Measurement of pancreatic cystic lesions on magnetic resonance imaging: efficacy of standards in reducing inter-observer variability

Improving the Reliability of Peer Review Without a Gold Standard

Peer review plays a crucial role in accreditation and credentialing processes as it can identify outliers and foster a peer learning approach, facilitating error analysis and knowledge sharing. However, traditional peer review methods may fall short in effectively addressing the interpretive variability among reviewing and primary reading radiologists, hindering scalability and effectiveness. Reducing this variability is key to enhancing the reliability of results and instilling confidence in the review process. In this paper, we propose a novel statistical approach called "Bayesian Inter-Reviewer Agreement Rate" (BIRAR) that integrates radiologist variability. By doing so, BIRAR aims to enhance the accuracy and consistency of peer review assessments, providing physicians involved in quality improvement and peer learning programs with valuable and reliable insights. A computer simulation was designed to assign predefined interpretive error rates to hypothetical interpreting and peer-reviewing radiologists. The Monte Carlo simulation then sampled (100 samples per experiment) the data that would be generated by peer reviews. The performances of BIRAR and four other peer review methods for measuring interpretive error rates were then evaluated, including a method that uses a gold standard diagnosis. Application of the BIRAR method resulted in 93% and 79% higher relative accuracy and 43% and 66% lower relative variability, compared to "Single/Standard" and "Majority Panel" peer review methods, respectively. Accuracy was defined by the median difference of Monte Carlo simulations between measured and pre-defined "actual" interpretive error rates. Variability was defined by the 95% CI around the median difference of Monte Carlo simulations between measured and pre-defined "actual" interpretive error rates. BIRAR is a practical and scalable peer review method that produces more accurate and less variable assessments of interpretive quality by accounting for variability within the group's radiologists, implicitly applying a standard derived from the level of consensus within the group across various types of interpretive findings.

Pancreatic cyst features predict future development of pancreatic cancer: results of a nested case-control study

BACKGROUND AND AIMS

Risk factors for pancreatic cancer among patients with pancreatic cysts are incompletely characterized. The primary aim of this study was to evaluate risk factors for development of pancreatic cancer among patients with pancreatic cysts.

METHODS

We conducted a retrospective case-control study of U.S. veterans with a suspected diagnosis of branch-duct intraductal papillary mucinous neoplasm from 1999 to 2013.

RESULTS

Age (hazard ratio [HR], 1.03 per year; 95% confidence interval [CI], 1.00-1.06), larger cyst size at cyst diagnosis (HR, 1.03 per mm; 95% CI, 1.01-1.04), cyst growth rate (HR, 1.22 per mm/y; 95% CI, 1.14-1.31), and pancreatic duct dilation (5-9.9 mm: HR, 3.78; 95% CI, 1.90-7.51; ≥10 mm: HR, 13.57; 95% CI, 5.49-33.53) were found to be significant predictors for pancreatic cancer on multivariable analysis.

CONCLUSIONS

Age, cyst size, cyst growth rate, and high-risk or worrisome features were associated with a higher risk of developing pancreatic cancer. Applying current and developing novel strategies is required to optimize early detection of pancreatic cancer after cyst diagnosis.

Risk Assessment and Radiomics Analysis in Magnetic Resonance Imaging of Pancreatic Intraductal Papillary Mucinous Neoplasms (IPMN)

