Development of a model of three-dimensional imaging for the preoperative planning of TaTME

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.

3D pelvimetry and biometric measurements: a surgical perspective for colorectal resections

PURPOSE

Male sex, high BMI, narrow pelvis, and bulky mesorectum were acknowledged as clinical variables correlated with a difficult pelvic dissection in colorectal surgery. This paper aimed at comparing pelvic biometric measurements in female and male patients and at providing a perspective on how pelvimetry segmentation may help in visualizing mesorectal distribution.

METHODS

A 3D software was used for segmentation of DICOM data of consecutive patients aged 60 years, who underwent elective abdominal CT scan. The following measurements were estimated: pelvic inlet, outlet, and depth; pubic tubercle height; distances from the promontory to the coccyx and to S3/S4; distance from S3/S4 to coccyx's tip; ischial spines distance; pelvic tilt; offset angle; pelvic inlet angle; angle between the inlet/sacral promontory/coccyx; angle between the promontory/coccyx/pelvic outlet; S3 angle; and pelvic inlet to pelvic depth ratio. The measurements were compared in males and females using statistical analyses.

RESULTS

Two-hundred patients (M/F 1:1) were analyzed. Out of 21 pelvimetry measurements, 19 of them documented a significant mean difference between groups. Specifically, female patients had a significantly wider pelvic inlet and outlet but a shorter pelvic depth, and promontory/sacral/coccyx distances, resulting in an augmented inlet/depth ratio when comparing with males (p < 0.0001). The sole exceptions were the straight conjugate (p = 0.06) and S3 angle (p = 0.17). 3D segmentation provided a perspective of the mesorectum distribution according to the pelvic shape.

CONCLUSION

Significant differences in the structure of pelvis exist in males and females. Surgeons must be aware of the pelvic shape when approaching the rectum.

The dead space after extirpation of rectum. Current management and searching for new materials for filling

Pelvic surgeries such as extirpation of the rectum or pelvic exenteration lead to a creation of a dead space, which can be cause of complication, such as bowel obstruction, perineal hernia, abscess or hematoma. A growing incidence of complication is expected in connection with the increasing use of laparoscopic and robotic approaches or ELAPE method. Since the bone structures do not allow compression, the only way to deal with the dead space is to fill it in. Present methods provide the filling with omental or myofascial flaps. The length and the mobility of the omental flap can be the limitation. Myofascial flaps are technically more demanding and bring the complications of a donor place. Synthetic or biological meshes do not deal with dead space problematic. Modern technologies using nanomaterials offer the possibility to produce a material with specific properties for example shape, inner structure, surface, or time of degradation. The modified material could also satisfy the requirements for filling the dead space after surgeries.

Anatomical Considerations and Procedure-Specific Aspects Important in Preventing Operative Morbidity during Transanal Total Mesorectal Excision

As transanal total mesorectal excision (taTME) becomes increasingly utilized, its technical challenges and potential pitfalls have become more clearly appreciated. This chapter explores the differences in how anatomy presents itself from the taTME vantage point as compared with traditional approaches to taTME, and how special problems unique to taTME pose a new set of operative challenges. Morbidity related, specifically, to the technique of taTME is also delineated with particular focus on male urethral injury.

Inflammatory bowel disease position statement of the Italian Society of Colorectal Surgery (SICCR): Crohn's disease

The Italian Society of Colorectal Surgery (SICCR) promoted the project reported here, which consists of a position statement of Italian colorectal surgeons to address the surgical aspects of Crohn's disease management. Members of the society were invited to express their opinions on several items proposed by the writing committee, based on evidence available in the literature. The results are presented, focusing on relevant points. The present paper is not an alternative to available guidelines; rather, it offers a snapshot of the attitudes of SICCR surgeons about the surgical treatment of Crohn's disease. The committee was able to identify some points of major disagreement and suggested strategies to improve quality of available data and acceptance of guidelines.

