First: To study the dye permeability (Evans blue) of the blood-brain barrier after exposure to components of the MRI electromagnetic fields. Static magnetic fields, low frequency magnetic fields, radiofrequency electromagnetic fields (RF), and a combination of these three types of fields were applied to Sprague-Dawley rats in these experiments.
Second: To study the leakage of endogenous albumin and fibrinogen during exposure to microwaves of 915 MHz (CW and modulated at various low frequencies (8-215 Hz)). In these experiments Fischer 344 rats were used.
| Exposure | Parameters |
|---|---|
|
Exposure 1:
Exposure duration:
continuous for 2 h
|
- |
|
Exposure 2:
Modulation type:
pulsed
Exposure duration:
continuous for 2 h
|
|
|
Exposure 3:
Modulation type:
pulsed
Exposure duration:
continuous for 2 h
|
|
|
Exposure 4:
915 MHz
Modulation type:
CW
|
|
|
Exposure 5:
915 MHz
Modulation type:
pulsed
|
|
|
Exposure 6:
Exposure duration:
continuous for 1 h
|
|
| Frequency | |
|---|---|
| Type | |
| Waveform | |
| Exposure duration | continuous for 2 h |
| Additional info | low frequency pulsed magnetic field (TVMF) |
| Modulation type | unspecified |
|---|
| Exposure source |
|
|---|
No parameters are specified for this exposure.
| Frequency | |
|---|---|
| Type | |
| Exposure duration | continuous for 2 h |
| Additional info | RF electromagnetic field (RF) |
| Modulation type | pulsed |
|---|---|
| Repetition frequency | 1 Hz |
| Additional info |
pulse width of 400 to 800 ms |
| Exposure source |
|
|---|
| Measurand | Value | Type | Method | Mass | Remarks |
|---|---|---|---|---|---|
| power | 0.2 W | - | - | - | - |
| Modulation type | pulsed |
|---|---|
| Repetition frequency | 1 Hz |
| Additional info |
pulse width of 400 to 800 ms |
| Exposure source |
|
|---|
| Measurand | Value | Type | Method | Mass | Remarks |
|---|---|---|---|---|---|
| magnetic flux density | 0.08 T | - | - | - | SMF |
| power | 0.2 W | - | - | - | RF |
| Frequency | 915 MHz |
|---|---|
| Type | |
| Charakteristic |
|
| Modulation type | pulsed |
|---|---|
| Additional info |
pulse rates of 8, 16, 50, and 215 Hz pulse widths of 0.6 to 4 ms |
| Frequency | |
|---|---|
| Type | |
| Exposure duration | continuous for 1 h |
| Additional info | spin echo MRI examination |
| Exposure source |
|
|---|
| Measurand | Value | Type | Method | Mass | Remarks |
|---|---|---|---|---|---|
| magnetic flux density | 2.35 T | - | - | - | - |
The conclusion is that radiofrequency radiation has a increasing effect on the permeability of the blood-brain barrier. The effect was found for CW radiation and more pronounced for pulsed RF radiation. The effect of MRI high field exposure could not be confirmed.
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