Dynamic MRI of the gallbladder lesions: differentiation of benign from malignant

Enhancement Patterns of Malignant Gallbladder Masses at Multiphasic Contrast-enhanced CT: Associations With Clinicoradiopathological Features

Purpose

To assess the enhancement patterns of malignant gallbladder masses at multiphasic contrast-enhanced computed tomography (CECT) and their association with the clinicoradiopathological features.

Material and methods

In this retrospective study, consecutive patients with mass-forming gallbladder cancer (GBC) who underwent biphasic [hepatic arterial phase (HAP) and portal venous phase (PVP)] CECT between January 2019 and January 2023 were included. The enhancement patterns at CT scans were assessed independently by two radiologists blinded to the clinicopathological data. The masses were categorized into the typical group (hypoattenuation relative to normal liver in HAP) and the atypical group (isoenhancement or hyperenhancement in HAP). Enhancement patterns in PVP were also evaluated. The association between enhancement characteristics and the pathological grade and type, radiological aggressiveness (biliary/vascular involvement, lymph node, liver, and omental metastases), resectability, and overall survival was assessed.

Results

Sixty-five patients (41 females, mean age was 52.5 ± 17.6 years) were included in the study. On HAP images, eight lesions (12.3%) were hyperattenuating, nine (13.8%) were isoattenuating, and 48 (73.8%) were hypoattenuating. Of the 17 masses in the atypical group, 8 (47.1%) lesions showed washout, and 9 showed persistent enhancement (52.9%) in the PVP. Heterogeneous peripheral and central enhancement in HAP were significantly associated with lymph node metastases (P = 0.019). Enhancement pattern was not significantly associated with pathological grade/type, other radiological features, resectability, and overall survival.

Conclusion

Mass-forming GBC has variable enhancement. Heterogeneous HAP enhancement is associated with lymph node metastases.

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.

Late/delayed gadolinium enhancement in MRI after intravenous administration of extracellular gadolinium-based contrast agents: is it worth waiting?

The acquisition of images minutes or even hours after intravenous extracellular gadolinium-based contrast agents (GBCA) administration ("Late/Delayed Gadolinium Enhancement" imaging; in this review, further termed LGE) has gained significant prominence in recent years in magnetic resonance imaging. The major limitation of LGE is the long examination time; thus, it becomes necessary to understand when it is worth waiting time after the intravenous injection of GBCA and which additional information comes from LGE. LGE can potentially be applied to various anatomical sites, such as heart, arterial vessels, lung, brain, abdomen, breast, and the musculoskeletal system, with different pathophysiological mechanisms. One of the most popular clinical applications of LGE regards the assessment of myocardial tissue thanks to its ability to highlight areas of acute myocardial damage and fibrotic tissues. Other frequently applied clinical contexts involve the study of the urinary tract with magnetic resonance urography and identifying pathological abdominal processes characterized by high fibrous stroma, such as biliary tract tumors, autoimmune pancreatitis, or intestinal fibrosis in Crohn's disease. One of the current areas of heightened research interest revolves around the possibility of non-invasively studying the dynamics of neurofluids in the brain (the glymphatic system), the disruption of which could underlie many neurological disorders.

Multiparametric MR imaging with diffusion-weighted, intravoxel incoherent motion, diffusion tensor, and dynamic contrast-enhanced perfusion sequences to assess gallbladder wall thickening: a prospective study based on surgical histopathology

OBJECTIVE

To investigate the diagnostic performance of a multiparametric magnetic resonance imaging (MRI) protocol comprising quantitative MRI (diffusion-weighted imaging (DWI), intravoxel incoherent motion (IVIM), diffusion tensor imaging (DTI), and dynamic contrast-enhanced (DCE) perfusion MRI) and conventional MRI in the characterization of gallbladder wall thickening (GWT).

METHODS

This prospective study comprised consecutive adults with GWT who underwent multiparametric MRI between July 2020 and April 2022. Two radiologists evaluated the MRI independently. The final diagnosis was based on surgical histopathology. The association of MRI parameters with malignant GWT was evaluated. The area under the curve (AUC) for the quantitative MRI parameters and diagnostic performance of conventional, and multiparametric MRI were compared. The interobserver agreement between two radiologists was calculated.

