MRI-based 3D pelvic autonomous innervation: a first step towards image-guided pelvic surgery

Robot-Assisted Pull-Through for Anorectal Malformations: Comparative Observational Study of Functional Outcomes with an Open Approach

Introduction: Robotic surgery has gained acceptance in the field of pediatric surgery but is still under assessment. Some limitations of this device are particularly encountered when performing specific tasks in small cavities, such as neonatal pelvis. The aim of this study was to compare the functional results of robot-assisted anorectal pull-through (RAARP) with posterior sagittal anorectoplasty (PSARP) in children with "high" types of anorectal malformations (ARMs). Materials and Methods: In this multicenter experience, we reviewed the patients operated for ARMs using the da Vinci® system between 2007 and 2020 in our national robotic program. Two groups of patients according to the surgical technique (robotic versus open) were compared based on the postoperative outcomes and long-term functional results using Kelly and Krickenbeck scores at 3 years of age. Results: Ten patients operated using RAARP were compared with 10 patients operated using PSARP (mean weight 8.1 ± 1.2 kg versus 8.6 ± 1.1 kg, respectively). The two groups were comparable in terms of the ARM classification and patient demographics. The clinical Kelly score was significantly lower for the PSAAP group (P = .012). The Krickenbeck constipation score was significantly lower for the RAARP group (P = .02), whereas no statistical difference was found for the soiling score and voluntary bowel movements. Conclusions: A concomitant laparoscopic approach using a robotic platform appears to be an alternative technique to the criterion standard for performing anorectal malformation surgery with satisfactory functional results. The enhanced potential of preserving perirectal nerves requires confirmation through longer follow-up studies focusing on functional assessment.

Current and future role of three-dimensional modelling technology in rectal cancer surgery: A systematic review

BACKGROUND

Three-dimensional (3D) modelling technology translates the patient-specific anatomical information derived from two-dimensional radiological images into virtual or physical 3D models, which more closely resemble the complex environment encountered during surgery. It has been successfully applied to surgical planning and navigation, as well as surgical training and patient education in several surgical specialties, but its uptake lags behind in colorectal surgery. Rectal cancer surgery poses specific challenges due to the complex anatomy of the pelvis, which is difficult to comprehend and visualise.

AIM

To review the current and emerging applications of the 3D models, both virtual and physical, in rectal cancer surgery.

METHODS

Medline/PubMed, Embase and Scopus databases were searched using the keywords "rectal surgery", "colorectal surgery", "three-dimensional", "3D", "modelling", "3D printing", "surgical planning", "surgical navigation", "surgical education", "patient education" to identify the eligible full-text studies published in English between 2001 and 2020. Reference list from each article was manually reviewed to identify additional relevant papers. The conference abstracts, animal and cadaveric studies and studies describing 3D pelvimetry or radiotherapy planning were excluded. Data were extracted from the retrieved manuscripts and summarised in a descriptive way. The manuscript was prepared and revised in accordance with PRISMA 2009 checklist.

RESULTS

Sixteen studies, including 9 feasibility studies, were included in the systematic review. The studies were classified into four categories: feasibility of the use of 3D modelling technology in rectal cancer surgery, preoperative planning and intraoperative navigation, surgical education and surgical device design. Thirteen studies used virtual models, one 3D printed model and 2 both types of models. The construction of virtual and physical models depicting the normal pelvic anatomy and rectal cancer, was shown to be feasible. Within the clinical context, 3D models were used to identify vascular anomalies, for surgical planning and navigation in lateral pelvic wall lymph node dissection and in management of recurrent rectal cancer. Both physical and virtual 3D models were found to be valuable in surgical education, with a preference for 3D printed models. The main limitations of the current technology identified in the studies were related to the restrictions of the segmentation process and the lack of 3D printing materials that could mimic the soft and deformable tissues.

CONCLUSION

3D modelling technology has potential to be utilised in multiple aspects of rectal cancer surgery, however, it is still at the experimental stage of application in this setting.

Visualizing the autonomic and somatic innervation of the female pelvis with 3D MR neurography: a feasibility study

BACKGROUND

Treatment of female pelvic malignancies often causes pelvic nerve damage. Magnetic resonance (MR) neurography mapping the female pelvic innervation could aid in treatment planning.

PURPOSE

To depict female autonomic and somatic pelvic innervation using a modified 3D NerveVIEW sequence.

