Sonographic anatomy of the gastrohepatic ligament

Endoscopic ultrasound of peritoneal spaces

The peritoneal cavity is subdivided into supracolic and infracolic compartments by transverse colon and its mesocolon. The supracolic compartment contains the liver, spleen, stomach, and lesser omentum. The infracolic compartment contains the coils of small bowel surrounded by ascending, transverse, and descending colon and the paracolic gutters. The imaging of different compartments is possible by various methods such as ultrasound (US) and computerized tomography. The treating physicians should be familiar with the relevant radiological anatomy of different compartments and spaces as accurate localization of fluid collection/lymph node in peritoneal cavity greatly aids in selection of a treatment strategy. The role of endoscopic US (EUS) is emerging for detail evaluation of all parts of peritoneal cavity as it provides an easy access for fine-needle aspiration from different compartments of peritoneal cavity. In this review, we describe the techniques of evaluation of different parts of supracolic compartments of peritoneum by EUS.

Evaluating Patients with Left Upper Quadrant Pain

Imaging plays a major role in the evaluation of patients who present to the emergency department with acute left upper quadrant (LUQ) pain. Multidetector computed tomography is currently the primary modality used for imaging these patients. The peritoneal reflections, subperitoneal compartment, and peritoneal spaces of the LUQ are key anatomic features in understanding the imaging appearance of acute diseases in this area. Diseases of the stomach, spleen, pancreas, and splenic flexure are encountered in patients with acute LUQ pain. Optimization of the imaging protocol is vital for accurate diagnosis and characterization of these diseases in the acute setting.

Detection of peritoneal carcinomatosis by EUS fine-needle aspiration: impact on staging and resectability (with videos)

BACKGROUND

Peritoneal carcinomatosis (PC) greatly affects cancer staging and resectability.

OBJECTIVE

To compare the PC detection rate by using EUS and noninvasive imaging and to determine the impact on staging and resectability.

DESIGN

Retrospective study.

SETTING

Single tertiary-care referral center.

PATIENTS

A prospectively maintained EUS database was reviewed to identify patients who underwent EUS-guided FNA (EUS-FNA) of a peritoneal anomaly. Findings were compared with a strict criterion standard that incorporated cytohistologic, radiologic, and clinical data.

INTERVENTION

EUS-FNA of a peritoneal anomaly.

MAIN OUTCOME MEASUREMENTS

Safety and diagnostic yield.

RESULTS

Of 106 patients, a criterion standard was available in 98 (39 female patients; median age, 65 years). The sensitivity, specificity, and accuracy of EUS-FNA versus CT/magnetic resonance imaging (MRI) was 91% versus 28%, 100% versus 85%, and 94% versus 47%, respectively. In newly diagnosed cancer patients, peritoneal FNA upstaged 17 patients (23.6%). Of 32 patients deemed resectable by pre-EUS CT/MRI, 15 (46.9%) were deemed unresectable based solely on peritoneal FNA. The odds of FNA changing the resectability status remained highly significant after adjustment for cancer type, time between CT/MRI and EUS-FNA, and the quality of CT/MRI. The malignant appearance of the peritoneal anomaly but not the presence of ascites on EUS predicted a positive FNA finding (odds ratio 2.56; 95% confidence interval, 1.23-5.4 and odds ratio 0.83; 95% confidence interval, 0.4-1.8, respectively). There were 3 adverse events among 4 patients. Two of the patients developed abdominal pain and one each hypertensive urgency and pancreatitis.

LIMITATIONS

Retrospective design, single-center, bias toward EUS as a diagnostic test.

CONCLUSION

Peritoneal EUS-FNA appears to safely detect radiographically occult PC and improve cancer staging and patient care.

Imaging of peritoneal ligaments by endoscopic ultrasound (with videos)

Double layered peritoneal folds or ligaments act as conduits for the passage of blood vessels in intraperitoneal organs and also provide a pathway for the spread of disease. It is difficult to identify these normal peritoneal folds at imaging. Computed tomography is the most common imaging modality used to detect diseases of the peritoneum. The ultrasound (US) has been also used for evaluation of diseases involving ligaments. Endoscopic ultrasound (EUS) is being increasingly used both for diagnostic and interventional purposes in abdomen. In this article, we have described the normal EUS anatomy of the peritoneal ligaments.

Techniques of imaging of nodal stations of gastric cancer by endoscopic ultrasound

Nodal staging is of crucial importance in the management of gastric cancer (GC). The available modalities of nodal imaging in GC do not provide a high sensitivity and specificity of lymph node status. Comparative study of endoscopic ultrasonography (EUS) and multislice spiral computed tomography in GC has shown greater accuracy of EUS for N staging. EUS is not used routinely in patients with GC as it is not available at all centers, and its accuracy is operator dependent. Standard techniques of identification of nodal station (as suggested by Japanese Research Society for the Study of Gastric Cancer) by EUS have not been described so far. Identification of each nodal station by EUS requires adequate knowledge of anatomy as well as understanding the proper technique to perform EUS. This review presents a method to identify the regional nodal stations of GC by linear EUS and hence will help in appropriate N staging of GC.

Endoscopic ultrasound description of liver segmentation and anatomy

Endoscopic ultrasound (EUS) can demonstrate the detailed anatomy of the liver from the transgastric and transduodenal routes. Most of the liver segments can be imaged with EUS, except the right posterior segments. The intrahepatic vascular landmarks include the major hepatic veins, portal vein radicals, hepatic arterial branches, and the inferior vena cava, and the venosum and teres ligaments are other important intrahepatic landmarks. The liver hilum and gallbladder serve as useful surface landmarks. Deciphering liver segmentation and anatomy by EUS requires orienting the scan planes with these landmarkstructures, and is different from the static cross-sectional radiological images. Orientation during EUS requires appreciation of the numerous scan planes possible in real-time, and the direction of scanning from the stomach and duodenal bulb. We describe EUS imaging of the liver with a curved linear probe in a step-by-step approach, with the relevant anatomical details, potential applications, and pitfalls of this novel EUS application.