Vascular evaluation using transabdominal ultrasound for gallbladder polyps

Update on the Role of Imaging in the Diagnosis, Staging, and Prognostication of Gallbladder Cancer

Gallbladder cancer (GBC) is a highly aggressive malignancy with dismal prognosis. GBC is characterized by marked geographic predilection. GBC has distinct morphological types that pose unique challenges in diagnosis and differentiation from benign lesions. There are no specific clinical or serological markers of GBC. Imaging plays a key role not only in diagnosis and staging but also in prognostication. Ultrasound (US) is the initial test of choice that allows risk stratification in wall thickening and polypoidal type of gallbladder lesions. US findings guide further investigations and management. Computed tomography (CT) is the test of choice for staging GBC as it allows comprehensive evaluation of the gallbladder lesion, liver involvement, lymph nodes, peritoneum, and other distant sites for potential metastases. Magnetic resonance imaging (MRI) and magnetic resonance cholangiopancreatography allow better delineation of the biliary system involvement. Contrast-enhanced US and advanced MRI techniques including diffusion-weighted imaging and dynamic contrast-enhanced MRI are used as problem-solving tools in cases where distinction from benign lesion is challenging at US and CT. Positron emission tomography is also used in selected cases for accurate staging of the disease. In this review, we provide an up-to-date insight into the role of imaging in diagnosis, staging, and prognostication of GBC.

Establishing a radiomics model using contrast-enhanced ultrasound for preoperative prediction of neoplastic gallbladder polyps exceeding 10 mm

BACKGROUND

A key challenge in the medical field is managing gallbladder polyps (GBP) > 10 mm, especially when their nature is uncertain. GBP with a diameter exceeding 10 mm are associated with an increased risk of gallbladder cancer, making the key to their management the differentiation between benign and malignant types. The current practice, due to the inability to predict accurately, leads to excessive surgeries and ineffective follow-ups, increasing patient risks and medical burdens.

PURPOSE

This study aims to establish an imaging radiomics model using clinical data and contrast-enhanced ultrasound (CEUS) to predict neoplastic GBP exceeding 10 mm in diameter preoperatively.

MATERIALS AND METHODS

Data from 119 patients with GBP > 10 mm of unknown origin were analyzed. A total of 1197 features were extracted from the GBP area using conventional ultrasound (US) and CEUS. Significant features were identified using the Mann-Whitney U test and further refined with a least absolute shrinkage and selection operator (LASSO) regression model to construct radiomic features. By integrating clinical characteristics, a radiomics nomogram was developed. The diagnostic efficacy of the preoperative logistic regression (LR) model was validated using receiver operating characteristic (ROC) curves, calibration plots, and the Hosmer-Lemeshow test. CEUS is an examination based on conventional ultrasound, and conventional two-dimensional ultrasound still poses significant challenges in differential diagnosis. CEUS has a high accuracy rate in diagnosing the benign or malignant nature of gallbladder space-occupying lesions, which can significantly reduce the preoperative waiting time for related examinations and provide more reliable diagnostic information for clinical practice.

RESULTS

Feature selection via Lasso led to a final LR model incorporating high-density lipoprotein, smoking status, basal width, and Rad_Signature. This model, derived from machine learning frameworks including Support Vector Machine (SVM), Logistic Regression (LR), Multilayer Perceptron (MLP), k-Nearest Neighbors (KNN), and eXtreme Gradient Boosting (XGBoost) with fivefold cross-validation, showed AUCs of 0.95 (95% CI: 0.90-0.99) and 0.87 (95% CI: 0.72-1.0) in internal validation. The model exhibited excellent calibration, confirmed by calibration graphs and the Hosmer-Lemeshow test (P = 0.551 and 0.544).

CONCLUSION

The LR model accurately predicts neoplastic GBP > 10 mm preoperatively. Radiomics with CEUS is a powerful tool for analysis of GBP > 10 mm. The model not only improves diagnostic accuracy and reduces healthcare costs but also optimizes patient management through personalized treatment plans, enhancing clinical outcomes and ensuring resources are more precisely allocated to patients who need surgery.

Establishing a preoperative predictive model for gallbladder adenoma and cholesterol polyps based on machine learning: a multicentre retrospective study

BACKGROUND

With the rising diagnostic rate of gallbladder polypoid lesions (GPLs), differentiating benign cholesterol polyps from gallbladder adenomas with a higher preoperative malignancy risk is crucial. This study aimed to establish a preoperative prediction model capable of accurately distinguishing between gallbladder adenomas and cholesterol polyps using machine learning algorithms.

MATERIALS AND METHODS

We retrospectively analysed the patients' clinical baseline data, serological indicators, and ultrasound imaging data. Using 12 machine learning algorithms, 110 combination predictive models were constructed. The models were evaluated using internal and external cohort validation, receiver operating characteristic curves, area under the curve (AUC) values, calibration curves, and clinical decision curves to determine the best predictive model.

