Imaging of Biliary Tree Abnormalities

Pathologic conditions of the biliary system, although common, can be difficult to diagnose clinically. Challenges in biliary imaging include anatomic variants and the dynamic nature of the biliary tract, which can change with age and intervention, blurring the boundaries of normal and abnormal. Choledochal cysts can have numerous appearances and are important to diagnose given the risk of cholangiocarcinoma potentially requiring surgical resection. Choledocholithiasis, the most common cause of biliary dilatation, can be difficult to detect at US and CT, with MRI having the highest sensitivity. However, knowledge of the imaging pitfalls of MRI and MR cholangiopancreatography is crucial to avoid misinterpretation. Newer concepts in biliary tract malignancy include intraductal papillary biliary neoplasms that may develop into cholangiocarcinoma. New paradigms in the classification of cholangiocarcinoma correspond to the wide range of imaging appearances of the disease and have implications for prognosis. Accurately staging cholangiocarcinoma is imperative, given expanding curative options including transplant and more aggressive surgical options. Infections of the biliary tree include acute cholangitis or recurrent pyogenic cholangitis, characterized by obstruction, strictures, and central biliary dilatation. Inflammatory conditions include primary sclerosing cholangitis, which features strictures and fibrosis but can be difficult to differentiate from secondary causes of sclerosing cholangitis, including more recently described entities such as immunoglobulin G4-related sclerosing cholangitis and COVID-19 secondary sclerosing cholangitis. The authors describe a wide variety of benign and malignant biliary tract abnormalities, highlight differentiating features of the cholangitides, provide an approach to interpretation based on the pattern of imaging findings, and discuss pearls and pitfalls of imaging to facilitate accurate diagnosis. ©RSNA, 2024 Supplemental material is available for this article.

Dual-energy CT in differentiating benign gallbladder wall thickening from wall thickening type of gallbladder cancer

OBJECTIVE

To evaluate the performance of dual-energy computed tomography (DECT) in differentiating non-acute benign from malignant gallbladder wall thickening (GBWT).

METHODS

This prospective study comprised consecutive adults with GBWT who underwent late arterial phase (LAP) and portal venous phase (PVP) DECT between January 2022 and May 2023. The final diagnosis was based on histopathology or 3-6 months follow-up imaging. DECT images in LAP and PVP were assessed independently by two radiologists. The demographic, qualitative, and quantitative parameters were compared between two groups Multivariate logistic regression was performed to determine the association between the aforementioned factors and malignant GBWT.

RESULTS

Seventy-five patients (mean age 56 ± 12.8 years, 46 females) were included. Forty-two patients had benign, and 33 had malignant GBWT. In the overall group, female gender (p = 0.018), lymphadenopathy (p = 0.011), and omental nodules (p = 0.044) were significantly associated with malignant GBWT. None of the DECT features differed significantly between benign and malignant GBWT in overall group. In the xanthogranulomatous cholecystitis (XGC, n = 9) vs. gallbladder cancer (GBC) (n = 33) subgroup, mean attenuation value at 140 keV LAP VMI was significantly associated with malignant GBWT [p = 0.023, area under curve 0.759 (95%CI 0.599-0.919)].

CONCLUSION

DECT-generated quantitative parameters do not add value in differentiating non-acute benign from malignant GBWT. However, DECT may have a role in differentiating XGC from GBC in a selected subgroup of patients. Further, larger studies may be necessary to confirm these findings.

CLINICAL RELEVANCE STATEMENT

In patients with non-acute gallbladder wall thickening in whom there is suspicion of xanthogranulomatous cholecystitis (XGC), DECT findings may allow differentiation of XGC from wall thickening type of gallbladder cancer.

KEY POINTS

Differentiation of benign and malignant gallbladder wall thickening (GBWT) at CT is challenging. Quantitative dual energy CT (DECT) features do not provide additional value in differentiating benign and malignant GBWT. DECT may be helpful in a subgroup of patients to differentiate xanthogranulomatous cholecystitis from gallbladder cancer.

A comprehensive exploration of gallbladder health: from common to rare imaging findings

This comprehensive review explores a wide range of imaging findings associated with the gallbladder (GB), from anatomic variants to rare diseases. Through an in-depth review of diagnostic modalities including ultrasound, magnetic resonance cholangiopancreatography, CT, and MRI, we aim to highlight the crucial role of imaging techniques in diagnosing GB disorders, as congenital anomalies, inflammatory diseases, neoplasms, and surgical complications. Employing a detailed analysis and comparison of imaging findings across various modalities, this review seeks to improve diagnostic accuracy for GB-related pathologies, facilitating optimal patient management.

Dual-energy CT in acute cholecystitis- features predicting culture-positive bile and outcome

PURPOSE

Low mono-energetic CT has been shown to improve visualization of acute abdominal inflammatory processes. We aimed to determine its utility in patients with acute cholecystitis and potential added value in clinical decision making.

METHODS

Sixty-seven consecutive patients with radiological signs of cholecystitis on contrast-enhanced dual-layer CT imaging were retrospectively identified over a four-year period (2/17-8/21). A ranked Likert scale was created for imaging findings present in acute cholecystitis, including gallbladder mucosal integrity and enhancement and pericholecystic liver parenchymal enhancement. These rankings were correlated with laboratory data, followed by sensitivity, specificity, and odds-ratios calculations.

RESULTS

Mucosal integrity and pericholecystic liver enhancement were better seen on low-energetic images by unanimous consensus. Presence of pericholecystic liver enhancement and poorer mucosal wall integrity correlated with positive bile cultures (sensitivity: 93.8 % and 96.9 %, specificity: 37.5 and 50.0 %; odds-ratio: 9.0[1.1-68.1 95 %CI] and 31.0 [2.7-350.7 95 %CI], p = 0.017 and p ≤ 0.001) in patients undergoing cholecystostomy (n = 40/67). Moreover, binary regression modeling showed that the strongest predictor variable for bile culture positivity was the score for pericholecystic liver enhancement (Exp(B) = 0.6, P = 0.022). By contrast, other laboratory markers and other imaging findings (such as GB wall thickness) showed lower sensitivities (76-82 %), specificities (16-21 %) and odds ratios (0.2-4.4) for the prediction of infected bile.

CONCLUSIONS

Pericholecystic liver enhancement and gallbladder wall integrity are better visualized on low-DECT images. These findings also potentially predict bile culture positivity in patients with cholecystitis, which may influence clinical management including the need for intervention.

The value of CT radiomics combined with deep transfer learning in predicting the nature of gallbladder polypoid lesions

BACKGROUND

Computed tomography (CT) radiomics combined with deep transfer learning was used to identify cholesterol and adenomatous gallbladder polyps that have not been well evaluated before surgery.

PURPOSE

To investigate the potential of various machine learning models, incorporating radiomics and deep transfer learning, in predicting the nature of cholesterol and adenomatous gallbladder polyps.

