Magnetic resonance imaging of the gallbladder: spectrum of abnormalities

Traveling gallstones: review of MR imaging and surgical pathology features of gallstone disease and its complications in the gallbladder and beyond

Gallstone-related disease comprises a spectrum of conditions resulting from biliary stone formation, leading to obstruction and inflammatory complications. These can significantly impact patient quality of life and carry high morbidity if not accurately detected. Appropriate imaging is essential for evaluating the extent of gallstone disease and assuring appropriate clinical management. Magnetic Resonance Imaging (MRI) techniques (including Magnetic Resonance Cholangiopancreatography (MRCP) are increasingly used for diagnosis of gallstone disease and its complications and provide high contrast resolution and facilitate tissue-level assessment of gallstone disease processes. In this review we seek to delve deep into the spectrum of MR imaging in diagnose of gallstone-related disease within the gallbladder and complications related to migration of the gallstones to the gall bladder neck or cystic duct, common hepatic duct or bile duct (choledocholithiasis) and beyond, including gallstone pancreatitis, gallstone ileus, Bouveret syndrome, and dropped gallstones, by offering key examples from our practice. Furthermore, we will specifically highlight the crucial role of MRI and MRCP for enhancing diagnostic accuracy and improving patient outcomes in gallstone-related disease and showcase relevant surgical pathology specimens of various gallstone related complications.

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.

Clinical value of diffusion-weighted MRI for differentiation between benign and malignant gallbladder disease: a systematic review and meta-analysis

BACKGROUND

Radiological differentiation between benign and malignant gallbladder disease is important but remains challenging. Furthermore, the clinical value of diffusion-weighted imaging (DWI) remains unclear.

PURPOSE

To determine the value of DWI in discriminating benign from malignant gallbladder disease by conducting a systematic review and meta-analysis.

MATERIAL AND METHODS

The literature was systematically searched. Studies analyzing diagnostic value of DWI in gallbladder disease with histopathology or follow-up as reference standard were included. Study selection and data extraction were done by two reviewers independently. Methodological quality was assessed using the QUADAS-2 tool. Sensitivity and specificity were calculated and displayed in a forest plot. A sensitivity analysis was performed in case of outliers. Pooled sensitivity and specificity of DWI were plotted on a hierarchical summary receiver operating characteristic curve. If available, the added value of DWI to conventional magnetic resonance imaging (MRI) sequences was analyzed.

RESULTS

Out of 2456 articles, eight studies fulfilled the inclusion criteria; 592 patients with 221 malignant lesions were included. Pooled sensitivity and specificity rates were 0.87 and 0.84, respectively. In two studies, diagnostic accuracy rates improved after adding DWI to conventional MRI (64% and 75% for conventional MRI vs. 89% and 94% after combining conventional MRI with DWI). In another study, the area under the curve increased from 0.92 to 0.95.

CONCLUSION

DWI appears to be an accurate imaging technique in discriminating benign from malignant gallbladder disease. To achieve optimal patient care, it should be part of multiparametric MRI and should be combined with other imaging modalities.

Diagnostic performance of preoperative CT in differentiating between benign and malignant origin of suspicious gallbladder lesions

PURPOSE

To determine diagnostic performance of preoperative CT in differentiating between benign and malignant suspicious gallbladder lesions and to develop a preoperative risk score.

METHOD

All patients referred between January 2007 and September 2018 for suspicion of gallbladder cancer (GBC) or incidentally found GBC were retrospectively analyzed. Patients were excluded when preoperative CT or histopathologic examination was lacking. Two radiologists, blinded to histopathology results, independently reviewed CT images to differentiate benign disease from GBC. Multivariable analysis and internal validation were used to develop a risk score for GBC. Model discrimination, calibration, and diagnostic performance were assessed.

RESULTS

In total, 118 patients with 39 malignant (33 %) and 79 benign (67 %) lesions were included. Sensitivity of CT for diagnosing GBC was 90 % (95 % confidence interval [CI]: 76-97). Specificity rates were 61 % (95 % CI: 49-72) and 59 % (95 % CI: 48-70). Three predictors of GBC (irregular lesion aspect, absence of fat stranding, and locoregional lymphadenopathy) were included in the risk score ranging from -1 to 4. Adequate performance was found (AUC: 0.79, calibration slope: 0.89). In patients allocated >0 points, the model showed higher performance in excluding GBC than the radiologists (sensitivity 92 % [95 % CI: 79-98]). Moreover, when allocated >3 points, the risk score was superior in diagnosing GBC (specificity 99 % [95 % CI: 93-100]).