RESULTS

Among the 110 combination predictive models, the Support Vector Machine + Random Forest (SVM + RF) model demonstrated the highest AUC values of 0.972 and 0.922 in the training and internal validation sets, respectively, indicating an optimal predictive performance. The model-selected features included gallbladder wall thickness, polyp size, polyp echo, and pedicle. Evaluation through external cohort validation, calibration curves, and clinical decision curves further confirmed its excellent predictive ability for distinguishing gallbladder adenomas from cholesterol polyps. Additionally, this study identified age, adenosine deaminase level, and metabolic syndrome as potential predictive factors for gallbladder adenomas.

CONCLUSION

This study employed the machine learning combination algorithms and preoperative ultrasound imaging data to construct an SVM + RF predictive model, enabling effective preoperative differentiation of gallbladder adenomas and cholesterol polyps. These findings will assist clinicians in accurately assessing the risk of GPLs and providing personalised treatment strategies.

Diagnostic Accuracy of Detective Flow Imaging Endoscopic Ultrasonography for Evaluating Blood Flow Within Mural Nodules of Intraductal Papillary Mucinous Neoplasms

Background/Objectives: Detective flow imaging (DFI) endoscopic ultrasonography (EUS) can identify the microvascular flow imaging of a mural nodule (MN) in an intraductal papillary mucinous neoplasm (IPMN) without the use of contrast agents. This retrospective study evaluated the diagnostic accuracy of DFI-EUS and its ability to evaluate the blood flow of MNs in IPMNs. Methods: Between April 2021 and September 2023, 68 patients with MNs in IPMNs observed on EUS images were retrospectively analyzed. Both DFI-EUS and contrast-enhanced EUS (CE-EUS) were performed during the same session. Three expert endosonographers blinded to the patients' clinical data assessed the MN images obtained with CE-EUS and DFI-EUS. First, DFI-EUS images were evaluated using a predefined scoring system; thereafter, CE-EUS images were evaluated. The diagnostic capability of DFI-EUS to detect MN blood flow was assessed with CE-EUS as the gold standard. Secondary outcomes included inter-reader agreement, the correlation between MN size and detection rates, and the association between DFI blood flow signal patterns and malignancy of MNs in surgically resected cases. Results: CE-EUS showed a contrast effect in the MN in 24 cases. Among these, DFI-EUS detected blood flow signals in 20 cases; false-positive results were not observed. DFI-EUS demonstrated a sensitivity of 83%, specificity of 100%, and accuracy of 93% for detecting MN blood flow. Inter-reader agreement was substantial (kappa values, 0.6-0.8). The subgroup analysis revealed that all MNs ≥ 10 mm had detectable blood flow on DFI-EUS, whereas MNs < 10 mm had reduced detection rates (75%; 12/16 cases). No significant correlation between the DFI blood flow signal patterns and MN malignancy of resected cases was observed. Conclusions: DFI-EUS demonstrated high diagnostic accuracy for detecting MN blood flow. Because of its simplicity and cost-effectiveness, DFI-EUS could be an alternative to CE-EUS for patients with MNs inside IPMNs.

Differential Diagnosis of Solid Pancreatic Lesions Using Detective Flow Imaging Endoscopic Ultrasonography

The differential diagnosis of solid pancreatic lesions (SPLs) using B-mode endoscopic ultrasonography (EUS) is challenging. Detective flow imaging (DFI) offers the potential for detecting low-flow vessels in the pancreas, thus enhancing diagnostic accuracy. This retrospective study aimed to investigate DFI-EUS findings of SPLs and analyze their differential diagnostic accuracy for pancreatic cancer. We included 104 patients with pathologically confirmed SPLs who underwent EUS between April 2021 and June 2023. Expert endosonographers, blinded to the patients' clinical data, evaluated images obtained through B-mode, eFLOW, and DFI-EUS. The frame rate and vessel detection sensitivity were compared between eFLOW and DFI, and the diagnostic criteria for pancreatic cancer were established. The visualization rate for vessels in SPLs was significantly higher with DFI-EUS (96%) compared to eFLOW (27%). Additionally, DFI showed a superior frame rate, sensitivity (99%), and accuracy (88%) for detecting pancreatic cancer, although with a modest specificity (43%). On DFI-EUS, characteristics such as hypovascularity, peritumoral vessel distribution, or spotty vessel form were suggestive of pancreatic cancer. DFI-EUS significantly improved the visualization of vascular structures within the SPLs, highlighting its efficacy as a diagnostic modality for pancreatic cancer.