MATERIAL AND METHODS

A retrospective analysis was conducted on clinical and imaging data from 100 patients with cholesterol or adenomatous polyps confirmed by surgery and pathology at our hospital between September 2015 and February 2023. Preoperative contrast-enhanced CT radiomics combined with deep learning features were utilized, and t-tests and least absolute shrinkage and selection operator (LASSO) cross-validation were employed for feature selection. Subsequently, 11 machine learning algorithms were utilized to construct prediction models, and the area under the ROC curve (AUC), accuracy, and F1 measure were used to assess model performance, which was validated in a validation group.

RESULTS

The Logistic algorithm demonstrated the most effective prediction in identifying polyp properties based on 10 radiomics combined with deep learning features, achieving the highest AUC (0.85 in the validation group, 95% confidence interval = 0.68-1.0). In addition, the accuracy (0.83 in the validation group) and F1 measure (0.76 in the validation group) also indicated strong performance.

CONCLUSION

The machine learning radiomics combined with deep learning model based on enhanced CT proves valuable in predicting the characteristics of cholesterol and adenomatous gallbladder polyps. This approach provides a more reliable basis for preoperative diagnosis and treatment of these conditions.

The Many Hidden Faces of Gallbladder Carcinoma on CT and MRI Imaging-From A to Z

Gallbladder carcinoma represents the most aggressive biliary tract cancer and the sixth most common gastrointestinal malignancy. The diagnosis is a challenging clinical task due to its clinical presentation, which is often non-specific, mimicking a heterogeneous group of diseases, as well as benign processes such as complicated cholecystitis, xanthogranulomatous cholecystitis, adenomyomatosis, porcelain gallbladder or metastasis to the gallbladder (most frequently derived from melanoma, renal cell carcinoma). Risk factors include gallstones, carcinogen exposure, porcelain gallbladder, typhoid carrier state, gallbladder polyps and abnormal pancreaticobiliary ductal junction. Typical imaging features on CT or MRI reveal three major patterns: asymmetric focal or diffuse wall-thickening of the gallbladder, a solid mass that replaces the gallbladder and invades the adjacent organs or as an intraluminal enhancement mass arising predominantly from the gallbladder fundus. The tumor can spread to the liver, the adjacent internal organs and lymph nodes. Depending on the disease stage, surgical resection is the curative treatment option in early stages and adjuvant combination chemotherapy at advanced stages. The purpose of this scientific paper is to fully illustrate and evaluate, through multimodality imaging findings (CT and MRI), different presentations and imaging scenarios of gallbladder cancer in six patients and thoroughly analyze the risk factors, patterns of spread and differential diagnosis regarding each particular case.

Imaging update on gallbladder adenomyomatosis and its mimics

Radiologists across many imaging modalities commonly encounter gallbladder adenomyomatosis. The classic imaging appearances of gallbladder adenomyomatosis are well described and confirm benignity. However, in clinical practice, adenomyomatosis can be challenging to differentiate from other gallbladder pathologies that require cholecystectomy. In this article, we describe the common and uncommon appearances of gallbladder adenomyomatosis on multimodality imaging, helping differentiate adenomyomatosis from non-benign gallbladder abnormalities. Accurately differentiating adenomyomatosis from its mimics provides the surgical team with important clinical and surgical management information, improving patient outcomes.

Gallstones Detection on Dual-Energy Computerized Tomography-Is It Ready for Real-World Use? A Retrospective Observational Study

AIMS

The aims of the study are to evaluate the performance of dual-energy computed tomography (DECT) imaging in the detection of noncalcified gallstones (GSs) and to assess its performance relative to transabdominal ultrasound (US) in identifying cholelithiasis.

METHOD

This study is a retrospective review of radiology records and images to find all patients who had both US and DECT scans within a 6-month period and were found to have GSs. Patients who did not have GSs on US served as the control group. The CT scans were reviewed by 4 radiologists who did not have access to the US results when assessing the presence or absence of GSs on the DECT scans. In case of any discrepancies among the radiologists, the majority opinion was considered. If there was a split opinion, a fifth reviewer was consulted. The data were analyzed to calculate sensitivity, specificity, positive and negative predictive values, as well as overall accuracy and to evaluate interreader variability. The absolute Hounsfield unit (HU) differences of the GSs and bile were compared between polychromatic (PC), virtual noncontrast (VNC), and virtual monochromatic (VMC) images.

RESULTS

Considering at least 3-reader agreement, sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were found to be 92%, 96%, 96%, 92%, and 94%, respectively. Individual reader sensitivity varied between 87% and 92%. There was good interobserver agreement with a Fleiss' kappa of 0.76. Quantification of the whole data set showed that no significant difference was observed in the HU values for the stones between the PC images and the VNC images. A significant increase was observed on the 50-keV VMC images compared with the PC and VNC images. In the study group, 17% stones were visualized only on the VNC or/and 50-keV VMC images, and not on the PC images. On quantitative analysis of these cases, there was a significant increase of HU in the VNC images as compared with PC images and a significant decrease of HU in the 50-keV VMC images as compared with PC images.

CONCLUSIONS

Low-keV images increase stone-bile contrast. Evaluation of cholelithiasis using VNC and 50-keV VMC images demonstrated a 14% increase in sensitivity relative to conventional CT.

Prognostic Effect of Liver Resection in Extended Cholecystectomy for T2 Gallbladder Cancer Revisited: A Retrospective Cohort Study With Propensity Score-matched Analysis

OBJECTIVE

This study aimed to evaluate the effect of liver resection on the prognosis of T2 gallbladder cancer (GBC).

BACKGROUND

Although extended cholecystectomy [lymph node dissection (LND) + liver resection] is recommended for T2 GBC, recent studies have shown that liver resection does not improve survival outcomes relative to LND alone.

METHODS

Patients with pT2 GBC who underwent extended cholecystectomy as an initial procedure and did not reoperation after cholecystectomy at 3 tertiary referral hospitals between January 2010 and December 2020 were analyzed. Extended cholecystectomy was defined as either LND with liver resection (LND+L group) or LND only (LND group). We conducted 2:1 propensity score matching to compare the survival outcomes of the groups.

RESULTS

Of the 197 patients enrolled, 100 patients from the LND+L group and 50 from the LND group were successfully matched. The LND+L group experienced greater estimated blood loss ( P <0.001) and a longer postoperative hospital stay ( P =0.047). There was no significant difference in the 5-year disease-free survival (DFS) of the 2 groups (82.7% vs 77.9%, respectively, P =0.376). A subgroup analysis showed that the 5-year DFS was similar in the 2 groups in both T substages (T2a: 77.8% vs 81.8%, respectively, P =0.988; T2b: 88.1% vs 71.5%, respectively, P =0.196). In a multivariable analysis, lymph node metastasis [hazard ratio (HR) 4.80, P =0.006] and perineural invasion (HR 2.61, P =0.047) were independent risk factors for DFS; liver resection was not a prognostic factor (HR 0.68, P =0.381).

CONCLUSIONS

Extended cholecystectomy including LND without liver resection may be a reasonable treatment option for selected T2 GBC patients.

