Resonator

No
 
1

2

3


Radius of ring resonator

R_{imp}

[mm]

18

5.55

1.5

Length of ring resonator

L_{imp}

[mm]

50

9.9

14

Dimension of ring wire axial

x_{wire}

[mm]

0.25

0.15

0.10

Dimension of ring wire radial

r_{wire}

[mm]

0.25

0.15

0.10

Number of rings (turns)

n_{r}
 
2

6

12

Volume of implant

V_{imp}

[cm^{3}]

50

1

0.1

Quality factor

Q
 
5

12.5

80

Total power loss of resonator

P_{loss}

[mW]

1000

50

32

SAR inside resonator (Eq. (3b))

SAR_{internal}

[W/kg]

1.8

1.7

5.1

Power loss of resonator due to SAR

P_{SAR}

[mW]

0.09

0.0016

0.0005

 Power losses P_{SAR} and P_{loss} are calculated for the MR sequence of Table 2. SAR_{internal} is evaluated with Eq. (3b). P_{SAR} can be calculated using SAR_{internal} and the mass inside the inductor (m_{imp} = ρ_{tissue} V_{imp}), whereas P_{loss} is calculated with the appropriate constants according to Eq. (7). P_{loss} for resonator no 2 was verified experimentally with temperature increase measurements after placing the resonator inside a phantom with known heat capacity.