RESULTS

Thirty-five patients (mean age, 56 years, 23 females) with GWT (25 benign and ten malignant) were evaluated. The quantitative MRI parameters significantly associated with malignant GWT were apparent diffusion coefficient on DWI (p = 0.007) and mean diffusivity (MD) on DTI (p = 0.013), perfusion fraction (f) on IVIM (p = 0.033), time to peak enhancement (TTP, p = 0.008), and wash in rate (p = 0.049) on DCE-MRI. TTP had the highest AUC of 0.790, followed by MD (0.782) and f (0.742) (p = 0.213) for predicting malignant GWT. Multiparametric MRI had significantly higher sensitivity (90% vs. 80%, p = 0.045) than conventional MRI for diagnosing malignant GWT. The two radiologists' reading had substantial to near-perfect agreement (kappa = 0.639-1) and moderate to strong correlation (interclass correlation coefficient = 0.5-0.88).

CONCLUSION

Multiparametric protocol incorporating advanced sequences improved the diagnostic performance of MRI for differentiating benign and malignant GWT.

KEY POINTS

• Multiparametric MRI had 90% sensitivity and 88% specificity for diagnosing malignant GWT, compared to 80% sensitivity and 88% specificity for conventional CE-MRI. • Among the quantitative MRI parameters, TTP (perfusion-MRI) had the highest AUC of 0.790, followed by MD (0.782) and IVIM-f (0.742). • For most quantitative MRI parameters, there was moderate to strong agreement (ICC = 0.5-0.88).

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.

Current update on gallbladder carcinoma

Gallbladder (GB) carcinoma is a relatively rare malignancy and is associated with poor prognosis. Numerous risk factors have been associated with the development of GB carcinoma. GB carcinomas may present as mass lesions replacing the GB, focal or diffuse thickening of the GB wall, and intraluminal mass in the GB. Various benign conditions can mimic GB carcinoma. This article reviews the epidemiology, pathology, clinical findings, imaging features, and management of GB carcinomas.

Imaging-based algorithmic approach to gallbladder wall thickening

Gallbladder (GB) wall thickening is a frequent finding caused by a spectrum of conditions. It is observed in many extracholecystic as well as intrinsic GB conditions. GB wall thickening can either be diffuse or focal. Diffuse wall thickening is a secondary occurrence in both extrinsic and intrinsic pathologies of GB, whereas, focal wall thickening is mostly associated with intrinsic GB pathologies. In the absence of specific clinical features, accurate etiological diagnosis can be challenging. The survival rate in GB carcinoma (GBC) can be improved if it is diagnosed at an early stage, especially when the tumor is confined to the wall. The pattern of wall thickening in GBC is often confused with benign diseases, especially chronic cholecystitis, xanthogranulomatous cholecystitis, and adenomyomatosis. Early recognition and differentiation of these conditions can improve the prognosis. In this minireview, the authors describe the patterns of abnormalities on various imaging modalities (conventional as well as advanced) for the diagnosis of GB wall thickening. This paper also illustrates an algorithmic approach for the etiological diagnosis of GB wall thickening and suggests a formatted reporting for GB wall abnormalities.

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.

Cross-sectional Imaging of Gallbladder Carcinoma: An Update

Gallbladder Carcinoma (GBCA) is the most common biliary tract malignancy. As the disease is often diagnosed clinically in an advanced stage, the survival rates are dismal. Imaging studies allow for an early diagnosis of malignancy, though the findings may be indistinguishable from non-malignant disease processes affecting the gallbladder. Attempts have been made to make a specific diagnosis of GBCA at an early stage on imaging studies. Ultrasonography (US) is the most commonly employed technique for gallbladder evaluation. Gallbladder wall thickening is the most common finding of early GBCA and in this context, US is non-specific. Recently, contrast enhanced ultrasound has been shown to be effective in differentiating benign from malignant disease. Multidetector computed tomography represents the most robust imaging technique in evaluation of GBCA. It provides relatively sensitive evaluation of mural thickening, though it is not entirely specific and issues in differentiating GBCA from xanthogranulomatous cholecystitis do arise. Due to its superior soft tissue resolution, Magnetic Resonance Imaging (MRI) provides excellent delineation of gallbladder and biliary tree involvement. When coupled with functional MRI techniques, such as diffusion-weighted and perfusion imaging, it provides a useful problem solving tool for interrogating the malignant potential of nonspecific gallbladder lesions and detection of metastases. Positron emission tomography has a role in detection of distant metastases and following patients following treatment for malignancy. We review the current role of various imaging modalities in evaluating patients with GBCA.