Leveraging Dual-Energy Computed Tomography to Improve Emergency Radiology Practice

Dual-energy computed tomography affords emergency radiologists with important tools to aid in the detection and discrimination of commonly encountered ED pathologies. In doing so, it can increase the speed of diagnosis and diagnostic certainty while sparing patients potentially unnecessary downsteam workups and radiation exposure. This article demonstrates these clinical benefits through a case-based approach.

Do not get stumped: multimodality imaging findings of early and late post-cholecystectomy complications

Cholecystectomy is the most performed intra-abdominal surgical procedure in the US, with 1.2 million performed annually, and is predominantly performed laparoscopically. Although largely safe, laparoscopic cholecystectomy results in higher rates of abdominal symptoms consisting of abdominal pain and dyspepsia, which may persist or recur, collectively known as post-cholecystectomy syndrome. This article aims to (1) provide an overview of post-cholecystectomy syndrome with an emphasis on biliary complications and emergent imaging findings, (2) illustrate the spectrum of imaging findings of early and late post-cholecystectomy complications, (3) enumerate the role of various imaging modalities in evaluating post-cholecystectomy complications and address the role of selective trans-catheter coil embolization in managing bile leaks, and (4) discuss pearls and pitfalls in imaging following cholecystectomy. While common first-line imaging modalities for post-cholecystectomy complications include CT and sonography, ERCP and MRCP can delineate the biliary tree with greater detail. Scintigraphy has a higher sensitivity and specificity than CT or sonography for diagnosing bile leak and may preclude the need for ERCP. Post-operative complications include biliary duct injury or leak, biliary obstruction, remnant gallbladder/cystic duct stones and inflammation, biliary dyskinesia, papillary stenosis, and vascular injury. Subtle cases resulting in lethal outcomes, such as hemorrhage from the gallbladder bed without major vessel injury, have also been described. Cases presented will include biliary complications such as post-cholecystectomy stump cholecystitis, nonbiliary complications such as subcapsular hematoma, and normal post-surgical findings such as oxidized regenerated cellulose. Post-operative biliary complications can cause significant morbidity and mortality, and thus familiarity with the expected post-surgical appearance of the gallbladder fossa and biliary tract, as well as understanding the spectrum of complications and associated multimodality imaging findings, are essential for emergency radiologists and those practicing in the acute care setting to direct appropriate patient management. Furthermore, many of the postoperative complications can be managed by noninvasive percutaneous interventional procedures, from drain placement to cystic artery and cystic duct stump embolization.

Treatment of asymptomatic gallstones in children with hereditary spherocytosis requiring splenectomy

BACKGROUND

Gallstones are common in hereditary spherocytosis (HS) and other chronic hemolytic diseases, with most affected patients being asymptomatic. Whether and how asymptomatic gallstones should be treated is controversial.

METHODS

We conducted a retrospective cohort study of pediatric patients with HS and asymptomatic gallstones to compare the clinical outcomes between the observation group (followed up with gallstones in situ) and the intervention group (cholecystectomy or cholecystolithotomy). The primary outcome was the composite of adverse outcomes, including gallstone-associated, gallbladder surgery-associated, and splenectomy-associated events. Secondary outcomes included the changes in the size and number of gallstones and the recurrence of gallstones.

RESULTS

Fifty-two patients were included (38 in the observation group and 14 in the intervention group), with a mean follow-up length of 5.2 years. Patients in the intervention group had a lower incidence of primary outcomes (7.1% vs. 42.1%) than patients in the observation group (OR, 0.12; 95%CI, 0.01-0.99). Patients with gallstones >5 mm in diameter had the highest risk of adverse events (47.4%). In the observation group, gallstone growth, disappearance, and stability were observed in 19.4%, 29.0%, and 51.6% of splenectomized HS patients, respectively. Small gallstones (diameter ≤5 mm) or sludge were more likely to be associated with disappearance (P = 0.04).

CONCLUSIONS

Most asymptomatic gallstones grow or persist in splenectomized HS patients for an extended period. Surgical treatment of asymptomatic gallstones in HS patients requiring splenectomy is associated with a lower risk of adverse outcomes.

LEVELS OF EVIDENCE

III (retrospective comparative study).

Optimal radiological gallbladder lesion characterization by combining visual assessment with CT-based radiomics

OBJECTIVES

Differentiating benign gallbladder diseases from gallbladder cancer (GBC) remains a radiological challenge because they can appear very similar on imaging. This study aimed at investigating whether CT-based radiomic features of suspicious gallbladder lesions analyzed by machine learning algorithms could adequately discriminate benign gallbladder disease from GBC. In addition, the added value of machine learning models to radiological visual CT-scan interpretation was assessed.

METHODS

Patients were retrospectively selected based on confirmed histopathological diagnosis and available contrast-enhanced portal venous phase CT-scan. The radiomic features were extracted from the entire gallbladder, then further analyzed by machine learning classifiers based on Lasso regression, Ridge regression, and XG Boosting. The results of the best-performing classifier were combined with radiological visual CT diagnosis and then compared with radiological visual CT assessment alone.

RESULTS

In total, 127 patients were included: 83 patients with benign gallbladder lesions and 44 patients with GBC. Among all machine learning classifiers, XG boosting achieved the best AUC of 0.81 (95% CI 0.72-0.91) and the highest accuracy rate of 73% (95% CI 65-80%). When combining radiological visual interpretation and predictions of the XG boosting classifier, the highest diagnostic performance was achieved with an AUC of 0.98 (95% CI 0.96-1.00), a sensitivity of 91% (95% CI 86-100%), a specificity of 93% (95% CI 90-100%), and an accuracy of 92% (95% CI 90-100%).

CONCLUSIONS

Machine learning analysis of CT-based radiomic features shows promising results in discriminating benign from malignant gallbladder disease. Combining CT-based radiomic analysis and radiological visual interpretation provided the most optimal strategy for GBC and benign gallbladder disease differentiation.

KEY POINTS

Radiomic-based machine learning algorithms are able to differentiate benign gallbladder disease from gallbladder cancer. Combining machine learning algorithms with a radiological visual interpretation of gallbladder lesions at CT increases the specificity, compared to visual interpretation alone, from 73 to 93% and the accuracy from 85 to 92%. Combined use of machine learning algorithms and radiological visual assessment seems the most optimal strategy for GBC and benign gallbladder disease differentiation.

Imaging of benign biliary pathologies

Pathologies of the biliary tree include a wide-spectrum of benign and malignant processes. The differential for benign disease includes congenital and acquired disease with variable prognosis and management pathways. Given the ability to mimic malignancy, benign processes are difficult to diagnose by imaging. Direct cholangiography techniques with tissue sampling are the gold standards for the diagnosis of benign and malignant biliary pathologies. Non-invasive imaging with ultrasound offers a first-line diagnostic tool while MRI/MRCP offers higher specificity for identifying underlying pathology and distinguishing from malignant disease. In this review, we focus on the imaging appearance of dilatation, cystic anomalies obstruction, inflammation, ischemia, strictures, pneumobilia, and hemobilia to help construct a differential for benign processes.

