Comparison between MRI with MR cholangiopancreatography and endoscopic ultrasonography for differentiating malignant from benign mucinous neoplasms of the pancreas

Optimization of Endoscopic Ultrasound Characteristics in the Diagnosis of Malignant Intraductal Papillary Mucinous Neoplasm

OBJECTIVES

Endoscopic ultrasound (EUS) is an excellent diagnostic tool that provides high-resolution images of pancreatic cystic lesions. However, its role in the diagnosis of malignant intraductal papillary mucinous neoplasm (IPMN) remains limited and unclear. We aimed to determine the usefulness of this modality for such diagnosis.

METHODS

Overall, 246 patients who underwent EUS for IPMN after computed tomography (CT)/magnetic resonance imaging (MRI) from April 2018 to June 2021 were followed up until March 2022. We assessed the added value of performing EUS after CT or MRI for diagnosing malignant IPMN, using receiver operating characteristic curve analysis. Walls as thick as 2 mm were considered thickened in this study if they were highly uneven.

RESULTS

EUS clearly enhanced accuracy in identifying enhancing nodules and thickened walls. The areas under the receiver operating characteristic curve and corresponding 95% confidence intervals were 0.655 (0.549-0.760) and 0.566 (0.478-0.654) upon CT/MRI but 0.853 (0.763-0.942) and 0.725 (0.634-0.817) when observed using EUS. The combination of nodule size, thickened wall, and main duct size yielded the highest area under the receiver operating characteristic curve (0.944 [0.915-0.973]).

CONCLUSIONS

EUS more accurately detects malignant IPMN, as uneven wall thickening and certain nodules cannot be identified with CT/MRI.

Association of high-risk stigmata and worrisome features with advanced neoplasia in intraductal papillary mucinous neoplasms (IPMN): A systematic review

BACKGROUND

This systematic review aimed to assess the diagnostic accuracy of the International Consensus Fukuoka Guidelines (ICG2017) in identifying high-risk lesions of Intraductal Papillary Mucinous Neoplasms (IPMNs).

METHODS

The ICG2017 revision committee conducted a comprehensive literature review to establish evidence-based statements on IPMNs. The review focused on articles examining the diagnostic value of imaging features (e.g., cyst or main pancreatic duct diameter), clinical symptoms associated with IPMN, and serum biomarkers. Five clinical questions regarding high-risk stigmata (HRS) and worrisome features (WF) in the ICG2017 guidelines were addressed.

RESULTS

A total of 210 articles were reviewed. The findings revealed a significant association between the presence of mural nodules ≥5 mm in diameter or solid components with contrast enhancement and the diagnosis of high-grade dysplasia or invasive carcinoma. Contrast-enhanced diagnostic tools, such as CT, MRI, or EUS, demonstrated the highest prediction rate and were recommended. Positive cytology was identified as an HRS, while symptoms like acute pancreatitis and cyst diameter growth ≥2.5 mm per year were considered WFs. The use of nomograms and multiple diagnostic factors was recommended for optimal IPMN management.

CONCLUSIONS

This systematic review provides evidence supporting the improved diagnostic accuracy of ICG2017 in identifying high-risk lesions of IPMN. The multidisciplinary incorporation of HRS and WF based on imaging findings and clinical symptoms is crucial. These findings should inform the revision of ICG2017, enhancing the evaluation and management of IPMN patients. By implementing these recommendations, clinicians can make more informed decisions, leading to better diagnosis and treatment outcomes for high-risk IPMN cases.

Computed high-b-value high-resolution DWI improves solid lesion detection in IPMN of the pancreas

OBJECTIVES

To examine the effect of high-b-value computed diffusion-weighted imaging (cDWI) on solid lesion detection and classification in pancreatic intraductal papillary mucinous neoplasm (IPMN), using endoscopic ultrasound (EUS) and histopathology as a standard of reference.

METHODS

Eighty-two patients with known or suspected IPMN were retrospectively enrolled. Computed high-b-value images at b = 1000 s/mm2 were calculated from standard (b = 0, 50, 300, and 600 s/mm2) DWI images for conventional full field-of-view (fFOV, 3 × 3 × 4 mm3 voxel size) DWI. A subset of 39 patients received additional high-resolution reduced-field-of-view (rFOV, 2.5 × 2.5 × 3 mm3 voxel size) DWI. In this cohort, rFOV cDWI was compared against fFOV cDWI additionally. Two experienced radiologists evaluated (Likert scale 1-4) image quality (overall image quality, lesion detection and delineation, fluid suppression within the lesion). In addition, quantitative image parameters (apparent signal-to-noise ratio (aSNR), apparent contrast-to-noise ratio (aCNR), contrast ratio (CR)) were assessed. Diagnostic confidence regarding the presence/absence of diffusion-restricted solid nodules was assessed in an additional reader study.

RESULTS

High-b-value cDWI at b = 1000 s/mm2 outperformed acquired DWI at b = 600 s/mm2 regarding lesion detection, fluid suppression, aCNR, CR, and lesion classification (p =  < .001-.002). Comparing cDWI from fFOV and rFOV revealed higher image quality in high-resolution rFOV-DWI compared to conventional fFOV-DWI (p ≤ .001-.018). High-b-value cDWI images were rated non-inferior to directly acquired high-b-value DWI images (p = .095-.655).

