Quantitative analysis of hepatic fat fraction by single-breath-holding MR spectroscopy with T 2 correction: phantom and clinical study with histologic assessment

Increased hepatic fat content (HFC) is a hallmark of non-alcoholic fatty liver (NAFL) disease, a common condition in liver transplant recipients. Proton MR spectroscopy (1H MRS) and MR imaging-based proton density fat fraction as the only diagnosis modality enable precise non-invasive measurement of HFC and, also, fatty acid profiles in vivo. Using 1H MRS at 3T, we examined 47 liver transplantation candidates and 101 liver graft recipients. A point-resolved spectroscopy sequence was used to calculate the steatosis grade along with the saturated, unsaturated and polyunsaturated fractions of fatty acids in the liver. The steatosis grade measured by MRS was compared with the histological steatosis grade. HFC, represented by fat fraction values, is adept at distinguishing non-alcoholic steatohepatitis (NASH), NAFL and non-steatotic liver transplant patients. Relative hepatic lipid saturation increases while unsaturation decreases in response to increased HFC. Additionally, relative hepatic lipid saturation increases while unsaturation and polyunsaturation both decrease in liver recipients with histologically proven post-transplant NASH or NAFL compared to non-steatotic patients. HFC, measured by in vivo 1H MRS, correlated well with histological results. 1H MRS is a simple and fast method for in vivo analysis of HFC and its composition. It provides non-invasive support for NAFL and NASH diagnoses.

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Usefulness of Proton MR Spectroscopy in Acute Cerebral Infarction: An Experimental and Clinical Study

Journal of the Korean Radiological Society ◽

10.3348/jkrs.1999.41.3.431 ◽

1999 ◽

Vol 41 (3) ◽

pp. 431

Author(s):

Won Jae Lee ◽

Heoung Keun Kang ◽

Gwang Woo Jeong ◽

Jeong Jin Seo

Keyword(s):

Clinical Study ◽

Cerebral Infarction ◽

Mr Spectroscopy ◽

Acute Cerebral Infarction ◽

Proton Mr Spectroscopy

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Alanine Aminotransferase Levels and Fatty Liver in Childhood Obesity: Associations with Insulin Resistance, Adiponectin, and Visceral Fat

The Journal of Clinical Endocrinology & Metabolism ◽

10.1210/jc.2006-1010 ◽

2006 ◽

Vol 91 (11) ◽

pp. 4287-4294 ◽

Cited By ~ 243

Author(s):

Tania S. Burgert ◽

Sara E. Taksali ◽

James Dziura ◽

T. Robin Goodman ◽

Catherine W. Yeckel ◽

...

Keyword(s):

Lipid Metabolism ◽

Insulin Sensitivity ◽

Fatty Liver ◽

Visceral Fat ◽

Resonance Imaging ◽

Fat Accumulation ◽

Glucose And Lipid Metabolism ◽

The Metabolic Syndrome ◽

Hepatic Fat ◽

Fat Fraction

Abstract Background: Concurrent with the rise in obesity, nonalcoholic fatty liver disease is recognized as the leading cause of serum aminotransferase elevations in obese youth. Nevertheless, the complete metabolic phenotype associated with abnormalities in biomarkers of liver injury and intrahepatic fat accumulation remains to be established. Methods: In a multiethnic cohort of 392 obese adolescents, alanine aminotransferase (ALT) levels were related with parameters of insulin sensitivity, glucose, and lipid metabolism as well as adipocytokines and biomarkers of inflammation. A subset of 72 adolescents had determination of abdominal fat partitioning and intrahepatic fat accumulation using magnetic resonance imaging. Findings: Elevated ALT (>35 U/liter) was found in 14% of adolescents, with a predominance of male gender and white/Hispanic race/ethnicity. After adjusting for potential confounders, rising ALT was associated with reduced insulin sensitivity and glucose tolerance as well as rising free fatty acids and triglycerides. Worsening of glucose and lipid metabolism was already evident as ALT levels rose into the upper half of the normal range (18–35 U/liter). When hepatic fat fraction was assessed using fast magnetic resonance imaging, 32% of subjects had an increased hepatic fat fraction, which was associated with decreased insulin sensitivity and adiponectin, and increased triglycerides, visceral fat, and deep to superficial sc fat ratio. The prevalence of the metabolic syndrome was significantly greater in those with fatty liver. Interpretation: Deterioration in glucose and lipid metabolism is associated even with modest ALT elevations. Hepatic fat accumulation in childhood obesity is strongly associated with the triad of insulin resistance, increased visceral fat, and hypoadiponectinemia. Hence, hepatic steatosis may be a core feature of the metabolic syndrome.