Dual-energy computed tomography of the abdomen: A reliable trouble-shooter

Dual-energy computed tomography (CT) systems have undergone significant evolution and advancements in technology since they came into clinical practice in 2006. The basic principle of dual-energy is comparing the attenuation of different materials when exposed to high and low energy levels. In this article, we provide a brief overview of the basics of dual-energy CT systems, a pictorial review of commonly encountered abdominal conditions, and its role as a trouble-shooter in various diagnostic difficulties.

Incidental Findings of Gallbladder and Bile Ducts-Management Strategies: General Aspects, Gallbladder Polyps and Gallbladder Wall Thickening-A World Federation of Ultrasound in Medicine and Biology (WFUMB) Position Paper

The World Federation of Ultrasound in Medicine and Biology (WFUMB) is addressing the issue of incidental findings with a series of position papers to give advice on characterization and management. The biliary system (gallbladder and biliary tree) is the third most frequent site for incidental findings. This first part of the position paper on incidental findings of the biliary system is related to general aspects, gallbladder polyps and other incidental findings of the gallbladder wall. Available evidence on prevalence, diagnostic work-up, malignancy risk, follow-up and treatment is summarized with a special focus on ultrasound techniques. Multiparametric ultrasound features of gallbladder polyps and other incidentally detected gallbladder wall pathologies are described, and their inclusion in assessment of malignancy risk and decision- making on further management is suggested.

Unusual Presentation of Bouveret Syndrome Resulting in Both Gastric Outlet Obstruction and Small Bowel Obstruction with Perforation

Our case describes an 83-year-old female who presented with severe abdominal pain, nausea, and bilious emesis of one day's duration. She had an endoscopic retrograde cholangiopancreatography (ERCP) with sphincterotomy and percutaneous transhepatic biliary drainage (PTCD) one year prior for choledocholithiasis with acute cholangitis in her home country, Scotland. Unfortunately, while visiting family in the United States, her PTCD became dislodged, and she developed progressive worsening abdominal pain. Computerized tomography of her abdomen showed pneumobilia, perigastric inflammation, a contracted gallbladder, small bowl inflammation with a likely transition point at the mid-jejunum, and a probable duodenal mass. The patient underwent an exploratory laparotomy with intraoperative findings of choledochoduodenal fistula with coincident gastric and small bowel obstruction (SBO) secondary to three large, mixed gallstones. One 3 cm gallstone was located at the pylorus and two (2.3 and 3 cm) gallstones were isolated in the mid-jejunum, with one of those causing isolated transmural pressure necrosis with subsequent perforation. Bouveret syndrome is a rare cause of gastric outlet obstruction (GOO) that manifests via an acquired cholecystoenteric fistula. Our patient presented with a concomitant GOO and SBO with perforation of the mid-jejunum. Timely diagnosis of Bouveret syndrome is essential, as most causes require emergent surgical intervention.

Role of Dual-Energy Computed Tomography in Gallbladder Disease: A Review

Gallbladder diseases are common and include a spectrum ranging from benign to cancer. Imaging plays an integral role in the diagnosis and in guiding appropriate management. While most patients with gallstone (GS) diseases can be evaluated with ultrasound, those with complicated GS disease, suspicion of cancer, or staging of cancer need additional cross-sectional imaging. Computed tomography (CT) is widely available and is often the imaging test of choice following an equivocal ultrasound or negative ultrasound in patients with unexplained symptoms. Conventional CT has limited sensitivity in detecting GS or common bile duct stones. In other scenarios, including diagnosis of acute cholecystitis (AC) and characterization of gallbladder wall thickening, an increase in accuracy using novel techniques is desirable. Dual-energy computed tomography (DECT) is increasingly incorporated into clinical practice. DECT has shown promising results in the detection of cholesterol stones that otherwise go unnoticed on conventional CT. However, its role beyond GS disease has largely been unexplored. In this review, we discuss the available literature on the DECT in biliary diseases and discuss the potential applications of this technique.

Hemorrhagic cholecystitis from isolated gallbladder injury following blunt abdominal trauma: An unusual case report

Introduction and importance

Gallbladder contusion after blunt abdominal trauma is a rare event that presents with diagnostic challenges. There is no clear evidence supporting conservative or surgical management of gallbladder contusion injuries, especially when they present in isolation. Here, we report the first case of an isolated gallbladder contusion injury after blunt abdominal trauma resulting in hemorrhagic cholecystitis that was successfully managed non-operatively.

Case presentation

A 22-year-old male patient presented with a 3-day history of severe right upper quadrant pain, leukocytosis, and elevated bilirubin after suffering blunt abdominal trauma from being kicked in the abdomen during a soccer game. The patient was evaluated using computed tomography (CT), ultrasound (US), and magnetic resonance cholangiopancreatography (MRCP). His imaging findings were consistent with cholecystitis without cholelithiasis. His bloodwork and imaging were initially concerning for choledocholithiasis, but were later determined to be blood products within the common bile duct (CBD). Through conservative management, which included antibiotics, bed rest, and bowel rest, he had complete resolution of symptoms and normalization of bloodwork after four days of admission and remained symptom free at 1-year.

Clinical discussion

This case serves to highlight isolated gallbladder contusion as a potential outcome of blunt abdominal trauma. We re-affirm the diagnostic inconsistencies between CT and US in the work-up of cholecystitis and other biliary pathology. Furthermore, we describe the role of non-operative management in the treatment of traumatic cholecystitis, in the absence of gallstones.

Conclusion

Gallbladder contusion and hemorrhagic cholecystitis after blunt abdominal trauma can be managed with non-operative interventions.

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Hemorrhagic cholecystitis is a rare diagnosis in blunt gallbladder trauma.

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Cholecystitis from trauma is a challenging radiological diagnosis in adults.

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Ultrasound and CT scans may not be able to differentiate gallstones from blood clots.

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Cholecystitis from trauma can be successfully managed non-operatively.

Beyond acute cholecystitis-gallstone-related complications and what the emergency radiologist should know

The purpose of this study is to emphasize the imaging features of complications of gallstones beyond the cystic duct on ultrasound (US), enhanced and nonenhanced computed tomography (CECT and NECT), magnetic resonance imaging (MRI), magnetic resonance cholangiopancreatography (MRCP), and endoscopic retrograde cholangiopancreatography (ERCP). This article includes a brief overview of gallstone imaging and emerging trends in the detection of gallstones. This review article will highlight complications of gallstones, including choledocholithiasis, gallstone pancreatitis, acute cholangitis, Mirizzi syndrome, cholecystobiliary and cholecystoenteric fistulas, and gallstone ileus. Imaging findings and limitations of US, CT, MRI, and ERCP will be discussed. The review article will also briefly discuss the management of each disease. The presence of gallstones beyond the level of the cystic duct can lead to a spectrum of diseases, and emergency radiologists play a critical role in disease management by providing a timely diagnosis. Documenting the location of a gallstone within the common bile duct (CBD) in symptomatic cholelithiasis and the presence of acute interstitial edematous pancreatitis and/or ascending cholangitis plays a pivotal role in disease management. Establishing the presence of ectopic gallstones and biliary-enteric fistulae has a significant role in directing patient management.

