Ultrasound and computed tomography in the evaluation of mesenteric lesions: A pictorial review

The mesentery is a broad fan-shaped fold of peritoneum that suspends the loops of small intestine from the posterior abdominal wall. Although primary neoplasms arising in the mesentery are rare, the mesentery is a major avenue for the dissemination of tumours, which can spread through hematogenous, lymphatic, direct or peritoneal seeding. Imaging helps in the diagnosis of these tumours and aids in directing appropriate treatment by assessing their size, extent and relationship with adjacent structures. The aim of this article is to describe the spectrum of imaging findings of the various mesenteric lesions using ultrasound and CT.

Contribution

Evaluation of the mesentery is often neglected during routine ultrasound (US) because of inadequate training and unfamiliarity with the common US features encountered with mesenteric disease. CT plays an essential role in the diagnosis of mesenteric disease. Knowledge of imaging characteristics of various mesenteric lesions helps in timely diagnosis and management.

Analysis of factors affecting the diagnostic yield of image-guided percutaneous core needle biopsy for peritoneal/omental lesions

PURPOSE

To evaluate the diagnostic yield, safety, and factors associated with the diagnostic yield of percutaneous core needle biopsy (PNB) for peritoneal/omental lesions.

METHODS

Consecutive 297 patients (67 men, 230 women; median age, 64 years [range 15-87]) who underwent a PNB for 311 peritoneal/omental lesions at a single center from April 2010 to March 2020 were evaluated retrospectively. The preprocedural CT findings, diagnostic yield, sensitivity, specificity, PPV, NPV, technical success rate, and adverse events were analyzed. Surgical or clinical diagnosis with follow-up was the diagnostic reference standard. Adverse events were evaluated using the Society of Interventional Radiology guidelines.

RESULTS

The median anteroposterior (AP) diameter and CT value of the target lesion were 24 mm (range 5-78) and 46 HU (range - 75 to 140), respectively. Ascites was interposed on the puncture route in 106 patients (34.1%). The technical success rate was 100%. The diagnostic yield, sensitivity, specificity, PPV, and NPV were 93.9%, 93.8%, 100%, 100%, and 20.8%, respectively. Minor complications were observed following five procedures (1.6%). The diagnostic yield was lower for fat-dominant lesions than for other lesions (82.6% vs. 95.8%, p = 0.002). The diagnostic PNB group had a greater AP diameter than did the non-diagnostic PNB group (27.3 ± 13.0 vs. 20.7 ± 8.4 mm, p = 0.037).

CONCLUSION

PNB for peritoneal/omental lesions provided a sufficiently high diagnostic yield and minimal adverse events. Lesions with a greater AP diameter and a higher density on CT would provide more diagnostic specimens from this technique.

Contrast-Enhanced Ultrasound-Guided Percutaneous Biopsy of the Peritoneum: A Series of 3 Cases

In the presence of peritoneal disease, patients often should undergo biopsy of the peritoneum for acquiring a specific pathologic diagnosis. Ultrasound is ideal for guiding peritoneal biopsy, although in some situations, it can be technically challenging. The addition of a contrast agent can improve the visualization of lesions and adjacent organs, providing radiologists increased confidence. A contrast agent can identify perfused areas within the target lesion, improving diagnostic accuracy. We present 3 cases of contrast-enhanced ultrasound-guided peritoneal biopsy. In all cases, we gained a specific diagnosis. No immediate or delayed complications occurred. Contrast-enhanced ultrasound-guided biopsy proved to be a simple, safe, and accurate diagnostic method.

Comparative Study of Ultrasound-guided Percutaneous Omental Biopsy in Cirrhotics and Noncirrhotics

BACKGROUND

To evaluate the safety and efficacy of ultrasound-guided (US-guided) omental biopsy in patients with liver cirrhosis and compare these with the noncirrhotic patients.

METHODS

We retrospectively studied the US-guided omental biopsies (73 males, 14 females with mean age 52.71 ± 15.90 y) between January 2012 and December 2018. Patients with biopsy-proven liver cirrhosis (n = 31) who underwent omental biopsy were included in Group 1, and patients without any features of the chronic liver disease (n = 56) were included in Group 2. The technical success, diagnostic parameters, complications, imaging appearance, and histopathology spectrum were compared between the two groups. Also, univariate analysis was done to evaluate the association of a parameter with histopathology.

