ARFI elastography of the omentum: feasibility and diagnostic performance in differentiating benign from malignant omental masses

Abstract

Objective: To evaluate the feasibility and diagnostic performance of acoustic radiation force impulse (ARFI) elastography in different omental masses (OM).

Design: This was a retrospective analysis of 106 patients with OM defined as omental thickness ≥1 cm, who underwent abdominal B-mode ultrasound (US) and standardised ARFI examinations of the OM between September 2018 and June 2021 at our university hospital. A cytohistological confirmation was available in 91/106 (85.8%) of all OM, including all 65/65 (100%) malignant OM (mOM) and 26/41 (63.4%) of benign OM (bOM). In 15/41 (36.6%) of bOM; cross-sectional imaging and or US follow-up with a mean duration of 19.8±3.1 months was performed. To examine the mean ARFI velocities (MAV) for potential cut-off values between bOM and mOM a receiver operating characteristic analysis was implemented.

Results: The MAV in the mOM group (2.71±1.04 m/s) was significantly higher than that of bOM group (1.27±0.87 m/s) (p<0.001). Using 1.97 m/s as a cut-off yielded a sensitivity and specificity of 76.9% and 85.4%, respectively, in diagnosing mOM (area under the curve=0.851, 95% CI=0.774 to 0.928).

Conclusion: ARFI elastography is feasible in the omentum and may represent a good non-invasive additional tool in differentiating bOM from mOM.

Keywords: GASTROINTESTINAL ULTRASOUND; IMAGING; RADIOLOGY; SURGICAL ONCOLOGY; TUMOUR MARKERS.

Figure 1

Flow diagram of the study patients. ARFI, acoustic radiation force impulse.

Figure 2

Benign omental mass. A 41-year-old male patient with unexplained ascites; (A) CT scan showing ascites and thickened omentum (courtesy of Professor Dr Mahnken, Department of Radiology, University Hospital Marburg), (B) US elastography image showing a mass-like echogenic omentum in the epigastric area with one ARFI measurement of 0.55 m/s, (C) the final ARFI report of the same mass sowing a mean ARFI velocity (MW) of 0.58 m/s. After surgical exploration, the diagnosis of bacterial peritonitis as a delayed presentation of a perforated subacute appendicitis was established and histologically confirmed.ARFI, acoustic radiation force impulse; US, ultrasound.

Figure 3

Malignant omental mass. A 51-year-old male patient with unexplained ascites; (A) CT scan showing ascites and inhomogeneous omental mass with multiple nodules (omental caking) (courtesy of Professor Dr Mahnken, Department of Radiology, University Hospital Marburg), (B) US elastography image showing an inhomogeneous multinodular OM in the left lower quadrant with one ARFI measurement of 2.51 m/s, (C) the final ARFI report of the same mass sowing a mean ARFI velocity (MW) of 2.54 m/s. The final histology of the US-guided omental biopsy as well as that of the surgical specimens was diffuse omental and peritoneal metastases from an appendiceal carcinoma. ARFI, acoustic radiation force impulse; OM, omental masses; US, ultrasound.

Figure 4

(A) Differences of mean ARFI velocities between benign and malignant omental masses (mOM) in the study. The mean ARFI velocity (MAV) in m/s is represented with an ‘X’ in each box, and the median ARFI velocity of each group is shown as a horizontal line within each box. (B) Receiver operator characteristic curve for the differences in mean ARFI velocities between benign and malignant omental masses. ARFI, acoustic radiation force impulse; bOM, benign OM.