Study type: Therapeutical study (experimental study)

No influence of magnetic fields on cell cycle progression using conditions relevant for patients during MRI med./bio.

By: Schiffer IB, Schreiber WG, Graf R, Schreiber EM, Jung D, Rose DM, Hehn M, Gebhard S, Sagemuller J, Spiess HW, Oesch F, Thelen M, Hengstler JG
Published in: Bioelectromagnetics 2003; 24 (4): 241-250
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Aim of study (acc. to author)

To examine whether exposure to magnetic fields relevant for magnetic resonance imaging (MRI) in clinical routine influences cell cycle progression in two tumor cell lines in vitro.

Endpoint

Exposure

Exposure Parameters
Exposure 1:
Exposure duration: continuous for 2 h
Exposure 2:
Exposure duration: continuous for 4 h or 24 h
Exposure 3: 100–200 Hz
Modulation type: pulsed
Exposure duration: intermittent, 40 s on/20 s off, for 2 h
Exposure 4: 100–200 Hz
Modulation type: pulsed
Exposure duration: intermittent, 40 s on/20 s off, for 2 h or 24 h
Exposure 5: 63.559 MHz
Modulation type: pulsed
Exposure duration: intermittent, 50 s on/10 s off, for 1 h
Exposure 6: 100 Hz–63.559 MHz
Modulation type: pulsed
Exposure duration: intermittent for 1 h as in E3 plus E5?

General information

Exposure to MFs was performed as described by Schreiber et al. [2001]. The exposed samples were located in the homogeneous center of the magnet at the isocenter of the gradient system.

Exposure 1

Main characteristics
Frequency
Type
Exposure duration continuous for 2 h
Exposure setup
Exposure source
  • clinical MR scanner
Setup For all exposures in the 1.5 T static field, T-25 cell culture bottles containing the cell suspensions were placed in a Styropor container within a heat-accumulator maintained at 36 ± 1 °C. The container was placed in the magnetic isocenter of the MR scanner.
Additional info Three different controls were also performed in three different places and under different climatic conditions.
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 1.5 T - measured - -
Additional parameter details

As a positive control, cells were exposed to 8 Gy γ irradiation from a 137Cs source at an observed dose rate of 5 Gy/min.

Measurement and calculation details

The homogeneous region and the MF strength were determined with a Hall effect sensor and NMR measurements.

Exposure 2

Main characteristics
Frequency
Type
Exposure duration continuous for 4 h or 24 h
Exposure setup
Exposure source
Setup The test vials, as well as the control samples, were kept at 37 °C by water pumped through rubber tubes surrounding the vials since the bore of the 7.05 T magnet was too small for the Styropor containers.
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 7.05 T - measured - -

Exposure 3

Main characteristics
Frequency 100–200 Hz
Type
Waveform
Exposure duration intermittent, 40 s on/20 s off, for 2 h
Additional info static MF with an additional time-varying bipolar gradient MF having spectral lines mainly at 100 and 200 Hz
Modulation
Modulation type pulsed
Pulse width 6 ms
Repetition frequency 100 Hz
Pulse type biphasic
Additional info

trapezoidal
Exposure setup
Exposure source
  • same setup as in E1 or E2
Setup The gradient MF was parallel to the static MF with its amplitude changing in a direction parallel to the cell flasks. The distance from the outer extension of the culture bottle which contained the tumour cells, to the magnet isocenter in the direction of the gradient field was less than 2.5 cm.
Additional info The full amplitude of the gradient field was present at the isocenter of the magnet.
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 1.5 T - measured - -
magnetic flux density 7.05 T - measured - -
Additional parameter details

The bipolar gradient MF of ± 10 mT/m amplitude and a slew rate of ± 10 mT/m/ms induced a maximum position dependent MF variation of 0.25 T/s in addition to the static MF. The static MF was not switched off during the measurements.

Measurement and calculation details

The power spectrum of the gradient MF was calculated by Fourier transformation of the time course.

Exposure 4

Main characteristics
Frequency 100–200 Hz
Type
Waveform
Exposure duration intermittent, 40 s on/20 s off, for 2 h or 24 h
Additional info static MF with an additional time-varying bipolar gradient MF having spectral lines mainly at 100 and 200 Hz
Modulation
Modulation type pulsed
Pulse width 6 ms
Repetition frequency 100 Hz
Pulse type biphasic
Additional info

trapezoidal
Exposure setup
Exposure source
  • same setup as in E2
Setup The exposure geometry was equivalent to the experimental settings at the 1.5 T system.
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 7.05 T - measured - -
Additional parameter details

The bipolar gradient MF of ± 100 mT/m amplitude and a slew rate of ± 100 mT/m/ms induced a maximum position dependent MF variation of 1 T/s in addition to the static MF. The static MF was not switched off during the measurements.

Exposure 5

Main characteristics
Frequency 63.559 MHz
Type
Polarization
Exposure duration intermittent, 50 s on/10 s off, for 1 h
Additional info static MF with an additional pulsed RF MF
Modulation
Modulation type pulsed
Pulse width 1 ms
Repetition frequency 50 Hz
Pulse type rectangular
Exposure setup
Exposure source
Setup The RF MF was generated by an extremity coil connected to the MR scanner and applied in a direction perpendicular to the static MF.
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 1.5 T - measured - static
magnetic flux density 5.8 µT peak value measured - RF
Measurement and calculation details

To calibrate the amplitude of the RF pulses, the automatic transmitter adjustment feature of the MR scanner was used. The static MF was not switched off during the measurements.

Exposure 6

Main characteristics
Frequency 100 Hz–63.559 MHz
Type
Waveform
Polarization
Exposure duration intermittent for 1 h as in E3 plus E5?
Additional info static MF with an additional time-varying bipolar gradient MF, having spectral lines mainly at 100 and 200 Hz, and an additional pulsed RF MF
Modulation
Modulation type cf. additional info, pulsed
Additional info

as in E3 plus E5
Exposure setup
Exposure source
  • same setup as in E3 plus E5
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 1.5 T - measured - static
magnetic flux density 5.8 µT peak value measured - RF
Additional parameter details

The bipolar gradient MF of ± 10 mT/m amplitude and a slew rate of ± 10 mT/m/ms induced a maximum position dependent MF variation of 0.25 T/s in addition to the static MF. The static MF was not switched off during the measurements.

Reference articles

Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated system:
Time of investigation:
  • after exposure

Main outcome of study (acc. to author)

No detectable effects of magnetic fields used for MRI in clinical imaging routines were observed in cell cycle analysis using the well established human leukemia HL60 cells and a second leukemia cell line (EA2 cells).

Study character:

Study funded by