RF transmission in MRI

[jobinshere@gmail.com]

Hi i have some Doubt in the RF Transmission in MRI Scanner.
1.Mainly the [b]theory behind the impedance matching importance in RF transmission,how it is happening while RF Transmission.

2.And is this RF is like a oscillating current to the body coil of the scanner to create RF.

3.Once the RF is emitted,if iam using a 3.0T scanner the larmour frequency will be 127.74MHz,will the RF will be pulsed only in one frequency which is 127.74 to create the resonance and to get image.

4.And if the gradient slope is applied in isocentre, frequncy will be 127.74MHz and i have acquired the signal,and what will be done if i wanted to acquire the image from nearby area which having spin difference 128.00MHZ will the table will move to isocentre to acquire the image or the RF frequency from the RF amp will change to 128 MHZ to resonate that area.

Thanks in advance
Jobins