Readout-segmented echo-planar diffusion-weighted imaging improves geometric performance for image-guided radiation therapy of pelvic tumors

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• 作者：Warren D. Foltz^a ; ^{warren.foltz@rmp.uhn.on.ca" class="auth_mail" title="E-mail the corresponding author} ; David A. Porter^b ; Anna Simeonov^a ; Amanda Aleong^a ; David Jaffray^a ; Peter Chung^a ; Kathy Han^a ; Cynthia Mé ; nard^a
• 关键词：Prostate cancer ; Cervical cancer ; MRI ; Diffusion weighted imaging ; Geometric distortion ; Image-guided radiotherapy
• 刊名：Radiotherapy and Oncology
• 出版年：2015
• 出版时间：December 2015
• 年：2015
• 卷：117
• 期：3
• 页码：525-531
• 全文大小：1219 K

文摘

Diffusion-weighted imaging using echo-planar imaging (EPI) is prone to geometric inaccuracy, which may limit application to image-guided radiation therapy planning, as well as for voxel-based quantitative multi-parametric or multi-modal approaches. This research investigates pelvic applications at 3 T of a standard single-shot (ssEPI) and a prototype readout-segmented (rsEPI) technique.

Materials and methods

Apparent diffusion coefficient (ADC) accuracy and geometric performance of rsEPI and ssEPI were compared using phantoms, and in vivo, involving 8 patients prior to MR-guided brachytherapy for locally advanced cervical cancer, and 19 patients with prostate cancer planned for tumor-targeted radiotherapy. Global and local deviations in geometric performance were tested using Dice Similarity Coefficients (DC) and Hausdorff Distances (HD).

Results

In cervix patients, DC increased from 0.76 ± 0.14 to 0.91 ± 0.05 for the high risk clinical target volume, and 0.62 ± 0.26 to 0.85 ± 0.08 for the gross tumor target volume. Tumors in the peripheral zone of the prostate gland were partly projected erroneously outside of the posterior anatomic boundary of the gland by 3.1 ± 1.6 mm in 11 of 19 patients using ADC-ssEPI but not with ADC-rsEPI.

Conclusions

Both cervix and prostate ssEPI are prone to clinically relevant geometric distortions at 3 T. rsEPI provides improved geometric performance without post-processing.