Intravascular Large B-Cell Lymphoma Presenting with Diffuse Gallbladder Wall Thickening: A Case Report and Literature Review

Intravascular large B-cell lymphoma is a rare subtype of extranodal diffuse B-cell lymphoma characterized by proliferation of neoplastic cells within the lumen of small and medium sized vessels. Clinical and imaging findings are nebulous as the intravascular subtype of lymphoma can involve a multitude of organs. Involvement of the gallbladder is extremely uncommon, and imaging findings can be easily confused for more prevalent pathologies. We report a case of intravascular large B-cell lymphoma in an 83-year-old male and review clinical presentation and imaging findings on CT, ultrasound, hepatobiliary iminodiacetic acid (HIDA) scan, and MRI. It is important for the radiologist to know about this disease as the imaging findings are atypical of other types of lymphoma, and this may lead to a delay in diagnosis and treatment.

PET/MR Imaging in Cancers of the Gastrointestinal Tract

PET/computed tomography (PET/CT) is an established hybrid imaging technique for staging and follow-up of gastrointestinal (GI) tract malignancies, especially for colorectal carcinoma. Dedicated hybrid PET/MR imaging scanners are currently available for clinical use. Although they will not replace regular use of PET/CT, they may have utility in selected cases of GI tract malignancies. The superior soft tissue contrast resolution and depiction of anatomy and the functional information obtained from diffusion-weighted imaging (DWI) provided by MR imaging in PET/MR imaging are advantages over CT of PET/CT for T staging and follow-up of rectal carcinoma and for better characterization of liver lesions. Functional information from DWI and use of liver-specific MR imaging contrast agents are an added advantage in follow-up of liver metastases after systemic and locoregional treatment. New radiotracers will improve the utility of PET/MR imaging in staging and follow-up of tumors, which may not be [18F]-2-fluoro-2-deoxy-d-glucose avid, such as hepatocellular carcinoma and neuroendocrine tumors. PET/MR imaging also has application in selected cases of cholangiocarcinoma, gallbladder cancer, and pancreatic carcinoma for initial staging and follow-up assessment.

Tumefactive gallbladder sludge: the MRI findings

AIM

To evaluate the conventional and diffusion-weighted magnetic resonance imaging (MRI) images of tumefactive gallbladder sludge.

MATERIALS AND METHODS

The institutional review board approved this retrospective study. Between January 2006 and January 2015, 3478 patients were diagnosed with gallbladder sludge by ultrasonography (US). Of them, 12 patients (eight male, four female; mean age, 63.6 years) with 12 tumefactive gallbladder sludge lesions, who underwent subsequent MRI for further evaluation within 1 month, were included in this study. Data regarding the clinical features, presence of enhancement, and signal intensities of the T2-, T1-, and diffusion-weighted images were collected.

RESULTS

All cases of tumefactive sludge were detected incidentally. None of the patients had any predisposing factors for biliary sludge. The tumefactive gallbladder sludge was predominantly seen as a well-defined mass-like lesion. It showed hyperintensity on T1-weighted images (91.7%, 11/12), and variable signal intensities on T2-weighted images. Most of the tumefactive sludge lesions showed no enhancement on the dynamic phases (90%, 9/10). There were no cases with diffusion restriction. Among the patients with follow-up US data (n=7), all the lesions were found to have either disappeared or decreased in size.

CONCLUSION

Although tumefactive gallbladder sludge on US can mimic gallbladder cancer, its hyperintensity on a T1-weighted image, and the absence of enhancement and diffusion restriction on MRI images can be helpful for differentiating it from a tumorous condition.

Polypoid lesions of the gallbladder: disease spectrum with pathologic correlation

Gallbladder polyps are seen on as many as 7% of gallbladder ultrasonographic images. The differential diagnosis for a polypoid gallbladder mass is wide and includes pseudotumors, as well as benign and malignant tumors. Tumefactive sludge may be mistaken for a gallbladder polyp. Pseudotumors include cholesterol polyps, adenomyomatosis, and inflammatory polyps, and they occur in that order of frequency. The most common benign and malignant tumors are adenomas and primary adenocarcinoma, respectively. Polyp size, shape, and other ancillary imaging findings, such as a wide base, wall thickening, and coexistent gallstones, are pertinent items to report when gallbladder polyps are discovered. These findings, as well as patient age and risk factors for gallbladder cancer, guide clinical decision making. Symptomatic polyps without other cause for symptoms, an age over 50 years, and the presence of gallstones are generally considered indications for cholecystectomy. Incidentally noted pedunculated polyps smaller than 5 mm generally do not require follow-up. Polyps that are 6-10 mm require follow-up, although neither the frequency nor the length of follow-up has been established. Polyps that are larger than 10 mm are typically excised, although lower size thresholds for cholecystectomy may be considered for patients with increased risk for gallbladder carcinoma, such as patients with primary sclerosing cholangitis.