Recent Advances in Endoscopic Ultrasound for Gallbladder Disease Diagnosis

Gallbladder (GB) disease is classified into two broad categories: GB wall-thickening and protuberant lesions, which include various lesions, such as adenomyomatosis, cholecystitis, GB polyps, and GB carcinoma. This review summarizes recent advances in the differential diagnosis of GB lesions, focusing primarily on endoscopic ultrasound (EUS) and related technologies. Fundamental B-mode EUS and contrast-enhanced harmonic EUS (CH-EUS) have been reported to be useful for the diagnosis of GB diseases because they can evaluate the thickening of the GB wall and protuberant lesions in detail. We also outline the current status of EUS-guided fine-needle aspiration (EUS-FNA) for GB lesions, as there have been scattered reports on EUS-FNA in recent years. Furthermore, artificial intelligence (AI) technologies, ranging from machine learning to deep learning, have become popular in healthcare for disease diagnosis, drug discovery, drug development, and patient risk identification. In this review, we outline the current status of AI in the diagnosis of GB.

The role of contrast-enhanced endoscopic ultrasound for biliary diseases

Contrast-enhanced endoscopic ultrasound (CE-EUS) has emerged as a promising diagnostic modality for assessing biliary diseases. CE-EUS is a noninvasive imaging technique that utilizes contrast agents to enhance the visualization of blood vessels and perfusion within target tissues. In the context of biliary diseases, CE-EUS allows for improved characterization of biliary lesions, aiding in differential diagnosis and treatment planning. This review highlights several key findings regarding the usefulness of CE-EUS in biliary disease assessment and therapeutic procedures.

Is ultrasonography accurate for the diagnosis of gallbladder polyps? A review of cholecystectomy specimens from patients diagnosed with gallbladder polyps over a 14-years period

INTRODUCTION

Incidence of gallbladder polyps is 0,3-12%. It is important to differentiate pseudopolyps (cholesterol polyps, adenomyomatosis, inflammatory polyps), which do not have the capacity to become malignant, from true polyps (adenomas and adenocarcinomas). The main risk factors for malignancy are >6-10 mm, growth, sessile morphology, Indian ethnicity and primary sclerosing cholangitis. Ultrasound is the gold standard for diagnosis. Most polyps diagnosed by ultrasound are pseudopolyps. The main objective of this study is to analyse whether ultrasound is accurate for diagnosing true polyps in patients undergoing surgery for this reason.

METHODS

Retrospective observational study with prospective data entry of patients undergoing elective cholecystectomy for gallbladder polyps from 2007 to 2021. Surgery was indicated in symptomatic patients and in those with risk factors. The study has been approved by the Clinical Research Ethics Committee of our hospital.

RESULTS

We included 124 patients in our study. An elective laparoscopic cholecystectomy was performed in all of them. The mean age was 55,4 years and 61% were women. Of all patients, 65% were symptomatic at diagnosis. Only 3 patients had true polyps (2,4%). All of them were tubular adenomas. The rest of patients were false positives (97,6%). The adenoma size was 11, 6 and 5 mm, respectively. The surgical indication was due to polyp size or due to associated biliary symptoms.

CONCLUSION

Ultrasonography is not accurate for the diagnosis of gallbladder polyps. Validation of other complementary tests for the diagnosis of gallbladder polyps in asymptomatic patients could be relevant to avoid unnecessary surgeries.

Usefulness of contrast-enhanced ultrasonography for biliary tract disease

Conventional ultrasonography (US) for biliary tract disease shows high time and spatial resolution. In addition, it is simple and minimally invasive, and is selected as a first-choice examination procedure for biliary tract disease. Currently, contrast-enhanced US (CEUS), which facilitates the more accurate assessment of lesion blood flow in comparison with color and power Doppler US, is performed using a second-generation ultrasonic contrast agent. Such agents are stable and provide a timeline for CEUS diagnosis. Gallbladder lesions are classified into three types: gallbladder biliary lesion (GBL), gallbladder polypoid lesion (GPL), and gallbladder wall thickening (GWT). Bile duct lesions can also be classified into three types: bile duct biliary lesion (BBL), bile duct polypoid lesion (BDPL), and bile duct wall thickening (BDWT). CEUS facilitates the differentiation of GBL/BBL from tumorous lesions based on the presence or absence of blood vessels. In the case of GPL, it is important to identify a vascular stalk attached to the lesion. In the case of GWT, the presence or absence of a non-contrast-enhanced area, the Rokitansky-Aschoff sinus, and continuity of a contrast-enhanced gallbladder wall layer are important for differentiation from gallbladder cancer. In the case of BDWT, it is useful to evaluate the contour of the contrast-enhanced medial layer of the bile duct wall for differentiating IgG4-related sclerosing cholangitis from primary sclerosing cholangitis. CEUS for ampullary carcinoma accurately reflects histopathological findings of the lesion. Evaluating blood flow in the lesion, continuity of the gallbladder wall, and contour of the bile duct wall via CEUS provides useful information for the diagnosis of biliary tract disease.