CONCLUSIONS

High-b-value cDWI may improve the detection and classification of solid lesions in IPMN. Combining high-resolution imaging and high-b-value cDWI may further increase diagnostic precision.

CLINICAL RELEVANCE STATEMENT

This study shows the potential of computed high-resolution high-sensitivity diffusion-weighted magnetic resonance imaging for solid lesion detection in pancreatic intraductal papillary mucinous neoplasia (IPMN). The technique may enable early cancer detection in patients under surveillance.

KEY POINTS

• Computed high-b-value diffusion-weighted imaging (cDWI) may improve the detection and classification of intraductal papillary mucinous neoplasms (IPMN) of the pancreas. • cDWI calculated from high-resolution imaging increases diagnostic precision compared to cDWI calculated from conventional-resolution imaging. • cDWI has the potential to strengthen the role of MRI for screening and surveillance of IPMN, particularly in view of the rising incidence of IPMNs combined with now more conservative therapeutic approaches.

Malignancy risk factors and prognostic variables of pancreatic mucinous cystic neoplasms in Chinese patients

BACKGROUND

Pancreatic mucinous cystic neoplasms (MCNs) represent one of the precursor lesions of pancreatic ductal adenocarcinoma, and their detection has been facilitated by advances in preoperative imaging. Due primarily to the rarity of MCNs, however, there is limited knowledge regarding the prognostic variables and high-risk factors for malignant transformation. A more comprehensive and nuanced approach is necessary to fill this gap and provide a basis for improved treatment decisions and patient outcomes.

AIM

To investigate the high-risk factors associated with malignant MCNs and to explore the prognostic factors of MCN with associated invasive carcinoma (MCN-AIC).

METHODS

All cases of resected MCNs from a single high-volume institution between January 2012 and January 2022 were retrospectively reviewed. Only cases with ovarian-type stroma verified by progesterone receptor staining were included. Preoperative features, histological findings and postoperative course were documented. Multivariate logistic regression was employed to investigate variables related to malignancy. Survival analysis was performed using the Kaplan-Meier curve, and the prognostic factors were assessed to evaluate the postoperative course of patients with MCN-AIC.

RESULTS

Among the 48 patients, 36 had benign MCNs, and 12 had malignant MCNs (1 high-grade atypical hyperplasia and 11 MCN-AIC). Age, tumour size, presence of solid components or mural nodules and pancreatic duct dilatation were identified as independent risk factors associated with malignancy. The follow-up period ranged from 12 mo to 120 mo, with a median overall survival of 58.2 mo. Only three patients with MCN-AIC died, and the 5-year survival rate was 70.1%. All 11 cases of MCN-AIC were stage I, and extracapsular invasion was identified as a prognostic factor for poorer outcomes.

CONCLUSION

The risk factors independently associated with malignant transformation of MCNs included age, tumour size, presence of solid components or mural nodules, and pancreatic duct dilatation. Our study also revealed that encapsulated invasion was a favourable prognostic factor in MCN-AIC patients.

CYSTIC PANCREATIC LESIONS: IMAGING VERSUS ANATOMOPATHOLOGICAL FINDINGS-HOW TO IMPROVE DIAGNOSTIC ACCURACY?

BACKGROUND

Pancreatic cystic lesions are a group of pancreatic neoplasms with different behavior and risk of malignancy. Imaging diagnosis and differentiation of these lesions remain a challenge.

AIMS

The aim of this study was to evaluate the agreement between computed tomography and/or magnetic resonance imaging and post-operative pathologic diagnoses of Pancreatic cystic lesions in a University Hospital of São Paulo State.

METHODS

A total of 39 patients with surgically diagnosed Pancreatic cystic lesions were enrolled, as a study cohort from 2009 to 2019. Preoperative radiological and final pathological diagnosis was correlated to measure computed tomography and/or magnetic resonance imaging diagnostic. Pancreatic adenocarcinoma, choledochal pancreatic cyst, mucinous cystadenoma, serous cystadenoma, intraductal papillary mucinous neoplasms, and pancreatic pseudocyst were classified as neoplastic cysts.

RESULTS

It was noted that 27 patients (69.23%) had preoperative computed tomography and magnetic resonance imaging, 11 patients (28.20%) had preoperative computed tomography only, and 1 patient had preoperative magnetic resonance imaging only. The values for diagnoses made only with computed tomography (p=0.47) and from the combination of computed tomography+magnetic resonance imaging (p=0.50) did also point to moderate agreement with the anatomopathological findings. The values pointed to a fair agreement for the diagnosis of mucinous cystadenoma (p=0.3), moderate agreement for intraductal papillary mucinous neoplasms (p= 0.41), good agreement for serous cystadenoma (p=0.79), and excellent agreement for choledochal pancreatic cyst (p=1), pancreatic pseudocyst (p=0.84), and Frantz tumor (p=1) (p<0.05).

CONCLUSIONS

The findings of computed tomography and/or magnetic resonance imaging have an equivalent diagnostic agreement with an anatomopathological diagnosis for differentiating benign from malignant Pancreatic cystic lesions and in suggesting a specific diagnosis. There is no statistical difference between the use of computed tomography alone and computed tomography+magnetic resonance imaging in the improvement of diagnostic accuracy.