CONCLUSIONS

Sensitivity rates of CT for differentiation between benign and malignant gallbladder lesions are high, however specificity rates are relatively low. The proposed risk score may facilitate differentiation between benign and malignant suspicious gallbladder lesions.

Surgeon-performed point-of-care ultrasound for acute cholecystitis: indications and limitations: a European Society for Trauma and Emergency Surgery (ESTES) consensus statement

BACKGROUND

Acute cholecystitis (AC), frequently responsible for presentation to the emergency department, requires expedient diagnosis and definitive treatment by a general surgeon. Ultrasonography, usually performed by radiology technicians and reported by radiologists, is the first-line imaging study for the assessment of AC. Targeted point-of-care ultrasound (POCUS), particularly in the hands of the treating surgeon, may represent an evolution in surgical decision-making and may expedite care, reducing morbidity and cost.

METHODS

This consensus guideline was written under the auspices of the European Society of Trauma and Emergency Surgery (ESTES) by the POCUS working group. A systematic literature search identified relevant papers on the diagnosis and treatment of AC. Literature was critically-appraised according to the GRADE evidence-based guideline development method. Following a consensus conference at the European Congress of Trauma & Emergency Surgery (Valencia, Spain, May 2018), final recommendations were approved by the working group, using a modified e-Delphi process, and taking into account the level of evidence of the conclusion.

RECOMMENDATIONS

We strongly recommend the use of ultrasound as the first-line imaging investigation for the diagnosis of AC; specifically, we recommend that POCUS may be adopted as the primary imaging adjunct to surgeon-performed assessment of the patient with suspected AC. In line with the Tokyo guidelines, we strongly recommend Murphy's sign, in conjunction with the presence of gallstones and/or wall thickening as diagnostic of AC in the correct clinical context. We conditionally recommend US as a preoperative predictor of difficulty of cholecystectomy. There is insufficient evidence to recommend contrast-enhanced ultrasound or Doppler ultrasonography in the diagnosis of AC. We conditionally recommend the use of ultrasound to guide percutaneous cholecystostomy placement by appropriately-trained practitioners.

CONCLUSIONS

Surgeons have recently embraced POCUS to expedite diagnosis of AC and provide rapid decision-making and early treatment, streamlining the patient pathway and thereby reducing costs and morbidity.

Diagnosis and Treatment of Gallbladder Polyps: Current Perspectives

INTRODUCTION

Gallbladder polyps (GBPs) are generally harmless, but the planning of diagnosis and treatment of the GBP is of clinical importance due to the high mortality risk of delays in the diagnosis of gallbladder carcinomas that show polypoid development.

MATERIALS AND METHODS

GBPs are usually incidentally detected during ultrasonographic (USG) examinations of the abdomen. The risk of carcinoma development from polypoid lesions in the literature is reported as 0-27%. There is no consensus about the management of the GBPs. Herein, we reviewed the contemporary data to update our knowledge about diagnosis and treatment of gallbladder polyps.

RESULTS

Polyps can be identified in five different groups, primarily as neoplastic and non-neoplastic. Cholesterol polyps account for 60% of all cases. The most common (25%) benign polypoid lesions after cholesterol polyps are adenomyomas.

CONCLUSION

Ultrasonography and endoscopic ultrasonography seems to be the most important tool in differential diagnosis and treatment. Ultrasonography should be repeated in every 3-12 months in cases that are thought to be risky. Nowadays, the most common treatment approach is to perform cholecystectomy in patients with polyps larger than 10 mm in diameter. Radical cholecystectomy and/or segmental liver resections should be planned in cases of malignancy.

HOW TO CITE THIS ARTICLE

Dilek ON, Karsu S, et al. Diagnosis and Treatment of Gallbladder Polyps: Current Perspectives. Euroasian J Hepatogastroenterol 2019;9(1):40-48.

A literature review of radiological findings to guide the diagnosis of gallbladder adenomyomatosis

BACKGROUND

Gallbladder adenomyomatosis (GA) is a benign gallbladder entity discovered as an asymptomatic gallbladder mass. Since gallbladder cancer is in the differential diagnosis for gallbladder masses, the ability to differentiate benign disease avoids a more extensive oncologic resection. This study sought to review imaging modalities used to diagnose GA.

METHODS

PubMed and SciVerse Scopus were systematically searched using the terms: "gallbladder adenomyomatosis" and "gallbladder imaging" for articles published between January 2000 and January 2015.