Lightweight deep neural networks for cholelithiasis and cholecystitis detection by point-of-care ultrasound

BACKGROUND AND OBJECTIVE

Emergency physicians (EPs) frequently deal with abdominal pain, including that is caused by either gallstones or acute cholecystitis. Easy access and low cost justify point-of-care ultrasound (POCUS) use as a first-line test to detect these diseases; yet, the detection performance of POCUS by EPs is unreliable, causing misdiagnoses with serious impacts. This study aimed to develop a machine learning system to detect and localize gallstones and to detect acute cholecystitis by ultrasound (US) still images taken by physicians or technicians for preliminary diagnoses.

METHODS

Abdominal US images (> 89,000) were collected from 2386 patients in a hospital database. We constructed training sets for gallstones with or without cholecystitis (N = 10,971) and cholecystitis with or without gallstones (N = 7348) as positives. Validation sets were also constructed for gallstones (N = 2664) and cholecystitis (N = 1919). We applied a single-shot multibox detector (SSD) and a feature pyramid network (FPN) to classify and localize objects using image features extracted by ResNet-50 for gallstones, and MobileNet V2 to classify cholecystitis. The deep learning models were pretrained using the COCO-2017 and ILSVRC-2012 datasets.

RESULTS

Using the validation sets, the SSD-FPN-ResNet-50 and MobileNet V2 achieved areas under the receiver operating characteristics curve of 0.92 and 0.94, respectively. The inference speeds were 21 (47.6 frames per second, fps) and 7 ms (142.9 fps).

CONCLUSIONS

A machine learning system was developed to detect and localize gallstones, and to detect cholecystitis, with acceptable discrimination and speed. This is the first study to develop this system for either gallstone or cholecystitis detection with absence or presence of each one. After clinical trials, this system may be used to assist EPs, including those in remote areas, for detecting these diseases.

Noninvasive Imaging Prior to Biliary Interventions

Noninvasive imaging is a crucial and initial step in the diagnostic algorithm of patients with suspected biliary pathology and directs the subsequent diagnostic and therapeutic workup, including the endoluminal and percutaneous biliary interventions. This article reviews the current noninvasive imaging methods for the evaluation of biliary system and further discusses their roles in the diagnostic workup of different biliary disease.

Acute cholecystitis in recent lung transplant patients: a single-institution series of 10 cases

OBJECTIVE

To evaluate the clinical and imaging findings of acute cholecystitis in recent lung transplant patients.

METHODS

We retrospectively reviewed all abdominal ultrasounds and computed tomography (CT) scans of patients who developed acute cholecystitis in the early postoperative period following lung transplantation from November 2014 to December 2020 in a tertiary care university hospital.

RESULTS

Ten patients (4.4%) were included in this series (6 male, mean age 62.9 years ± 2.1 [standard deviation]) of a total 227 lung transplant patients performed from November 2014 to December 2020 (172 unilateral and 55 bilateral). Nine (90%) patients received a double-lung transplant and seven (70%) required extracorporeal circulation during surgery. Acute cholecystitis occurred during the initial admission for lung transplantation (average of 33 ± 25.9 days post-transplantation). Six patients (60%) died during admission with an average of 24.3 ± 21.8 days after cholecystectomy. The most frequent imaging findings were gallbladder wall discontinuity or decreased gallbladder mural enhancement (100%, 10 patients) and gallbladder distension (90%, 9 patients). All acute cholecystitis were found to be ischemic / gangrenous at surgery and/or pathology, 40% (4 patients) were hemorrhagic and 30% (3 patients) were perforated, one of them with a cholecystoduodenal fistula. Fungal cholecystitis was demonstrated at histological exam in one patient.

CONCLUSION

Acute cholecystitis in the early postoperative period after lung transplantation is an important cause of morbidity and mortality. Ischemic or gangrenous cholecystitis prevails. The key imaging findings are parietal perfusion defects and gallbladder distension, which can easily go unnoticed if not specifically looked for.

Spectral detector CT applications in advanced liver imaging

OBJECTIVE

Spectral detector CT (SDCT) has many applications in advanced liver imaging. If appropriately utilized, this technology has the potential to improve image quality, provide new diagnostic information, and allow for decreased radiation dose. The purpose of this review is to familiarize radiologists with the uses of SDCT in liver imaging.

CONCLUSION

SDCT has a variety of post-processing techniques, which can be used in advanced liver imaging and can significantly add value in clinical practice.

Concealed gallbladder perforation: a rare case report

Acute acalculous cholecystitis remains an elusive clinical diagnosis possibly due to complex clinical setting in which this entity develops, lack of large prospective controlled trials that evaluate various diagnostic modalities, thus dependence on a small database for clinical decision making. Concealed gallbladder perforation is rare. Herein, we report an 82-year-old female who presented with a right upper quadrant pain and features of local peritonitis. Abdominal ultrasound was suggestive of cholecystitis while computed tomography (CT) scan reported a perforated gallbladder with pericholecystic fluid collection. The patient underwent successful cholecystectomy; and intra-operatively, similar findings as those reported on imaging were seen. Unfortunately, she succumbed shortly post-operatively due to pulmonary embolism. Our report highlights the importance CT scan in patients with vague abdominal symptoms followed by sudden resolution. It also reminds the importance of considering the diagnosis of concealed gallbladder perforation as a differential in patients with peritonitis, as it may be missed by routine radiological investigations.

Complications of cholecystitis: a comprehensive contemporary imaging review

Acute cholecystitis is a common cause of right upper quadrant pain in patients presenting to the emergency department. Ultrasound, computed tomography, HIDA scans, and magnetic resonance imaging are increasingly utilized to evaluate suspected cases. The prognosis of acute cholecystitis is usually excellent with timely diagnosis and management. However, complications associated with cholecystitis pose a considerable challenge to the clinician and radiologist. Complications of acute cholecystitis may result from secondary bacterial infection or mural ischemia secondary to increased intramural pressure. The recognized subtypes of complicated cholecystitis are hemorrhagic, gangrenous, and emphysematous cholecystitis, as well as gallbladder perforation. Acute acalculous cholecystitis is a form of cholecystitis that occurs as a complication of severe illness in the absence of gallstones or without gallstone-related inflammation. Complicated cholecystitis may cause significant morbidity and mortality, and early diagnosis and recognition play a pivotal role in the management and early surgical planning. As appropriate utilization of imaging resources plays an essential role in diagnosis and management, the emergency radiologist should be aware of the spectrum of complications related to cholecystitis and the characteristic imaging features. This article aims to offer a comprehensive contemporary review of clinical and cross-sectional imaging findings of complications associated with cholecystitis. In conclusion, cross-sectional imaging is pivotal in identifying the complications related to cholecystitis. Preoperative detection of this complicated cholecystitis can help the care providers and operating surgeon to be prepared for a potentially more complicated procedure and course of recovery.

