Figure - available from: International Journal of Colorectal Disease
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Axial MRI measurements taken at level of the IT (pelvic floor). Distances: CRRect, center of the rectum to the outer edge of the muscular wall of the rectum; CRAntWall, center of the rectum to the midpoint of the pubic symphysis; Pelvic Perim, soft tissue perimeter defined by the outline of the muscular or bony structures comprising the deep border of the pelvis; Rectal perimeter, outline of the muscular wall of the rectum; ITDist, between the ischial tuberosities
Source publication
PurposeSelection of an open or minimally invasive approach to total mesorectal excision (TME) is generally based on surgeon preference and an intuitive assessment of patient characteristics but there consensus on criteria to predict surgical difficulty. Pelvimetry has been used to predict the difficult surgical pelvis, typically using only bony lan...
Citations
... Although radiological images are most commonly used to diagnose the disease, they can provide information to the surgeon about the details of the anatomical area to be operated on before surgery. Pelvimetric measurements are used in gynaecological and obstetric or rectal surgeries [12][13][14]. However, unlike other surgical procedures in prostate surgery, determination of the patient's detailed pelvic anatomy with preoperative radiological images is rarely used in the urology. ...
Purpose
To evaluate the diagnostic performance of pelvimetric measurements, in particular the pelvic dimension index (PDI)/prostate volume (PV) ratio (PDI/PV), in predicting positive surgical margin (PSM) in prostate cancer (PC).
Materials and methods
127 patients who had pre-operative pelvic imaging were included in this study. Demographic and clinical data were recorded. Apical depth (AD), interspinous distance (ISD), intertuberous distance (ITD), bony femoral width (BFW), soft-tissue width (SW), symphysis angle (SA), anteroposterior diameter of the pelvic inlet (API), anteroposterior diameter of the pelvic mid-plane (APM), anteroposterior diameter of the pelvic outlet (APO), pelvic depth (PD), bony width index (BWI), soft tissue width index (SWI), pelvic cavity index (PCI), PDI and PV were measured on MRI or CT. Using PDI and PV, we developed a new parameter of “PDI to PV ratio” (PDI/PV). Logistic regression analysis was used to determine the predictive potential of variables in detection of PSM.
Results
The AD, PV, SA and total prostate specific antigen (PSA) were significantly higher in PSM( +), while PDI, BWI, SWI, API, PDI/PV and PD were significantly lower in PSM( +) (p < 0.05). In multivariate analysis, PDI/PV ratio and clinical stage were all significant predictor of PSM, where PDI/PV ratio was the strongest predictor, followed by clinical stage.
Conclusion
Pelvimetric measurements indicating deep location of the prostatic apex rather than pelvic width are more effective in predicting PSM. Prediction of PSM with pelvimetric measurements, in particular PDI/PV ratio, may be helpful for surgical planning in preoperative period.
... In addition, pelvic surgery is more di cult than abdominal surgery due to pelvic stenosis and the special bony structural angles of the pelvis. Thus, urologists and colorectal surgeons have increasingly focused on pelvic measurements and the description of a "hostile pelvis" [10,11]. Pelvic measurements allow for a better understanding and awareness of the "hostile pelvis," thus reducing the incidence of complications. ...
... Further, a larger MFA may limit the surgical space in the pelvis. However, some studies have shown that pelvic measurements such as interspinous distance do not correlate with surgical di culty [11,25,35]. Research has also suggested that a smaller MFA may lead to early pelvic wall in ltration and involvement of adjacent organs. ...
Aim
Intersphincteric resection (ISR) is an anus-preserving procedure for the treatment of low rectal cancer. However, some patients have difficult ISR procedures due to pelvic stenosis. We aim to build a machine learning (ML) model to predict the difficulty of ISR.
Methods
We retrospectively collected information of 163 patients with low rectal cancer who underwent laparoscopic ISR from January 2017 to August 2022. The prediction models of surgical difficulty were constructed by five MLs. External validation of the European MRI and Rectal Cancer Surgery (EuMaRCS) score was also performed.
Results
Of 163 patients,36 (22.1%) were assessed as difficult, and 127 (77.9%) were assessed as non-difficult. 9 variables were finally included through lasso regression and binary logistic regression. Two main types of models were constructed, with one retaining all variables, with random forest (RF) performing best (accuracy, 0.878; positive predictive value [PPV], 1; negative predictive value [NPV], 0.867; sensitivity, 0.4; specificity, 1; area under the curve [AUC], 0.877; 95% confidence interval [CI], 0.732–1). The other category retained the 9 variables screened, with support vector machine (SVM) performing best(accuracy, 0.857; PPV, 0.636; NPV, 0.921; sensitivity, 0.7; specificity, 0.897; AUC, 0.854; 95% CI, 0.698–1). The EuMaRCS score did not show a better predictive performance in our study.
Conclusions
The ML models we developed were found to be more accurate in comparison to the EuMaRCS score. The pelvimetry-based ML model can be used as an effective predictive tool for identifying the difficulty of ISR for low rectal cancer.
BACKGROUND
A complete total mesorectal excision is the gold standard in curative rectal cancer surgery. Ensuring quality is challenging in a narrow pelvis, and obesity amplifies technical difficulties. Pelvimetry is the measurement of pelvic dimensions, but its role in gauging preoperatively difficulty of proctectomy is largely unexplored.
OBJECTIVE
To determine pelvic structural factors associated with incomplete total mesorectal excision following curative proctectomy and build a predictive model for total mesorectal excision quality.
DESIGN
Retrospective cohort study.
SETTING
A quaternary referral center database of patients diagnosed with rectal adenocarcinoma (2009-2017).
PATIENTS
Curative-intent proctectomy for rectal adenocarcinoma.
INTERVENTIONS
All radiological measurements were obtained from preoperative CT-images using validated imaging processing software tools. Completeness of total mesorectal excision was obtained from histology reports.
MAIN OUTCOME MEASURES
Ability of radiological pelvimetry and obesity measurements to predict total mesorectal excision quality.
RESULTS
Of the 410 cases meeting inclusion criteria, 362 had a complete total mesorectal excision (88%). A multivariable regression identified a deeper sacral curve (per 100 mm ² [OR: 1.14, 95% CI: 1.06-1.23, p < 0.001]), and greater transverse distance of pelvic outlet (per 10 mm [OR:1.41, 95% CI: 1.08-1.84, p = 0.012]) as independently associated with incomplete total mesorectal excision. An increased area of pelvic inlet (per 10 cm ² ); OR: 0.85, [95% CI: 0.75-0.97, p = 0.02] was associated with a higher rate of complete mesorectal excision. No difference in visceral obesity ratio and visceral obesity (ratio >0.4 vs.<0.4) between body mass index (<30 vs. ≥30) or sex was identified. A model was built to predict mesorectal quality using variables: depth of sacral curve, area of pelvic inlet and transverse distance of pelvic outlet.
LIMITATIONS
Retrospective analysis not controlled for choice of surgical approach.
CONCLUSIONS
Pelvimetry is predictive of total mesorectal excision quality in rectal cancer surgery and can alert surgeons preoperatively to cases of unusual difficulty. This predictive model may contribute to treatment strategy and aid in comparison of outcomes between traditional and novel techniques of total mesorectal excision. See Video Abstract