MATERIAL AND METHODS

Prospective study in 20 female volunteers (n = 6 normal, n = 14 cervical pathology) who underwent a modified 3D short TI inversion recovery (STIR) turbo spin-echo (TSE) scan with a motion-sensitive driven equilibrium (MSDE) preparation radiofrequency pulse and flow compensation. Modifications included offset independent trapezoid (OIT) pulses for inversion and MSDE refocusing. Maximum intensity projections (MIP) were evaluated by two observers (Observer 1, Observer 2); image quality was scored as 2 = high, 1 = medium, or 0 = low with the sciatic nerve serving as a reference. Conspicuity of autonomic superior (SHP) and bilateral inferior hypogastric plexuses (IHP), hypogastric nerves, and somatic pelvic nerves (sciatic, pudendal) was scored as 2 = well-defined, 1 = poorly defined, or 0 = not seen, and inter-observer agreement was determined.

RESULTS

Images were of medium to high quality according to both observers agreeing in 15/20 (75%) of individuals. SHP and bilateral hypogastric nerves were seen in 30/60 (50%) of cases by both observers. Bilateral IHP was seen in 85% (34/40) by Observer 1 and in 75% (30/40) by Observer 2. Sciatic nerves were well identified in all cases, while pudendal nerves were seen bilaterally by Observer 1 in 65% (26/40) and by Observer 2 in 72.5% (29/40). Agreement between observers for scoring nerve conspicuity was in the range of 60%-100%.

CONCLUSION

Modified 3D NerveVIEW renders high-quality images of the female autonomic and pudendal nerves.

Neurovascular and lymphatic vessels distribution in uterine ligaments based on a 3D reconstruction of histological study: to determine the optimal plane for nerve-sparing radical hysterectomy

OBJECTIVE

To present the distribution of neurovascular and lymphatic vessels in uterine ligaments using 3D models based on the pathological staining of serial 2D sections of postoperative specimens.

METHODS

Serial transverse sections of fresh uterine ligaments from a patient with stage IB1 cervical squamous cell carcinoma were studied using the computer-assisted anatomic dissection (CAAD) technique. The sections were stained with hematoxylin and eosin, Weigert elastic fibers, D2-40 and immunostainings (sheep anti-tyrosine hydroxylase and rabbit anti-vasoactive intestinal peptide). The sections were then digitalized, registered and reconstructed three-dimensionally. Then, the 3D models were analyzed and measured.

RESULTS

The 3D models of the neurovascular and lymphatic vessels in uterine ligaments were created, depicting their precise location and distribution. The vessels were primarily located in the upper part of the ligaments model, while the pelvic autonomic nerves were primarily in the lower part; the lymphatic vessels were scattered in the uterine ligaments, without obvious regularity.

CONCLUSION

CAAD is an effective anatomical method to study the precise distribution of neurovascular and lymphatic vessels in uterine ligaments. It can present detailed anatomical information about female pelvic autonomic innervation and the spatial relationship between nerves and vessels and may provide a better understanding of nerve-sparing radical hysterectomy.

A step towards stereotactic navigation during pelvic surgery: 3D nerve topography

BACKGROUND

Long-term morbidity after multimodal treatment for rectal cancer is suggested to be mainly made up by nerve-injury-related dysfunctions. Stereotactic navigation for rectal surgery was shown to be feasible and will be facilitated by highlighting structures at risk of iatrogenic damage. The aim of this study was to investigate the ability to make a 3D map of the pelvic nerves with magnetic resonance imaging (MRI).

METHODS

A systematic review was performed to identify a main positional reference for each pelvic nerve and plexus. The nerves were manually delineated in 20 volunteers who were scanned with a 3-T MRI. The nerve identifiability rate and the likelihood of nerve identification correctness were determined.

RESULTS

The analysis included 61 studies on pelvic nerve anatomy. A main positional reference was defined for each nerve. On MRI, the sacral nerves, the lumbosacral plexus, and the obturator nerve could be identified bilaterally in all volunteers. The sympathetic trunk could be identified in 19 of 20 volunteers bilaterally (95%). The superior hypogastric plexus, the hypogastric nerve, and the inferior hypogastric plexus could be identified bilaterally in 14 (70%), 16 (80%), and 14 (70%) of the 20 volunteers, respectively. The pudendal nerve could be identified in 17 (85%) volunteers on the right side and in 13 (65%) volunteers on the left side. The levator ani nerve could be identified in only a few volunteers. Except for the levator ani nerve, the radiologist and the anatomist agreed that the delineated nerve depicted the correct nerve in 100% of the cases.

CONCLUSION

Pelvic nerves at risk of injury are usually visible on high-resolution MRI with dedicated scanning protocols. A specific knowledge of their course and its application in stereotactic navigation is suggested to improve quality of life by decreasing the likelihood of nerve injury.

