significant increase of ratios tNAA/tCr (p=0.018) and tCho/tCr (p=0.003) ratios in transgenic boars. We suppose that the majority of the observed changes are predominantly related to changes in energy metabolism caused by decrease of tCr.

Influence of breathing on the measurement of lipids in the myocardium by ¹H MR spectroscopy.

The myocardium examination by MR spectroscopy is very challenging due to movements caused by the cardiac rhythm and breathing. The aim of the study was to investigate the influence of breathing on the quantitative measurement of lipid/water ratios in different groups of volunteers and different measuring protocols. We examined the lipid content of myocardium at 3T using the proton single voxel spectroscopy. Three protocols (free breathing, breath hold and the use of respiratory navigator) controlled by ECG were used for the examination of 42 adult volunteers including 14 free divers. Spectra were evaluated using jMRUI software. An average content of lipids in the healthy interventricular septum, gained by all protocols was equal to 0.6 %, which is in agreement with other published data. Based on the quality of examinations and the highest technical success, the best protocol seems to be the one containing a respiratory navigator since it is more acceptable by patients. Based on our results and the literature data we can conclude that MR spectroscopy is able to distinguish patients from controls only if their myocardial lipid content is higher than 1.6 % (mean value of lipids plus two standard deviations).

The relationships between quantitative MR parameters in hippocampus in healthy subjects and patients with temporal lobe epilepsy.

We introduce a new magnetic resonance (MR) method based on a pixel-by-pixel image processing to examine relationships between metabolic and structural processes in the pathologic hippocampus. The method was tested for lateralization of the epileptogenic zone in patients with temporal lobe epilepsy (TLE). Twenty patients with drug-resistant TLE and fifteen healthy controls were examined at 3T. The measurement protocol contained T2-weighted MR images, spectroscopic imaging, diffusion tensor imaging and T2 relaxometry. Correlations between quantitative MR parameters were calculated on a pixel-by-pixel basis using the CORIMA program which enables automated pixel identification in the normal tissue according to control data. All MR parameters changed in the anteroposterior direction in the hippocampus and correlation patterns and their slopes differed between patients and controls. Combinations of T2 relaxation times with metabolite values represent the best biomarkers of the epileptogenic zone. Correlations with mean diffusivity did not provide sufficiently accurate results due to diffusion image distortions. Quantitative MR analysis non-invasively provides a detailed description of hippocampal pathology and may represent complementary tool to the standard clinical protocol. However, the automated processing should be carefully monitored in order to avoid possible errors caused by MR artifacts.

Effect of acute hyperinsulinemia on brain metabolism evaluated by 1H MR spectroscopy--a pilot study.

To determine whether acutely-induced supraphysiological hyperinsulinemia influences brain metabolism in patients with type 1 diabetes (D) and healthy controls (C) as detected by MR Spectroscopy. Group D consisted of 4 patients with the average duration of diabetes for 7 years. They were matched according to age, sex and BMI to 4 healthy controls. 1H MR Spectroscopy was performed with a 1.5 Tesla. Spectra were obtained from parietooccipital white matter repeatedly during a 3-h hyperinsulinemic euglycemic clamp with 2 mU.kg(-1).min(-1). In group D, significantly lower basal concentrations of N-acetylaspartate (p=0.02), choline (p=0.03), creatine (p=0.002) and inositol (p=0.007) were detected compared to C. After the induction of hyperinsulinemia, concentrations of choline, creatine, GABA, inositol, lactate, NAA and composite signal glutamate + glutamine (Glx) stayed stable. The detection of glucose signal is less realiable at 1.5 Tesla but we registered the alteration in glucose concentration (p=0.003) in the whole group. Originally sightly elevated glucose concentration in D decreased on the contrary to the increase of originally lower glucose level in C. In conclusions, brain metabolism was altered in D. Short term supraphysiological euglycemic hyperinsulinemia induced changes in the concentration of brain glucose in both C and D.

In vivo 31P MR spectroscopy of human kidney grafts using the 2D-chemical shift imaging method.

The aim of this work was to evaluate the possibility to use in vivo (31)P magnetic resonance spectroscopy (MRS) for the diagnosis of kidney graft dysfunction after transplantation. We examined 68 kidney grafted patients using a 1.5 T MR scanner. (31)P MRS was performed using the 2D-chemical shift imaging method. The patients were divided into 4 groups: acute rejection episode; acute tubular necrosis; late graft dysfunction; or good renal function. We measured the signal intensities of phosphomonoesters (PME), inorganic phosphate (Pi), phosphodiesters (PDE), and α-, ß-, γ-adenosine triphosphate (ATP; with contributions of α- and ß-adenosine diphosphate) and their ratios. Patients with an acute rejection episodes showed a significantly elevated PME/ß-ATP and PDE/ß-ATP, PME/Pi, and PDE/Pi signal ratios compared with the control group. The group with acute tubular necrosis had decreased ratios. Patients with late graft dysfunction revealed only an insignificant decrease in PME/Pi and PDE/Pi ratios. We concluded that (31)P MRS was capable of distinguishing the two main causes of graft dysfunction early after transplantation.