RESULTS

A total of 14 articles were reviewed in this analysis. Contemporary series report the use of ultrasound (US), computed tomography (CT) or magnetic resonance imaging (MRI) in GA imaging. Ultrasound detection of Rokitansky-Aschoff sinuses, visualized as small cystic spaces with associated "comet-tail" or "twinkling" artifact, is pathognomonic for GA. A "Pearl-Necklace" sign of small connected sinuses on MRI or "Rosary" sign on CT are additional characteristics that may assist in establishing a diagnosis.

CONCLUSION

Ultrasound is the most commonly used tool to investigate GA. If not diagnostic, CT or MRI are effective in attempting to differentiate a benign or malignant cholecystic mass. Characteristic signs should lead the surgeon to perform a laparoscopic cholecystectomy in symptomatic patients or manage non-operatively in asymptomatic patients.

Preoperative staging of gallbladder carcinoma using biliary MR imaging

PURPOSE

To evaluate the performance of biliary MRI, including unenhanced imaging, gadolinium-enhanced (Gd-E) dynamic imaging, and MR cholangiography, for the preoperative staging of gallbladder cancer (GBC).

MATERIALS AND METHODS

Our institutional review board approved this retrospective study. Eighty-six, consecutive patients with surgically resected and pathologically confirmed GBCs and who underwent preoperative MRI, including unenhanced T1- and T2-weighted images, MR cholangiography, and dynamic imaging, were enrolled in this study. Two observers independently evaluated the biliary MR images regarding the T- and N-staging of GBCs and graded their diagnostic confidence for the staging using a 5-point scale. Receiver operating curve analysis was performed to evaluate the diagnostic performance of MR in the staging of GBC. Interobserver agreement was evaluated using kappa statistics.

RESULTS

The overall accuracy of T- and N-staging using biliary MRI was 84.9% and 77.9% for observer 1 and 69.8% and 74.4% for observer 2. There was good interobserver agreement regarding the T stage (k = 0.828). The Az (AUC: area under the curve) values of the diagnostic ability of MRI to differentiate ≥ T1b from ≤ T1a lesions, were 0.979 and 0.955 for both observers (P < 0.0001).

CONCLUSION

Biliary MRI with MR cholangiography allows moderately accurate preoperative T staging and N staging of GBCs. It also shows an excellent diagnostic ability for differentiating ≥ T1b lesions from ≤ T1a lesions, which can be helpful for preoperative planning.

Role of diffusion-weighted magnetic resonance imaging in the diagnosis of gallbladder cancer

PURPOSE

To determine the additional diagnostic value of high b-value diffusion-weighted imaging (DWI) compared to conventional biliary magnetic resonance imaging (MRI) for differentiating gallbladder (GB) cancer from benign GB diseases with wall thickening.

MATERIALS AND METHODS

Thirty-nine patients with GB cancers and 36 patients with cholecystitis having preoperative biliary MRIs were included. All patients underwent unenhanced T1- and T2-weighted imaging (T2WI), Gd-enhanced dynamic MRI, and DWI (b values 0, 100, 500, 1000 s/mm(2) ). Two radiologists independently analyzed two sets of MRI for characterization of GB lesions: a conventional biliary image (CBI) set with T1- and T2WI and a dynamic image; and a DWI set composed of DWI and a CBI set. Diagnostic accuracy and sensitivity were evaluated using the receiver operator characteristic method. The mean apparent diffusion coefficient (ADC) values of the lesions were also calculated.

RESULTS

The Az values were 0.856 and 0.960 for reviewers 1 and 2, respectively, with the CBI set and increased to 0.952 and 0.983 with the DWI set. The mean ADC value of GB carcinoma was 1.46 ± 0.45 × 10(-3) mm(2) /s and that of cholecysititis was 2.16 ± 0.56 × 10(-3) mm(2) /s (P < 0.0001).

CONCLUSION

Adding DWI to the standard biliary MRI protocol may improve sensitivity for distinguishing GB cancers from benign GB diseases with wall thickening.

Diagnostic and prognostic role of laparoscopic staging for gallbladder carcinoma

BACKGROUND

The aim of this study was to evaluate the diagnostic and prognostic role of staging laparoscopy in gallbladder carcinoma (GBC).

METHODS

From January 2007 through December 2010, 79 GBC patients without evidence of metastatic disease on preoperative imaging underwent staging laparoscopy. Peritoneal and liver metastases were assessed by a single surgeon in a systematic manner. Resection rate, safety, and survival analysis were compared between the laparoscopy group and no laparoscopy group.