Diffusion-weighted magnetic resonance imaging of gallbladder adenocarcinoma: analysis with emphasis on histologic grade

PURPOSE

To investigate the value of diffusion-weighted imaging (DWI) for differentiating gallbladder adenocarcinoma from adenoma, and predicting histologic grades of gallbladder adenocarcinoma.

MATERIALS AND METHODS

Fourty-three gallbladder adenocarcinomas and 8 adenomas were included. We compared apparent diffusion coefficient (ADC) values between adenocarcinoma and adenoma, and ADC values of gallbladder adenocarcinoma among the histologic grade.

RESULTS

Gallbladder adenocarcinoma (1.041×10(-3)mm(2)/s) showed significantly lower ADC values than adenoma (2.039×10(-3)mm(2)/s) (P<.001). Well-differentiated adenocarcinoma (1.290×10(-3)mm(2)/s) showed significantly higher ADC values than higher-grades (1.104×10(-3) and 0.915×10(-3)mm(2)/s in moderately- and poorly-differentiated, respectively) (P<.001).

CONCLUSION

DWI can help to differentiate gallbladder adenocarcinoma from adenoma, and well-differentiated from higher-grade adenocarcinoma.

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.

Magnetic resonance evaluations of biliary malignancy and condition at high-risk for biliary malignancy: Current status

Tumors of the biliary tree are relatively rare; but their incidence is rising worldwide. There are several known risk factors for bile duct cancers, and these are seem to be associated with chronic inflammation of the biliary epithelium. Herein, 2 risk factors have been discussed, primary sclerosing cholangitis and reflux of pancreatic juice into the bile duct, as seen in such as an abnormal union of the pancreatic-biliary junction because magnetic resonance imaging (MRI) is used widely and effectively in the diagnosis of these diseases. When biliary disease is suspected, MRI can often help differentiate between benignity and malignancy, stage tumors, select surgical candidates and guide surgical planning. MRI has many advantages over other modalities. Therefore, MRI is a reliable noninvasive imaging tool for diagnosis and pre-surgical evaluation of bile duct tumors. Nowadays remarkable technical advances in magnetic resonance technology have expanded the clinical applications of MRI in case of biliary diseases. In this article, it is also discussed how recent developments in MRI contributes to the diagnosis of the bile duct cancer and the evaluation of patients with risk factors affecting bile duct cancer.

Diffusion-weighted MRI for differentiation of benign from malignant lesions in the gallbladder

AIM

To investigate the value of diffusion-weighted imaging (DWI) for differentiating benign from malignant gallbladder lesions.

MATERIALS AND METHODS

One hundred and twenty-six patients who had undergone magnetic resonance imaging (MRI) with DWI, in whom the histopathological diagnosis of their gallbladder lesions was confirmed by biopsy or surgery were retrospectively analysed. Thirty-six malignant and 90 benign lesions were included. Two radiologists categorized gallbladder lesions into seven types on two imaging sets [T2-weighted imaging (WI) alone and combined T2WI and DWI (b = 800 s/mm(2))] according to the presence of wall thickening, layered patterns, morphology of the mass, and diffusion restriction. Disagreements were resolved in consensus. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of each imaging set for diagnosing gallbladder carcinoma were calculated. The diagnostic performance of each imaging set was calculated using receiver operating characteristic (ROC) curve analysis. Additionally, ADC values of malignant and benign gallbladder lesions were compared separately for 1.5 and 3 T MRI.

RESULTS

The sensitivity, specificity, PPV, and NPV of diagnosis at T2WI were 97.2%, 86.7%, 74.5%, and 98.7%, respectively. The sensitivity, specificity, PPV, and NPV using combined T2WI and DWI were 97.2%, 92.2%, 83.3%, and 98.8%, respectively. Diagnostic accuracy for gallbladder carcinoma slightly improved after adding DWI, from 0.92 to 0.95 (p < 0.05). ADC values for gallbladder carcinoma were significantly lower than those for benign lesions. Mean ADC values of malignant and benign lesions were 0.97 ± 0.25 × 10(-3) and 1.72 ± 0.56 × 10(-3) mm(2)/s, respectively, at 1.5 T (p < 0.001), and 1.04 ± 0.38 × 10(-3) and 2.2 ± 0.72 × 10(-3) mm(2)/s, respectively, at 3 T (p < 0.001).

CONCLUSION

DWI can improve diagnostic accuracy for differentiating benign from malignant gallbladder lesions.

The varying faces of gall bladder carcinoma: pictorial essay

The objective of this review is to highlight the pertinent imaging features and potential pitfalls in the diagnosis and staging of gall bladder carcinoma. This condition is notoriously non-specific on imaging on many occasions, particularly in its early stages; gall bladder carcinoma shows numerous features that overlap with a large number of benign conditions, leading to delayed diagnosis and incurable disease. Radiologists should be familiar with its typical and atypical imaging features.

