NiTi stents have been shown to permit lumen visualization with MRI, which is necessary for assessment of in-stent restenosis using MR angiography. However, device geometry influences the degree of radiofrequency shielding that the device will produce. This shielding effect reduces the RF field strength within the lumen, and therefore the effective flip angle. Owing to reciprocity, the received MR signal will also be attenuated to the same degree. Shielding effects can vary across the volume enclosed by the stent. In this study, a two-image single acquisition method is presented to quantitatively map flip angles across a selected image slice. This method overcomes errors in flip angle determination that result from imperfect slice profile effects by using a hard contrast pulse which affects one of two gradient echo images acquired in a single acquisition event. Numerical models involving integration of the Bloch equation demonstrate that flip angle estimations using slice selective image acquisition methods will produce underestimation of flip angle of as much as 15%. Models of the hard pulse method indicate that errors of less than 1% can be achieved in this estimation. Experimental data in phantom preparations with NiTi biliary stents demonstrate that lumen contrast can be improved by over 20% by increasing flip angles according to measured attenuation coefficients with the hard pulse method vs those determined using slice selective methods. The new method is suitable for use in rapid evaluation of RF attenuation throughout the volume of a stent for design assessment to improve MR imaging compatibility.