Intraductal papillary mucinous neoplasms (IPMNs) are a very common incidental finding during patient radiological assessment. These lesions may progress from low-grade dysplasia (LGD) to high-grade dysplasia (HGD) and even pancreatic cancer. The IPMN progression risk grows with time, so discontinuation of surveillance is not recommended. It is very important to identify imaging features that suggest LGD of IPMNs, and thus, distinguish lesions that only require careful surveillance from those that need surgical resection. It is important to know the management guidelines and especially the indications for surgery, to be able to point out in the report the findings that suggest malignant degeneration. The imaging tools employed for diagnosis and risk assessment are Computed Tomography (CT) and Magnetic Resonance Imaging (MRI) with contrast medium. According to the latest European guidelines, MRI is the method of choice for the diagnosis and follow-up of patients with IPMN since this tool has a highest sensitivity in detecting mural nodules and intra-cystic septa. It plays a key role in the diagnosis of worrisome features and high-risk stigmata, which are associated with IPMNs malignant degeneration. Nowadays, the main limit of diagnostic tools is the ability to identify the precursor of pancreatic cancer. In this context, increasing attention is being given to artificial intelligence (AI) and radiomics analysis. However, these tools remain in an exploratory phase, considering the limitations of currently published studies. Key limits include noncompliance with AI best practices, radiomics workflow standardization, and clear reporting of study methodology, including segmentation and data balancing. In the radiological report it is useful to note the type of IPMN so as the morphological features, size, rate growth, wall, septa and mural nodules, on which the indications for surveillance and surgery are based. These features should be reported so as the surveillance time should be suggested according to guidelines.

Pancreatic Cyst Size Measurement on Magnetic Resonance Imaging Compared to Pathology

BACKGROUND

While multiple cyst features are evaluated for stratifying pancreatic intraductal papillary mucinous neoplasms (IPMN), cyst size is an important factor that can influence treatment strategies. When magnetic resonance imaging (MRI) is used to evaluate IPMNs, no universally accepted sequence provides optimal size measurements. T2-weighted coronal/axial have been suggested as primary measurement sequences; however, it remains unknown how well these and maximum all-sequence diameter measurements correlate with pathology size. This study aims to compare agreement and bias between IPMN long-axis measurements on seven commonly obtained MRI sequences with pathologic size measurements.

METHODS

This retrospective cohort included surgically resected IPMN cases with preoperative MRI exams. Long-axis diameter tumor measurements and the presence of worrisome features and/orhigh-risk stigmata were noted on all seven MRI sequences. MRI size and pathology agreement and MRI inter-observer agreement involved concordance correlation coefficient (CCC) and intraclass correlation coefficient (ICC), respectively. The presence of worrisome features and high-risk stigmata were compared to the tumor grade using kappa analysis. The Bland-Altman analysis assessed the systematic bias between MRI-size and pathology.

RESULTS

In 52 patients (age 68 ± 13 years, 22 males), MRI sequences produced mean long-axis tumor measurements from 2.45-2.65 cm. The maximum MRI lesion size had a strong agreement with pathology (CCC = 0.82 (95% CI: 0.71-0.89)). The maximum IPMN size was typically observed on the axial T1 arterial post-contrast and MRCP coronal series and overestimated size versus pathology with bias +0.34 cm. The radiologist interobserver agreement reached ICCs 0.74 to 0.91 on the MRI sequences.

CONCLUSION

The maximum MRI IPMN size strongly correlated with but tended to overestimate the length compared to the pathology, potentially related to formalin tissue shrinkage during tissue processing.

Surveillance of Pancreatic Cystic Neoplasms

Pancreatic cystic neoplasms (PCNs) are increasingly detected because of the widespread use of cross-sectional imaging and overall aging population. While the majority of these cysts are benign, some can progress to advanced neoplasia (defined as high-grade dysplasia and invasive cancer). As the only widely accepted treatment for PCNs with advanced neoplasia is surgical resection, accurate preoperative diagnosis, and stratification of malignant potential for deciding about surgery, surveillance or doing nothing remains a clinical challenge. Surveillance strategies for pancreatic cysts (PCNs) combine clinical evaluation and imaging to assess changes in cyst morphology and symptoms that may indicate advanced neoplasia. PCN surveillance heavily relies on various consensus clinical guidelines that focus on high-risk morphology, surgical indications, and surveillance intervals and modalities. This review will focus on current concepts in the surveillance of newly diagnosed PCNs, especially on low-risk presumed intraductal papillary mucinous neoplasms (those without worrisome features and high-risk stigmata), and appraise current clinical surveillance guidelines.

