Prostate T(1) 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 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.

Results

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.

Conclusion

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.