Sectional Anatomy of the Peritoneal Reflections of the Upper Abdomen in the Coronal Plane

Classification of the colonic splenic flexure based on three-dimensional CT analysis

Background

Mobilization of the splenic flexure can be a challenging surgical step in colorectal surgery. This study aimed to classify the splenic flexure based on the three-dimensional (3D) coordinates of the splenic hilum and left renal hilum. This classification was used to compare splenic flexure mobilization during colorectal resection.

Methods

CT images of patients with colorectal cancer treated between April 2018 and December 2019 were analysed retrospectively. 3D mutual positioning of the splenic flexure from the ligament of Treitz to the splenic hilum or the left renal hilum was used to classify patients into three groups using cluster analysis. The difference in the procedure time between groups was also analysed in a subset of patients undergoing laparoscopic colectomy with complete splenic flexure mobilization.

Results

Of 515 patients reviewed, 319 with colorectal cancers were included in the study and categorized based on the 3D coordinates of the splenic hilum and left renal hilum as caudal (100 patients), cranial (118) and lateral (101) positions. Male sex (P < 0.001), older age (P = 0.004) and increased bodyweight (P = 0.043) were independent characteristics of the lateral group in multiple logistic regression analysis. Thirty-four patients underwent complete splenic flexure mobilization during the study period; this took significantly longer (mean 78.7 min) in the lateral group than in the caudal and cranial groups (41.8 and 43.2 min respectively; P = 0.006).

Conclusion

Locating the splenic flexure using 3D coordinates could be helpful in predicting a longer duration for mobilization of the splenic flexure.

The Peritoneum: What Nuclear Radiologists Need to Know

The peritoneum is the largest and most complex serous membrane in the human body. The peritoneal membrane is composed of a layer of mesothelium supported by a thin layer of connective tissue. The peritoneum is one continuous sheet, forming two layers and a potential space between them - the peritoneal cavity- which is subdivided into multiple communicating spaces containing small amount of serous fluid that facilitates frictionless movement of mobile intraabdominal viscera. Peritoneum also contributes to fluid exchange mechanism and plays a role in immune response. The peritoneum is subject to many neoplastic and non-neoplastic processes including infections, trauma, developmental and inflammatory processes. Different Nuclear Medicine imaging techniques can be used to diagnose peritoneal diseases, most of these techniques can be customized depending on the clinical scenario and expected findings. Peritoneal scintigraphy can detect abnormal peritoneal communication or compartmentalization. Several nuclear medicine techniques can help characterize intraperitoneal fluid collections and differentiate sterile from infected fluid. PET imaging plays an important role in imaging of different neoplastic and non-neoplastic peritoneal pathologies. Nuclear radiologists need to be familiar with peritoneal anatomy and pathology to interpret peritoneal findings in dedicated peritoneal nuclear medicine imaging studies, as part of more general nuclear medicine scans, or on CT or MRI component of hybrid imaging studies. The purpose of this article is to review the normal peritoneal anatomy, various pathologic processes involving the peritoneum, and different nuclear medicine and hybrid imaging techniques that can help detect, characterize, and follow up peritoneal pathology.

Gastric lymphatic flows may change before and after endoscopic submucosal dissection: in vivo porcine survival models

BACKGROUND AND STUDY AIM

Standard gastrectomy with lymphadenectomy is recommended following endoscopic submucosal dissection (ESD) due to the risk of lymph-node metastasis for resected cancers. However, when lymphatic flows remain unchanged after ESD, a minimally invasive function-preserving surgery based on the sentinel node (SN) concept may be applicable. In this study, using porcine survival models, we aimed to investigate whether gastric lymphatic flows were modified following ESD.

METHODS

Twelve pigs, each with one simulating lesion 3 cm in size, were used. Indocyanine green (ICG) fluid was endoscopically injected into the submucosa in four quadrants surrounding the lesion. Following laparoscopic observation of lymphatic flows, the lesions were resected by ESD. After 4 weeks, ICG fluid was injected in four quadrants surrounding the scar and lymphatic flows were observed in the same manner as the initial procedure. The distribution of lymphatic flows, including stained SNs, was compared.

