Diffusion-weighted MRI of the Prostate: Advantages of Zoomed EPI with Parallel-transmit-accelerated 2D-selective Excitation Imaging
The purpose of our study was to evaluate the use of 2D-selective, parallel-transmit excitation magnetic resonance imaging (MRI) for diffusion-weighted echo-planar imaging (pTX-EPI) of the prostate, and to compare it to conventional, single-shot EPI (c-EPI).
The MRI examinations of 35 patients were evaluated in this prospective study. PTX-EPI was performed with a TX-acceleration factor of 1.7 and a field of view (FOV) of 150 × 90 mm2, whereas c-EPI used a full FOV of 380 × 297 mm2. Two readers evaluated three different aspects of image quality on 5-point Likert scales. To quantify distortion artefacts, maximum diameters and prostate volume were determined for both techniques and compared to T2-weighted imaging.
The zoomed pTX-EPI was superior to c-EPI with respect to overall image quality (3.39 ± 0.62 vs 2.45 ± 0.67) and anatomic differentiability (3.29 ± 0.65 vs 2.41 ± 0.65), each with p < 0.0001. Artefacts were significantly less severe in pTX-EPI (0.93 ± 0.73 vs 1.49 ± 1.08), p < 0.001. The quantitative analysis yielded a higher agreement of pTX-EPI with T2-weighted imaging than c-EPI with respect to coronal (ICCs: 0.95 vs 0.93) and sagittal (0.86 vs 0.73) diameters as well as prostate volume (0.94 vs 0.92). Apparent diffusion coefficient (ADC) values did not differ significantly between the two techniques (p > 0.05).
Zoomed pTX-EPI leads to substantial improvements in diffusion-weighted imaging (DWI) of the prostate with respect to different aspects of image quality and severity of artefacts.
• Recent technical developments in MRI allow the use of accelerated, spatially-selective excitation (parallel-transmit, pTX)
• pTX can be used for zoomed echo-planar prostate imaging (pTX-EPI)
• pTX-EPI improves different aspects of image quality in prostate MRI
• Distortion artefacts are reduced by the use of pTX-EPI in prostate MRI
• Further studies should aim at assessing the diagnostic accuracy of pTX-EPI
KeywordsParallel-transmit pTX-acceleration Echo-planar imaging Zoom-EPI Prostate
Apparent diffusion coefficient
Benign prostatic hyperplasia
Conventional EPI (full field of view)
Echo train length
Field of view
Intraclass correlation coefficient
Region of interest
Echo-planar imaging using parallel transmission technology
The scientific guarantor of this publication is Kolja M. Thierfelder. The authors of this manuscript declare no relationships with any companies whose products or services may be related to the subject matter of the article. The authors state that this work has not received any funding. No complex statistical methods were necessary for this paper. Institutional Review Board approval was obtained. Written informed consent was obtained from all subjects (patients) in this study. Methodology: prospective, diagnostic study, performed at one institution.
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