Diagnostic value of EUS-guided SF6 pancreatography for pancreatic cystic lesions on cyst communication with the pancreatic duct

Background and Objectives

ERCP remains the reliable method to determine whether pancreatic cystic lesions (PCLs) and pancreatic duct communicate when other modalities (computed tomography, magnetic resonance imaging, and EUS) fail. However, complications after ERCP are still a risk that should not be ignored. In this study, we evaluated the value of EUS-guided SF6 pancreatography (ESP) for the diagnosis of PCLs focusing on pancreatic cyst communication with the pancreatic duct.

Patients and Methods

We reviewed the database of medical records to retrieve the clinicopathological data of the patients with PCLs who had undergone ESP, and analyzed the diagnostic value of ESP to determine communication between the cyst and the pancreatic duct. The inclusion criteria were as follows: (1) PCLs were pathologically diagnosed by postsurgery specimen or through-the-needle biopsy and (2) ESP was performed to determine communication between the pancreatic cyst and the pancreatic duct.

Results

Pathological diagnosis confirmed communication with the pancreatic duct in all eight patients with positive pancreatography, among whom seven were branch-duct-intraductal papillary mucinous neoplasm (BD-IPMN) and one was the main duct-IPMN. Pathological diagnosis confirmed noncommunication with the pancreatic duct in 20 of the 21 patients with negative pancreatography, among whom 11 were mucinous cystic neoplasm, 7 were serous cystic neoplasm, 1 was solid pseudopapillary neoplasm, 1 was pancreatic pseudocyst, and 1 was BD-IPMN. The accuracy, sensitivity, specificity, positive predictive value, and negative predictive value of ESP to determine communication between the pancreatic cyst and the pancreatic duct were 96.6% (28/29), 88.9% (8/9), 100% (20/20), 100% (8/8), and 95.2% (20/21), respectively.

Conclusions

ESP achieved high accuracy to determine communication between the pancreatic cyst and the pancreatic duct.

Clinical and Molecular Attributes and Evaluation of Pancreatic Cystic Neoplasm

Intraductal papillary mucinous neoplasms (IPMNs) and mucinous cystic neoplasms (MCNs) are all considered "Pancreatic cystic neoplasms (PCNs)" and show a varying risk of developing into pancreatic ductal adenocarcinoma (PDAC). These lesions display different molecular characteristics, mutations, and clinical manifestations. A lack of detailed understanding of PCN subtype characteristics and their molecular mechanisms limits the development of efficient diagnostic tools and therapeutic strategies for these lesions. Proper in vivo mouse models that mimic human PCNs are also needed to study the molecular mechanisms and for therapeutic testing. A comprehensive understanding of the current status of PCN biology, mechanisms, current diagnostic methods, and therapies will help in the early detection and proper management of patients with these lesions and PDAC. This review aims to describe all these aspects of PCNs, specifically IPMNs, by describing the future perspectives.

Comparison of Preoperative Imaging Modalities for the Assessment of Malignant Potential of Pancreatic Cystic Lesions: A Network Meta-analysis

PURPOSE

The aims of this study are to compare the performance of various preoperative imaging modalities for assessing the malignant potential of pancreatic cystic lesions (PCLs) through a network meta-analysis (NMA) and to clarify the role of 18 F-FDG PET in the management of patients with PCL.

METHODS

PubMed, EMBASE, and Cochrane Library were searched for the studies evaluating the performance of preoperative imaging modalities for identifying malignant PCLs. The NMA was performed for 4 representative categories of various imaging modalities in terms of diagnostic performance for differentiating malignant from benign PCL and intraductal papillary mucinous neoplasms only as a subgroup analysis. To calculate the probability of each imaging modality being the most effective diagnostic method, the surface under the cumulative ranking curve values were obtained.

RESULTS

A total of 1018 patients from 17 direct comparison studies using 2 or more preoperative imaging modalities were included for differentiating malignant from benign PCL. The positive predictive value (PPV) and accuracy of 18 F-FDG PET were significantly higher than that of CT (PPV: odds ratio [OR], 2.66; 95% credible interval [CrI], 1.21-6.17; accuracy: OR, 2.63; 95% CrI, 1.41-5.38) or MRI (PPV: OR, 2.50; 95% CrI, 1.09-6.26; accuracy: OR, 2.50; 95% CrI, 1.28-5.47) in all PCLs, as well as in the subgroup analysis for intraductal papillary mucinous neoplasm only. 18 F-FDG PET showed the highest surface under the cumulative ranking curve values in all diagnostic performance areas of sensitivity, specificity, PPV, negative predictive value, and accuracy, followed by MRI or CT.

CONCLUSIONS

The results from this NMA suggest that 18 F-FDG PET is the best preoperative imaging modality for differentiating malignant from benign PCLs and that it can be used for the preoperative evaluation of PCLs.

Narrative review of intraductal papillary mucinous neoplasms: pathogenesis, diagnosis, and treatment of a true precancerous lesion

OBJECTIVE

Although considerable progress has been made in our understanding of intraductal papillary mucinous neoplasm (IPMN) of the pancreas, there are still some problems to be solved.

BACKGROUND

IPMN is one of the most important precancerous lesions of pancreatic cancer, but the relationship between IPMN and pancreatic cancer, and the specific mechanism of the development from IPMN to invasive carcinoma, remain to be explored in depth. With the development of imaging, the detection rate of IPMN has been greatly improved. However, the degree of malignancy of IPMN is difficult to assess, and its classification criteria and surgical treatment strategies are still controversial. Therefore, there is an urgent need for the best treatment plan for IPMN and research that can better predict IPMN recurrence and tumor malignancy.