The Asian Federation of Societies for Ultrasound in Medicine and Biology (AFSUMB) Guidelines for Contrast-Enhanced Endoscopic Ultrasound

The Asian Federation of Societies for Ultrasound in Medicine and Biology aimed to provide information on techniques and indications for contrast-enhanced harmonic endoscopic ultrasound (CH-EUS), and to create statements including the level of recommendation. These statements are based on current scientific evidence reviewed by a Consensus Panel of 15 internationally renowned experts. The reliability of clinical questions was measured by agreement rates after voting. Six statements were made on techniques, including suitable contrast agents for CH-EUS, differences between contrast agents, setting of mechanical index, dual imaging and duration and phases for observation. Thirteen statements were made on indications, including pancreatic solid masses, pancreatic cancer staging, pancreatic cystic lesions and mural nodules, detection of subtle pancreatic lesions, gallbladder sludge and polyps, hepatic lesions, lymph nodes, subepithelial lesions, visceral vascular diseases, guidance of fine needle aspiration and evaluation for local therapy. These international expert consensus guidelines will assist endosonographers in conducting CH-EUS according to evidence-based information.

The Role of Dual-Energy Computed Tomography in Locating Gastrointestinal Tract Perforations

Objective With each passing day, dual-energy computed tomography (DECT) is being used more frequently in the evaluation of abdominal pathologies. In this article, we aimed to assess the role of dual-energy CT in locating gastrointestinal perforations, which are among the causes of acute abdomen. Materials and methods All patients who underwent DECT due to acute abdomen in a COVID-19 designated hospital between June 1st, 2020 and December 31st, 2020, who were found to have gastrointestinal tract (GIT) perforation and underwent surgery were included in the study. DECT results and intraoperative findings of the patients were compared. Results Thirteen patients (nine males and four females) who underwent DECT for acute abdomen and were diagnosed with perforation in the gastrointestinal system were included in the study. The mean age of the patients was 57.6 years (range: 11-85 years). Two patients had gastric perforation, three had duodenal perforations, and one patient had a perforation in the gallbladder wall. Two patients were diagnosed with jejunal perforations, one patient with Meckel's diverticulum, and three patients with colorectal perforation. Although free air was detected in the abdomen of one patient, perforation could not be located. In patients with GIT perforation who were operated on following DECT imaging, the perforation location shown on DECT correlated 100% with the perforation locations detected during surgery. Conclusion DECT is significantly effective in planning surgical treatment and determining the foci of perforation in GIT perforations.

Hemorrhagic cholecystitis: ultrasound and CT imaging findings-a retrospective case review series

PURPOSE

Gallbladder pathology is diverse, and imaging tests are essential tools for its diagnosis. Acute cholecystitis has multiple manifestations or complications, one of which is hemorrhagic cholecystitis (HC). In the current literature, this pathology has been described only in the spectrum of acute cholecystitis complications, case reports, or series with a maximum of 2 to 3 cases. After a retrospective review, we present 11 cases of hemorrhagic cholecystitis and discuss its various causes, clinical presentations, and findings on ultrasound (US) and computed tomography (CT), considering dual-energy CT and magnetic resonance imaging (MRI).

METHODS

A retrospective review of 6 years (2012-2018) of hemorrhagic cholecystitis cases diagnosed at our hospital was performed. A search engine of medical terms was used and the database of radiological cases in the emergency department of the hospital. After a careful review by two emergency and one abdominal radiologists, 11 patients were identified as hemorrhagic cholecystitis cases according to their clinical, radiological, and surgical records and confirmed with pathology reports.

RESULTS

Both lithiasis and anticoagulation/antiplatelet therapy were the most common etiologies found (9 patients, 82%). The clinical presentation may be misleading, simulating a usual cholecystitis episode with abdominal pain, nausea, and vomiting, or manifesting with signs of bile duct obstruction, hematemesis, or anemia that may compromise the patient hemodynamically and become fatal. US is useful, but CT is the most complete test for evaluating hemorrhagic cholecystitis and was performed in all the patients. The common findings were inflammatory changes in all patients (100%), hemobilia in 10 patients (91%), hemoperitoneum in 6 patients (55%), intestinal bleeding in 3 patients (27%), and occasionally perihepatic hematomas or signs of active bleeding.

CONCLUSION

Although a rare entity, hemorrhagic cholecystitis may be present, and management can be delayed if the appropriate imaging modality is not used for diagnosis.

Current and New Biomarkers for Early Detection, Prognostic Stratification, and Management of Gallbladder Cancer Patients

Gallbladder cancer (GBC) is an aggressive disease that shows evident geographic variation and is characterized by a poor prognosis, mainly due to the late diagnosis and ineffective treatment. Genetic variants associated with GBC susceptibility, including polymorphisms within the toll-like receptors TLR2 and TLR4, the cytochrome P450 1A1 (CYP1A1), and the ATP-binding cassette (ABC) transporter ABCG8 genes, represent promising biomarkers for the stratification of patients at higher risk of GBC; thus, showing potential to prioritize cholecystectomy, particularly considering that early diagnosis is difficult due to the absence of specific signs and symptoms. Similarly, our better understanding of the gallbladder carcinogenic processes has led to identify several cellular and molecular events that may influence patient management, including HER2 aberrations, high tumor mutational burden, microsatellite instability, among others. Despite these reports on interesting and promising markers for risk assessment, diagnosis, and prognosis; there is an unmet need for reliable and validated biomarkers that can improve the management of GBC patients and support clinical decision-making. This review article examines the most potentially significant biomarkers of susceptibility, diagnosis, prognosis, and therapy selection for GBC patients, highlighting the need to find and validate existing and new molecular biomarkers to improve patient outcomes.

Gallbladder cancer revisited: the evolving role of a radiologist

Gallbladder cancer is the most common malignancy of the biliary tract. It is also the most aggressive biliary tumor with the shortest median survival duration. Complete surgical resection, the only potentially curative treatment, can be accomplished only in those patients who are diagnosed at an early stage of the disease. Majority (90%) of the patients present at an advanced stage and the management involves a multidisciplinary approach. The role of imaging in gallbladder cancer cannot be overemphasized. Imaging is crucial not only in detecting, staging, and planning management but also in guiding radiological interventions. This article discusses the role of a radiologist in the diagnosis and management of gallbladder cancer.

Benefit of dual-layer spectral CT in emergency imaging of different organ systems

Computed tomography (CT) has been the first choice of imaging technique in the emergency department and has a crucial role in many acute conditions. Since its implementation, spectral CT has gained widespread application with the potential to improve diagnostic performance and impact patient care. In spectral CT, images are acquired at two different energy levels allowing this technique to differentiate tissues by exploiting their energy-dependent attenuation properties. Dual-layer spectral CT provides additional information with its material decomposition applications that include virtual non-contrast imaging, iodine density, and effective atomic number (Zeff) maps along with virtual monoenergetic images without the need for preselection of a protocol. This review aims to demonstrate its added value in the emergency department in different organ systems enabling better evaluation of inflammatory and ischaemic conditions, assessment of organ perfusion, tissue/lesion characterisation and mass detection, iodine quantification, and the use of lower volumes of contrast medium. With improved diagnostic performance, spectral CT could also aid in rapid decision-making to determine the treatment method in many acute conditions without increased radiation dose to the patient.

