To adapt a magnetization-prepared spiral imaging technique, termed T1prep, for time-efficient radiofrequency (RF)-insensitive prostate T1 quantification at 1.5 T and evaluate signal-to-noise ratio (SNR) limits to voxel-based versus subregion analysis.
Materials and Methods
A magnetization-prepared spiral imaging technique was adapted for robust T1 contrast development, multislice imaging within 5 minutes, and data regression to a monoexponential decay. In vitro testing evaluated RF insensitivity of the multislice acquisition plus method accuracy. A pilot study was performed in 15 patients with low or intermediate risk localized prostate cancer.
The multislice design displayed excellent RF insensitivity (<1% error for RF mistunings to ± 20%) and accuracy (within 3% of gold standard for T1 values between 140 and 2100 msec). A clinical pilot study reported significantly reduced T1 from PZ to CG to tumor subregions (PZ: 1421 ± 168 msec, n = 11; CG: 1314 ± 49 msec, n = 13; 1246 ± 68 msec, n = 8). SNR measurements identified an inappropriateness of voxel-based analysis.
T1prep can quantify prostate T1 as an adjunct measure for quantitative perfusion measurements and longitudinal treatment response monitoring. Intrapatient heterogeneities support T1 assessment within individual patients. SNR calculations will support a transition to voxel-based analysis in future trials. J. Magn. Reson. Imaging 2011. © 2011 Wiley-Liss, Inc.