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Detection and elimination of signal errors due to unintentional movements in biomedical magnetic induction tomography spectroscopy (MITS)

S. Issa
S. Issa
 und 
H. Scharfetter
H. Scharfetter
   | 31. Dez. 2018
Journal of Electrical Bioimpedance's Cover Image
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Online veröffentlicht: 31. Dez. 2018
Seitenbereich: 163 - 175
Eingereicht: 16. Dez. 2018
DOI: https://doi.org/10.2478/joeb-2018-0021
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© 2018 S. Issa, H. Scharfetter published by Sciendo
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Fig. 1

Functional mechanism of the D&E technique. Green curve: imaginary target signal, red curve: real marker signal; IoT: index of truncation. The sharp jumps in the marker signal indicate the occurrence of unwanted target movements during measurement, and help to detect the corresponding erroneous changes in the target signal, which are of too small magnitudes.
Functional mechanism of the D&E technique. Green curve: imaginary target signal, red curve: real marker signal; IoT: index of truncation. The sharp jumps in the marker signal indicate the occurrence of unwanted target movements during measurement, and help to detect the corresponding erroneous changes in the target signal, which are of too small magnitudes.

Fig. 2

Equivalent measurement model for a marked biological target in biomedical MITS. Z and R represent the impedance and resistance of the target and marker, respectively; L#, I# and V# represent the inductance, current and voltage, respectively, with respect to the indexed component; M## represents the mutual inductance between the two indexed components.
Equivalent measurement model for a marked biological target in biomedical MITS. Z and R represent the impedance and resistance of the target and marker, respectively; L#, I# and V# represent the inductance, current and voltage, respectively, with respect to the indexed component; M## represents the mutual inductance between the two indexed components.

Fig. 3

The mechanical body and elliptical coil system of the used MITS tomograph. The two-plane transceiver array is fitted in a custom-built, robust wooden table which has some kind of opening mechanism that allows positioning a test person or a large test phantom into the coil system.
The mechanical body and elliptical coil system of the used MITS tomograph. The two-plane transceiver array is fitted in a custom-built, robust wooden table which has some kind of opening mechanism that allows positioning a test person or a large test phantom into the coil system.

Fig. 4

Geometry of the transmitter (TX) and the receiver (RX) forming the transceiver. Left: front view, right: top view. All dimensions are given in [mm].
Geometry of the transmitter (TX) and the receiver (RX) forming the transceiver. Left: front view, right: top view. All dimensions are given in [mm].

Fig. 5

Experimental setup and geometry of the coil system. Top: top view, bottom: long-side view; TRX: transceiver. For the sake of clarity, the lower TX2 was made transparent and its 3D view was deactivated. The red marker in the figure is either an active or a passive one, depending on the experiment. The dotted, curved blue arrow symbolizes an unwanted (rotational) movement of the measured medium. All dimensions are given in [mm].
Experimental setup and geometry of the coil system. Top: top view, bottom: long-side view; TRX: transceiver. For the sake of clarity, the lower TX2 was made transparent and its 3D view was deactivated. The red marker in the figure is either an active or a passive one, depending on the experiment. The dotted, curved blue arrow symbolizes an unwanted (rotational) movement of the measured medium. All dimensions are given in [mm].

Fig. 6

Reconstructed images Im(Δσerr) of the rotated target medium in the error detection measurements. A: with an active marker at 500 kHz, B: with a passive marker at 500 kHz, C: with an active marker at 200 kHz, D: with a passive marker at 200 kHz. The dotted white and cyan circles mark the initial and final positions of the sphere before and after rotation, respectively.
Reconstructed images Im(Δσerr) of the rotated target medium in the error detection measurements. A: with an active marker at 500 kHz, B: with a passive marker at 500 kHz, C: with an active marker at 200 kHz, D: with a passive marker at 200 kHz. The dotted white and cyan circles mark the initial and final positions of the sphere before and after rotation, respectively.

Fig. 7

Acquired real and imaginary frames of the total received signal before and after medium rotation in the error detection measurements. A: with an active marker at 500 kHz, B: with a passive marker at 500 kHz, C: with an active marker at 200 kHz, D: with a passive marker at 200 kHz. Green curve: imaginary signal showing the signal error Im(Δverror) to be eliminated; red curve: real signal showing the detection signal Re(Δverror) to be used to detect Im(Δverror). Note the differently scaled y-axes of the graphs. The first invisible 15 frames (1 - 15) were used for phase calibration purposes [13] and are therefore not shown.
Acquired real and imaginary frames of the total received signal before and after medium rotation in the error detection measurements. A: with an active marker at 500 kHz, B: with a passive marker at 500 kHz, C: with an active marker at 200 kHz, D: with a passive marker at 200 kHz. Green curve: imaginary signal showing the signal error Im(Δverror) to be eliminated; red curve: real signal showing the detection signal Re(Δverror) to be used to detect Im(Δverror). Note the differently scaled y-axes of the graphs. The first invisible 15 frames (1 - 15) were used for phase calibration purposes [13] and are therefore not shown.

