3D vascular anatomy of the presacral space: impact of age and adiposity

Determination of the width of the presacral space on magnetic resonance imaging among adults in south-western Nigeria

BACKGROUND

The presacral space is a clinically relevant potential space and contents may give rise to a variety of benign and malignant conditions, hence the need for detailed knowledge of its dimensions.

PURPOSE

To determine the width of the presacral space and existing variations among adults in south-western Nigeria using a magnetic resonance imaging (MRI) technique.

MATERIAL AND METHODS

A total of 369 consenting adults were included in the study. Measurements of the presacral space were then made electronically by consensus of two radiologists. Values derived were recorded and subjected to analyses of variance.

RESULTS

The mean normal widths of the presacral space in men and women were 11.7 mm and 11.1 mm at the S1 level, 11.7 mm and 10.35 mm at the S2 level, and 12.3 mm and 9.7 mm at the S3 level, respectively. Measurements of the presacral space width were significantly larger in the male population. Variations in the dimensions due to age greater than 40 years, male sex, and increasing body mass index (BMI) were also noted.

CONCLUSION

This study provides baseline dimensions under more physiological conditions and gives more accurate information about the true width of the space in Nigerian adults. Variations due to age, sex, and BMI may also be considered while interpreting abnormal values.

Iliac vein variation in the sacral promontory on three-dimensional computed tomography angiography: a prospective observational study before laparoscopic sacrocolpopexy

INTRODUCTION AND HYPOTHESIS

Venous injury may occur during exposure of the anterior longitudinal ligament at the anterior sacral promontory (SP). We aimed to quantitatively measure the extent of the vascular window (VW) in front of the SP in patients with internal iliac vein (IIV) variations using preoperative three-dimensional computed tomography angiography (3DCTA). We hypothesized that patients with IIV variations would have a narrow VW.

METHODS

This prospective observational study included patients scheduled for laparoscopic sacrocolpopexy (LSC) between July 2022 and April 2023 who underwent preoperative 3DCTA. The primary endpoint was the VW measurement in the standard and variant IIV groups using 3DCTA before LSC. The secondary endpoint was the difference between the two IIV groups adjusted for age, body mass index, hypertension, and diabetes using an analysis of covariance (ANCOVA) model. Multiple regression analysis was performed to analyze the effect of factors on the distance from the SP to great vascular bifurcations.

RESULTS

There were 20 cases of IIV variation (20.2%). VW was 28.8 ± 12.4 mm in the variant group and 39.6 ± 12.6 mm in the standard group (p = 0.001). In the ANCOVA model, IIV variations affected VW (coefficient, -11.8; 95% confidence interval [CI], -18.4 to -5.08, p < 0.001). Multivariate analysis revealed that the aorta-SP distance decreased with age (coefficient, -0.44; 95% CI, -0.77 to -0.11, p = 0.009).

CONCLUSIONS

One in five women has a vascular variant at the SP that restricts the "safe" zone of fixation to < 3 cm.

Anatomy of the internal iliac vein around the sacral promontory based on CT three-dimensional (3D) reconstruction

INTRODUCTION AND HYPOTHESIS

The area around the sacral promontory (SP) is the targeted location of various pelvic operations. We examined the internal iliac vein (IIV) configurations around the SP by computed tomography angiography (CTA) three-dimensional (3D) reconstruction to describe its anatomy and provide accurate anatomical parameters for relevant operations to reduce intraoperative vascular injury.

METHODS

We retrospectively studied 2078 CTA 3D model datasets from Nanfang Hospital patients examined for gynecological diseases from December 2009 to October 2020. The IIVs of the above cases were divided into standard and variant IIVs, and variant IIVs were subdivided into different subtypes. To compare the size of the avascular area around the SP between standard and variant IIVs, we selected the two subtypes with the highest variation rate for comparison with the standard IIV type.

RESULTS

The most common types of variant IIVs were 5a (5.15%) and 3a (5.05%). The results showed larger values in the standard group than in the 3a and 5a groups for the confluence of common iliac vein (CCIV) height (37.73±12.05 vs. 28.93±10.17 vs. 27.27±7.58 mm, P < 0.05), distance between the iliac vessels (49.47±9.47 mm vs. 37.08±9.36 vs. 37.73±8.94 mm, P < 0.05), and SP exposure width (44.94±6.39 mm vs. 36.83±8.29 vs. 36.93±7.91, P < 0.05).

CONCLUSIONS

Variant IIVs may increase the risk of surgery by reducing the avascular area compared with standard IIVs. Therefore, when operating around the SP, special attention should be given to variant IIVs and avoiding vascular injury.

Morphometric analysis of the lumbar vertebrae and intervertebral discs in relation to abdominal aorta: CT-based study

Purpose

Although lumbar discectomy is the most common procedure in spine surgery, reports about anatomical relations between discs and prevertebral vessels are limited. Aim of this research was to investigate morphometric of the lumbar region and the relations between intervertebral discs (IVDs) and abdominal aorta.

Methods

557 abdominal computed tomography scans were assessed. For each spinal column level from Th12/L1 down to L4/L5, we investigated: intervertebral disc’s and vertebra’s height, width, length, and distance from aorta or common iliac artery (CIA). Those arteries were also measured in two dimensions and classified based on location.

