Prostate T1 Quantification Using a Magnetization-Prepared Spiral Technique

Purpose: To adapt a magnetization-prepared spiral imaging technique, termed T1prep, for time-efficient radiofrequency (RF)-insensitive prostate T-1 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 T-1 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. Results: The multislice design displayed excellent RF insensitivity (<1% error for RF mistunings to +/- 20%) and accuracy (within 3% of gold standard for T-1 values between 140 and 2100 msec). A clinical pilot study reported significantly reduced T-1 from PZ to CG to tumor subregions (PZ: 1421 +/- 168 msec, n = 11; CG: 1314 +/- 49 msec, n = 13; 1246 +/- 68 msec, it = 8). SNR measurements identified an inappropriateness of voxel-based analysis. Conclusion: T-1 prep can quantify prostate T-1 as an adjunct measure for quantitative perfusion measurements and longitudinal treatment response monitoring. Intrapatient heterogeneities support T-1 assessment within Individual patients. SNR calculations will support a transition to voxel-based analysis in future trials.