The Role of Magnetic Resonance Imaging (MRI) in the Diagnosis of Pancreatic Cystic Lesions (PCLs)

Pancreatic cystic lesions (PCLs) are a common incidental finding on cross-sectional imaging. Given the high signal to noise and contrast resolution, multi-parametric capability and lack of ionizing radiation, magnetic resonance imaging (MRI) has become the non-invasive method of choice to predict cyst type, risk stratify the presence of neoplasia, and monitor changes during surveillance. In many patients with PCLs, the combination of MRI and the patient's history and demographics will suffice to stratify lesions and guide treatment decisions. In other patients, especially those with worrisome or high-risk features, a multimodal diagnostic approach that includes endoscopic ultrasound (EUS) with fluid analysis, digital pathomics, and/or molecular analysis is often necessary to decide on management options. The application of radiomics and artificial intelligence in MRI may improve the ability to non-invasively stratify PCLs and better guide treatment decisions. This review will summarize the evidence on the evolution of MRI for PCLs, the prevalence of PCLs using MRI, and the MRI features to diagnose specific PCL types and early malignancy. We will also describe topics such as the utility of gadolinium and secretin in MRIs of PCLs, the limitations of MRI for PCLs, and future directions.

Lower Interobserver Reliability for Nondimensional Intracystic Features Among Abdominal Radiologists for Characterizing Intraductal Papillary Mucinous Neoplasms Using Magnetic Resonance Imaging

OBJECTIVES

Current guidelines recommend magnetic resonance imaging (MRI)/magnetic resonance cholangiopancreatography (MRCP) for risk stratification of intraductal papillary mucinous neoplasms (IPMNs). We assessed the interobserver agreement among radiologists in evaluating and risk stratifying IPMNs.

METHODS

This single-center study evaluated 30 patients with IPMNs who had undergone MRI/MRCP, endoscopic ultrasound, and/or surgical resection. Six abdominal radiologists evaluated the MRI/MRCPs to document multiple parameters. The analysis applied Landis and Koch κ interpretation for categorical variables and intraclass correlation coefficient (r) for continuous variables.

RESULTS

Radiologists demonstrated almost perfect agreement for location (κ = 0.81, 95% confidence interval [CI], 0.74-0.87), size (r = 0.95; 95% CI, 0.89-0.98), and main pancreatic duct diameter (r = 0.98; 95% CI, 0.96-0.99). Substantial agreement was observed for communication with the main pancreatic duct (κ = 0.66; 95% CI, 0.57-0.75) and classification of IPMN subtype (κ = 0.77; 95% CI, 0.67-0.86). Presence of intracystic nodules (κ = 0.31; 95% CI, 0.21-0.42) and wall thickening (κ = 0.09; 95% CI, -0.01 to 0.18) reached only fair and slight agreement, respectively.

CONCLUSIONS

Although MRI/MRCP is excellent in the evaluation of spatial aspects, there is lower reliability for nondimensional characteristics of IPMNs. These data support guideline-recommended complementary evaluation of IPMNs with MRI/MRCP and endoscopic ultrasound.

Incidence of pancreatic cancer during long-term follow-up in patients with incidental pancreatic cysts smaller than 2 cm

PURPOSE

To assess the long-term malignancy risk of incidental small pancreatic cysts.

MATERIALS AND METHODS

In this HIPAA-compliant, IRB-approved, retrospective, multi-institutional study, the long-term incidence of pancreatic cancer was compared between patients with and without small pancreatic cysts. Patients with incidental pancreatic cysts ≥ 0.5 and < 2.0 cm in maximal diameter, detected on MRI performed between 1999 and 2011, represented the "small pancreatic cyst" group. Patients that underwent MRI between 2005 and 2011 and had no reported pancreatic cysts represented the comparison "no cyst" group.