RESULTS

In ten lesions (83.3%), the distribution of flows remained unchanged. However, in one lesion, the flow along the right gastric epiploic artery (R-GEA) disappeared on the lesser curvature of the middle stomach. In addition, in one lesion, the flow along R-GEA emerged on the lesser curvature of the lower stomach.

CONCLUSIONS

Our study revealed that, despite ESD, lymphatic flows remained unchanged in most parts of the stomach. The SN concept may be applied after ESD, except for lesions on the lesser curvature. However, in the case of the lesser curvature, special care must be given to the SN concept.

CT findings in diagnosis of gastric bare area invasion: potential prognostic factors for proximal gastric carcinoma

PURPOSE

To investigate the correlation between the preoperative CT findings in diagnosis of gastric bare area (GBA) invasion and the 3-year-overall survival (OS) of patients with proximal gastric carcinoma (PGC).

METHODS

108 consecutive patients with PGC confirmed by biopsy underwent MDCT scan prior to gastrectomy were enrolled retrospectively from Dec 2009 to Dec 2014. GBA invasion in PGC were evaluated by measuring the direct CT signs including transmural involvement and lymph nodes in the GBA. The indirect signs were also evaluated including the infiltration of the diaphragm, gastrophrenic ligament and perigastric fat. Kaplan-Meier estimates with log-rank test and Cox proportional hazard model were used for analysis.

RESULTS

The two raters achieved excellent agreement. Univariate Kaplan-Meier estimates indicated that postoperative chemotherapy (p = 0.003), transmural involvement (p < 0.001), lymph nodes in the GBA (p = 0.015) and cT staging (p = 0.002) were associated with OS. Cox proportional hazard model indicated that the transmural involvement (HR = 8.194, 95% CI 2.15-31.266), diaphragm involvement (HR = 0.21, 95% CI 0.042-0.986), perigastric fat infiltration (HR = 0.125, 95% CI 0.018-0.885; HR = 0.02, 95% CI 0.001-0.264), and cT staging were independent prognostic factors for OS.

CONCLUSION

CT findings of GBA invasion in patients with PGC, not only the transmural involvement but also the indirect signs are independent prognostic factors potentially, which should be given more emphasis in future clinical practice.

Primary and secondary disease of the peritoneum and mesentery: review of anatomy and imaging features

The largest and most complex serosal membrane in the body, the peritoneum, lines the abdominal cavity, and the abdominopelvic viscera. It is frequently involved in a variety of benign and malignant processes. While secondary involvement of the peritoneum is more common, primary tumors can be a diagnostic challenge. Knowledge of the anatomy is crucial in understanding the various pathologic processes. Cross-sectional imaging plays an important role in diagnosing and evaluating the extent of the disease processes. This article reviews the imaging anatomy of the peritoneum and mesentery and the common pathologies involving it.

Visualization of the omental bursa and its spatial relationships to left subphrenic extraperitoneal spaces by the second Chinese Visible Human model

Purpose

In order to overcome the obstacle that detailed spatial relationships of the omental bursa to its related spaces cannot be displayed clearly by thick-slice sectional anatomical imaging and computed tomography, we designed a new approach to three-dimensional (3D) visualization of the omental bursa.

Methods

By Amira^® software, we employed thin-slice cross-sectional images of the upper abdomen retrieved from second Chinese Visible Human datasets to display the spatial relationships of the omental bursa to its related spaces, especially to the left subphrenic extraperitoneal spaces. Moreover, these spatial relationships were presented on 3D sections reconstructed from second Chinese Visible Human images and computed tomography images.

Results

Of importance, the gastric bare area is located among the superior, inferior, and splenic recesses. The appearance of the foramen bursae omenti majoris is the only pathway communicating between the superior and inferior recesses of the omental bursa, and also is the anatomic landmark between the superior and inferior recesses. The splenic recess is surrounded from behind by the splenic bare area and the gastric bare area.