METHODS

From the online database Web of Science (https://webofknowledge.com/) and PubMed (https://pubmed.ncbi.nlm.nih.gov/), we use specific retrieval strategies to retrieve relevant articles based on the topics we discussed, and we review and discuss them.

CONCLUSIONS

This paper discusses the related research and progress of IPMN in recent years to improve the understanding of the incidence, diagnosis, treatment, and prognosis of this disease. The follow-up and monitoring of IPMN is particularly important, but the specific strategy also remains controversial.

Diagnostic Accuracy of MRI for Differentiation of Benign and Malignant Pancreatic Cystic Lesions Compared to CT and Endoscopic Ultrasound: Systematic Review and Meta-analysis

BACKGROUND

Differentiation of benign and malignant pancreatic cystic lesions on MRI, computed tomography (CT), and endoscopic ultrasound (EUS) is critical for determining management.

PURPOSE

To perform a systematic review evaluating the diagnostic accuracy of MRI for diagnosing malignant pancreatic cystic lesions, and to compare the accuracy of MRI to CT and EUS.

STUDY TYPE

Systematic review and meta-analysis.

DATA SOURCES

MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials, Web of Science, and Scopus were searched until February 2020 for studies reporting MRI accuracy for assessing pancreatic cystic lesions.

FIELD STRENGTH

1.5T or 3.0T.

ASSESSMENT

Methodologic and outcome data were extracted by two reviewers (AU and MA, 2 years of experience each). All studies of pancreatic cystic lesions on MRI were identified. Studies with incomplete MRI technique were excluded. Risk of bias was assessed using the Quality Assessment of Diagnostic Accuracy Studies (QUADAS)-2 tool.

STATISTICAL TESTS

Sensitivity/specificity was pooled using bivariate random-effects meta-analysis with 95% confidence intervals (95%CI). Pairwise-comparison of MRI to CT and EUS was performed. The impact of gadolinium-based contrast agents, mucinous lesions, and risk of bias were explored using meta-regression.

RESULTS

MRI pooled sensitivity was 76% (95%CI 67% to 84%) and specificity was 80% (95%CI 74% to 85%) for distinguishing benign and malignant lesions. MRI and CT had similar sensitivity (P = 0.822) and specificity (P = 0.096), but MRI was more specific than EUS (80% vs. 75%, P < 0.05). Studies including only contrast-enhanced MRI were more sensitive than those including unenhanced exams (P < 0.05). MRI sensitivity and specificity did not differ for mucinous lesions (P = 0.537 and P = 0.384, respectively) or for studies at risk of bias (P = 0.789 and P = 0.791, respectively).

DATA CONCLUSION

MRI and CT demonstrate comparable accuracy for diagnosing malignant pancreatic cystic lesions. EUS is less specific than MRI, which suggests that, in some cases, management should be guided by MRI findings rather than EUS.

LEVEL OF EVIDENCE

3 TECHNICAL EFFICACY STAGE: 2.

Intraductal papillary mucinous neoplasm of the pancreas: diagnostic performance of the 2017 international consensus guidelines using CT and MRI

OBJECTIVES

To assess the diagnostic performance of the 2017 international consensus guidelines for intraductal papillary mucinous neoplasm (IPMN) of the pancreas and to compare the diagnostic performance and intermodality agreement between contrast-enhanced CT and MRI.

METHODS

We retrospectively evaluated patients with surgical resection of IPMN of the pancreas who underwent preoperative CT and MRI between 2009 and 2019. Two radiologists evaluated the clinical and imaging features of IPMN of pancreas according to the 2017 international consensus guideline. Univariable and multivariable analyses were performed to identify significant predictors of malignancy in IPMN. The diagnostic abilities of CT and MRI were compared, and their intermodality agreement was determined.

RESULTS

Of 175 patients (mean age, 64 years; 116 males), 88 (50.3%) had malignant IPMN. On multivariable analysis, all three high-risk stigmata (main pancreatic duct [MPD] ≥ 10 mm, mural nodule ≥ 5 mm, and obstructive jaundice) and two worrisome features (MPD 5-9 mm and elevated carbohydrate antigen 19-9) were associated with malignant IPMN on CT and MRI (p < 0.05). A mural nodule < 5 mm on MRI was also associated with malignant IPMN (OR 5.3, p = 0.009). The diagnostic accuracy of high-risk stigmata showed no difference between CT and MRI (73.7% vs. 75.4%, p = 0.505), with good to excellent intermodality agreement.

CONCLUSIONS

Current high-risk stigmata had the strongest association with malignant IPMN on CT and MRI. Although MRI is superior to CT for identifying mural nodules, diagnostic performance for differentiating malignant from benign IPMNs was similar between CT and MRI.

KEY POINTS

• The current high-risk stigmata in the 2017 International Consensus Guidelines had the strongest association with malignant IPMN on CT and MRI. • MRI is better than CT for identifying enhancing mural nodule. • Diagnostic performance for differentiating malignant from benign IPMNs was similar between CT and MRI.