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Changing effect of lung volume on respiratory drive in man

Journal of Applied Physiology ◽

10.1152/jappl.1975.38.5.768 ◽

1975 ◽

Vol 38 (5) ◽

pp. 768-773 ◽

Cited By ~ 2

Author(s):

N. N. Stanley ◽

M. D. Altose ◽

S. G. Kelsen ◽

C. F. Ward ◽

N. S. Cherniack

Keyword(s):

Human Subjects ◽

Inhibitory Effect ◽

Breath Holding ◽

Breath Hold ◽

Respiratory Drive ◽

Lung Inflation ◽

Single Breath ◽

Single Breath Hold ◽

Sustained Effect ◽

Residual Capacity

Experiments were conducted on human subjects to study the effect of lung inflation during breath holding on respiratory drive. Two series of experiments were performed: the first to examine respiratory drive during a single breath hold, the second designed to examine the sustained effect of lung inflation on subsequent breath holds. The experiments involved breath holding begun either at the end of a normal expiration or after a maximum inspiration. When breath holding was repeated at 10-min intervals, the increase in BHT produced by lung inflation was greater in short breath holds (after CO2 rebreathing) than in long breath holds (after hyperventilation). If breath holds were made in rapid succession, the first breath hold was much longer when made at total lung capacity than at functional residual capacity, but this effect of lung inflation diminished in subsequent breath holds. It is concluded that the inhibitory effect of lung inflation decays during breath holding and is regained remarkably slowly during the period of breathing immediately after breath holding.

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Fast vs. slow exhalation before O2 inhalation alters subsequent phase III slope

Journal of Applied Physiology ◽

10.1152/jappl.1984.56.1.52 ◽

1984 ◽

Vol 56 (1) ◽

pp. 52-56 ◽

Cited By ~ 3

Author(s):

T. S. Hurst ◽

B. L. Graham ◽

D. J. Cotton

Keyword(s):

Total Lung Capacity ◽

Normal Subjects ◽

Phase Iii ◽

Breath Holding ◽

Small Airways ◽

Residual Volume ◽

Lung Capacity ◽

Single Breath ◽

Subsequent Phase ◽

Phase Iii Slope

We studied 10 symptom-free lifetime non-smokers and 17 smokers all with normal pulmonary function studies. All subjects performed single-breath N2 washout tests by either exhaling slowly (“slow maneuver”) from end inspiration (EI) to residual volume (RV) or exhaling maximally (“fast maneuver”) from EI to RV. After either maneuver, subjects then slowly inhaled 100% O2 to total lung capacity (TLC) and without breath holding, exhaled slowly back to RV. In the nonsmokers seated upright phase III slope of single-breath N2 test (delta N2/l) was lower (P less than 0.01) for the fast vs. the slow maneuver, but this difference disappeared when the subjects repeated the maneuvers in the supine position. In contrast, delta N2/l was higher for the fast vs. the slow maneuver (P less than 0.01) in smokers seated upright. For the slow maneuver, delta N2/l was similar between smokers and nonsmokers but for the fast maneuvers delta N2/l was higher in smokers than nonsmokers (P less than 0.01). We suggest that the fast exhalation to RV decreases delta N2/l in normal subjects by decreasing apex-to-base differences in regional ratio of RV to TLC (RV/TLC) but increases delta N2/l in smokers, because regional RV/TLC increases distal to sites of small airways obstruction when the expiratory flow rate is increased.

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Single-Breath Breath Holding Measurement of Pulmonary Blood Flow: Comparison to Direct Fick Cardiac Output

Clinical Science ◽

10.1042/cs071036pa ◽

1986 ◽

Vol 71 (s15) ◽

pp. 36P-36P ◽

Cited By ~ 1

Author(s):

A.H. Kendrick ◽

A. Rozkovec ◽

M. Papouchado ◽

J. West ◽

J.E. Bees ◽

...