Fig. 8

Corrected versions Im(Δσcorr) of the erroneous images Im(Δσerr) in figure (6), respectively, after applying the D&E technique. The dotted white circle marks the same initial position of the sphere before rotation in the error detection measurements.
Corrected versions Im(Δσcorr) of the erroneous images Im(Δσerr) in figure (6), respectively, after applying the D&E technique. The dotted white circle marks the same initial position of the sphere before rotation in the error detection measurements.

Fig. 9

Reconstructed images Im(Δσtrue) of the non-rotated target medium in the reference measurements. The dotted white circle marks the position of the sphere which was identical to the initial position of the sphere before rotation in the error detection measurements.
Reconstructed images Im(Δσtrue) of the non-rotated target medium in the reference measurements. The dotted white circle marks the position of the sphere which was identical to the initial position of the sphere before rotation in the error detection measurements.

Some quantitative data on the corrected signals Im(Δvcorr) relevant to the corrected images Im(Δσcorr) in figure (8).

Imagef [kHz]Im(Δvcorr) [V]Im(N) [V]SNR [dB]
A500-14.11 x 10-66.15 x 10-967.21
C200-3.34 x 10-65.55 x 10-955.59
B500-14.15 x 10-66.21 x 10-967.15
D200-3.32 x 10-67.06 x 10-953.45

Some quantitative data on the true signals Im(Δvtrue) relevant to the true images Im(Δσtrue) in figure (9).

Imagef [kHz]Im(Δvtrue) [V]Im(N) [V]SNR [dB]
A500-14.21 x 10-66.65 x 10-966.60
B200-3.30 x 10-64.71 x 10-956.91

Accuracy of the corrected signals Im(Δvcorr) with respect to the true signals Im(Δvtrue). Im(Δvcorr) and Im(Δvtrue) are taken from tables (5, 7), respectively, where in case of Im(Δvcorr) there are two values per frequency because the original error detection measurements were conducted with an active and a passive marker at each frequency.

f [kHz]Im(Δvtrue) [V]Im(Δvcorr) [V]δ%
500-14.21 x 10-6-14.11 x 10-60.70
-14.15 x 10-60.42
200-3.30 x 10-6-3.34 x 10-61.21
-3.32 x 10-60.61

Some quantitative data on the corrected images Im(Δσcorr) in figure (8).

Imagef [kHz]Im(Δσcorr) [S/m]Im(Nbg) [S/m]CNR
A500-2.3134.351 x 10-253.16
C200-0.5351.183 x 10-245.22
B500-2.3194.289 x 10-254.07
D200-0.5321.233 x 10-243.15

Some quantitative data on the detection signals Re(Δverror) in figure (7).

MarkerGraphf [kHz]Re(Δverror) [V]Re(N) [V]SNR [dB]
ActiveA50018.18 x 10-64.42 x 10-972.28
C2004.75 x 10-65.90 x 10-958.12
PassiveB500-12.38 x 10-66.20 x 10-966.01
D200-7.15 x 10-64.71 x 10-963.63

Some quantitative data on the signal errors Im(Δverorr) in figure (7).

MarkerImagef [kHz]Im(Δverror) [V]Im(N) [V]SNR [dB]
ActiveA500-8.56 x 10-63.75 x 10-967.17
C200-1.96 x 10-65.01 x 10-951.85
PassiveB500-8.55 x 10-63.58 x 10-967.56
D200-1.96 x 10-65.33 x 10-951.31

Some quantitative data on the true images Im(Δσtrue) in figure (9).

Imagef [kHz]Im(Δσtrue) [S/m]Im(Nbg) [S/m]CNR
A500-2.3294.327 x 10-253.82
B200-0.5311.205 x 10-244.07

Some quantitative data on the erroneous signals Im(Δverr) relevant to the erroneous images Im(Δσerr) in figure (6).

MarkerImagef [kHz]Im(Δverr) [V]Im(N) [V]SNR [dB]
ActiveA500-10.09 x 10-64.94 x 10-966.20
C200-2.27 x 10-65.28 x 10-952.67
PassiveB500-10.11 x 10-64.91 x 10-966.27
D200-2.27 x 10-66.19 x 10-951.29

Some quantitative data on the erroneous images Im(Δσerr) in figure (6).

MarkerImagef [kHz]Im(Δσerr) [S/m]Im(Nbg) [S/m]CNR
ActiveA500-1.6612.856 x 10-258.16
C200-0.3630.815 x 10-244.54
PassiveB500-1.6632.824 x 10-258.89
D200-0.3630.802 x 10-245.26
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