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.

Gallbladder carcinoma update: multimodality imaging evaluation, staging, and treatment options

OBJECTIVE

The purpose of this article is to review the epidemiology, multimodality imaging findings, differential diagnosis, pathologic staging, and current treatment options of gallbladder carcinoma.

CONCLUSION

Understanding the characteristic appearances of primary gallbladder carcinoma at multiple imaging modalities can facilitate diagnosis and enable more accurate staging for triage to extended resection or an alternate therapy.

Application of modern imaging methods in diagnosis of gallbladder cancer

The poor prognosis of gallbladder cancer (GBC) is related to its dissemination capacity and usually late diagnosis due to its non-specific clinical appearance. Recent improvements in hepatobiliary surgery have underlined the importance of an early specific diagnosis, which requires a multidisciplinary approach and, when possible, specialized equipment. The first step in an early diagnosis is to identify patients in the appropriate epidemiological setting (e.g., incidental finding, chronic cholecystitis) for the correct interpretation of test results. It is desirable to enhance the sensitivity of the initial ultrasound (US) examination by use of the appropriate technology in skilled specialist hands. When GBC is suggested by US findings, FDG-PET can be considered complementary to establish the benign/malignant nature of the lesion and to obtain a primary staging study. If GBC is confirmed, thin slice spiral CT can contribute valuable information on local spread. In this regard, recent hybrid PET-CT systems provide structural and functional information simultaneously and may offer early and accurate T, N, and M staging with an improved specificity.

Evaluation of gall bladder carcinoma with dynamic magnetic resonance imaging and magnetic resonance cholangiopancreatography

The objective of this study is to evaluate the efficacy of dynamic MRI with magnetic resonance cholangiopancreatography (MRCP) in the preoperative assessment of gall bladder carcinoma. Magnetic resonance imaging and MRCP were carried out in 15 patients with gall bladder carcinoma before surgery and the imaging findings correlated with surgical and pathological findings. Gall bladder carcinoma manifested as focal or diffuse wall thickening in 73% (11/15) and as a mass replacing the gall bladder in 27% (4/15). All tumours showed enhancement in the early phase, which persisted into the delayed phase. The sensitivity and specificity of MRI with MRCP in detecting hepatic invasion, lymph node metastasis and bile duct invasion was 87.5 and 86%, 60 and 90%, and 80 and 100%, respectively. Magnetic resonance imaging correctly diagnosed duodenal invasion in only 50% and in none of the two patients with peritoneal metastasis. In conclusion, dynamic MRI with MRCP is an accurate and a reliable method of showing gall bladder carcinoma and in assessing its local and regional extent as part of preoperative assessment.

Diagnostic imaging of carcinomas of the gallbladder and the bile ducts

Early diagnosis and accurate staging of carcinomas of the gallbladder and the bile ducts are helpful in improving the prognosis. Ultrasonography (US), a useful initial modality when exploring the background of jaundice or non-specific gastrointestinal complaints, sensitively reveals bile duct obstruction in particular. In unclear cases, or if US suggests a resectable biliary malignancy, computed tomography (CT), magnetic resonance imaging (MRI) with magnetic resonance cholangiography (MRC) and / or traditional cholangiography often provide additional information, and imaging-guided fine-needle biopsy or an endoscopic brush sample may verify the malignant nature of the tumor. Complementary modalities are usually needed for accurate staging, and traditional cholangiography is often performed for therapeutic purposes as well. Comparative studies of MRI with MRC and multidetector CT in biliary cancers would be welcome.

MR Imaging of the Gallbladder and Biliary System

MR imaging is an established technique for the diagnosis of a spectrum of biliary and gallbladder pathologies and continues to improve with the advent of technologic advances, including new contrast agents and new sequences that are capable of improving upon the contrast resolution and signal-to-noise that are afforded by conventional MR imaging. These improvements already have shown promise for the increasing role of MRC as the initial modality in assessing living liver donors and evaluating post-operative hepato-biliary complications. Improved spatial resolution and the added functional or physiologic information afforded by MR imaging promise ever expanding clinical applicability and usefulness.