Magnetic resonance (MR) for mural nodule detection studying Intraductal papillary mucinous neoplasms (IPMN) of pancreas: Imaging-pathologic correlation

PURPOSE

Magnetic Resonance (MR) is recommended to diagnose Intraductal Papillary Mucinous Neoplasms (IPMN) and in the follow-up of borderline lesions. The purpose of this work is to evaluate the diagnostic accuracy of dynamic MR with Diffusion Weighted Imaging (DWI) in the identification of mural nodules of pancreatic IPMN by using pathological analysis as gold standard.

MATERIALS AND METHODS

Ninety-one preoperative MR with histopathological diagnosis of IPMN were reviewed by two radiologists. Presence, number and size of mural nodule, signal intensity of the nodule on T1-weighted imaging (T1-WI) after contrast medium administration and on DWI. Inter-observer agreement was evaluated.

RESULTS

Significant correlation (p < 0.0001) were found for presence of nodules > 5 mm on MR and pathological specimen, size and number of mural nodules evaluated on pathological review and degree of dysplasia, size and number of mural nodules evaluated on MR and tumoral dysplasia, presence of nodule > 5 mm with enhancement after contrast medium administration and hyperintensity on DWI and degree of dysplasia. Interobserver agreement was moderate for the presence of mural nodule (K = 0.56), for the presence of high signal intensity on DWI (K = 0.57) and enhancement of mural nodule (K = 0.58). Apparent Diffusion Coefficient (ADC) map histogram analysis showed a correlation between Entropy of the entire cystic lesion and the degree of dysplasia (p < 0.034).

CONCLUSIONS

MR with dynamic and DWI sequences was an accurate method for the identification of ≥ 5 mm solid nodules of the IPMNs and correlate with the lesion malignancy. Entropy, calculated from the histogram analysis of the IPMN ADC map, correlated with the lesion dysplasia.

A new needle-based confocal laser endomicroscopy pattern of malignant pancreatic mucinous cystic lesions (with video)

Background and Objectives:

The diagnosis of malignant pancreatic cystic lesions (PCLs) remains challenging. Needle-based confocal laser endomicroscopy (nCLE) is an emerging promising imaging technique capable of real-time in vivo microscopic imaging of the cyst wall. We aimed to develop and validate a new nCLE diagnostic criteria for malignant mucinous cystic lesions (MLs).

Methods:

Patients referred for EUS-FNA of indeterminate PCLs with at least one worrisome features according to Fukouka consensus were consecutively prospectively enrolled from July 2016 to July 2018. The final diagnosis was based on surgical histology, cytopathology, or committee consensus. Five investigators nonblindly reviewed nCLE features and identified potential diagnostic feature for malignant MLs, which was also reviewed in histology imaging accordingly. Furthermore, the nCLE diagnostic feature was evaluated with an independent nCLE dataset by two investigators in a double-blind manner.

Results:

A nCLE pattern of dark aggregates of neoplastic cells was identified as diagnostic for MLs, which was consistent with histological findings of irregular branching and budding in malignant MLs. An independent validation revealed that the accuracy, sensitivity, and specificity of this feature for the diagnosis of malignant MLs were 94%, 75%, and 100%, respectively.

Conclusion:

The new nCLE criterion is promising for diagnosis of malignant MLs which warrants further confirmation in large cohort.

Prognosis of resected intraductal papillary mucinous neoplasm of the pancreas: using revised 2017 international consensus guidelines

PURPOSE

Although there has been considerable effort to define pre-operative features to predict the malignant potential of intraductal papillary mucinous neoplasms (IPMNs), the prognostic value of pre-operative clinical and MRI features has not been assessed. The aim of this study was to determine pre-operative clinical and MRI features that are predictive of disease-specific death or recurrence in patients undergoing pancreatic resection for IPMNs.

METHODS

We performed a retrospective analysis of 167 patients (mean age, 65 years; 114 men and 53 women) who underwent pre-operative MRI and surgical resection of IPMN of pancreas between 2009 and 2019. We evaluated disease-specific survival (DSS) and recurrence-free survival (RFS). Prognostic factor analysis was performed using clinical and MRI features according to the 2017 international consensus guidelines.

RESULTS

Of 167 patients, 86 (51.5%) had benign IPMNs and 81 (48.5%) had malignant IPMNs (48 [28.7%] invasive carcinoma and 33 [19.8%] high grade). On multivariable analysis, mural nodule size (hazard ratio [HR], 1.11; 95% confidence interval [CI], 1.04-1.18 and HR 1.07; 95% CI 1.03-1.12) and obstructive jaundice (HR 5.01; 95% CI 1.44-17.46 and HR 5.60; 95% CI 2.42-12.99) were the significant variables that were associated with DSS and RFS. The presence of lymphadenopathy (HR 50.7; 95% CI 4.0-643.0; P = 0.002) was the significant factor for DSS. IPMNs with mural nodule showed a significantly lower 5-year DSS (83.7% vs. 100%, P value < 0.01) and RFS (73.1% vs. 95.0%, P value < 0.01) compared with IPMNs with no mural nodule.

CONCLUSIONS

Mural nodule size on MRI and obstructive jaundice were prognostic markers in the pre-operative evaluation of patients with IPMN of pancreas.

Magnetic resonance morphologic features predict progression of incidental pancreatic cystic lesions during follow-up

PURPOSE

We aimed to evaluate which morphologic features on magnetic resonance imaging (MRI) could predict the progression of pancreatic cystic lesions (PCLs) that are suitable for follow-up.