Gallbladder polyps and adenomyomatosis

Incidental findings are commonly detected during examination of the gallbladder. Differentiating benign from malignant lesions is critical because of the poor prognosis associated with gallbladder malignancy. Therefore, it is important that radiologists and sonographers are aware of common incidental gallbladder findings, which undoubtedly will continue to increase with growing medical imaging use. Ultrasound is the primary imaging modality used to examine the gallbladder and biliary tree, but contrast-enhanced ultrasound and MRI are increasingly used. This review article focuses on two common incidental findings in the gallbladder; adenomyomatosis and gallbladder polyps. The imaging features of these conditions will be reviewed and compared between radiological modalities, and the pathology, epidemiology, natural history, and management will be discussed.

Conventional Ultrasound Combined With Contrast-Enhanced Ultrasound in Differential Diagnosis of Gallbladder Cholesterol and Adenomatous Polyps (1-2 cm)

OBJECTIVES

This study aimed to determine ultrasonic image characteristics that enable differentiation between cholesterol and adenomatous polyps and to assess the diagnostic efficacy of combining conventional ultrasound (CUS) with contrast-enhanced ultrasound (CEUS).

METHODS

Eighty-nine patients with gallbladder polyps of 1-2 cm in diameter were enrolled and examined by CUS and CEUS before cholecystectomy. The appearances on CUS and CEUS were recorded and analyzed. The receiver operating characteristic (ROC) curve was used to calculate the optimal size threshold for distinguishing cholesterol from adenomatous polyps. A logistic regression analysis was performed to identify diagnostic variables. ROC analysis was performed to evaluate the diagnostic efficacy of the size, the independent variables, and the combined factors.

RESULTS

There were differences in size, number, vascularity on CUS and intralesional vascular shape, wash-out, and area under the curve on CEUS between the two groups (P < .05). ROC analysis indicated that a maximum diameter of 1.45 cm was the optimal threshold for the prediction of adenomatous polyps. The logistic regression analysis proved that the single polyp, presence of vascularity, and intralesional linear vessels were associated with adenomatous polyps (P < .05). ROC analysis showed that the area under the ROC curve, sensitivity, and specificity for the combination of the three independent variables were 0.858, 87.3%, and 67.6%. The number combined with intralesional vascular shape had the highest diagnostic sensitivity of 91.2%.

CONCLUSIONS

The combination of CUS and CEUS demonstrated great significance in the differential diagnosis of cholesterol and adenomatous polyps.

How Can We Manage Gallbladder Lesions by Transabdominal Ultrasound?

The most important role of ultrasound (US) in the management of gallbladder (GB) lesions is to detect lesions earlier and differentiate them from GB carcinoma (GBC). To avoid overlooking lesions, postural changes and high-frequency transducers with magnified images should be employed. GB lesions are divided into polypoid lesions (GPLs) and wall thickening (GWT). For GPLs, classification into pedunculated and sessile types should be done first. This classification is useful not only for the differential diagnosis but also for the depth diagnosis, as pedunculated carcinomas are confined to the mucosa. Both rapid GB wall blood flow (GWBF) and the irregularity of color signal patterns on Doppler imaging, and heterogeneous enhancement in the venous phase on contrast-enhanced ultrasound (CEUS) suggest GBC. Since GWT occurs in various conditions, subdividing into diffuse and focal forms is important. Unlike diffuse GWT, focal GWT is specific for GB and has a higher incidence of GBC. The discontinuity and irregularity of the innermost hyperechoic layer and irregular or disrupted GB wall layer structure suggest GBC. Rapid GWBF is also useful for the diagnosis of wall-thickened type GBC and pancreaticobiliary maljunction. Detailed B-mode evaluation using high-frequency transducers, combined with Doppler imaging and CEUS, enables a more accurate diagnosis.

[Gallbladder polyps: modern approaches to diagnostics and treatment]

Gallbladder polyps are an elevation of the mucous membrane that protrudes into the lumen of the gallbladder cavity. Their prevalence in the general population varies from 0.3 to 13.8%. According to the modern classification, polyps of the gallbladder are divided into benign non-tumor, benign tumor and malignant tumor polyps. A review of modern literature presents cohort and randomized controlled trials, including those summarized in meta-analyzes and systematic reviews, suggesting that the dominant form of polypoid formations of the gallbladder are cholesterol pseudo-polyps with no malignant potential associated with impaired cholesterol metabolism, often combined with gallbladder cholesterosis, metabolic syndrome and cardiovascular morbidity. Evidence is building up on the effectiveness of ursodeoxycholic acid for controlling components of the metabolic syndrome and cardiovascular risks. Ursodeoxycholic acid preparations may become promising for the management of cholesterol polyps.