• Journal of Biomedical Engineering Research
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• v.18 no.1
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• pp.87-96
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• 1997

A pixel profile in the conventional DANTE sequence is so poor that the excited area by DANTE sequence is a small portion of a pixel. This causes poor signal to noise ratio in DANTE image. In this paper, a frequency modulated(FM) DANTE imaging sequence is proposed to improve pixel profile in DANTE image. A DANTE pulse train is shaped by an FM function so that all the spins within a pixel are excited, thereby improving the signal to noise ratio. It also shows that the pixel profiles are dependent on the sweep in FM signal. Computer simulations and experimental result obtained using a 7.0 T NMR imaging system are presented.

• Proceedings of the KOSOMBE Conference
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• v.1995 no.05
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• pp.42-44
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• 1995

The original DANTE sequence and its variations have limitation in excitation profile (a sinc function-like excitation) due to the finite duration of the DANTE pulsetrain. This sinc function-like selection profile excites only a small fraction of the spins in the pixel thereby results in poor signal to noise ratio (only about ${\sim}1%$ of normal MR imaging sequence). Therefore, this poor signal to noise ratio (SNR) has been the main drawback of the original DANTE sequence. To improve the signal to noise ratio, phases of individual RF pulses in the DANTE pulse train were modulated so that more spins in the object were excited ($1{\sim}3$). We have introduced a new FM (Frequency Modulation) DANTE sequence and analyzed the signal intensity and excitation profiles.