The 3D reconstructions of female pelvic autonomic nerves and their related organs based on MRI: a first step towards neuronavigation during nerve-sparing radical hysterectomy

OBJECTIVES

To present in vivo female pelvic autonomous innervation and the relationship between nerves and their related organs by three-dimensional (3D) reconstruction based on magnetic resonance imaging (MRI).

METHODS

Thirty patients with cervical cancer who underwent pelvic MRI and agreed to undergo additional magnetic resonance neurography (MRN) sequences were enrolled in the present study. MRI images from the same patient were acquired using T2-weighted fat saturation (T2W FS) and 3D-STIR-SPACE sequences. Detailed two-dimensional (2D) segmentation and 3D reconstruction of pelvic autonomic nerves (PAN) were performed on the basis of the images of the two sequences using 3D reconstruction software. The 2D segmentation and 3D reconstruction of pelvic organs were based on T2W FS images. The consistency of the 3D models of pelvic autonomous innervation constructed from the two sequences were analysed and compared, the pelvic autonomous innervation was presented, and the relationship between nerves and their related organs was characterised.

RESULTS

The 3D reconstructions of PAN were successfully obtained from 3D-STIR-SPACE and T2W FS sequences in 30 patients and showed high correspondence. T2W FS images also enabled 3D reconstructions of pelvic organs to visualise the 3D distribution of PAN and the positional relationships between nerves and their related organs.

CONCLUSION

The pelvic autonomic nerves and their related organs can be reconstructed on the basis of MRI to present personalised 3D anatomical information and offer individualised guidance during nerve-sparing radical hysterectomy (NSRH).

KEY POINTS

• Nerve-sparing radical hysterectomy is a developing trend in cervical cancer surgery • MRI allows reconstructions of pelvic autonomic nerves and their related organs • The 3D reconstructions provide detailed 3D anatomical information on nerves.

3D Models of Female Pelvis Structures Reconstructed and Represented in Combination with Anatomical and Radiological Sections

We present a computer program designed to visualize and interact with three-dimensional models of the main anatomical structures of the female pelvis. They are reconstructed from serial sections of corpse, from the Visible Human project of the Medical Library of the United States and from serial sections of high-resolution magnetic resonance. It is possible to represent these three-dimensional structures in any spatial orientation, together with sectional images of corpse and magnetic resonance imaging, in the three planes of space (axial, coronal and sagittal) that facilitates the anatomical understanding and the identification of the set of visceral structures of this body region. Actually, there are few studies that analysze in detail the radiological anatomy of the female pelvis using three-dimensional models together with sectional images, making use of open applications for the representation of virtual scenes on low cost Windows® platforms. Our technological development allows the observation of the main female pelvis viscera in three dimensions with a very intuitive graphic interface. This computer application represents an important training tool for both medical students and specialists in gynecology and as a preliminary step in the planning of pelvic floor surgery.

A Comprehensive Review of Medical Imaging Equipment Used in Cadaveric Studies

Medical imaging techniques have led to great advances in clinical anatomy and forensic pathology. New and emerging technologies allow healthcare professionals to view and understand the human body from different perspectives. This gives way to new and improved interventions, treatment plans, and an overall understanding of the human body. Herein, we present a comprehensive review of the various medical imaging equipment used in cadaveric studies along with their individual strengths and limitations.

The quest for precision in transanal total mesorectal excision

Transanal total mesorectal excision (TME) is an emerging minimally invasive approach to rectal cancer, with encouraging preliminary results. However, the new surgical anatomy of the bottom-up approach complicates surgical understanding and increases the risks of inadvertent injuries to crucial anatomical structures, including nerves. Key elements to improve the safety and stimulate interest in such a complex technique might be robotics and image guidance, to enhance the level of precision. In this editorial, some of the technologies that could be used for precision TME are outlined, in light of the experience of our Institute for Image-Guided Surgery.

Urogenital dysfunctions after treatment of rectal cancer

A significant part of rectal cancer survivors will experience urogenital dysfunction induced by the treatment. Significant progress has been made in order to improve the total mesorectal technique through different approaches (open, laparoscopic, robotic, transanal). Rectal cancer surgery is technically difficult notably deep in the pelvis, and therefore the most frequent cause of the postoperative dysfunction is the surgical nerve damage of the autonomic nerves at this level. The main objectives of these efforts were to obtain maximal oncological results and to achieve better functional outcomes including less postoperative urogenital dysfunctions. Our purpose was to build a comprehensive review of the existing literature data regarding this issue from past to present.