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Visualizing Brain Inflammation with a Shingled-Leg Radio-Frequency Head Probe for 19 F/ 1 H MRI

by:QY Precision      2019-09-22
Magnetic resonance imaging (MRI)
Provides an opportunity to track cells in the body.
Although there are major challenges to dissect cells and signal sensitivity limitations from recipient tissues.
In this study, we aim to address these limitations in order to study the inflammation in the autoimmunity JE.
We built a very small double.
Adjustable radio frequency (RF)
For 19F (fluorine)and 1H (proton)
Rat nerve imaging
This novel design eliminates the need for additional electrical components on the probe structure and provides a unified
Field and good signal-to-noise ratio.
We use fluorescence-
19F nanoparticles were labeled and can be investigated for the dynamics of inflammatory cells between the central nervous system and the lymphatic system during the development of polio, even in areas of the brain where conventional probes are not easy to see
19F/1 h MR neural imaging will enable us to study the nature of immune cell infiltration during brain inflammation for a long time.
Before construction, various probe designs were simulated with a microwave studio (MWS)(CST, Darmstadt; Germany)
Penn State Bird Cage builder (BB).
After the analysis of EMF simulation results,leg low pass (LP)
Probe Design is selected.
The details and dimensions of the simulation are selected as close as possible to the desired bird cage size: diameter = 18.
4mm, total length = 39mm, foot width = 1mm, foot length = 33mm, tail ring width = 3mm, radio frequency shield diameter = 58mm.
Since the capacitance value required for the building estimated by the bird cage builder is very small (e. g. for H (400u2005MHz)C=1. 17u2005pF)
It is impossible to design such a bird cage using a chip capacitor.
Therefore, we chose to build the capacitor into the structure of the RF probe by grinding the copper bars on both sides of the double-sided copper packet PCB (Printing circuit-board)
There are overlapping areas between the two.
Sketch showing 32-
The leg F/h lp bird cage design was then simulated in MWS.
On each side of the PCB, depending on the capacitance and the desired frequency, the arrangement of the copper bars can only overlap a few mm.
Long inner copper tape (shown in black)
Overlap with the peripheral Copper Belt (shown in white)
Connected together through the end ring.
We first calculate the overlap required to achieve the frequency of the basic Bird Cage (birdcage mode)of 388u2005MHz (
Frequency in the middle of F and H frequencies).
According to the cage builder, this basic frequency requires a capacitor of 1. 38u2005pF.
Calculate the overlapping area between bands required to achieve the necessary capacitance (C)
, We used the formula of the flat plate capacitor: Where e = vacuum dielectric constant (8. 85418*10u2005F/m)
, A = overlapping area, d = PCB thickness corresponding to the distance between overlapping bars.
For the subsequent probe structure, we selected a special flexible PCB with a high relative dielectric constant (ε ≈ 10)
Thickness 400 μ μm.
With these values, the capacitance is 0.
22 pf per mm overlap.
For the basic frequency of 388 MHz (1. 38u2005pF)
We calculated an overlapping area of 6.
27mm, suitable for 28.
We then degrade the basic frequency pattern symmetrically to achieve the desired H and F modes.
For the H mode, 2 are overlapped by the area of 3.
The 14mm is tuned to 400 mhz, and for F mode, 2 overlap 9 regions.
39 inch mm is tuned to 376 inch MHz.
Displays the circuit diagram showing the distribution of all capacitors built into the RF probe structure and the corresponding ports.
Build 32-
We used a CNC (
Computer numerical control)
Machine Protomat 100 (
LPKF from Garbsen, Germany)
To grind 32 copper bands on the PCB, add 18 μm copper on both sides (
Thickness = 400 μ m; Taconic CER-10).
PCB is made of low loss material (
Loss factor tan delta = 0 at 400 mhz. 0025)
And has a high dielectric constant (ε ≈ 10).
According to the simulation and calculation, 28 overlap 6.