RESULTS

Disseminated disease was detected in 27 patients and no further surgery was performed; the overall accuracy for detecting unresectable disease was 67.5% (27/40), with 39 (75%) and 27 (51.9%) receiving resection and curative resection. In 203 GBC patients undergoing laparotomy, 90 (44.3%) and 53 (26.1%) patients received resection and curative resection; therefore, the resection rate and curative resection rate were significantly much higher in the laparoscopy group (p < 0.000).

CONCLUSIONS

Staging laparoscopy in GBC is sensitive in detecting disseminated disease and increases the curative resection rate, shortens the recovery time, and has no negative implications on overall survival; therefore, we suggest the routine use of staging laparoscopy in patients with GBC without evidence of disseminated disease on preoperative imaging.

High b-value diffusion-weighted MRI in differentiation between benign and malignant polypoid gallbladder lesions

BACKGROUND

Several studies have reported the effectiveness of high b-value diffusion-weighted MR imaging (DWI) in the abdominal region, and have found that various malignant tumors may show high signal intensity on DWI, reflecting their high cellularity and/or their long relaxation time. The value of ADC measurement has also been documented for the diagnosis of several abdominal malignancies.

PURPOSE

To retrospectively evaluate the usefulness of high b-value DWI in differentiating between benign and malignant polypoid gallbladder lesions.

MATERIAL AND METHODS

The study population consisted of 10 benign (three hyperplastic polyps and seven adenomas) and 13 malignant (all adenocarcinomas) polypoid gallbladder lesions. DWI was evaluated by two observers. Qualitatively, the signal intensity of the lesions on DWI was visually evaluated and categorized as iso, high, or very high. Quantitatively, the ADC values of the lesions were measured from ADC maps. Statistical analysis was performed using a two-tailed Fisher's exact test and the Mann-Whitney test, respectively.

RESULTS

Qualitative analysis revealed a statistical difference (P = 0.0041). Six of 10 benign lesions were categorized as iso, and the remaining four were categorized as high. In the 13 malignant lesions, one was categorized as iso, five as high, and seven as very high. The ADC values of the malignant lesions (1.34 ± 0.50 × 10(-3) mm(2)/sec) were significantly lower than those of the benign lesions (2.26 ± 0.44 × 10(-3) mm(2)/sec) (P = 0.00016).

CONCLUSION

High b-value DWI may be useful for differentiating between benign and malignant polypoid gallbladder lesions by the visual assessment of DWI and ADC measurement.

Biliary, pancreatic, and hepatic imaging for the general surgeon

Technologic advancements have allowed imaging modalities to become more useful in the diagnosis of hepatobiliary and pancreatic disorders. Computed tomography scanners now use multidetector row technology with contrast-delayed imaging for quicker and more accurate imaging. Magnetic resonance imaging with cholangiopancreatography can more clearly delineate liver lesions and the biliary and pancreatic ducts, and can diagnose pathologic conditions early in their course. Newer technologies, such as single-operator cholangioscopy and endoscopic ultrasonography, have sometimes shown superiority to traditional modalities. This article addresses the literature regarding available imaging techniques in the diagnosis and treatment of common surgical hepatobiliary and pancreatic diseases.

False positive diagnosis of metastatic esophageal carcinoma on positron emission tomography: a case report of cholecystitis simulating a hepatic lesion

Esophageal cancer has been increasing in incidence for the last several decades. The current staging evaluation includes computed tomography, endoscopic ultrasonography, and F-18 fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT), which influences the treatment options. PET/CT is limited in its ability to differentiate hypermetabolic metastatic disease from acute/chronic inflammatory conditions, and this must be considered during interpretation. This is the case report of a 77-year-old man with esophageal cancer whose PET/CT demonstrated increased F-18 FDG uptake in the right lobe of the liver. This was originally interpreted at an outside institution as suspicious for metastatic disease, which would have precluded potential surgical cure. Subsequent reinterpretation and additional imaging including magnetic resonance imaging suggested that the uptake in the liver was likely due to adjacent gallbladder inflammation. On the basis of this interpretation, an abdominal exploration, liver biopsy, cholecystectomy, and transhiatal esophagectomy were performed. Final pathology of the gallbladder revealed perforated cholecystitis and a pericholecystic abscess (related to a prior septic episode), which were responsible for the increased radiotracer uptake. This case is presented to illustrate the importance of considering benign etiologies that may mimic metastatic disease when interpreting PET/CT scans.