Gallbladder carcinoma: an initial clinical experience of reduced field-of-view diffusion-weighted MRI

BACKGROUND

The purpose of this study is to compare the diagnostic value, imaging quality and apparent diffusion coefficient (ADC) value of reduced field-of-view diffusion-weight imaging (r-FOV DWI) and full field-of-view diffusion-weight imaging (f-FOV DWI) in patients with gallbladder carcinoma and other lesions of gallbladder.

METHODS

Two hundred ninety-six patients with gallbladder diseases underwent both r-FOV DWI and f-FOV DWI on a 3.0 T MRI scanner. Two radiologists assessed subjective image quality parameters independently. The Wilcoxon signed-rank test was used to compare subjective qualitative image score. Objective quality values and the mean ADC values were analyzed by paired t-test. The correlation between pathological results and mean ADC value were estimated using Spearman rank correlation analysis.

RESULTS

The CNR value (10.23 ± 2.92) and image quality score (13.84 ± 1.07) of r-FOV DWI were significantly higher than those of f-FOV DWI (5.24 ± 1.29 P<0.001; 10.41 ± 1.11 P<0.001). There was no significant difference between mean ADC values of the two DWI sequences for all three groups (Group 1, chronic cholecystitis; Group 2, benign lesions of gallbladder; Group 3, gallbladder carcinoma. P = 0.239, 0.974 and 0.226 respectively). For both DWI sequences, the mean ADC values were the highest in the group of cholecystitis and the lowest in the group of gallbladder carcinoma (2.49 ± 0.14 vs 1.49 ± 0.12; 2.50 ± 0.14 vs 1.50 ± 0.13, for f-FOV and r-FOV respectively), the differences among groups were statistically significant (P<0.01). The mean ADC values for both DWI sequences were negatively correlated with the group number, which increased with the malignant tendency of lesions (r = - 0.892, P<0.01; r = - 0.913, P<0.01 for f-FOV and r-FOV respectively).

CONCLUSION

Reduced Field-of-view Diffusion-weighted MRI is a good tool to diagnosis the gallbladder carcinoma, with better image quality and without affecting ADC values.

Evaluation of gallbladder wall thickening: a multimodality imaging approach

INTRODUCTION

Gallbladder (GB) wall thickening is a relatively common finding on imaging. While there are clear recommendations for the management of gallstones, GB wall thickening presents a significant challenge. Despite advances in radiological as well as endoscopic techniques, the ability to characterize GB wall thickening is still limited.

AREAS COVERED

This review summarizes the currently available literature on various imaging investigations to characterize GB wall thickening. This review also summarizes the differences between benign and malignant GB wall thickening based on available imaging modalities. Transabdominal ultrasonography is the first-line investigation for evaluation of GB wall thickening. However, further characterization requires additional imaging tests. Magnetic resonance imaging (MRI) with the use of gadolinium and diffusion-weighted sequence is the preferred modality for GB wall characterization.

EXPERT OPINION

The accurate characterization of GB wall thickening is a challenging task. The available imaging criteria allow differentiation of benign and malignant GB wall thickening with moderate accuracy. The advanced imaging techniques, including contrast enhanced ultrasound, contrast-enhanced endoscopic ultrasound, and shear wave elastography, continue to evolve. There is a need for a well-designed reporting system for GB wall thickening to ensure uniformity of reporting of imaging tests, especially in regions with a high prevalence of GB cancer.

Dual energy CT in clinical routine: how it works and how it adds value

Dual energy computed tomography (DECT), also known as spectral CT, refers to advanced CT technology that separately acquires high and low energy X-ray data to enable material characterization applications for substances that exhibit different energy-dependent x-ray absorption behavior. DECT supports a variety of post-processing applications that add value in routine clinical CT imaging, including material selective and virtual non-contrast images using two- and three-material decomposition algorithms, virtual monoenergetic imaging, and other material characterization techniques. Following a review of acquisition and post-processing techniques, we present a case-based approach to highlight the added value of DECT in common clinical scenarios. These scenarios include improved lesion detection, improved lesion characterization, improved ease of interpretation, improved prognostication, inherently more robust imaging protocols to account for unexpected pathology or suboptimal contrast opacification, length of stay reduction, reduced utilization by avoiding unnecessary follow-up examinations, and radiation dose reduction. A brief discussion of post-processing workflow approaches, challenges, and solutions is also included.

Utility of ultrasound in acute pancreatitis

Ultrasound plays an essential role in the initial evaluation of patients with suspected or confirmed acute pancreatitis. In addition to evaluation of the pancreatic parenchyma, ultrasound is used for assessment of the gallbladder, biliary tree, peripancreatic tissues, and regional vascular structures. While enlarged and edematous pancreas are classic sonographic features of acute pancreatitis, the pancreas may appear sonographically normal in the setting of acute pancreatitis. Nonetheless, sonographic evaluation in this setting is valuable because assessment for etiologic factors such as gallstones or evidence of biliary obstruction are best performed with ultrasound. Complications of pancreatitis such as peripancreatic fluid collections, venous thrombosis, or arterial pseudoaneurysm can be identified with careful and focused ultrasound examination. Knowledge of various scanning techniques can help to mitigate some of the commonly encountered barriers to sonographic visualization of the pancreas and right upper quadrant structures. Ultrasound can also be used for guidance of percutaneous treatment such as drainage of fluid collections or pseudoaneurysm thrombosis. Difficulty in differentiating edematous from necrotizing pancreatitis can be mitigated with the use of contrast-enhanced ultrasound to assess pancreatic parenchymal enhancement.

CT imaging, classification, and complications of acute pancreatitis

Acute pancreatitis is an increasingly common condition and can result in significant morbidity and mortality. Contrast enhanced computed tomography (CECT) is the primary initial imaging modality in the characterization of acute pancreatitis. In this article, we provide sample CECT technical acquisition parameters for pancreatic imaging. We also review the classification systems for acute pancreatitis and give examples of common and uncommon complications of acute pancreatitis.

