Compared with SFA intake, n-6 PUFAs reduce liver fat and modestly improve metabolic status, without weight loss. A high n-6 PUFA intake does not cause any signs of inflammation or oxidative stress. Downregulation of PCSK9 could be a novel mechanism behind the cholesterol-lowering effects of PUFAs. This trial was registered at clinicaltrials.gov as NCT01038102.

Dixon imaging techniques derive chemical shift-separated water and fat images, enabling the quantification of fat content and forming an alternative to fat suppression. Whole-body Dixon imaging is of interest in studies of obesity and the metabolic syndrome, and possibly in oncology. A three-point Dixon method is proposed where two solutions are found analytically in each voxel. The true solution is identified by a multiseed three-dimensional region-growing scheme with a dynamic path, allowing confident regions to be solved before unconfident regions, such as background noise. 2p-Phase unwrapping is not required. Whole-body datasets (256 3 184 3 252 voxels) were collected from 39 subjects (body mass index 19.8-45.4 kg/m 2 ), in a mean scan time of 5 min 15 sec. Water and fat images were reconstructed offline, using the proposed method and two reference methods. The resulting images were subjectively graded on a four-grade scale by two radiologists, blinded to the method used. The proposed method was found superior to the reference methods. It exclusively received the two highest grades, implying that only mild reconstruction failures were found. The computation time for a whole-body dataset was 1 min 51.5 sec 6 3.0 sec. It was concluded that wholebody water and fat imaging is feasible even for obese subjects, using the proposed method. Magn Reson Med 63:1659-1668, 2010. V C 2010 Wiley-Liss, Inc.Key words: three-point Dixon; whole-body MRI; water and fat separation; chemical shift imaging; fat suppression By utilizing the property of chemical shift, MR signals arising from different chemical species can be separated. Dixon techniques use a spectrum model to derive chemical shift-separated water and fat images from multiple source images acquired at different echo times (points). Dixon water-only images form an alternative to fat suppression techniques, such as short tau inversion recovery and spectral inversion recovery, that is potentially insensitive to magnetic field inhomogeneity.Due to the ability of fat quantification (1), Dixon imaging is of interest in studies of obesity and the metabolic syndrome. Whole-body Dixon imaging allows accurate investigation of adipose tissue distribution (2) and may also be useful in oncology (3).Dixon's original two-point method (4) assumed that the phase difference in the source images was caused by chemical shift only and did not account for other sources of phase distortion, such as amplitude of static field (B 0 ) inhomogeneity. However, the requirement of a homogeneous magnetic field can be relaxed by including B 0 inhomogeneity in the signal model. This has been done by acquiring an additional image, giving a three-point method (5-7), or by modification of the two-point method (8).Two main challenges for Dixon methods are the ambiguity of identifying water and fat, and 2p phase unwrapping of the B 0 field map. However, by acquiring the source images with constant echo spacing, these problems can be separated. In fact, phase unwrapping is not necessary for water and fat ...

The two-point Dixon method is a proton chemical shift imaging technique that produces separated water-only and fat-only images from a dual-echo acquisition. It is shown how this can be achieved without the usual constraints on the echo times. A signal model considering spectral broadening of the fat peak is proposed for improved water/fat separation. Phase errors, mostly due to static field inhomogeneity, must be removed prior to least-squares estimation of water and fat. To resolve ambiguity of the phase errors, a corresponding global optimization problem is formulated and solved using a message-passing algorithm. It is shown that the noise in the water and fat estimates matches the Cramér-Rao bounds, and feasibility is demonstrated for in vivo abdominal breath-hold imaging. The water-only images were found to offer superior fat suppression compared with conventional spectrally fat suppressed images. Magn Reson Med 65:994-1004, 2011.

A major cause of impaired gas exchange during general anaesthesia is atelectasis, causing pulmonary shunt. A 'vital capacity' (VC) manoeuvre (i.e. inflation of the lungs up to 40 cm H 2 O, maintained for 15 s) may re-expand atelectasis and improve oxygenation. However, such a manoeuvre may cause adverse cardiovascular effects. Reducing the time of maximal inflation may improve the margin of safety. The aim of this study was to analyse the change over time in the amount of atelectasis during a VC manoeuvre in 12 anaesthetized adults with healthy lungs. I.v. anaesthesia with controlled mechanical ventilation (VT 9 (SD 1) ml kg -1 ) was used. For the VC manoeuvre, the lungs were inflated up to an airway pressure (Paw) of 40 cm H 2 O. This pressure was maintained for 26 s. Atelectasis was assessed by analysis of computed x-ray tomography. The amount of atelectasis, measured at the base of the lungs, was 4.0 (SD 2.7) cm 2 after induction of anaesthesia. The decrease in the amount of atelectasis over time during the VC manoeuvre was described by a negative exponential function with a time constant of 2.6 s. At an inspired oxygen concentration of 40%, Pa O 2 increased from 17.2 (4.0) kPa before to 22.2 (6.0) kPa (Pϭ0.013) after the VC manoeuvre. Thus in anaesthetized adults undergoing mechanical ventilation with healthy lungs, inflation of the lungs to a Paw of 40 cm H 2 O, maintained for 7-8 s only, may re-expand all previously collapsed lung tissue, as detected by lung computed tomography, and improve oxygenation. We conclude that the previously proposed time for a VC manoeuvre may be halved in such subjects. 1999; 82: 551-6 Br J Anaesth

PEEP = 10 cmH2O reduced atelectasis formation after a VCM, when FiO2 = 1.0 was used. Thus, a VCM followed by PEEP = 10 cmH2O should be considered when patients are ventilated with a high FiO2 and gas exchange is impaired.