Larger RF Coils – Knee, Extremities or Primate Head

Knee, Other Extremities, or Primate Head High-Field RF Imaging Coils

Doty rf Litz and Litzcage Modules

  • Highest homogeneity
  • Highest S/N
  • Quick, simple tuning for all sample sizes
  • Double-resonance, multi-nuclear tuning available

Knee imaging at high fields with conventional coils has often been problematic because of the enormous difference in loading between a small and a large patient. The unique tuning/balancing methods utilized in all Doty coils make tune-up predictable, simple, and quick.  

image001_005Newknee2Aa

  3 T Knee Image – Sagittal                            3T Knee Image – Axial

Images are from a 3 T Doty linear Litz coil.

Images courtesy of Dr. Qing X. Yang,

Hershey Medical Center, Penn State University.

       

18 x 18 cm FOV CP Litzcage Knee Coils

1H

MHz

τ 90

μ s

Square pulse,

Power, W

Light load

Heavy load

64

120

180

1000

80

100

350

1500

125

100

500

1500

170

125

500

1500

200

150

500

1500

Light load – 35 mM Saline,  

Heavy Load – 100 mM Saline, at 75% of ID

Our linear Litz coils are recommended for double-resonance applications, and their exceptional sensitivity and homogeneity are demonstrated in the images shown above. Typical efficiency of a double-resonance Litz coil is illustrated in the table below.

18 x 18 cm FOV H/P Litz Knee Coils

Tuning

1H

MHz

Light Load

τ 90(μs) @ 500W

Heavy Load

τ 90(μs) @ 1 kW

1H

31P
1H
31P

1H/X

64

100

170

110

130

1H/X

80

120

180

130

150

1H/X

125

150

230

200

200

Light load – 35 mM  Saline,  

Heavy Load – 100 mM Saline, at 75% of ID

 

Other Typical RF Litz Volume Coils

Clear I.D. mm

O.D. mm

Tuning

1H

MHz

Moderate Load

τ 90(μs) @ 500 W

Heavy Load

τ 90(μs) @ 1 kW

1H

31P
1H
31P

100

150

1H
128

36

82

100

150

1H/X
200

58

80

110

160

130

200

1H/X
170

85

110

160

200
135
200
1H
128
70
130
150
220
1H
128
90
200
150
230
1H/X
128
100
140
210
200
150
220
1H
170
120
270
200
300
1H/X
128
160
320
300
340

Length of the homogeneous region – 80% of the coil ID

Moderate load – 50 mM  Saline, 70% of the coil ID 

Heavy Load – 100 mM Saline, 75% of the coil ID

Our passive CP “Litzcages” (no integral preamps or switches) have consistently demonstrated dramatically superior B1 homogeneity and improved S/N in independent comparisons to conventional birdcages and TEM resonators at frequencies from 125 MHz to 750 MHz.  Moreover, our knee coils include window slots to facilitate accurate positioning and monitoring.

The S/N of these coils is superior to that of other semi-open coils of similar FOV, and the B1homogeneity can only be described as extraordinary.

For additional information about the Doty Litz coil design:

F. David Doty, George Entzminger Jr, and Cory D. Hauck,”Error-Tolerant RF Litz Coils for NMR/MRI”, J. Magn. Reson.,1999, 140:17-31.

image004_025

RF Litz coil module

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