Capacitor 1 is achieved in 27mm.
38 pf, so the basic frequency is 38 8 mhz.
For H mode (
Port 1, marked * in)
3 Reduction in overlap. 13u2005mm to 3. 14u2005mm (C1=0. 69pF)
For F mode (
Port 2, marked **)
Overlap increased by 3. 12u2005mm to 9. 39u2005mm (C2=2. 08u2005pF). For fine-
Gradually reduce the shielding diameter from 58mm to 48mm.
Also, for the load
Dependent tuning (C1t and C2t)and matching (C1m and C2m)
Four little trimmercapacitors (1-10pF)were used.
The constructed cage RF probe is shown.
The size of the RF probe is as follows: outer diameter = 20. 42u2005mm;
Head probe inner diameter = 16mm, total length = 43.
29 u2005 mm, each width = 1.
11mm, length = 36 per leg.
63mm, end ring width = 3.
RF shield diameter 33mm (not shown)=48u2005mm.
All parts of the housing of 32-
The leg LP head RF probe is designed using Autodesk Inventor 2011 (Autodesk Inc.
San Rafael, California, USA)
And has a 3D printer BST postges (Dimension Inc.
MN, Eden Prairie, United States of America).
RF performance of the head RF probe-including measurement of a full set of scattering parameters (S-parameter)
Determine the reflection coefficient and coupling between the two ports ()
-Tested using a 2-channel vector network analyzer (
Rohde & Schwarz Limited
KG of Memmingen, Germany).
To block unwanted coaxial shielding current, we used Barron on each channel as close as possible to the bird cage probe.
Barron is half. rigid cable (diameter 1. 5u2005mm)
, Bent into a ring with a radius of 7.
5mm, welded on a small piece of printed circuit board.
2 3mm chip capacitors in 2 ranges. 2u2005pF–2.
7 pf is used to tune Barron to 376 mhz and 400 mhz.
For simulation, we use MWS ()in which a 15-Falcon tube ml (
Conductivity: σ = 0.
33 s/m, relative dielectric constant: E = 78)
Used as a phantom for loading RF probes;
We simulated the load that a normal mouse head would add to the probe. The transmit-
Activity component ()
RF probes can be measured by several flipping
Angle mapping technology.
For measurement, the probe is loaded with a 15 ml tube filled with a saline solution mixed with CuSO (0. 3u2005g/L)
Reduce the T relaxation time to c. 600u2005ms.
This reduces the associated effects, thus reducing the measurement time.
We applied a time for Phantom measurement-
A complete set of rectangles based on simple and precise technology
Selective pulse preparation (
Pulse length = 1 MS)
Then there is the spoiler gradient that destroys any lateral magnetized.
Such a 3D distribution of longitudinal magnetism (M)
7 different preparation pulse power settings were produced for the entire volume of interest.
After each preparation step, M-
Distribution of central slices using standard 2D gradient mapping
Echo sequence with small flip
Angle and length TR (TR min. 5*T=3u2005s)to avoid T-
Related effects: TR = 3000 ms, TE = 6 µms, slice thickness 1 * mm, FOV = (15 × 15)
Mm, matrix 64 × 64, NEX = 1,7 preparation pulse (
Attenuation = 150 kbps dB, 56. 4u2005dB, 44. 4u2005dB, 39. 5u2005dB, 36. 4u2005dB, 32. 3u2005dB, 31. 3u2005dB)
, Scan time = 35 min.
MRI and post-fixation experiments for ensuingF/H in the experimental mice of the leaves (
Histological and flow cell technique)
We have prepared nanoparticles with high fluorine (F)
Content and DiI fluorescence.