Role of Ultrasound and CT in the Workup of Right Upper Quadrant Pain in Adults in the Emergency Department: A Retrospective Review of More Than 2800 Cases

OBJECTIVE. The purpose of this study was to compare ultrasound and CT in the diagnostic evaluation of right upper quadrant pain in adults in the emergency department. MATERIALS AND METHODS. A retrospective review was conducted of adult emergency department encounters for right upper quadrant pain over a 5-year period, excluding those for prior cholecystectomy, current pregnancy, and trauma. Imaging study reports were reviewed for gallbladder and nongallbladder explanations of right upper quadrant pain and were considered positive for cholecystitis when two or more supportive features were present. Encounter outcomes were evaluated on the basis of pathology data and clinical management. RESULTS. Among the encounters, 2859 met the study inclusion criteria, and 18% met the study definition of cholecystitis by pathologic or clinical criteria. The following metrics showed no statistically significant difference between ultrasound and CT, respectively: sensitivity, 61% and 55%; specificity, 91% and 92%; positive predictive value, 63% and 63%; and negative predictive value, 91% and 90%. Both modalities were performed in 20% of encounters. In the subgroup analysis, ultrasound showed an acute nongallbladder abnormality that was missed at a preceding CT examination in only 1 of 238 cases (0.4%). CT showed an acute nongallbladder abnormality missed at a preceding ultrasound examination in 103 of 322 cases (32%). CONCLUSION. CT is noninferior to ultrasound in both ruling in and ruling out the diagnosis of cholecystitis in adult patients undergoing emergency evaluation of right upper quadrant pain and offers the advantage of depicting acute nongallbladder abnormalities.

Evaluation of the CT Scan as the First Examination for the Diagnosis and Therapeutic Strategy for Acute Cholecystitis

BACKGROUND

The CT scan has supplanted the abdominal ultrasound for emergency examinations. A comparison of CT scan and ultrasound performance for the diagnosis and management of acute cholecystitis in acute care was proposed. The hypothesis is that the CT scan may be sufficient for the diagnosis of acute cholecystitis, which would allow faster progress to surgery.

METHODS

The retrospective study of consecutive patients operated for acute cholecystitis or gallbladder distension with pre-operative imaging within 48 h in one centre.

RESULTS

Between 2015 and 2017, a total of 341 cholecystectomies were performed in our centre. The analysis involved 120 patients. Ultrasound had better sensitivity than the CT scan, respectively, 79.4% [70.5-86.6] and 52.3% [42.5-62.1], but less specificity, with 61.5% [31.6-86.1] and 92.3% [64.0-99.8], respectively. However, there was a significant difference in favour of the CT scan for the diagnosis of complicated cholecystitis (p 0.004). The positive likelihood ratio of complicated cholecystitis is better at CT scan (7.8) [2.7-23.1] than in ultrasound (1.0) [0.1-9.7]. CT scan and ultrasound are equivalent for the diagnosis of acute cholecystitis, but CT scan is more efficient for the diagnosis of complicated cases (Youden index J 0.3 vs 0.001).

CONCLUSION

It is possible to place the surgical indication of cholecystectomy on the only data of the CT scan. We propose a decision-making algorithm that uses the CT scan to make the diagnosis and decide on emergency treatment for complicated cases or that allows us to propose a delayed surgery for simple cholecystitis.

Imaging of Acute Hepatobiliary Dysfunction

Abdominal pain is a common cause for emergency department visits in the United States, and biliary tract disease is the fifth most common cause of hospital admission. Common causes of acute hepatobiliary include gallstones and its associated complications and multiple other hepatobiliary etiologies, including infectious, inflammatory, vascular, and neoplastic causes. Postoperative complications of the biliary tract can result in an acute abdomen. Imaging of the hepatobiliary tree is integral in the diagnostic evaluation of acute hepatobiliary dysfunction, and imaging of the biliary tree requires a multimodality approach utilizing ultrasound, computed tomography, nuclear medicine, and MR imaging.

[Radiologic diagnosis of the gallbladder and bile ducts - part 2 : Acute and chronic cholecystitis, primary sclerosing cholangitis (PSC), benign and malignant masses of the biliary system]

Upper abdominal pain, icterus and cholestasis are the symptoms leading to evaluation of the biliary tract. Together with its complications biliary stone disease is the main reason for inflammation of the biliary system. A distinction is made between acute and chronic variants. In chronic bile duct inflammation primary sclerosing cholangitis (PSC), primary biliary cirrhosis (PBC) and more recently IgG4-associated sclerosing cholangitis are of particular importance. Besides benign and tumor-like-lesions, malignant entities as gallbladder carcinoma and cholangiocarcinoma (CCC) in its three locations have to be mentioned. Despite all recent improvements, specificity of bile-tract imaging still remains limited, especially regarding malignant masses. Therefore the final diagnosis is made in many cases by histological analysis.

[Radiologic diagnostics of the gall bladder and bile ducts-part 1 : Imaging techniques-normal variants and congenital disorders-cholelithiasis]

Upper abdominal pain, icterus and cholestasis are the main symptoms leading to evaluation of the biliary tract. Since the advent of contrast-enhanced ultrasound techniques the accuracy of bile duct imaging has significantly improved. This is also true for computed tomography using isotropic secondary reconstructions as well as magnetic resonance imaging (MRI) including MR cholangiography (MRC), classically and after iv injection of hepatobiliary contrast agent. Diffusion-weighted imaging sequences have a recently proven ability for improving biliary tract imaging. These technical improvements provide the depiction of the non-dilated biliary tract system in diagnostic quality. Therefore, normal variants and congenital disorders of biliary tract anatomy are delineated as well as insights into the postoperative situs and complications related to surgery. Cholelithiasis is the most frequent disease of the gall bladder and biliary tract. Together with related complications, in the majority of cases it is also the reason for bile duct inflammation. Due to the immediate need for treatment special care has to be taken for hydrops of the gall bladder.

Endoscopic Interventions in Acute Pancreatitis: What the Advanced Endoscopist Wants to Know

Endoscopic interventions play an important role in the modern management of pancreatic fluid collections. Successful management of pancreatitis is dependent on proper classification of the disease and its local complications. The 2012 revised Atlanta classification divides acute pancreatitis into subtypes of necrotizing pancreatitis and interstitial edematous pancreatitis (IEP) on the basis of the radiologic presence or absence of necrosis, respectively. Local complications of IEP include acute pancreatic fluid collections and pseudocysts, which contain fluid only and are differentiated by the time elapsed since the onset of symptoms. Local complications of necrotizing pancreatitis include acute necrotic collections and walled-off necrosis, which contain nonliquefied necrotic debris and are differentiated by the time elapsed since the onset of symptoms. Endoscopic techniques are used to treat local complications of pancreatitis, often in a step-up approach, by which less invasive techniques are preferred initially with potential subsequent use of more invasive procedures, dependent on the patient's clinical response and collection evolution. Common interventions performed by the advanced endoscopist include endoscopic transmural drainage and endoscopic transmural necrosectomy. However, some collections require a multimodal approach with adjunctive placement of percutaneous drainage catheters or the use of videoscopic-assisted retroperitoneal débridement. Additional endoscopic interventions may be required in the setting of pancreatic or biliary duct stones or strictures. Common complications of endoscopic intervention in the setting of pancreatitis include bleeding, infection, perforation, and stent migration. This article reviews the classification of acute pancreatitis, familiarizes radiologists with the common endoscopic techniques used in its management, and improves identification of the clinically relevant imaging findings and procedural complications related to endoscopic interventions in pancreatitis. ^©RSNA, 2018.