METHODS

A total of 2176 MRI findings of PCLs were retrospectively reviewed between January 2009 and December 2016. The study population was composed of 223 patients. Clinical data and morphologic features of PCLs were recorded. We divided the individuals into two sub-groups according to the final features on MRI. Univariable and multivariable regression analyses were performed to identify independent risk factors for progression of PCLs.

RESULTS

A total of 84 PCLs (37.7%) progressed during follow-up, while 139 PCLs (62.3%) were stable. Age (odds ratio [OR], 1.042; P = 0.017), number of lesions (OR, 0.491; P = 0.048), communication to pancreatic duct (PD) (OR, 2.425; P = 0.007) and presence of septa (OR, 6.105; P < 0.001) were significant independent factors for progression of PCLs. Among 84 lesions that progressed, 23 lesions (27.4%) increased to ≥ 30 mm in diameter or showed worrisome imaging features at the end of follow-up that needed clinical intervention. The initial size and communication to PD were independent factors for progression of PCLs necessitating clinical intervention (P < 0.001 and P = 0.011, respectively).

CONCLUSION

Age, number of the lesions, communication to PD and presence of septa were independent risk factors for the progression of PCLs, and the initial size and communication to PD could potentially predict PCLs needing clinical interventions.

MRI of the Pancreas

MRI has played a critical role in the evaluation of patients with pancreatic pathologies, from screening of patients at high risk for pancreatic cancer to the evaluation of pancreatic cysts and indeterminate pancreatic lesions. The high mortality associated with pancreatic adenocarcinomas has spurred much interest in developing effective screening tools, with MRI using magnetic resonance cholangiopancreatography (MRCP) playing a central role in the hopes of identifying cancers at earlier stages amenable to curative resection. Ongoing efforts to improve the resolution and robustness of imaging of the pancreas using MRI may thus one day reduce the mortality of this deadly disease. However, the increasing use of cross-sectional imaging has also generated a concomitant clinical conundrum: How to manage incidental pancreatic cystic lesions that are found in over a quarter of patients who undergo MRCP. Efforts to improve the specificity of MRCP for patients with pancreatic cysts and with indeterminate pancreatic masses may be achieved with continued technical advances in MRI, including diffusion-weighted and T₁ -weighted dynamic contrast-enhanced MRI. However, developments in quantitative MRI of the pancreas remain challenging, due to the small size of the pancreas and its upper abdominal location, adjacent to bowel and below the diaphragm. Further research is needed to improve MRI of the pancreas as a clinical tool, to positively affect the lives of patients with pancreatic abnormalities. This review focuses on various MR techniques such as MRCP, quantitative imaging, and dynamic contrast-enhanced imaging and their clinical applicability in the imaging of the pancreas, with an emphasis on pancreatic malignant and premalignant lesions. Level of Evidence 5 Technical Efficacy Stage 3 J. MAGN. RESON. IMAGING 2021;53:347-359.

Pancreatic mucinous cystic neoplasms: a clinicopathological study of 11 cases and detailed review of literature

Background

Mucinous cystic neoplasms (MCNs) of pancreas are relatively rare, occur almost exclusively in middle-aged females, and are overwhelmingly located in the body and tail of the pancreas, histologically show an ovarian type stroma. MCNs are premalignant, low aggressive tumors. Here we describe the clinicopathologic and radiologic features and follow up of cases diagnosed in our practice. We also present a detailed review of recent literature.

Materials and methods

Based on strict criteria, 11 cases diagnosed between 2002 and 2016 were included in the study.

Results

All cases were reviewed histologically. Mean and median age was 46.7 and 46 years respectively. All patients were females and 9 out of 11 cases were located in the body and/or tail of the pancreas. Mean tumor size was 8 cm. Grossly, cysts were uni or multilocular and ranged from a few millimeters to several centimeters in diameter. Microscopically, all cases showed characteristic tall columnar, mucin producing epithelium and ovarian type stroma. Atypia was mild in 8 cases and severe in 3 cases. The latter 3 cases were classified as non-invasive MCNs with high grade dysplasia (2 cases) and MCN with an associated invasive carcinoma (1 case). On immunohistochemistry, all cases showed epithelial positivity for cytokeratin AE1/AE3 and stromal positivity for vimentin and smooth muscle actin. Follow up was available in 7 cases. All patients were alive and well with no recurrence.

Conclusions

Our cases show features similar to those described in other published studies although cases in our series tended to be larger in number. Since these tumors are relatively rare, premalignant and have strict diagnostic criteria, they must always be considered in the differential diagnosis of pancreatic mucinous cystic lesions. Larger studies incorporating greater number of patients and more detailed follow up will help in increasing our understanding of MCNs.

Usefulness of noncontrast MRI in differentiation between gallbladder carcinoma and benign conditions manifesting as focal mild wall thickening

BACKGROUND

Magnetic resonance imaging (MRI) is a reliable imaging tool for evaluating gallbladder carcinoma, but it is costly and time-consuming.

PURPOSE

To compare noncontrast MRI with multidetector row CT (MDCT) and gadoxetic acid-enhanced whole MRI in distinguishing gallbladder carcinoma from benign disease.

MATERIALS AND METHODS

101 patients (36 with gallbladder carcinoma and 65 with benign disease) with mild focal gallbladder wall thickening were included. Two radiologists reviewed the MDCT and MRI to determine the differential features between malignancy and benignity. Then, the diagnostic performance of MDCT and MRI (T1-, T2- and diffusion-weighted images) with and without gadoxetic acid enhancement in the diagnosis of gallbladder carcinoma was evaluated.