Keyword(s):

Blood Flow ◽

Cardiac Output ◽

Pulmonary Blood Flow ◽

Breath Holding ◽

Single Breath

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Single-breath CO diffusing capacity influenced by initial alveolar partial pressure of CO

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.1998.275.1.r339 ◽

1998 ◽

Vol 275 (1) ◽

pp. R339-R342

Author(s):

Hartmut Heller ◽

Klaus-Dieter Schuster

Keyword(s):

Mass Spectrometry ◽

Partial Pressure ◽

Breath Holding ◽

Gas Mixture ◽

Residual Volume ◽

Diffusing Capacity ◽

Time Intervals ◽

Single Breath ◽

Identical Manner ◽

End Tidal

The purpose of this study was to assess the influence of incorrect determinations of the initial alveolar partial pressure of carbon monoxide (CO) at the beginning of breath holding (Pia CO) on the pulmonary CO diffusing capacity of the lung (Dl CO). Single-breath maneuvers were performed on 14 anesthetized and artificially ventilated rabbits, using 0.2% CO in nitrogen as the indicator gas mixture. Inflation and deflation procedures were carried out in an identical manner on each animal, with inflation always starting from residual volume. End-tidal partial pressure of CO was determined by respiratory mass spectrometry and was used to calculate Dl CO values with the application of the three-equation ( method 1), as well as the conventional ( method 2), solution. In each rabbit, method 2 caused Dl CO values to be overestimated when compared with method 1, and this overestimation decreased with increasing time intervals of CO uptake. Because we were able to recalculate this deviation using Pia COvalues that were obtained by taking the diffusive removal of CO during inflation into account, we concluded that errors in estimating Pia CO by applying method 2 significantly contribute to the discrepancy between both methods.

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Labeled carbon dioxide (C18O2): an indicator gas for phase II in expirograms

Journal of Applied Physiology ◽

10.1152/japplphysiol.01360.2003 ◽

2004 ◽

Vol 97 (5) ◽

pp. 1755-1762 ◽

Cited By ~ 9

Author(s):

Holger Schulz ◽

Anne Schulz ◽

Gunter Eder ◽

Joachim Heyder

Keyword(s):

Carbon Dioxide ◽

Phase Ii ◽

Dead Space ◽

Moment Analysis ◽

Cumulative Distribution ◽

Breath Holding ◽

Power Moment ◽

Single Breath ◽

Dead Space Volume ◽

Space Volume

Carbon dioxide labeled with 18O (C18O2) was used as a tracer gas for single-breath measurements in six anesthetized, mechanically ventilated beagle dogs. C18O2 is taken up quasi-instantaneously in the gas-exchanging region of the lungs but much less so in the conducting airways. Its use allows a clear separation of phase II in an expirogram even from diseased individuals and excludes the influence of alveolar concentration differences. Phase II of a C18O2 expirogram mathematically corresponds to the cumulative distribution of bronchial pathways to be traversed completely in the course of exhalation. The derivative of this cumulative distribution with respect to respired volume was submitted to a power moment analysis to characterize volumetric mean (position), standard deviation (broadness), and skewness (asymmetry) of phase II. Position is an estimate of dead space volume, whereas broadness and skewness are measures of the range and asymmetry of functional airway pathway lengths. The effects of changing ventilatory patterns and of changes in airway size (via carbachol-induced bronchoconstriction) were studied. Increasing inspiratory or expiratory flow rates or tidal volume had only minor influence on position and shape of phase II. With the introduction of a postinspiratory breath hold, phase II was continually shifted toward the airway opening (maximum 45% at 16 s) and became steeper by up to 16%, whereas skewness showed a biphasic response with a moderate decrease at short breath holding and a significant increase at longer breath holds. Stepwise bronchoconstriction decreased position up to 45 ± 2% and broadness of phase II up to 43 ± 4%, whereas skewness was increased up to twofold at high-carbachol concentrations. Under all circumstances, position of phase II by power moment analysis and dead space volume by the Fowler technique agreed closely in our healthy dogs. Overall, power moment analysis provides a more comprehensive view on phase II of single-breath expirograms than conventional dead space volume determinations and may be useful for respiratory physiology studies as well as for the study of diseased lungs.

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