However the longer RF pulses required to obtain a more rectangular tag profile may not be optimal since the decrease in the tag center estimation error is small. The other factor effecting the tag center estimation error is the line spread function. As the high frequency components of the line spread function increase, the error decreases. Here the limitation for increasing the high frequency components of the line spread function is the imaging method itself. The truncation of the k-space data is one of the important factors.
Truncation causes a sinc type point spread function.
All the other possible sources that may effect the point spread function broaden the sinc. Thus by increasing the imaging quality, the tag center estimation error can be decreased. The tag center estimation is proportional to the pixel separation. However, decreasing the pixel separation results in a diminished contrast to noise ratio which is inversely proportional with the error. Therefore increasing the image resolution may not decrease the tag center estimation error.