T2-weighted prostate imaging using echo-planar imaging at 3T

Purpose: T2‐weighting in fast spin echo (FSE) images is unavoidably affected by T1‐mixing due to stimulated echoes. The purpose of this research is to evaluate the feasibility of using a multishot echo‐planar (EPI) technique to image the prostate at 3 Tesla without an endorectal coil and to compare T2 quantification using EPI with that based off of FSE images. Method and Materials: All experiments were performed on a GE Signa 3 Tesla whole body scanner with an 8‐channel torso phased‐array coil. T2‐weighted images were acquired of a healthy volunteer at echo times (TEs) of 40, 80 and 110 ms with a multishot spin‐echo EPI. Other imaging parameters were: 32cm FOV, 16 shots, TR = 2000ms, acquisition matrix = 256×512, receiver bandwidth = ±250 kHz. FSE images were obtained of the same volunteer with TEs of 60, 120, and 180ms and these acquisition parameters: 16cm FOV, TR = 3900ms, acquisition matrix = 256×256, ETL = 16, bandwidth = ±32kHz. A total of eleven slices covering the entire prostate were collected using both techniques. Results: The EPI images showed few artifacts and were noted to provide better T2‐contrast than the FSE images. For a region‐of‐interest in the peripheral zone of the prostate, T2 values derived from FSE images (134±15 ms) are substantially larger than those based on EPI images (76±1 ms). This observation is consistent with the apparent lengthening of T2 due to T1 mixing in FSE images. Conclusion: Using EPI with high receiver bandwidth, our results indicate that high quality T2‐weighted images of the prostate can be obtained at 3T without an endorectal coil. T2‐weighted images by EPI provide pure T2‐contrast and possibly more accurate T2‐determination than conventional FSE images. © 2005, American Association of Physicists in Medicine. All rights reserved.