研究のタイプ: 治療に関する研究 (experimental study)

[MRI時の患者に関係する条件による細胞周期に対する磁界の影響はない] med./bio.

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

著者: 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
掲載誌: Bioelectromagnetics 2003; 24 (4): 241-250
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この研究は、臨床用の磁気共鳴画像法（MRI）に関連する磁界（MF）へのばく露をインビトロで実施し、2つの腫瘍細胞株（HL60およびEA2）の細胞周期の進行に影響するか否かを調べた。ばく露したMFは4タイプ、（i）静磁界（1.5および7.05 T）、（ii）超低周波傾斜磁界（ELFMGF：100 Hzで±10 mT/ mの傾斜、または100 Hzで±100 mT/ m傾斜、（iii）無線周波数（RF）範囲のパルス化高周波MF（63.6 MHz、5.8 µT）、（iv）（i-iii）の組み合わせ、である。ばく露期間は1〜24時間とした。細胞周期分布（G（0）/ G（1）、S、およびG（2）/ M）を、フローサイトメトリーによって分析した。その結果、細胞周期分析では、ばく露細胞と対照細胞に差は見られなかった；予想どおり、放射線照射（8 Gy）を受けたHL60およびEA2細胞の陽性対照は、強いG（2）/ M停止を示した、と報告している。

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研究目的（著者による）

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.

影響評価項目

ばく露

ばく露 パラメータ
ばく露1:
  • DC/static
ばく露時間: continuous for 2 h
ばく露2:
  • DC/static
ばく露時間: continuous for 4 h or 24 h
ばく露3: 100–200 Hz
Modulation type: pulsed
ばく露時間: intermittent, 40 s on/20 s off, for 2 h
ばく露4: 100–200 Hz
Modulation type: pulsed
ばく露時間: intermittent, 40 s on/20 s off, for 2 h or 24 h
ばく露5: 63.559 MHz
Modulation type: pulsed
ばく露時間: intermittent, 50 s on/10 s off, for 1 h
ばく露6: 100 Hz–63.559 MHz
Modulation type: pulsed
ばく露時間: 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.

ばく露1

主たる特性
周波数
  • DC/static
タイプ
  • magnetic field
ばく露時間 continuous for 2 h
ばく露装置
ばく露の発生源／構造
  • clinical MR scanner
ばく露装置の詳細 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 information Three different controls were also performed in three different places and under different climatic conditions.
パラメータ
測定量 値 種別 Method Mass 備考
磁束密度 1.5 T - 測定値 - -
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.

測定および計算の詳細

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

ばく露2

主たる特性
周波数
  • DC/static
タイプ
  • magnetic field
ばく露時間 continuous for 4 h or 24 h
ばく露装置
ばく露の発生源／構造
  • 89 mm bore superconducting laboratory NMR magnet system
ばく露装置の詳細 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.
パラメータ
測定量 値 種別 Method Mass 備考
磁束密度 7.05 T - 測定値 - -

ばく露3

主たる特性
周波数 100–200 Hz
タイプ
  • magnetic field
波形
  • pulsed
ばく露時間 intermittent, 40 s on/20 s off, for 2 h
Additional information 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 information

trapezoidal
ばく露装置
ばく露の発生源／構造
  • same setup as in E1 or E2
ばく露装置の詳細 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 information The full amplitude of the gradient field was present at the isocenter of the magnet.
パラメータ
測定量 値 種別 Method Mass 備考
磁束密度 1.5 T - 測定値 - -
磁束密度 7.05 T - 測定値 - -
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.

測定および計算の詳細

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

ばく露4

主たる特性
周波数 100–200 Hz
タイプ
  • magnetic field
波形
  • pulsed
ばく露時間 intermittent, 40 s on/20 s off, for 2 h or 24 h
Additional information 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 information

trapezoidal
ばく露装置
ばく露の発生源／構造
  • same setup as in E2
ばく露装置の詳細 The exposure geometry was equivalent to the experimental settings at the 1.5 T system.
パラメータ
測定量 値 種別 Method Mass 備考
磁束密度 7.05 T - 測定値 - -
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.

ばく露5

主たる特性
周波数 63.559 MHz
タイプ
  • electromagnetic field
偏波
  • linear
ばく露時間 intermittent, 50 s on/10 s off, for 1 h
Additional information static MF with an additional pulsed RF MF
Modulation
Modulation type pulsed
Pulse width 1 ms
Repetition frequency 50 Hz
Pulse type rectangular
ばく露装置
ばく露の発生源／構造
  • E1と同じ装置
  • plus extremity coil for RF MF
ばく露装置の詳細 The RF MF was generated by an extremity coil connected to the MR scanner and applied in a direction perpendicular to the static MF.
パラメータ
測定量 値 種別 Method Mass 備考
磁束密度 1.5 T - 測定値 - static
磁束密度 5.8 µT peak 測定値 - RF
測定および計算の詳細

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.

ばく露6

主たる特性
周波数 100 Hz–63.559 MHz
タイプ
  • electromagnetic field
波形
  • pulsed
偏波
  • linear
ばく露時間 intermittent for 1 h as in E3 plus E5?
Additional information 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 information, pulsed
Additional information

as in E3 plus E5
ばく露装置
ばく露の発生源／構造
  • same setup as in E3 plus E5
パラメータ
測定量 値 種別 Method Mass 備考
磁束密度 1.5 T - 測定値 - static
磁束密度 5.8 µT peak 測定値 - 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

ばく露を受けた生物:

方法 影響評価項目／測定パラメータ／方法

研究対象とした生物試料:
調査の時期:
  • ばく露後

研究の主なアウトカム（著者による）

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).

研究の種別:

研究助成