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

Abstract

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.

Figure 1. Flow chart of visualization of the LES and its related structures.

Figure 2. Visualization of the anatomy of the LES on CVH2.

The LES is imaged on cross-sections from the inferior (A–C) and in 3D (D, E). (A) Starting cross-section of the LES. (B) Ending cross-section of the LES. On this section, the gastropancreatic ligament serves as the bottom margin of the LES. (C) Cross-section of the superior part of the pancreatic body. The appearance of the pancreatic body marks the disappearance of the LES; namely, the appearance of the peripancreatic space. (D) Posterointernal view of the spatial relationships of the LES to the stomach and pancreas. (E) Anteroexternal view of the LES. A: LES; B: gastric wall; C: left diaphragm; D: hepatogastric recess; E: distal esophagus; F: liver; G: upper segment of the left layer of the gastrophrenic ligament; H: lung; I: superior recess of the omental bursa; J: foramen bursae omenti majoris; K: inferior recess of the omental bursa; L: lesser omentum; M: gastropancreatic ligament; N: left retroperitoneal space; O: left adrenal gland; P: posterior gastric vein; Q: narrow space; R: left gastric vein and its branches; S: left gastric artery; T: pancreas; U: peripancreatic space; a: anterointernal leg; b: superior margin; c: diagonal line; d: posteroexternal leg; e: inferior margin.

Figure 3. Spatial relationship between the GBA and LSFS on cross-sections from the inferior.

(A) The GBA and LSFS overlap on upper sections of CVH2. (B) The GBA and the LSFS are separated by the lower segment of the left layer of the gastrophrenic ligament on lower sections of CVH2. (C, D) The LSFS is superimposed on the GBA on cross-sections of the CVH1 and VHMA. The thin adipose layer located between the white and green lines represents the LSFS. A: GBA; B: LSFS; C: posterior gastric vein; D: gastric wall; E: diaphragm; F: lesser omentum; G: lower segment of the left layer of the gastrophrenic ligament; H: left retroperitoneal space.

Figure 4. Manifestation of the spatial relationship between the LES and left retroperitoneal space on oblique sagittal planes.

(A, B) Visualization of the communication relationship between the left retroperitoneal space and the LES from the lateral superior view on CVH2 and CT images, respectively. The anterior renal fascia is represented as a blue line and labeled by a black arrow on CVH2 and CT images, respectively. The posterior renal fascia is represented as a green line and labeled by an arrowhead on CVH2 and CT images, respectively. A: left adrenal gland; B: LES; C: pancreas; D: esophageal hiatus; E: left diaphragm; F: retrocrural space.

Figure 5. Visualizing the distribution of internal structures of the LES on CVH2 by transparent processing.

(A, B) Posterointernal and anteroexternal view of the LES in 3D. The left gastric artery and vein pass through the anteroinferior part of the GBA and enter the lesser omentum. The left gastric lymph nodes are situated behind the left gastric vessels in the GBA, and the left cardiac lymph nodes are situated at the fat pad of the GBA. These structures are located at the corresponding position in the LES. The trunk of the posterior gastric vein passes through the lower segment of the left layer of the gastrophrenic ligament, the GBA, the LSFS, and the GBA, near the posterior border of the LES. Finally, this trunk penetrates through the upper segment of the left layer of the gastrophrenic ligament and enters the posterior wall of the gastric fundus. Similarly, the posterior branch of the posterior gastric vein goes straight through the lower segment of the left layer of the gastrophrenic ligament at its posterior margin and reaches the gastric wall. A: GBA; B: LSFS; C: posterior gastric vein and its branches; D: lower segment of the left layer of the gastrophrenic ligament; E: left gastric artery; F: left gastric vein and its branches; G: upper segment of the left layer of the gastrophrenic ligament; H: left cardiac lymph nodes; I: left gastric lymph nodes.

Figure 6. Visualizing the spatial relationship of the LES to the left retroperitoneal space on CVH2.

(A, B) Posterointernal and anteroexternal view of the spatial relationship between LES and left retroperitoneal space in 3D. The upper pole of the left retroperitoneal space overlaps with the lower portion of the LSFS, but the left retroperitoneal space is separated from the GBA by the lower segment of left layer of the gastrophrenic ligament. The left retroperitoneal space communicates with the LES across the LSFS. A: GBA; B: LSFS; C: the lower segment of left layer of the gastrophrenic ligament; D: the upper segment of left layer of the gastrophrenic ligament; E: upper portion of the left retroperitoneal space; F: left adrenal gland.

Figure 7. Manifestation of the LES on axial CT image from the inferior.

A: LES; B: lesser omentum; C: left gastric artery; D: posterior gastric artery; E: narrow space; F: hepatic bare area; G: right adrenal gland.

Figure 8. Presentation of the triangular-shaped LES on coronal MPR images from the front.

(A, B) Visualization of the LES on CVH2 and CT images, respectively. A: LES; B: left crura of the diaphragm; C: gastric cardia; D: gastric fundus; E: pancreas; F: splenic artery; G: splenic vein; H: root of the celiac trunk; I: right crura of the diaphragm.