Composite hyaluronate-type I collagen-fibrin scaffold in the therapy of osteochondral defects in miniature pigs.

The potential of novel scaffold containing sodium hyaluronate, type I collagen, and fibrin was investigated in the regeneration of osteochondral defects in miniature pigs. Both autologous chondrocyte-seeded scaffolds and non-seeded scaffolds were implanted into two defects located in the non-weight-bearing zone of the femoral trochlea (defect A was located more distally and medially, defect B was located more proximally and laterally). Control defects were left untreated. Twelve weeks after the operation, the knees were evaluated in vivo using MRI. Six months after the implantation, the defects were analyzed using MRI, histological, and immunohistochemical analysis. In the A defects of chondrocyte-seeded scaffold group, hyaline cartilage and fibrocartilage was formed, containing type II collagen, acidic and neutral glycosaminoglycans while the non-seeded scaffold group was predominantly filled with fibrocartilage. Defects in the control group were predominantly filled with fibrous tissue. Histomorphometric analysis of photomicrographs revealed a significantly higher amount of hyaline cartilage in the cell-seeded scaffold group in A defects than in other groups. Both scaffold groups in A defects showed significantly less fibrous tissue than cell-seeded defects B and the control group. Both histological and MRI analysis proved that the novel composite scaffold has a potential to regenerate osteochondral defects within six months.

Classification of calf muscle MR images by texture analysis.

AIM: To evaluate a method of texture analysis (TA) for the description of magnetic resonance (MR) images of healthy and diseased calf muscles and to compare this method with standard radiological evaluation. METHODS: A total of 93 subjects (20 controls, seven healthy children of hypertonic parents, five diabetic patients and 61 subjects with muscle malfunction of various origin) underwent MR imaging of the calf muscle and texture analysis of images was performed. The results of TA were analysed by t-statistics and principal component analysis. Images of subjects were divided into four groups according to the assessment of three radiologists and this categorization of subjects was compared with the results from TA. RESULTS: We extracted seven features (from a total number of 282) which were successfully used for the description of the texture of T1w MR images of calf muscles. The results of classification by TA are in 80% agreement with the categorization made by the radiologists. In some cases, TA is able to describe changes not apparent by visual inspection. CONCLUSION: The TA of MR images of calf muscles can be used for the objective description of changes in muscles and could help radiologists to distinguish between healthy and diseased tissue.

Differences in fMRI and MRS in a monozygotic twin pair discordant for schizophrenia (case report).

OBJECTIVE: This paper presents functional magnetic resonance imaging (fMRI) and magnetic resonance spectroscopy (MRS) findings in a monozygotic twin pair discordant for schizophrenia. METHOD: Functional magnetic resonance imaging was used to determine hemispheric lateralization for speech and proton MRS (1H-MRS) was employed to assess the extent of putative insult to anterior hippocampus. RESULTS: Despite concordant right handedness, subject with schizophrenia displayed bilateral activation in areas subserving speech with greater extent of the total activated area compared with the healthy twin. The affected twin displayed relative bilateral decrease in N-acetylaspartate/creatin concentration in the anterior hippocampus compared with the healthy one. CONCLUSION: This is an evidence for non-genetic impairment of cerebral lateralization in monozygotic twin with schizophrenia.

MR in phenylketonuria-related brain lesions.

PURPOSE: Phenylketonuria (PKU) patients were examined by different MR techniques to explain the pathological changes observed in periventricular white brain matter using conventional MR imaging. MATERIAL AND METHODS: Fifteen patients with treated classical PKU were examined by 1H spectroscopy, relaxometry and diffusion imaging on a whole-body 1.5-T MR imager. RESULTS: Known PKU lesions characterized by T2 enhancement in periventricular white matter were observed in all patients. The MR spectra from the lesioned areas showed a significant decrease in choline concentration. The mean ADC of water decreased and tortuosity increased in PKU lesions compared to control data. CONCLUSION: The results support the following hypothesis: The T2 increase in the PKU lesion reflects a raised concentration of free water molecules (about 15%) that have an increased trajectory between collisions compared to the same region in controls. The increase in water mobility might be explained by changes in extracellular space volume and myelin sheaths, which, presumably, have a different geometry with more hydrophobic sites in PKU patients. The changes result in increased tortuosity and may be confirmed by the loss of anisotropy in PKU lesions.

Application of two-dimensional CSI for absolute quantification of phosphorus metabolites in the human liver.

There have recently been a number of studies dealing with the absolute quantification of concentrations of MR-visible phosphorus compounds in different tissues. The use of absolute values rather than intensity ratios may furnish additional information about metabolic changes associated with different diseases. The purpose of this study was to develop a general procedure for measuring molar metabolite concentrations and to apply it with respect to the evaluation of human liver 31P-MRS data measured using a standard slice-selective two-dimensional CSI sequence and commercial 1H/31P surface coil. The experimental determination of all surface coil-related factors influencing signal intensity was undertaken using a gradient echo imaging technique that can be adapted to commercial systems. The resulting values for healthy volunteers (N = 9) showed concentrations of PME = 2.8 +/- 1.3 mM, PDE = 9.9 +/- 2.7 mM, P(i) = 1.7+/-0.7 mM, and ATP = 3.6 +/- 0.9 mM in the human liver. The data are quite consistent with published findings.