These particles are PERF-600-15-crown-5-ether (
Flowhill PFCE, Derbyshire, UK)
And 630 mu M 1, 1 \'~Dioctadecyl-3,3,3\',3\'-
Four methyl groups and doc insects (
Molecular probe DiI®, Invitrogen, damstadt, Germany)
And was prepared by first emulsion PFCE in Pluronic F-68 (Sigma-
Aldridge, Germany)
By direct ultrasonic treatment, a battery that destroys titanium ultrasound (
Berlin, Berlin, Bandelin, Thorpe, GM70, Germany)
As mentioned earlier. After 1:1 (v/v)
Diluted with DPBS, further ultrasonic treatment of PFCE emulsion in the presence of 630 μm DiI for PFCE-
DiI nanoparticles emulsion containing 600 mM PFCE.
To remove the free DiI, PFCE-
Then clarify DiI nanoparticles emulsion on gel G-50 (Sigma-
Aldridge, Germany)columns.
Using Malvern Zetasizer Nano instrument to determine the average diameter of nanoparticles by dynamic light scattering (
Marvin instruments, Worcester, UK).
After adding DiI, the particle size remains the same.
In order to determine the uptake capacity of the preparation particles and to optimize the F and DiI content, we marked the bone marrow-derived branch-like cells (BMDC)with the PFCE-
DiI nanoparticles
As mentioned earlier, BMDC was prepared from BM suspension.
To put it simply, BM-from the femurs of the mice in the capital-
1640 medium containing 10% FCS (
Biochrom, Germany)
And added GM-of 100ng ng/ml-CSF.
Animal experiments are conducted in accordance with the guidelines provided and approved by the Animal Welfare Division of the National Health and Social Affairs Office of Berlin ().
Female SJL/J mice (
Janvier SAS, Le Genest-St-Isle, France)
Subcutaneous immunization with a purity of 250 μg PLP> 95% (
Baiyao Co. , Ltd. , UK)
With the complete Fushi supplement and heat-
Killing M. tuberculosis (H37Ra, Difco).
Toxin of Botox (250u2005ng;
List of American Biological Laboratories)
Administered in 0 days and 2 days.
Every day after immunization, the mice were weighed and scored as follows: 0, no disease;
1. the tail is weak and the positive reflection is weak; 2, paraparesis; 3, paraplegia;
4. paralysis of weakness or paralysis of the front limb;
Dying or dead animals
Five days after AE induction, the mice were given DiI-
Labeled nanoparticles containing 5 μ mol PFCE.
For F/h mri, AE mice were anesthesia using an isofluranea mixture of inhalation anesthesia (0. 5–1. 5%)
Before and during MR meetings, pressurize air and oxygen.
Mice are placed on the mouse holder of the small animal MR scanner (
Brook Biospin USR 94/20, Brook Biospin, ertringen, Germany)
The head is located inside the H/f rf probe and then moves to the center of the magnet.
After obtaining the reconnaissance image using 2D FLASH (
MRI software Paravision 5.
1, Biospin, ertringen Brook, Germany)
, The RF head probe is tuned to the resonance frequency of H and F and then matched to the characteristic impedance (50u2005Ohm)
Use the tuning monitor of the animal MR scanner.
The following automatic system settings include 1 and 2 orders to fine-
Tuning of homogeneity of the magnetic field of a We the H: TR = 500 MS, TE = 53 MS, FOV = (40 × 16 × 16)
Mm, matrix = 320 × 128, rare factor = 16, NEX = 1 (scan time ca. 25u2005min);
For F: TR = 1000 u2005 ms, TE = 6 u2005 ms, FOV = (40 × 16 × 16)
Mm, matrix = 100 × 40, zero fill acceleration 2, rare factor = 40, NEX = 128 (
Scan time = 45 min).
For an overview scan and for Mrs F\'s reference, we used a 2D Flash protocol for F: TR = 15 MS, TE = 3.
3 u2005 ms, 1 quick Teng 3mm slice, in-
Plane resolution (400 × 400)μm, NEX=2048 (
Scan time = 15 min)
For H: TR = 473 kbps ms, TE = 13 ms, 22 pieces, in-plane resolution (73 × 73)μm, NEX=16 (
Scan time = 25 min).
