Revista nº 815

Fernando J, et al. | Anatomic variations of the healthy colon 19 Actual Med.2022;107(815):18- 26 INTRODUCTION The anatomy of the colon has been extensively studied. Seminal works have described in detail the colon’s embryonic development (1) the morphology of its different segments, and its relationships with adjacent structures, including viscera and bones. (2,3) In addition, corpse dissection studies have helped to expand this organ. (4,5) The radiological anatomy of the colon is well-known, assisting study of the substantial anatomical variability of this organ. (6) Three-dimensional reconstruction technologies based on radiological images, whether obtained via computerized tomography, nuclear magnetic resonance, or virtual colonoscopy, has been an important development in this respect, allowing enhanced anatomical description of the colon. (7- 10) Moreover, three-dimensional reconstruction improves the clinical applicability of results, helping to establish preoperative surgical planning strategies that facilitate surgical approaches and the development of operative techniques for this organ. (11-13) It can also allow the development of virtual anatomical models and simulation models for teaching and training in specific medical techniques, such as through computer models (14) models integrated in Portable Document Format (PDF) files for virtual navigation through the reconstructed structures (15,16) and physical models developed with current 3D printing methods. (17) The aim of this study was to describe and analyze how sex, age, and BMI influence the anatomy of the colon, as determined using three-dimensional reconstructions from computed tomography (CT) scans. MATERIAL AND METHODS Sample selection One hundred and thirty patients were selected from the Hospital Royo Villanova in Zaragoza, each of whom underwent an abdominal CT scan with intravenous contrast after providing informed consent. Informed consent was obtained from all study participants. The clinical rationale for the CT scan should not influence the normal anatomy of the colon, and the study did not utilize scans that showed pathology at that level. In addition, all studied CT scans did not show intra- abdominal findings that might have an influence on anatomical changes. Those cases that did not meet these requirements were not included in the ultimate analysis. The variables sex, age, and body mass index (BMI) were analyzed using information collected from each patient included in the study. BMI values were not obtained in 4 of the 130 patients (3.07%). These data allowed us to make three groups stratified by sex (men vs. women), age (65 years or younger vs. over 65, according to the median age of the study sample), and BMI (classified as normal weight if BMI was less than 24.99, overweight if BMI was between 25 and 29.99, and obese if BMI was greater than 30). The use of the images and the retrospective collection of data were approved by the Clinical Research Ethics Committee of Aragón (CE PI17/O168). The work has been carried out in accordance with The Code of Ethics of the World Medical Association (Declaration of Helsinki) for experiments involving humans. Image collection and processing. The Siemens Somatom Perspective 64-slice CT (Siemens Medical Solutions, Erlangen, Germany) scanner was used to obtain all images. CT sections of the abdomen were made at 3-mm thicknesses. The images were converted into DICOM format using the platforms Syngo Via and Indra Alma 3D. The processing and measurement software packages used were OsiriX, Adobe Photoshop Elements 11 Editor, and ImageJ. The surface of the colon was manually identified in all sections, changing the image density to obtain the three-dimensional reconstruction. Colour was applied to this three-dimensional image with the software Adobe Photoshop Elements 11. Reference points were identified in axial CT sections, which were reflected in the three-dimensional image. These included the midpoint of the pubic symphysis (PUBIS), the origin of the superior mesenteric artery (SMA), the origin of the inferior mesenteric artery (IMA), the highest point of the colon in the right hemiabdomen—in the area of transition between the ascending colon and the transverse colon (hepatic flexure (HF)—the highest point of the colon in the left hemiabdomen—in the transition zone between the transverse colon and the descending colon (splenic flexure (SF))—the entrance of the terminal ileum into the caecum (ICJ), and the sigmoid-descending colon junction—in the entrance area to the pelvis (SDJ). The proposed length and angle measures are detailed in the attached figure (Figure 1A-C). These measurements were made with ImageJ software and calculated in pixels, subsequently transformed into centimeters, and expressed in sexagesimal degrees. Statistical analysis. The morphometric data obtained were analyzed with SPSS. Quantitative variables were described by either the mean and standard deviation (SD) or the range and interquartile range (IQR). For comparisons between two quantitative variables, Student’s t-test or Mann- Whitney U test was used according to the results of Kolmogorov-Smirnov normality testing. Analysis of