Results

54.58% of patients were male. There was a significant difference in arterial-disc distances (ADDs) between genders at the levels: L1/L2 (1.32 ± 1.97 vs. 0.96 ± 1.78 mm; p = 0.0194), L2/L3 (1.97 ± 2.16 vs. 1.15 ± 2.01 mm; p < 0.0001), L3/L4 (2.54 ± 2.78 vs. 1.71 ± 2.61 mm; p = 0.0012), also for both CIAs (left CIA 3.64 ± 3.63 vs. 2.6 ± 3.06 mm; p = 0.0004 and right CIA: 7.96 ± 5.06 vs. 5.8 ± 4.57 mm; p < 0.001)—those ADDs were higher in men at all levels. The length and width of IVD increased alongside with disc level with the maximum at L4/L5.

Conclusion

Bifurcations of the aorta in most cases occurred at the L4 level. Collected data suggest that at the highest lumbar levels, there is a greater possibility to cause injury of the aorta due to its close anatomical relationship with discs. Females have limited, in comparison to males, ADD at L1/L2, L2/L3, and L3/L4 levels what should be taken into consideration during preoperative planning of surgical intervention.

A Novel Transforaminal Approach to Presacral Abscess

BACKGROUND

Presacral abscess is a common disease in the developing countries. Treatments include minimally invasive percutaneous drainage and open surgical debridement. Percutaneous drainage under computed tomography (CT) guidance has been recommended by the American College of Radiology as a good alternative to surgical drainage before elective surgical treatment. Because of the many anatomic obstacles, the presacral space can be one of the most difficult locations to access. There are several reported access routes like transabdominal, transgluteal, transvaginal, transperineal, transanal, precoccygeal, transpedicular, and so on. We introduce a novel approach, the trans-sacral-foramen approach, to drain presacral abscess under CT guidance.

METHODS

A 47-year-old woman who had lumbar laminectomy debridement for epidural abscess was diagnosed with residual presacral abscess. She was placed in the prone position. One-step technique was applied. Intermittent CT scans were obtained during drainage catheter (8F) advancement into the sacral posterior foramen. The stylet was withdrawn and an approximately 60° angle for catheter trajectory was used to best reach the sacral anterior foramen due to the inherent pelvic tilt. When the catheter tip reached the presacral abscess, the abscess cavity was aspirated with a syringe, pus was drained, and catheter was fixed to skin. Sensitive antibiotics were administered.

RESULTS

After 2 weeks magnetic resonance imaging (MRI) showed significant reduced abscess and the catheters were removed. At 18-month follow-up, MRI showed intervertebral fusion at the lumbosacral segment.

CONCLUSIONS

Trans-sacral-foramen approach is the shortest path to reach the presacral abscess. The approach is easier and safer than the others for patients with indication.

Exploration of the safe suture area of the presacral space in sacrocolpopexy by 3-dimensional (3D) models reconstructed from CT

INTRODUCTION AND HYPOTHESIS

The objective of this study, a digital in vivo anatomical study based on patient-specific three-dimensional (3D) models reconstructed from computed tomography (CT) scans, was to clarify the anatomy of the presacral space and suggest a safe area for complication-free graft or mesh fixation.

METHODS

We retrospectively studied 182 CT angiography (CTA) datasets from Han Chinese women examined for gynecological diseases from January 2018-June 2020; we used Mimics 21.0 to create 176 3D models of the female presacral space. The distances of pelvic structures from the presacral vessels and ureters were standardized and measured in 3D mode.

RESULTS

The distances from the median sacral artery (MSA) to the bilateral great vessels and bilateral ureters at the sacral promontory (SP) level were similar to the respective distances from the midpoint of the SP (MSP) to those four structures (p > 0.05). At the level of the first transverse line, when the MSA was right of the midline, the MSA was 20.74 ± 3.86 mm from the medial edge of the left first anterior sacral foramen. When the MSA was left of the midline, its average distance from the medial edge of the right first anterior sacral foramen was 20.89 ± 4.92 mm. The SP was 9.71 ± 4.49 mm and 40.39 ± 6.74 mm, respectively, from the first and second sacral transverse veins along the midline.

CONCLUSIONS

To preserve important vasculature, we recommend a 30 × 20-mm (L × W) avascular rectangular-shaped area, 10 mm below the SP and alongside the MSA, for safe graft or mesh attachment during sacrocolpopexy.

Surface anatomy and lumbar lordosis angle

Awareness of the anatomical variations in abdominal surface anatomy with emphasis on relation to the abdominal planes may facilitate anatomical education and physical examination and inconvenience surgical intervention by giving surgeons more insight in surgical planning and training. This study was designed to verify whether the anatomical planes promote to the comprehension of surface anatomy and how the lumbar lordosis angle affects the vertebral level of the bifurcation of great vessels. This retrospective study was performed using computed tomography angiography images of 155 patients ranging from 18 up to 82 years. The vertebral levels of the celiac truncus, superior mesenteric artery, portal vein confluence, right and left renal arteries were within the transpyloric plane in 60%, 70%, 56.1% and 48.3-36.2% of patients, respectively. The inferior mesenteric artery was below the subcostal plane in 58% of patients. The aortic bifurcation (AB) was mostly corresponded to the level of L4 and was located within the umbilical plane in 73.1% of patients. The level of the inferior vena cava (IVC) confluence was within the supracristal plane in 54% of patients. We measured the mean value of the AB, IVC and lumbar lordosis angles as 39.54°, 58.05° and 54.26°, respectively. The AB and IVC levels showed a downward shift with decreasing lumbar lordosis angle. Precise knowledge of these relationships is crucial in clinical practice and surgical approaches to the anterior lumbosacral spine for safer and effective surgery.