Gallbladder wall thickening: MR imaging and pathologic correlation with emphasis on layered pattern

The aim of this study was to correlate MR findings of gallbladder wall thickening with pathologic findings on the basis of the layered pattern and to evaluate the diagnostic value of MR imaging in gallbladder disease. We retrospectively evaluated the source images of HASTE sequences for MR cholangiography in 144 patients with gallbladder wall thickening. The layered pattern of thickened wall was classified into four patterns. Type 1 shows two layers with a thin hypointense inner layer and thick hyperintense outer layer. Type 2 has two layers of ill-defined margin. Type 3 shows multiple hyperintense cystic spaces in the wall. Type 4 shows diffuse nodular thickening without layering. MR findings of a layered pattern of thickened gallbladder were well correlated with histopathology. Chronic cholecystitis matched to type 1, acute cholecystitis corresponded to type 2, adenomyomatosis showed type 3, and the gallbladder carcinomas showed type 4. All four layered patterns were associated with PPV of 73% or greater, sensitivity of 92% or greater and specificity of 95% or greater. Our results indicate that MR findings of gallbladder wall thickening are characteristic in each entity and correlate well with pathologic findings. The classification of the layered pattern may be valuable for interpreting thickened gallbladder wall.

Differential diagnosis of gallbladder cancer using positron emission tomography with fluorine-18-labeled fluoro-deoxyglucose (FDG-PET)

BACKGROUND AND OBJECTIVES

The purpose of this paper is to evaluate the utility of positron emission tomography (PET) with fluorine-18-labeled fluoro-deoxyglucose (FDG) in the preoperative differential diagnosis of gallbladder tumors. We performed PET studies of gallbladder tumors in order to predict the malignancy of these tumors preoperatively.

METHODS

Sixteen patients who had protuberant lesions in the gallbladder and who were scheduled to undergo surgery were studied with PET using FDG. Focally increased FDG uptake in the gallbladder region was considered malignant. The FDG-PET findings were compared with the histological findings of surgical pathology.

RESULTS

Sensitivity of FDG-PET was 75% (6/8 patients). One of two false-negative cases suffered from diabetes mellitus, and in the other case, the lesion was small. Specificity was 87.5% (7/8 patients). A case with xanthogranulomatous cholecystitis (XGC) was the only false-positive case.

CONCLUSIONS

FDG-PET may be able to provide important information for evaluating the malignancy of gallbladder tumors.

Imaging benign and malignant disease of the gallbladder

This article reviews the imaging of various benign and malignant diseases of the gallbladder. Clinical findings and imaging features using ultrasound, CT, and MR for the detection and evaluation of gallstones, acute cholecystitis, xanthogranulomatous cholecystitis, adenomyomatosis, and carcinoma of the gallbladder among other disorders are discussed.

Preoperative evaluation of gallbladder carcinoma: efficacy of combined use of MR imaging, MR cholangiography, and contrast-enhanced dual-phase three-dimensional MR angiography

PURPOSE

To determine the efficacy of the combined use of magnetic resonance (MR) imaging, MR cholangiography (MRC), and MR angiography (MRA) in the preoperative evaluation of gallbladder carcinoma.

MATERIALS AND METHODS

During a 20-month period, 41 patients with proven gallbladder carcinomas were referred for MR examination, including MR imaging, MRC, and gadolinium-enhanced dual-phase MRA to determine the operability of their gallbladder carcinoma. Eighteen patients who underwent surgery within six days of the MR examination were included in this study. All MR images were analyzed in order to assess bile duct invasion, vascular invasion, hepatic invasion or metastasis, lymph node metastasis, and invasion into adjacent organs.

RESULTS

Surgical and histopathologic findings revealed hepatic invasion in nine patients, bile duct invasion in nine, vascular invasion in three, and lymph node metastasis in 10. The sensitivity and specificity of MR examination were, respectively, 100% and 89% for bile duct invasion, 100% and 87% for vascular invasion, 67% and 89% for hepatic invasion, and 56% and 89% for lymph node metastasis.

CONCLUSION

The "all-in-one" MR protocol, including MR imaging, MRC, and MRA, can be an effective diagnostic method in the preoperative work-up for gallbladder carcinoma.

Diagnosis and staging of gallbladder carcinoma. Evaluation with dynamic MR imaging

The purpose of this study is to determine the ability of dynamic magnetic resonance imaging (MRI) in the diagnosis and staging of gallbladder cancer (GBC). Images of dynamic MRI of hepatobiliary system combined with MR cholangiography (MRC) of 18 patients with pathologically proved gallbladder cancer were correlated with pathological and operative findings. Focal or diffuse wall thickening was present in 10 patients. In five patients, the tumor appeared as a fungating or intramural mass. A tumor replacing the gallbladder was found in two patients and a small cancer in cystic duct in one patient. The tumor featured early and irregular enhancement, which persisted throughout the dynamic study. Metastatic nodes were found by surgicopathology in 13 patients and were depicted by the dynamic MRI in 11 patients. Local invasion to liver was found by surgery in 12 patients and correctly detected by MRI in 11 patients. MRI detected duodenum invasion in three out of six patients and none of the three cases with omental metastasis. In conclusion, dynamic MRI is useful and reliable in staging of advanced gallbladder cancer. MRI combined with MRC is sensitive in detection of obstructive jaundice, liver invasion as well as liver and lymph nodes metastasis. It is more difficult to delineate the invasion to duodenum and omental metastasis by MRI.