RESULTS

The technical success, sample adequacy, diagnostic accuracy of Group 1 were 100%, 96.77%, and 96.77%, respectively, and for Group 2, these were 100%, 98.21%, and 98.21%, respectively. The sensitivity, specificity, positive predictive value, negative predictive value of Group 1 were 95%, 100%, 100%, 91.67%, respectively, and for Group 2, these were 97.92%, 100%, 100%, 88.89%, respectively. There was one complication of abdominal wall hematoma in Group 1 (3.2%), which was managed conservatively. Smudged imaging appearance and nonspecific inflammation on histopathology were more common in Group 1, and there was a significant association of increased omental thickening with specific pathology in Group 1.

CONCLUSION

US-guided omental biopsy in patients with liver cirrhosis is safe and effective with comparable results to noncirrhotic patients.

Diagnostic performance of imaging-guided core needle biopsy of the mesentery and peritoneum

OBJECTIVE

To evaluate the diagnostic performance of imaging-guided core needle biopsy of nodules and diffuse infiltration of the omentum or of the peritoneum.

MATERIAL AND METHODS

We retrospectively evaluated 57 patients who underwent core needle biopsy of the peritoneum or of the omentum between March 2014 and January 2017. We used computed tomography (CT) to plan the biopsy. Biopsies were guided by CT or ultrasonography (US). We classified the results as diagnostic (benign / malignant) or inconclusive (inadequate sample). We calculated the sensitivity, specificity, positive-predictive value, and negative predictive value. We analyzed whether the specimen was diagnostic depending on the imaging technique used (CT or US) and on the type of omental or peritoneal involvement from which the specimen was obtained (mass, nodule, or diffuse involvement).

RESULTS

All (100%) the percutaneous biopsies were diagnostic. The sensitivity of the technique was 98.18% and the specificity was 100%. The positive predictive value was 100% and the negative predictive value was 50%. Both the specimens obtained under CT guidance (n=10) and those obtained under US guidance (n=47) were diagnostic. Likewise, biopsies of masses (n=24), of nodules (n=17), and even of diffuse infiltration (n=16) of the peritoneum or omentum enabled the histologic diagnosis. The rate of complications was 1.75% (one death).

CONCLUSION

Percutaneous core needle biopsy has high sensitivity regardless of the imaging technique used to guide the technique (CT or US) and of the type of lesion biopsied (mass, nodule, diffuse infiltration). It is a useful technique with a very low rate of complications, although severe complications can occur.

Ultrasound-Guided Percutaneous Core Needle Biopsy of Abdominal Viscera: Tips to Ensure Safe and Effective Biopsy

Ultrasound-guided percutaneous core needle biopsy (USPCB) is used extensively in daily clinical practice for the pathologic confirmation of both focal and diffuse diseases of the abdominal viscera. As a guidance tool, US has a number of clear advantages over computerized tomography or magnetic resonance imaging: fewer false-negative biopsies, lack of ionizing radiation, portability, relatively short procedure time, real-time intra-procedural visualization of the biopsy needle, ability to guide the procedure in almost any anatomic plane, and relatively lower cost. Notably, USPCB is widely used to retrieve tissue specimens in cases of hepatic lesions. However, general radiologists, particularly beginners, find USPCB difficult to perform in abdominal organs other than the liver; indeed, a full understanding of the entire USPCB process and specific considerations for specific abdominal organs is necessary to safely obtain adequate specimens. In this review, we discuss some points and techniques that need to be borne in mind to increase the chances of successful USPCB. We believe that the tips and considerations presented in this review will help radiologists perform USPCB to successfully retrieve target tissue from different organs with minimal complications.

Mesenteric tumors: diagnosis and treatment

Mesenteric tumors are rare and consist of a heterogeneous group of lesions. Masses may arise from any of the mesenteric components: peritoneum, lymphatic tissue, fat, and connective tissue. Cellular proliferation can also arise from infectious or inflammatory processes. They can be classified as solid or cystic, benign or malignant. Mesenteric tumors are usually discovered incidentally or during investigation of non-specific symptoms. While clinical examination and imagery may suffice to make the diagnosis, histopathology is often required by either needle percutaneous or surgical biopsy, or immediate excision. Therapeutic management options vary widely depending on the nature of the lesion; they range from simple observation or medical therapy to surgery. Benign well-delineated mesenteric masses that are symptomatic can often be treated by simple enucleation. But invasive malignant tumors require a carcinologic resection; a careful preoperative evaluation to assess the relationship between the mass and adjacent vascular and digestive structures is essential since they may dictate the need for extensive sacrifice of bowel with resultant intestinal insufficiency due to short bowel syndrome.