Objective To compare the various partial Fourier reconstruction algorithms in MRI image processing and their advantages and disadvantages for improving algorithm .Methods Based on the conjugate symmetry in k‐space data in the partial Fourier reconstruction algorithm theory ,the 1 .5T medical magnetic resonance equipment was utilized ,the k‐space data were collect‐ed ,in reconstruction ,only 55% -80% of full data were utilized to simulate the partial collection pattern and reconstruct the images by using the several algorithms of zero filling ,conjugate synthesis ,Homodyne detection and POCS .Results The results presented that the ringing artifact was most obvious in the conjugate filling pattern and the POCS algorithm had the best effect for eliminating the ringing artifact .Conclusion The POCS algorithm repeatedly uses the weighted iteration with low frequency phase positions , which eliminates artifact ,meanwhile causes the lose of high frequency image details ,moreover the time consuming is longer ;the Ho‐modyne algorithm can keep a good balance between maintaining the image details and diminishing ringing .If the Sinc function serves as a weighting function for conducting phase unwrapping ,the image quality may be further improved .

OBJECTIVETo compare the performance of three different types of RF coil in 3.0T MRI, the signal-to-noise ratio (SNR) and image uniformity in 3.0 Tesla magnetic resonance imaging system have been studied.

MATERIALS AND METHODSIn addition to the measurement of SNR and Uniformity based on the protocol recommend by AAPM, the images had also been analyzed using SPSS and MATLAB to get the SNR distribution along two vertical direction and the whole imaging plane.

RESULTSThe SNR with T/R birdcage coil and 8-ch surface coil is seven and twelve times higher than surface coil in the region of interest (ROI), which was set in the center of the phantom images. With regard to the spatial variation of sensitivity, the uniformity of T/R birdcage coil and 8-ch surface coil are also much higher than that of surface coil.

CONCLUSIONThe images from T/R birdcage and phased array coils are all better than those of surface coil. The SNR of the images from phased array coil is highest while the uniformity of the images from T/R birdcage coil is highest.

Magnetic Resonance Imaging ; instrumentation ; Materials Testing ; methods ; Phantoms, Imaging ; Radio Waves ; Signal-To-Noise Ratio

In this paper, an overview is given on the optimization methods of designing RF coil array. Advantages and disadvantages are also discussed.
Equipment Design ; Magnetic Resonance Imaging ; instrumentation ; methods ; Radio Waves

Objective To explore the value of retrievable inferior vena cava (IVC) filter placement for prevention of perioperative pulmonary embolism (PE) in patients with lower extremity/pelvic fracture with deep vein thrombosis (DVT).Methods Clinical data of 1 891 lower extremity/pelvic fracture patients combined with DVT were retrospectively analyzed.Totally 411 patients with permanent filters were excluded,and the other patients were divided into filter group (n=843) and control group (n=637) according to whether receiving retrievable IVC filter placement or not.The incidence of perioperative symptomatic PE and mortality were compared between the two groups.Results In filter group,Optease nonpermanent filters were inserted in 218 patients,and the mean indwelling time was (14.3±3.6) days.Celcet filters were inserted in 625 patients,and the filters were successfully removed in 566 out of 578 patients who underwent filter removal surgery (97.92％,566/578),and the mean indwelling time was (15.8±4.1) days.The incidence of PE in filter group (0.12％[1/843]) was significantly lower than that in control group (1.57％ [10/637],P＜0.05).Among the patients who received chemical anticoagulant therapy,the incidence of PE in filter group and control group was 0.14 ％ (1/700) and 1.47％(9/612),respectively (P＜0.05).Conclusion Retrievable IVC filter placement is a safe and effective method for preventing perioperative symptomatic and fatal PE in lower extremity/pelvic fracture patients with DVT.

Uch37 is a de-ubiquitinating enzyme that is activated by Rpn13 and involved in the proteasomal degradation of proteins. The full-length Uch37 was shown to exhibit low iso-peptidase activity and is thought to be auto-inhibited. Structural comparisons revealed that within a homo-dimer of Uch37, each of the catalytic domains was blocking the other's ubiquitin (Ub)-binding site. This blockage likely prevented Ub from entering the active site of Uch37 and might form the basis of auto-inhibition. To understand the mode of auto-inhibition clearly and shed light on the activation mechanism of Uch37 by Rpn13, we investigated the Uch37-Rpn13 complex using a combination of mutagenesis, biochemical, NMR, and small-angle X-ray scattering (SAXS) techniques. Our results also proved that Uch37 oligomerized in solution and had very low activity against the fluorogenic substrate ubiquitin-7-amino-4-methylcoumarin (Ub-AMC) of de-ubiquitinating enzymes. Uch37Δ(Hb,Hc,KEKE), a truncation removal of the C-terminal extension region (residues 256-329) converted oligomeric Uch37 into a monomeric form that exhibited iso-peptidase activity comparable to that of a truncation-containing the Uch37 catalytic domain only. We also demonstrated that Rpn13C (Rpn13 residues 270-407) could disrupt the oligomerization of Uch37 by sequestering Uch37 and forming a Uch37-Rpn13 complex. Uch37 was activated in such a complex, exhibiting 12-fold-higher activity than Uch37 alone. Time-resolved SAXS (TR-SAXS) and FRET experiments supported the proposed mode of auto-inhibition and the activation mechanism of Uch37 by Rpn13. Rpn13 activated Uch37 by forming a 1:1 stoichiometric complex in which the active site of Uch37 was accessible to Ub.
Binding Sites ; Catalytic Domain ; Chromatography, Gel ; Crystallography, X-Ray ; Humans ; Membrane Glycoproteins ; chemistry ; genetics ; metabolism ; Nuclear Magnetic Resonance, Biomolecular ; Protein Binding ; Protein Conformation ; Protein Multimerization ; Scattering, Small Angle ; Ubiquitin Thiolesterase ; chemistry ; genetics ; metabolism ; Ultracentrifugation