Conclusion

As one of the subphrenic spaces, the omental bursa with its related spaces was imaged three-dimensionally using a visualization technique. Familiarity with the anatomic location and spatial relationships of the omental bursa to its related spaces may be beneficial for the differential diagnosis and intervention, improving outcome.

Electronic supplementary material

The online version of this article (doi:10.1007/s00276-015-1462-3) contains supplementary material, which is available to authorized users.

Visualization of the left extraperitoneal space and spatial relationships to its related spaces by the visible human project

BACKGROUND

The major hindrance to multidetector CT imaging of the left extraperitoneal space (LES), and the detailed spatial relationships to its related spaces, is that there is no obvious density difference between them. Traditional gross anatomy and thick-slice sectional anatomy imagery are also insufficient to show the anatomic features of this narrow space in three-dimensions (3D). To overcome these obstacles, we used a new method to visualize the anatomic features of the LES and its spatial associations with related spaces, in random sections and in 3D.

METHODS

In conjunction with Mimics® and Amira® software, we used thin-slice cross-sectional images of the upper abdomen, retrieved from the Chinese and American Visible Human dataset and the Chinese Virtual Human dataset, to display anatomic features of the LES and spatial relationships of the LES to its related spaces, especially the gastric bare area. The anatomic location of the LES was presented on 3D sections reconstructed from CVH2 images and CT images.

PRINCIPAL FINDINGS

What calls for special attention of our results is the LES consists of the left sub-diaphragmatic fat space and gastric bare area. The appearance of the fat pad at the cardiac notch contributes to converting the shape of the anteroexternal surface of the LES from triangular to trapezoidal. Moreover, the LES is adjacent to the lesser omentum and the hepatic bare area in the anterointernal and right rear direction, respectively.

CONCLUSION

The LES and its related spaces were imaged in 3D using visualization technique for the first time. This technique is a promising new method for exploring detailed communication relationships among other abdominal spaces, and will promote research on the dynamic extension of abdominal diseases, such as acute pancreatitis and intra-abdominal carcinomatosis.

[Peritoneum and mesenterium. Radiological anatomy and extent of peritoneal diseases]

The abdominal cavity is subdivided into the peritoneal cavity, lined by the parietal peritoneum, and the extraperitoneal space. It extends from the diaphragm to the pelvic floor. The visceral peritoneum covers the intraperitoneal organs and part of the pelvic organs. The parietal and visceral layers of the peritoneum are in sliding contact; the potential space between them is called the peritoneal cavity and is a part of the embryologic abdominal cavity or primitive coelomic duct. To understand the complex anatomical construction of the different variants of plicae and recesses of the peritoneum, an appreciation of the embryologic development of the peritoneal cavity is crucial. This knowledge reflects the understanding of the peritoneal anatomy, deep knowledge of which is very important in determining the cause and extent of peritoneal diseases as well as in decision making when choosing the appropriate therapeutic approach, whether surgery, conservative treatment, or interventional radiology.

Greater and lesser omenta: normal anatomy and pathologic processes

The peritoneum is the largest serous membrane in the body and the one with the most complex structure. The omentum is a double-layered extension of the peritoneum that connects the stomach to adjacent organs. The peritoneal reflections form the greater and lesser omenta, and the natural flow of peritoneal fluid determines the route of spread of intraperitoneal fluid and consequently of disease processes within the abdominal cavity. The omenta serve both as boundaries for disease processes and as conduits for disease spread. The omenta are frequently involved by infectious, inflammatory, neoplastic, vascular, and traumatic processes. Computed tomography (CT) is a primary diagnostic method for evaluation of omental diseases, most of which may manifest with nonspecific clinical features. Multidetector CT with multiplanar reformation allows accurate examination of the complex anatomy of the peritoneal cavity, knowledge of which is the key to understanding the pathologic processes affecting the greater and lesser omenta.