Gallbladder carcinoma: findings at MR imaging with MR cholangiopancreatography

PURPOSE

To describe magnetic resonance (MR) imaging and MR cholangiopancreatography (MRCP) findings in gallbladder carcinoma, and to correlate these findings with available surgical and biopsy information.

METHODS

Preoperative MR images (T1-weighted spin-echo, T2-weighted fast spin-echo, single shot fast spin-echo, and dynamic gadolinium-enhanced gradient echo) in 34 patients with gallbladder carcinoma were retrospectively reviewed for appearance of the primary neoplasm and for demonstration of hepatic, peritoneal, duodenal, and nodal involvement. Imaging findings were then compared with surgical findings (n = 19 patients) and histologic findings (n = 15 patients).

RESULTS

Gallbladder carcinoma manifested at MR imaging as focal gallbladder wall thickening with an eccentric mass in 76% (26/34) of cases. The most common types of regional spread demonstrated were direct liver invasion in 91% (31/34), lymphadenopathy in 76% (26/34), and biliary tract invasion in 62% (21/34). Sensitivity for direct hepatic invasion was 100%, and was 92% for lymph node metastasis.

CONCLUSION

MRI and MRCP can provide information relevant to preoperative staging of gallbladder carcinoma.

MR imaging of the gallbladder

T2-weighted imaging and MRCP, which have high sensitivity to edema and fluid, are paramount in the evaluation of certain gallbladder diseases, such as cholelithiasis, cholecystitis, adenomyomatosis, and cystic duct abnormalities. Dynamic gadolinium-enhanced MR imaging has the potential to differentiate among the many nonspecific-appearing lesions involving the gallbladder. MR imaging may not yet replace ultrasound as the workhorse of acute gallbladder imaging. Currently, MRCP is an ideal complementary study to inconclusive sonographic studies and can help plan surgical intervention in the setting of acute cholecystitis. Further investigation of hepatobiliary contrast agents, however, may reveal that MR imaging may be considered as first-line imaging in the acute setting.

Differential diagnosis of polypoid lesions of the gallbladder by endoscopic ultrasonography

BACKGROUND

Transabdominal ultrasonography (US) has made the detection of gallbladder polyps easier, but the differential diagnosis of polyps less than 20 mm remains difficult. Therefore, we evaluated the usefulness of endoscopic ultrasonography (EUS) for the differential diagnosis of gallbladder polyps.

METHODS

Among patients with gallbladder polyps less than 20 mm, we reviewed 89 patients who underwent US and EUS before surgery and assessed the results of differential diagnoses by them.

RESULTS

In all, 86.5% of these polyps were precisely diagnosed by EUS. However, only 51.7% were diagnosed by US. Sensitivity, specificity, and positive and negative predictive values of EUS at the diagnosis of carcinoma were 91.7%, 87.7%, 75.9%, and 96.6%, respectively. Those of US were 54.2%, 53.8%, 54.2%, and 94.6%, respectively.

CONCLUSIONS

EUS may markedly improve the accuracy of the differential diagnosis of gallbladder polyps. Therefore, EUS is thought to play an important role in determining the treatment strategy for gallbladder polyps.

Possibility of Differential Diagnosis of Small Polypoid Lesions in the Gallbladder Using FDG-PET

Purpose: We discuss three cases of patients with small polypoid lesions of gallbladder in which we successfully differentiated the malignancy or benignity preoperatively using positron emission tomography (PET) scanning with 18F-labelled deoxyglucose (FDG).Methods and Results: The first case involves a 47-year-old woman who had a 15 x 10 mm polypoid lesion of the gallbladder. FDG-PET was performed and revealed no FDG uptake. The histopathological diagnosis was a cholesterol polyp. The second case is a 56-year-old woman who had a 22 x 8 mm polypoid lesion in the neck of the gallbladder and wall-thickening of the fundus. FDG-PET was performed and no FDG uptake was found. The postoperative diagnosis was pseudo-tumorous sludge in the neck and adenomyomatosis of the fundus. The third case is a 77-year-old man who had a 15 x 15 mm polypoid lesion in the gallbladder. PET revealed a focus of FDG uptake at the site of the gallbladder. The histopathologic diagnosis was adenocarcinoma. Focal FDG uptake was the sole indicator of a malignant tumor of the gallbladder.Conclusions: FDG-PET may become one of the most useful tools for the accurate preoperative diagnosis of gallbladder carcinoma.

