| 摘要 |
PURPOSE: To expand a test range by setting a first pulse within a pulse row containing at least four rf pulses to a frequency selecting 90 deg. exciting pulse and setting either one of the rf pulse continuing to the first pulse and the rf pulse continuing to a third pulse to a re-focusing pulse. CONSTITUTION: A measuring sequence is started by a pulse P1 being a 90 deg. exciting pulse and at least one 180 deg. time reversal pulse Pn is allowed to succeed to this pulse P1 after a standby periodτni . After the standby periodτni, one other rf pulse or sevelal rf pulses Pni can be succeeded. The pulse row Pni of 180 deg. can be set, for example, to the same frequency selection pulse and, by this constitution, a signal can be improved. An inclined magnetic field is applied or not applied to a final 180 deg. time reversal pulse Pni or Pn after a standby periodτ2 during a period of second 90 deg. exciting pulses P2 , Pn or Pni or Pn2 and/or between these pulses.
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