In order to quantify the F content in a specific region of the brain of mice, we used a single element spectrum (SVS)
, Especially the point-resolved spectrum (PRESS).
For this reason, we placed (3 × 3 × 3)
Mm body elements in the area of interest (
Here is the brain and cortex)of the mouse-brain ().
Then, we use the FastMap method from Paravision, for the volume ratio magnetic field (B)shimming.
After obtaining the spectrum with a press machine --
Mrs. F\'s agreement: TR = 500 MS, TE = 11.
6 Pax ms, voxelsize (3 × 3 × 3)mm, NEX512 (
Scan time = 13 min).
To quantify the F signal, we obtained the f mrs calibration curve using the same pressure protocol, which contained three 15 ml Falcon tubes containing different concentrations of PFCE emulsion (
10, 20 and 40mm).
In order to conduct histological and immune tissue chemistry studies, AE mice were infused via heart with 20 ml cold PBS after terminal anesthesia.
After that, continue perfusion with 20 ml cold PFA (4% in PBS).
Then extract the brain, spinal cord, and secondary lymph organs, and then
Fixed overnight at 4 °c in 4% PFA
Then freeze the tissue with sucrose (30% in PBS)
At 4 °c, slice on a 50 μm thick slice at a low temperature thermostat at 20 °c and process on the same day.
Clean and incubate free-floating slices with anti-Mac2 antibodies (
ACRIS GmbH, Helford, Germany), CD4 (
BD Pharmingen, Heidelberg, Germany), CD3 (
Serotec duseldorf, Germany), F4-80 (
Fell gend, Germany)and MPO (
Abcam, Cambridge, UK)
Overnight at 4 °c, then washed in PBS and incubated with secondary antibodies bound to Cy3 (
Jackson, West Grove, Pennsylvania, United States of America)
For 2 hours at room temperature.
Part of the slice-
Conjugate B220 (
Fell gend, Germany).
After antibody incubation, the slices are mounted on a standard slide and Vectashield-DAPI (
Bollingame Vector Laboratory, California, USA)
For fluorescent microscopy.
Using a fluorescence microscope (BZ-
9000, keenz, Neu-
Fort D). For(FACS)
In the experiment, after the terminal anesthesia, mice were injected with 20 ml cold PBS through the heart.
After extraction, organs (
Brain, spinal cord, lymph node, spleen)
Mechanical dissociation by 70 μm nylon cell filter (
BD Falcon Hotel Heidelberg, Germany)
Enter the RPMI medium (
5% FCS included)
Centrifugal at 4 °c.
In order to remove the contaminated red blood cells from the isolated tissue, lysate buffer was used.
For the central nervous system, use the 37% colll gradient (1. 125–1. 135u2005g/ml; Sigma-
Aldridge, Germany).
Result cell and-CD16/32 Fc-Blocking of receptors (
BD Pharmingen™Heidelberg, Germany)
15 min, wash in FACS buffer and ready to use APC-
Marked cd3-
Conjugate CD19, Pacific Blue
Combined CD11b and APC-
Antibody binding CD11c (
EBioscience, Frankfurt, Germany).
Mice were subjected to final anesthesia and were infused with 4% formaldehyde and 0 by heart.
Use 5% propolis before brain extraction. A 3u2005mm cube (
Attached news-
Voxels for spectrum)
Anatomy of the small forehead and the rearfixed (
24 hours in 2% glucose aldehyde and then 4 hours in 1% tin oxide).
After dehydration, embed the tissue into the poly/bed 812 (
Eppelheim, Germany).
The semi-thin sections were stained with hexidine blue, and the ultra-thin sections were stained with uranium acetate/lead citrate.
Usage fee moghani electronic microscope imaging of slices (
Einhoven, NL)
Software for items (Olympus-
Minster SIS, Germany).
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