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Vertical
Bore Imaging, 3-Axes Gradient Probes
NB
and WB MRI Probes (with gradients and RF) |
5
mm to 12 mm Imaging
Probes
- Highest
S/N
- 350
G/cm at 2.3% duty cycle,
water
cooled
- Quick,
convenient, multi-X tuning
- For
magnets up to 900 MHz
- 5,
8, 10, or 12 mm RF Coils
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Our
MRI probes are designed for high-field magnets
with 40 to 72 mm
inside the RT shims. The MRI probe includes the
26-40 gradient coil and 1H or 1H/X,
rf Litz coils. The probe permits highest
gradients at highest fields.
The MRI probe is normally provided with conventional top "NMR-tube" access.
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A
Doty Scientific 12 mm vertical bore imaging probe
with Model 26-40 three axis gradients was
used to acquire high resolution rat kidney images in a Varian
800 MHz narrow bore magnet.
High resolution images from a healthy
rat kidney were acquired at 800 MHz, without contrast
(NF), and with contrast (CF). The plot below each
image shows the percent change in signal intensity
(from
mean) versus length, along the yellow line. Each
spike on the plot under the contrasted kidney represents
a single kidney glomerulus (100-150 µm diameter).
Images courtesy of Scott Beeman, Dr. Brian Cherry,
Dr. Jeff
Yarger, and Dr. Kevin Bennett, Arizona State University.
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Partially
assembled 3 axis gradient coils
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3
Axis Gradient Coils |
Parameter
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Model
26-40
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Units
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Cooling
method
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Water
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Diameter
di for 4%
local deviation
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14
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mm
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Length zi for 4%
local deviation
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17
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mm
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Diameter
di for 10%
local deviation
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18
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mm
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Length zi for 10%
local deviation
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22
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mm
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Nearest Gradient
Null point
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15.4
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mm
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Outside
diameter, do
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39.6
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mm
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Coil
half-length, h1
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36.1
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mm
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RF
shield diameter,dS
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26
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mm
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Clear
bore, di
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23.6
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mm
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Max
inductance, L
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37
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μH
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Max
DC resistance, RE
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1.4
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Ω
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Min
gradient gain, α
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48
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mT/Am
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Max
shielding error at
1.5 d0
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0.4
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%
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Min
slew rate, GS = αV/L, at
1 V
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1,189
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T/m/s
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Continuous
current, IRMS
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A
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Continuous
gradient, GC
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53
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G/cm
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Peak
Voltage
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120
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V
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Approx.
EPI Acoustic Noise, 7 T
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70
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dBa
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Rise
time to GC for
100 V
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4.6
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μs
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Total
mass
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0.4
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kg
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In the
table above, the performance for the X and Y axes are each
as indicated above, and the Z axis is typically better in slew
rate, continuous gradient, and volume of linear region.
Local
deviation (or differential linearity) is defined as the
rms deviation from the mean gradient over the specified
di-ameter, di, and length, zi, of the cylindrical sample
region. The half-length h1 is the distance from the center
to the closer of the two external end surfaces. Eddy currents
from the internal RF shield are negligible. The gradient
slew rate GS is the instantaneous rate of change in gradient
when a 1 V step is applied. The continuous current ratings
are true continuous ratings for a single axis with no time
limit and adequate cooling. Derate the current 30% when
all three axes are driven simultaneously.
*
For additional gradient specifications – See
MRI 3 Axis Gradient coils
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RF
Litz Volume
Coils For Vertical Bore NB or WB Probes
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RF Coil
I.D.
(mm)
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Shield
Diameter
(mm)
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Tuning
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1H
MHz
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Mod.
Load
τ 90 ( μs)
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Heavy
Load
τ 90 ( μs)
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1H
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31 P
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1H
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31 P
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10
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26
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1H/X
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500
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9
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12
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10
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14
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12
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26
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1H
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500
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9
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-
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12
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-
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10
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26
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1H/X
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600
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11
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13
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12
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15
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12
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26
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1H
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800
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10
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-
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16
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-
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For
the above coils, the length of homogeneous region is 80%
of the coil ID. Coils with a multi-x channel normally
tune 31P through 13C simply by changing
plug-in capacitors. All coils feature simple tuning, high
B1 homogeneity, external rf shield,
and susceptibility matching near the sample region.
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Effectiveness
of the litzcage coil:
Effectiveness of the litzcage coil can be seen in the 50
micron resolution of the Mouse brain and Baby Atlantic Sharpnose
Shark tail below.
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Mouse
brain at 750 MHz, 50-micron
resolution
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Baby Atlantic sharpnose
shark,
50-micron
resolution
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Both
images were taken using a 21 mm CP Litzcage rf
coil at 750 MHz inside a Doty vertical bore imaging probe.
Images
courtesy of Dan Plant, University of Florida, Brain Institute.
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Preprint
available– RF
Coil Technology for Small-Animal MRI.
Download
a preprint of “RF Coil Technology for Small-Animal MRI”,
by F. David Doty, George Entzminger, Jatin Kulkarni, Kranti Pamarthy
and John P. Staab, published in [NMR Biomed. 2007; 20: 304-325,
published online in Wiley Interscience, at www.interscience.wiley.com,
DOI: 10.1002/nbm.1149].
Download
750 MHz Imaging Poster
Please
contact sales with
questions or quote requests.
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