Practical considerations in T1 mapping of prostate for dynamic contrast enhancement pharmacokinetic analyses.

There are many challenges in developing robust imaging biomarkers that can be reliably applied in a clinical trial setting. In the case of dynamic contrast-enhanced (DCE) MRI, one such challenge is to obtain accurate precontrast T(1) maps for subsequent use in two-compartment pharmacokinetic models commonly used to fit the MR enhancement time courses. In the prostate, a convenient and common approach for this task has been to use the same 3D spoiled gradient-echo sequence used to collect the DCE data, but with variable flip angles (VFAs) to collect data suitable for T(1) mapping prior to contrast injection. However, inhomogeneous radiofrequency conditions within the prostate have been found to adversely affect the accuracy of this technique. Herein we demonstrate the sensitivity of DCE pharmacokinetic parameters to precontrast T(1) values and examine methods to improve the accuracy of T(1) mapping with flip angle-corrected VFA SPGR methods, comparing T(1) maps from such methods with "gold standard" reference T(1) maps generated with saturation recovery experiments performed with fast spin-echo (FSE) sequences.