DTI fiber tracking at 3T MR using b-1000 value in the depiction of periprostatic nerve before and after nervesparing prostatectomy Poster No.: C-2328 Congress: ECR 2012 Type: Scientific Paper Authors: C. Marigliano, V. Panebianco, A. Marcantonio, D. Lisi, A. Sciarra, R. Passariello; Rome/IT Keywords: Genital / Reproductive system male, MR-Diffusion/Perfusion, Surgery, Neoplasia DOI: 10.1594/ecr2012/C-2328 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. www.myesr.org Page 1 of 11
Purpose To demonstrate how Diffusion Tensor Imaging technique can improve the visualization of periprostatic Nerve describing the location and distribution of entire neurovascular plexus around the prostate before and after nerve-sparing prostatectomy. Page 2 of 11
Methods and Materials In this prospective study, 33 patients scheduled for prostatectomy (age range, 55-78 years; mean age, 64.8 ± 12.3 years) underwent MRI on a 3-Tesla scanner (Discovery MR750, GE Healthcare) equipped with an 8-channel torso phased-array coil (HD Body - GE Healthcare) and an endorectal coil (e-coil, Medrad). Patients with extracapsular cancer extension or NVB compression were not included. Prostate specific antigen (PSA) levels were not considered because our focus was on the technical feasibility of assessing anatomic structures and not on clinical aspects. Three patients were excluded due to poor image quality (blurring or artifacts). The protocol included a 2D T2-weighted fast spin echo (FSE) sequence in 3 planes, 3D T2-weighted fast imaging employing steady-state acquisition (FIESTA-C), axial DWI, and DTI acquisition (16 2 gradient directions). Particularly, a diffusion weighting b value of 1000 s/mm was used, and the DTI acquisition time was less than 4 min, while total protocol time was less than 25 min. An MR perfusion study was performed after intravenous injection of 10 ml of paramagnetic contrast medium (gadobutrol [nome Label]), followed by a 15-ml saline chaser (administered at a flow rate of 3 ml/s); the images obtained with this sequence were not analyzed in this study. Page 3 of 11
Results 3D-DTI (Figg. 1,2,3) allowed to describe the entire plexus of the periprostatic nerve fibers in all directions, while 2D and 3D T2 morphological sequences Fig. 4) were only able to depict part of the fibers, obtaining the visualization of the fibers course plane by plane; furthermore, DTI have demonstrated the fibers dispersed around the prostate on both sides without missing the significant percentage present in the anterior and anterolateral sectors (including submillimetre calber fibers). Page 4 of 11
Images for this section: Fig. 1: Fig.1 Upper left DTI (b-1000) image (TR = 5000, TE = 2,4 ) shows the ROIs traced over periprostatic tissue surrounding the peripheral zone (a), upper right image shows the correspondent fractional anisotropic map with the same ROIs (b). At the bottom the entire course of the periprostatic right and left nerve fibers is well depicted (c) and (d) after post-processing; P = prostate. Department of Radiological Sciences, University of Rome - Rome/IT Page 5 of 11
Fig. 2: Fig. 2 Coronal view of the prostate: a) the histopathologic finding shows the complexity of the neurovascular periprostatic plexus, b) anatomical view clarifies the course of the predominant component of NVB (neurovascular bundle); c) and d) DTI processed images of posterior and anterior coronal view shows respectively the irregular course of the fibers of the whole nerve plexus (yellow arrows). Department of Radiological Sciences, University of Rome - Rome/IT Page 6 of 11
Fig. 3: Fig. 3 Sagittal view of the NVB: a) histopathologic findig shows only a section of the periprostatic nerve; b) anatomical view simplifies the visualization of some fibers (B = bladder, U = urethra, R= rectum, S = seminal vescicle); c) DTI post-processing image localizes correctly the course of NVB; d) the predominant component of periprostatic lateral nerve is well shown by DTI; e) anatomical axial view of the prostatic lodge represents both side NVB; f) the NVB is entirely depicted by the DTI processed images. Department of Radiological Sciences, University of Rome - Rome/IT Page 7 of 11
Fig. 4: Fig. 4: 2D T2 weighted axial images (TR = 8500, TE = 110, FA = 110) show: prostate gland at base level (a), middle (b) and at the apex (c). 3D T2 weighted images (TR = 4.9, TE= 2.6, FA = 90) are displayed below according to the 2D T2 weighted images; d) prostate gland is shown at base level by volume viewer tool on three main planes (sagittal, coronal, axial) with volumetric representation; in e) and f) the middle third and the apex are respectively shown (the arrows indicate the predominant component of NVB); P = prostate. Department of Radiological Sciences, University of Rome - Rome/IT Page 8 of 11
Conclusion DTI MR offers the optimal representation of the widely distribution of periprostatic plexus; so it can be useful to guide proper nerve-sparing surgery, with intra-fascial or extra-fascial approach and subsequent recovery of erectile function after RP. Page 9 of 11
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