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. Author manuscript; available in PMC: 2020 Oct 1.
Published in final edited form as: IEEE Trans Med Imaging. 2019 Feb 11;38(10):2389–2399. doi: 10.1109/TMI.2019.2898202

Fig. 8. Experimental relationships and theoretical expectations between pulsed waveform amplitude and pulsed MPI performance for 27.4 nm particles.

Fig. 8.

A 2.5 kHz square wave with varying amplitudes was used. (a) Pulsed MPI 1D point-spread functions show higher signal but worse resolution with increasing excitation amplitude. (b) Spatial resolution improves and approaches that of the Langevin model as the excitation amplitude → 0. The results match our theory as our approach to integrating the time domain signal for each half-period collapses all of the information of the half-period into a single value. Mathematically this presents as convolution of the ideal with a rectangular function. (c) Pulsed MPI peak signal improves with increasing excitation amplitude as a larger portion of the tracer’s M-H curve is covered per pulse. Amplitude is therefore a flexible way of trading off spatial resolution and SNR.