Magnetic resonance imaging and diseases of the liver and biliary tract. Part 2. Magnetic resonance cholangiography and angiography and conclusions

Magnetic resonance cholangiography (MRC) relies on the strong T2 signal from stationary liquids, in this case bile, to generate images. No contrast agents are required, and the failure rate and risk of serious complications is lower than with endoscopic retrograde cholangiopancreatography (ERCP). Data from MRC can be summated to produce an image much like the cholangiogram obtained by using ERCP. In addition, MRC and conventional MRI can provide information about the biliary and other anatomy above and below a biliary obstruction. This provides information for therapeutic intervention that is probably most useful for hilar and intrahepatic biliary obstruction. Magnetic resonance cholangiography appears to be similar to ERCP with respect to sensitivity and specificity in detecting lesions causing biliary obstruction, and in the diagnosis of choledocholithiasis. It is also suited to the assessment of biliary anatomy (including the assessment of surgical bile-duct injuries) and intrahepatic biliary pathology. However, ERCP can be therapeutic as well as diagnostic, and MRC should be limited to situations where intervention is unlikely, where intrahepatic or hilar pathology is suspected, to delineate the biliary anatomy prior to other interventions, or after failed or inadequate ERCP. Magnetic resonance angiography (MRA) relies on the properties of flowing liquids to generate images. It is particularly suited to assessment of the hepatic vasculature and appears as good as conventional angiography. It has been shown to be useful in delineating vascular anatomy prior to liver transplantation or insertion of a transjugular intrahepatic portasystemic shunt. Magnetic resonance angiography may also be useful in predicting subsequent variceal haemorrhage in patients with oesophageal varices.

Accurate and rapid quantitative dynamic contrast-enhanced breast MR imaging using spoiled gradient-recalled echoes and bookend T(1) measurements

A method is presented that converts dynamic T(1)-weighted spoiled gradient-recalled echo (SGRE) image intensities into estimates of T(1) without the errors associated with imperfections in the slice profile and transmitter coil magnetic field (B(1)). The method involves T(1) measurements performed before and after a series of dynamic SGRE images. These measurements serve to calibrate and correct the SGRE signal strength equation used to estimate T(1). Simulations and phantom experiments were performed to test the method for slice-selective (two-dimensional) and slab-selective (three-dimensional) imaging, as well as for imaging performed with optimized and un-optimized B(1). For nearly all test conditions, T(1) was estimated accurately (within 10%) over a range of T(1) values expected in vivo ( approximately 1200 --> 300 msec). This method should be useful for quantifying dynamic SGRE imaging for many different applications including breast MR imaging. Magn Reson Med 42:746-753, 1999.

Differential diagnosis of small polypoid lesions of the gallbladder: the value of endoscopic ultrasonography

OBJECTIVE

To evaluate the accuracy of endoscopic ultrasonography (EUS) in making a differential diagnosis of small (< or =20 mm) polypoid lesions of the gallbladder.

SUMMARY BACKGROUND DATA

Differential diagnosis of these lesions is often difficult using conventional imaging modalities.

METHODS

The findings of EUS and transabdominal ultrasonography were retrospectively analyzed in 65 surgical cases of small polypoid lesions (cholesterol polyp in 40, adenomyomatosis in 9, adenoma in 4, and adenocarcinoma in 12).

RESULTS

Polypoid lesions exceeding 10 mm suggested malignancy. EUS showed a tiny echogenic spot or an aggregation of echogenic spots with or without echopenic areas in 95% of patients with cholesterol polyps. EUS showed multiple microcysts or comet tail artifact in all adenomyomatosis cases. Adenomas and adenocarcinomas were not associated with the echogenic spots, microcysts, or artifacts. Among adenomas and adenocarcinomas, all sessile lesions were adenocarcinomas. EUS differentiated among polypoid lesions more precisely than ultrasonography (97% vs. 71%).

CONCLUSIONS

A tiny echogenic spot or an aggregation of echogenic spots and multiple microcysts or comet tail artifact is pathognomonic for cholesterol polyp and adenomyomatosis, respectively. Polypoid lesions without these findings indicate adenoma or adenocarcinoma on EUS. Routine use of EUS is recommended for differential diagnosis of polypoid gallbladder lesions when ultrasonography shows no signs indicative of either cholesterol polyp or adenomyomatosis.