Inflammatory bowel disease position statement of the Italian Society of Colorectal Surgery (SICCR): ulcerative colitis

The Italian Society of Colorectal Surgery (SICCR) promoted the project reported here, which consists of a Position Statement of Italian colorectal surgeons to address the surgical aspects of ulcerative colitis management. Members of the society were invited to express their opinions on several items proposed by the writing committee, based on evidence available in the literature. The results are presented, focusing on relevant points. The present paper is not an alternative to available guidelines; rather, it offers a snapshot of the attitudes of SICCR surgeons about the surgical treatment of ulcerative colitis. The committee was able to identify some points of major disagreement and suggested strategies to improve the quality of available data and acceptance of guidelines.

Pelvic exenterations for primary rectal cancer: Analysis from a 10-year national prospective database

AIM

To identify short-term and oncologic outcomes of pelvic exenterations (PE) for locally advanced primary rectal cancer (LAPRC) in patients included in a national prospective database.

METHODS

Few studies report on PE in patients with LAPRC. For this study, we included PE for LAPRC performed between 2006 and 2017, as available, from the Rectal Cancer Registry of the Spanish Association of Surgeons [Asociación Española de Cirujanos (AEC)]. Primary endpoints included procedure-associated complications, 5-year local recurrence (LR), disease-free survival (DFS) and overall survival (OS). A propensity-matched comparison with patients who underwent non-exenterative surgery for low rectal cancers was performed as a secondary endpoint.

RESULTS

Eight-two patients were included. The mean age was 61.8 ± 11.5 years. More than half of the patients experienced at least one complication. Surgical site infections were the most common complication (abdominal wound 18.3%, perineal closure 19.4%). Thirty-three multivisceral resections were performed, including two hepatectomies and four metastasectomies. The long-term outcomes of the 64 patients operated on before 2013 were assessed. The five-year LR was 15.6%, the distant recurrence rate was 21.9%, and OS was 67.2%, with a mean survival of 43.8 mo. R+ve resection increased LR [hazard ratio (HR) = 5.58, 95%CI: 1.04-30.07, P = 0.04]. The quality of the mesorectum was associated with DFS. Perioperative complications were independent predictors of shorter survival (HR = 3.53, 95%CI: 1.12-10.94, P = 0.03). In the propensity-matched analysis, PE was associated with better quality of the specimen and tended to achieve lower LR with similar OS.

CONCLUSION

PE is an extensive procedure, justified if disease-free margins can be obtained. Further studies should define indications, accreditation policy, and quality of life in LAPRC.

Innovation in the imaging perianal fistula: a step towards personalised medicine

BACKGROUND

Perianal fistula is a topic both hard to understand and to teach. The key to understanding the treatment options and the likely success is deciphering the exact morphology of the tract(s) and the amount of sphincter involved. Our aim was to explore alternative platforms better to understand complex perianal fistulas through three-dimensional (3D) imaging and reconstruction.

METHODS

Digital imaging and communications in medicine images of spectral attenuated inversion recovery magnetic resonance imaging (MRI) sequences were imported onto validated open-source segmentation software. A specialist consultant gastrointestinal radiologist performed segmentation of the fistula, internal and external sphincter. Segmented files were exported as stereolithography files. Cura (Ultimaker Cura 3.0.4) was used to prepare the files for printing on an Ultimaker 3 Extended 3D printer. Animations were created in collaboration with Touch Surgery™.

RESULTS

Three examples of 3D printed models demonstrating complex perianal fistula were created. The anatomical components are displayed in different colours: red: fistula tract; green: external anal sphincter and levator plate; blue: internal anal sphincter and rectum. One of the models was created to be split in half, to display the internal opening and allow complexity in the intersphincteric space to better evaluated. An animation of MRI fistulography of a trans-sphincteric fistula tract with a cephalad extension in the intersphincteric space was also created.

CONCLUSION

MRI is the reference standard for assessment of perianal fistula, defining anatomy and guiding surgery. However, communication of findings between radiologist and surgeon remains challenging. Feasibility of 3D reconstructions of complex perianal fistula is realized, with the potential to improve surgical planning, communication with patients, and augment training.