Chronic liver disease: relaxometry in the brain after liver transplantation.

Relaxometry revealed changes in the basal ganglia in T(1) and T(2) relaxation times due to liver disease. Manganese is probably responsible for T(1) and T(2) shortening (as the concentration is known to be higher in both the liver and blood due to hepatic cirrhosis). The aim of this study was to follow possible recovery after liver transplantation by MR relaxometry. Together with a group of 20 healthy volunteers we scanned 53 patients before and after liver transplantation (some of them repeatedly). Both T(1) and T(2) values were evaluated in the basal ganglia, thalamus, and frontal white matter. T(1) relaxation time was shortened by approx. 20-25% compared to the control group, probably the result of manganese deposition in the brain caused by hepatic cirrhosis. After liver transplantation the relaxation time recovered gradually with almost normal values reached approx. 2 years after surgery. T(1) recovery was observed in all evaluated structures. Similar results were observed with T(2) relaxation in the basal ganglia and thalamus. In the white matter T(2) remained low even 2 years after surgery.

Application of LCModel for quality control and quantitative in vivo 1H MR spectroscopy by short echo time STEAM sequence.

The linear combination of model spectra (LCModel) calculation of a parameter for long-term quality control, kT, was introduced, representing the ratio of the temporal and nominal intensities of CH3 groups of lactate and acetate in a quality control phantom. This procedure is a part of the quality assurance of the scanner using fully automatic measurement and calculation of kT parameters, and utilizing Shewhart regulation control charts for continuous evaluation of the magnetic resonance (MR) scanner setting. The application of the kT parameter for the correction of in vivo data increases the precision of molar concentration determination by about 4%. This was tested by the quantitative in vivo MR determination of the molar concentrations of 13 prominent metabolites (N-acetylaspartate (NAA), N-acetylaspartylglutamate, creatine and phosphocreatine (Cr), choline-containing compounds (Cho), myo-inositol, scyllo-inositol, gamma-aminobutyric acid, glutamine, glutamate, glucose, lactate, alanine, taurine) in the white matter and hippocampus of the brain in groups of volunteers, using a short echo time stimulated echo acquisition mode sequence (echo time = 10 ms) and the LCModel technique. The repeatability of the measurement of prominent metabolites such as NAA, Cr and Cho was found to be around 10% (relative standard deviation, n = 6); precision in a group of volunteers (n = 20 and 28, respectively) was in the range of approximately 13-20%. For other metabolites, which are measured with a lower signal-to-noise ratio, the precision can be much lower.

Comparison of MR spectroscopy and MR imaging with contrast agent in children with cerebral astrocytomas.

We studied 33 patients with astrocytomas of different grades (68 examinations) by magnetic resonance imaging (MRI) and proton MR spectroscopy ((1)H-MRS). We found that in 80% of the spectra, the presence of signals in the area of 0.8-1.5 ppm, assigned to lipids/lactate in (1)H-MR spectra, correlated with signal enhancement after Gd-DTPA administration. We suggest that visibility of lipid/lactate signals could be due to blood-brain barrier damage, which is characterized by contrast agent enhancement.

1H MR spectroscopy in patients with mesial temporal epilepsy.

The study provides a review of the basic examination procedures and results of proton magnetic resonance spectroscopy (1H MRS) in patients suffering from mesial temporal lobe epilepsy (MTLE). The source of seizures in MTLE is most often an epileptogenic focus secondary to hippocampal sclerosis. 1H MRS currently plays an important role in the non-invasive diagnosis of this type of epileptogenic lesion. The decisive 1H MRS parameter characterizing an epileptogenic lesion is a statistically significantly decreased value of N-acetylaspartate levels compared with control values, most often associated with a decrease in the ratios of the intensities of NAA/Cr, NAA/Cho and NAA/(Cr + Cho) signals. Moreover, MRS makes it possible to distinguish bilateral involvement of mesial temporal structures typically associated with a bilateral decrease in the levels of metabolites and/or their ratios. As regards other metabolic compounds which play an important role in the pathobiochemistry of epilepsy, MRS is employed to study the action of gamma-aminobutyric acid (GABA), inositol, lactate, glutamine, and glutamate, the clinical function of which has not been fully clarified as yet. It is in this context that one should consider the application of 1H MRS in evaluating the action of some new anti-epileptic agents affecting excitatory and inhibitory amino acids. There is no doubt that in vivo 1H MRS, along with other imaging methods, has made a significant contribution to the clinical and biochemical description of epileptic seizures and has assumed a prominent position among the techniques of pre-operative examination in epileptic surgery.