RESULTS

The benign group more often showed T2 necklace sign or T2 hyperintensity within the thickened wall (P < 0.0001) and T1 hyperintensity within the wall or gallbladder lumen (P = 0.0002). Meanwhile, malignancy more frequently showed T2 moderate hyperintensity of the thickened wall, papillary appearance, and diffusion restriction (all P < 0.0001). There were significant differences in sensitivity (79.2% vs 98.6% for observer 1; 84.7% vs 100% for observer 2) and specificity (80.7% vs 96.9%; 79.2% vs 95.4%) between the MDCT and noncontrast MRI (P < 0.05). We found similar diagnostic values between the noncontrast MRI and whole MRI (P = 0.479-1.000) for both observers.

CONCLUSION

Noncontrast MRI could be a useful alternative to gadoxetic acid-enhanced MRI in the diagnosis of gallbladder carcinoma that presents as mild gallbladder wall thickening on MDCT.

Role of Radiological Imaging in the Diagnosis and Characterization of Pancreatic Cystic Lesions: A Systematic Review

The evidence on the ability of radiological tests to predict a specific diagnosis and also their aptitude in identifying pathological markers indicative of malignancy in cystic lesions of the pancreas remains inconclusive. We conducted a systematic review on MEDLINE for the use of computed tomography (CT), magnetic resonance imaging, and positron emission tomography/CT (PET/CT) in the diagnosis and characterization of these cysts. The accuracy of CT scan for reaching a specific diagnosis was 39% to 61.4%, whereas its accuracy for differentiating benign from malignant lesions was 61.9% to 80%. Magnetic resonance imaging showed a better accuracy in identifying a specific diagnosis of 50% to 86%, whereas its accuracy in differentiating benign from malignant lesions was 55.6% to 87%. The use of magnetic resonance imaging was superior to CT scan in identifying septations, mural nodules, and ductal communication. The sensitivity of PET/CT in diagnosing malignancy was 85.7% to 100% with a reported accuracy of 88% to 95%. The evidence gathered from this review suggests that the adequacy of CT imaging in full characterization of pancreatic cysts is suboptimal, and therefore a low threshold for supplementary imaging is advised. The use of PET/CT should be considered in high-risk patients with equivocal findings.

Patients with pancreatic cystic neoplasms can benefit from management of multidisciplinary team: Experience from a Chinese academic center

BACKGROUND

Pancreatic cystic neoplasms (PCNs) are a spectrum of neoplasms that can be benign or malignant. The accuracy of diagnosis is critical for this disease since different types of PCNs are treated differently using various modalities. The use of a multidisciplinary team (MDT) has been shown to improve the management and outcomes of various diseases. We aimed to determine the performance of MDT in the management of PCNs.

METHODS

We retrospectively reviewed 167 pathologically-proven PCN patients and divided them among three groups according to their surgical data and treatment modalities: 1) historical control group (HC group); 2) concurrent control group (CC group); and 3) MDT group. The composition of subtypes of PCNs, preoperative diagnostic accuracy, postoperative complications, and postoperative hospital stay were compared among the three groups.

RESULTS

The incidence of SCN reduced in the MDT group, while the incidence of IPMN was much higher (P < 0.05). MDT management significantly improved the accuracy of preoperative diagnosis (71.7%) and also increased the individual diagnostic accuracies of ultrasound, CT, and MRI/MRCP. Postoperative pancreatic fistula was significantly reduced in the MDT group (28.3%; P < 0.001). Furthermore, the mean hospital stay after surgery in the MDT group (10.37 days) was shorter than those of the other two groups (27.35 days in HC group, and 19.28 days in CC group; P < 0.05).

CONCLUSION

For patients with PCN, MDT management was associated with an improvement in the overall accuracy of preoperative diagnosis, a lower incidence postoperative morbidity, and decreased length of hospital stay.

Management Algorithm for Cystic Pancreatic Lesions

Cystic pancreatic lesions are common findings in an aging society due to an increasing availability of high-resolution cross-sectional imaging. Although the overall prevalence of malignancy and the rate of malignant conversion are low, especially mucinous pancreatic cystic lesions such as intraductal papillary mucinous neoplasm and mucinous cystic neoplasm harbor significant malignant potential depending on their morphology and size. Recently updated guidelines recommend sophisticated algorithms for initial workup and surveillance based on individual characteristics of the cystic lesion and the patient, thus weighing the lifetime risk for malignancy against the adverse event rate of potentially curative surgery in the light of number and location of cystic lesions, age of the patient, comorbidities, and the resulting life expectancy as well as the effect of repeated follow-up examinations on the patient's quality of life. This article summarizes recommendations from available guidelines and proposes a pragmatic approach to the clinical management of pancreatic cystic lesions.

