Verde Ana S C, Santinha Joao, Carrasquinha Eunice, Loucao Nuno, Gaivao Ana, Fonseca Jorge, Matos Celso, Papanikolaou Nikolaos
Head of Computational Clinical Imaging Group, Centre for the Unknown, Champalimaud Foundation, Av. Brasilia, 1400-038, Lisbon, Portugal.
Philips Healthcare, Lisbon, Portugal.
Insights Imaging. 2020 Nov 27;11(1):126. doi: 10.1186/s13244-020-00927-x.
To study the diffusion tensor-based fiber tracking feasibility to access the male urethral sphincter complex of patients with prostate cancer undergoing Retzius-sparing robot-assisted laparoscopic radical prostatectomy (RS-RARP).
Twenty-eight patients (median age of 64.5 years old) underwent 3 T multiparametric-MRI of the prostate, including an additional echo-planar diffusion tensor imaging (DTI) sequence, using 15 diffusion-encoding directions and a b value = 600 s/mm. Acquisition parameters, together with patient motion and eddy currents corrections, were evaluated. The proximal and distal sphincters, and membranous urethra were reconstructed using the deterministic fiber assignment by continuous tracking (FACT) algorithm, optimizing fiber tracking parameters. Tract length and density, fractional anisotropy (FA), axial diffusivity (AD), mean diffusivity (MD), and radial diffusivity (RD) were computed. Regional differences between structures were accessed by ANOVA, or nonparametric Kruskal-Wallis test, and post-hoc tests were employed, respectively, TukeyHSD or Dunn's.
The structures of the male urethral sphincter complex were clearly depicted by fiber tractography using optimized acquisition and fiber tracking parameters. The use of eddy currents and subject motion corrections did not yield statistically significant differences on the reported DTI metrics. Regional differences were found between all structures studied among patients, suggesting a quantitative differentiation on the structures based on DTI metrics.
The current study demonstrates the technical feasibility of the proposed methodology, to study in a preoperative setting the male urethral sphincter complex of prostate cancer patients candidates for surgical treatment. These findings may play a role on a more accurate prediction of the RS-RARP post-surgical urinary continence recovery rate.
研究基于扩散张量的纤维追踪技术在评估接受保留Retzius间隙机器人辅助腹腔镜根治性前列腺切除术（RS-RARP）的前列腺癌患者男性尿道括约肌复合体方面的可行性。
28例患者（中位年龄64.5岁）接受了前列腺的3T多参数MRI检查，包括一个额外的回波平面扩散张量成像（DTI）序列，使用15个扩散编码方向且b值=600 s/mm²。对采集参数以及患者运动和涡流校正进行了评估。使用确定性纤维分配连续追踪（FACT）算法重建近端和远端括约肌以及膜部尿道，并优化纤维追踪参数。计算纤维束长度和密度、分数各向异性（FA）、轴向扩散率（AD）、平均扩散率（MD）和径向扩散率（RD）。通过方差分析或非参数Kruskal-Wallis检验评估结构之间的区域差异，并分别采用TukeyHSD或Dunn事后检验。
使用优化的采集和纤维追踪参数，通过纤维束成像能够清晰描绘男性尿道括约肌复合体的结构。使用涡流和受试者运动校正对报告的DTI指标没有产生统计学上的显著差异。在研究的所有患者结构之间发现了区域差异，表明基于DTI指标对结构进行了定量区分。
本研究证明了所提出方法的技术可行性，即在术前评估中研究拟行手术治疗的前列腺癌患者的男性尿道括约肌复合体。这些发现可能有助于更准确地预测RS-RARP术后尿失禁的恢复率。
