Exposures of 8 h duration were made on day 9 and/or day 12 of gestation. Effects of a combined treatment regime using continuous wave, ultrasound (1 MHz unfocused, without MRI) on day 9 and MRI on day 12 were also investigated. Fetal data were taken on day 18 of gestation. Data from adult animals that were exposed in utero were taken on day 50 postpartum.
animals were treated in seven groups: i) sham ii) MRI exposure on day 9 of gestation iii) MRI exposure on day 12 of gestation iv) MRI exposure on day 9 and day 12 of gestation v) ultrasound exposure on day 9 and MRI exposure on day 12 vi) sham exposure on day 9 and MRI exposure on day 12 vii) ultrasound exposure on day 9 and sham exposure on day 12
|Pulse width||5 ms|
Spin echo sequence with standard characteristics (TR/TE 2000/30 ms) was applied.
|Exposure duration||30 s|
|power density||5 W/cm²||-||-||-||-|
Significant differences in biological endpoints following in utero exposure to complex MRI field conditions were revealed.
Fetal weights of the irradiated groups ranged from 11% (day 9 MRI) to 17% (day 9 ultrasound, day 12 MRI) lower than those of the cage control and sham-exposed fetuses. Crown-rump length of exposed animals was reduced by 8%. The postpartum death rate increased significantly and was as high as 38% following MRI exposure on day 9 and day 12 of gestation. Daily sperm production was reduced by 44% in adults exposed to MRI on day 12 of gestation. A reduction in testis weight and volume in the adult males was also found, but the difference was not statistically significant.
No effect was revealed on embryonic deaths, sex ratio, body weight at day 50, spleen weight, or seminal vesicle weight.
The data show that in utero exposure of mice to high field, long duration MRI conditions alone or in combination with ultrasound exposure reduces fetal growth, neonatal survival, and male reproductive development when it occurs during sensitive times of the developmental cycle (day 9 and/or day 12), and that some of these effects are permanent.