An unusual association of diffuse adenomyomatosis with dysplastic adenoma in chronic calculous cholecystitis: case presentation

Background

Gallbladder adenomyomatosis is an epithelial proliferation and hypertrophy of the muscularis mucosae of the gallbladder. Rokitansky-Aschoff sinuses are a characteristic of this condition. The segmental adenomyomatosis has a higher risk of developing into gallbladder carcinoma, especially in the fundal region of elderly patients.

We report the case of a patient affected by chronic calculous cholecystitis with diffuse adenomyomatosis associated with dysplastic adenoma.

Case presentation

An 81-year-old woman presented at our hospital with a 1-year history of intermittent pain localized at the right upper abdominal quadrant, without diffusion to any other body part. On physical examination the abdomen was soft, not distended, and tender to palpation in the right upper quadrant. Murphy sign was negative. Laboratory tests were normal. The patient was scheduled for a laparoscopic cholecystectomy, and neither endoscopic ultrasonographic scan nor magnetic resonance imaging was performed. The operation, performed after obtaining informed consent, was uncomplicated and the intra-operative pathological examination showed no malignancy. The definitive pathological examination of the gallbladder showed: multiple stones of cholesterol origin; diffuse mucosal adenomyomatosis; and a 1.1 cm pedunculated mass localized at the fundus, whose surface was lumpy. This mass was diagnosed as an adenoma with multiple areas of severe dysplasia.

Conclusions

The adenoma of the gallbladder, together with the dysplasia, represents a biological carcinogenetic model. Carcinoma has rarely been reported in adenomyomatosis. Degenerative risk suggests surgery should be mandatory when there is a concomitant presence of large adenoma and adenomyomatosis.

Gallbladder abnormalities in carcinoma of pancreatic head: findings on MR imaging

BACKGROUND

Our objective is to study the gallbladder abnormalities on MR images associated with carcinoma of the pancreatic head.

METHODS

Thirty-six patients who had surgical resection of pancreatic head carcinoma were retrospectively analyzed regarding the appearance of the tumor and gallbladder on MR imaging performed within one month before surgery. The changes of the gallbladder wall, and the dimension of the gallbladder, cystic duct, pericholecystic region, and common bile duct (CBD) on MR imaging were noted.

RESULTS

About 92% (33/36) of patients had at least one gallbladder abnormality on MR imaging, including thickened gallbladder wall (58%), gallbladder wall striation (19%), gallbladder wall severe enhancement (44%), enlarged gallbladder (33%), gallbladder stone (19%), dilatation of cystic duct (67%), focally increased liver parenchymal enhancement adjacent to the gallbladder (19%), and pericholecystic fluid (11%). 64% of patients had dilated CBD. The diameter of the cystic duct was correlated with those of the CBD (r = 0.45, P < 0.01) and gallbladder (r = 0.56, P < 0.0001). Enlarged gallbladder, dilatation of the cystic duct, and CBD were correlated with chronic cholecystitis.

CONCLUSION

Most patients with pancreatic head carcinoma show gallbladder abnormalities on MR imaging. Cystic duct dilatation follows CBD dilatation and is the primary cause for dilated gallbladder and chronic cholecystitis in carcinoma of pancreatic head.

[Imaging in the diagnosis and the staging of gallbladder tumors]

Most of gallbladder tumors are benign. Adenoma, cholesterol polyps, or adenomyomatosis are most frequently typical on ultrasonographic images. All symptomatic lesions must be considered as indications for surgery. It may be difficult to identify precancerous or malignant lesion. Polyps over 1cm are indication for preventive cholecystectomy. In case of suspicious polyp or suspicious wall thickening, endoscopic ultrasonography can be helpful to evaluate local tumoral spread and eliminate differential diagnosis. Unfortunately, diagnosis of gallbladder cancer is often late, when surgical resection can't be curative. Computed tomography and magnetic resonance imaging examinations are then useful for local and metastatic staging.

The diagnostic MRCP examination: overcoming technical challenges to ensure clinical success

The magnetic resonance cholangiopancreatography (MRCP) examination has all but replaced the diagnostic endoscopic retrograde cholangiopancreatography (ERCP) examination for imaging the biliary tree and pancreatic ducts in many practical aspects of the clinical setting. Despite this increase in popularity, many magnetic resonance imaging (MRI) radiographers still find aspects of the MRCP examination quite challenging. The aim of this tutorial paper is to provide useful technical advice on how to overcome such perceived challenges and thus produce a successful diagnostic MRCP examination. This paper will be of interest to novice MRI radiographers who are at the beginning of their learning curve in MRCP examination. Other MRI radiographers who are interested in practical tips for protocol variations may also find the paper useful.