European evidence-based guidelines on pancreatic cystic neoplasms

Evidence-based guidelines on the management of pancreatic cystic neoplasms (PCN) are lacking. This guideline is a joint initiative of the European Study Group on Cystic Tumours of the Pancreas, United European Gastroenterology, European Pancreatic Club, European-African Hepato-Pancreato-Biliary Association, European Digestive Surgery, and the European Society of Gastrointestinal Endoscopy. It replaces the 2013 European consensus statement guidelines on PCN. European and non-European experts performed systematic reviews and used GRADE methodology to answer relevant clinical questions on nine topics (biomarkers, radiology, endoscopy, intraductal papillary mucinous neoplasm (IPMN), mucinous cystic neoplasm (MCN), serous cystic neoplasm, rare cysts, (neo)adjuvant treatment, and pathology). Recommendations include conservative management, relative and absolute indications for surgery. A conservative approach is recommended for asymptomatic MCN and IPMN measuring <40 mm without an enhancing nodule. Relative indications for surgery in IPMN include a main pancreatic duct (MPD) diameter between 5 and 9.9 mm or a cyst diameter ≥40 mm. Absolute indications for surgery in IPMN, due to the high-risk of malignant transformation, include jaundice, an enhancing mural nodule >5 mm, and MPD diameter >10 mm. Lifelong follow-up of IPMN is recommended in patients who are fit for surgery. The European evidence-based guidelines on PCN aim to improve the diagnosis and management of PCN.

Agreement among Magnetic Resonance Imaging/Magnetic Resonance Cholangiopancreatography (MRI-MRCP) and Endoscopic Ultrasound (EUS) in the evaluation of morphological features of Branch Duct Intraductal Papillary Mucinous Neoplasm (BD-IPMN)

BACKGROUND/OBJECTIVES

To evaluate the agreement between the imaging modalities MRI-MRCP and EUS in cystic lesions of the pancreas which were thought to be a BD-IPMN.

METHODS

Multicenter retrospective study included all patients between 2010 and 2015 with a suspected BD-IPMN who underwent an EUS and MRI-MRCP within 6 months or less of each other. Location, number, size, worrisome features and high-risk stigmata were evaluated. Interobserver agreement was evaluated by Kappa score.

RESULTS

173 patients were included (97 UHSC, 76 UCLH-RFH), mean age 65 (range 25-87 years), 66 males. When comparing both modalities there was good agreement for the location of the cyst. The median lesion size was larger by MRI-MRCP than EUS although it was not significant. With regards to worrisome features, there was moderate agreement for main PD of 5-9 mm and abrupt change (k = 0.45 and 0.52). Fair agreement was seen for the cyst wall thickening (k = 0.25). No agreement was seen between the presence of non-enhanced mural nodules or lymphadenopathy (k < 0). With regards to high-risk stigmata, poor agreement was obtained for the detection of an enhanced solid component (k = 0.12). No agreement was observed for main PD > 10 mm (k < 0).

CONCLUSIONS

In this multicentre study of patients with a BD-IPMN under active surveillance, most disagreement between these modalities was seen in the proximal pancreas. There was generally only minimal concordance between the imaging findings of EUS and MRI-MRCP for the detection of high-risk stigmata and worrisome features.

Viscoelastic properties of human pancreatic tumors and in vitro constructs to mimic mechanical properties

Pancreatic ductal adenocarcinoma (PDAC) is almost universally fatal, in large part due to a protective fibrotic barrier generated by tumor-associated stromal (TAS) cells. This barrier is thought to promote cancer cell survival and confounds attempts to develop effective therapies. We present a 3D in vitro system that replicates the mechanical properties of the PDAC microenvironment, representing an invaluable tool for understanding the biology of the disease. Mesoscale indentation quantified viscoelastic metrics of resected malignant tumors, inflamed chronic pancreatitis regions, and histologically normal tissue. Both pancreatitis (2.15 ± 0.41 kPa, Mean ± SD) and tumors (5.46 ± 3.18 kPa) exhibit higher Steady-State Modulus (SSM) than normal tissue (1.06 ± 0.25 kPa; p < .005). The average viscosity of pancreatitis samples (63.2 ± 26.7 kPa·s) is significantly lower than that of both normal tissue (252 ± 134 kPa·s) and tumors (349 ± 222 kPa·s; p < .005). To mimic this remodeling behavior, PDAC and TAS cells were isolated from human PDAC tumors. Conditioned medium from PDAC cells was used to culture TAS-embedded collagen hydrogels. After 7 days, TAS-embedded gels in control medium reached SSM (1.45 ± 0.12 kPa) near normal pancreas, while gels maintained with conditioned medium achieved higher SSM (3.38 ± 0.146 kPa) consistent with tumors. Taken together, we have demonstrated an in vitro system that recapitulates in vivo stiffening of PDAC tumors. In addition, our quantification of viscoelastic properties suggests that elastography algorithms incorporating viscosity may be able to more accurately distinguish between pancreatic cancer and pancreatitis.

STATEMENT OF SIGNIFICANCE

Understanding tumor-stroma crosstalk in pancreatic ductal adenocarcinoma (PDAC) is challenged by a lack of stroma-mimicking model systems. To design appropriate models, pancreatic tissue must be characterized with a method capable of evaluating in vitro models as well. Our indentation-based characterization tool quantified the distinct viscoelastic signatures of inflamed resections from pancreatitis, tumors from PDAC, and otherwise normal tissue to inform development of mechanically appropriate engineered tissues and scaffolds. We also made progress toward a 3D in vitro system that recapitulates mechanical properties of tumors. Our in vitro model of stromal cells in collagen and complementary characterization system can be used to investigate mechanisms of cancer-stroma crosstalk in PDAC and to propose and test innovative therapies.