RESULTS

The "small pancreatic cyst" group included 267 patients, ages 63.4 ± 11.8 years, 166/267 (62%) women with a mean follow-up of 8.6 ± 4.3 years, median 9.2 years; the "no cyst" group included 1,459 patients, ages 64.6 ± 12 years, 794/1,459 (54%) women with a mean follow-up of 7.0 ± 4.2 years, median 7.8 (p values 0.12, 0.02, < 0.001, respectively). Two/267 (0.7%) patients developed pancreatic cancer at a separate location from the known cyst in the "small pancreatic cyst" group, with a cancer rate of 0.9 (95% CI 0.1-3.1) cases per 1,000 patient-years. In the "no cyst" cohort, 18/1,459 (1.2%) patients developed pancreatic cancer, with a cancer rate of 1.8 (95% CI 1.2-3.1) cases per 1,000 patient-years (p = 0.6). The all-cause mortality was similar in both groups: 57/267 (21%) vs. 384/1,459 (26%) (p = 0.09).

CONCLUSION

The long-term risk of pancreatic malignancy in asymptomatic patients with incidental pancreatic cysts less than 2 cm is 0.9 cases per 1,000 patient-years of follow-up, similar to those without pancreatic cysts. These very few pancreatic cancers developed at a separate location from the known cyst.

KEY POINTS

• After a median of 9.2 years of follow-up, the risk of pancreatic malignancy in patients with an asymptomatic small pancreatic cyst was 0.9 cases per 1,000 patient-years of follow-up, similar to those without pancreatic cysts. • Very few pancreatic cancer cases developed in the location separate from the known pancreatic cyst.

MRI follow-up for pancreatic intraductal papillary mucinous neoplasm: an ultrashort versus long protocol

Purpose

To evaluate whether an ultrashort-protocol (USP) MRI including only T2-weighted HASTE axial and 3D MRCP SPACE sequences adequately measures the largest diameter of the largest cyst and the main pancreatic duct (MPD) and identifies worrisome features (WF) and high-risk stigmata (HRS) when compared to longer protocols (LP, long protocol; SP, short protocol; S-LP, short or long protocol). We also calculated reductions in costs associated with USP.

Methods

This retrospective study included 183 IPMN patients. Two radiologists compared two imaging sets (USP versus S-LP) per patient, comparing the mean values of the largest cyst and MPD and agreement regarding the presence or absence of cystic or MPD mural nodules and solid pancreatic tumors. The interobserver agreement for cystic mural nodules and WF/HRS was evaluated, using the Bland-Altman plot and Cohen’s Kappa.

Results

A total of 112 IPMN patients were evaluated. For detecting cysts or MPD nodules, WF/HRS, and solid pancreatic tumors, USP and S-LP coincided in 94.9%, 99.1%, 92.4%, and 99.1% of cases, respectively. Both USP and S-LP identified all true cystic mural nodules. The mean size of the largest cyst and MPD was 19.48/19.67 mm and 3.24/3.33 mm using USP versus S-LP, while the mean differences for USP versus S-LP were 0.19 mm and 0.08 mm. The USP cost was 39% of LP cost and 77% of SP. Interobserver agreement was moderate to strong.

Conclusions

For IPMN surveillance, an ultrashort-protocol MRI provides nearly identical information to the more expensive longer protocols.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s00261-021-03382-4.

Branch-duct intraductal papillary mucinous neoplasm (IPMN): Are cyst volumetry and other novel imaging features able to improve malignancy prediction compared to well-established resection criteria?

OBJECTIVES

Current guidelines base the management of intraductal papillary mucinous neoplasms (IPMN) on several well-established resection criteria (RC), including cyst size. However, malignancy may occur in small cysts. Since branch-duct (BD) IPMN are not perfect spheres, volumetric and morphologic analysis might better correlate with mucin production and grade of dysplasia. Nonetheless, their role in malignancy (high-grade dysplasia/invasive cancer) prediction has been poorly investigated. Previous studies evaluating RC also included patients with solid-mass-forming pancreatic cancer (PC), which may affect the RC yield. This study aimed to assess the role of volume, morphology, and other well-established RC in malignancy prediction in patients with BD- and mixed-type IPMN after excluding solid masses.

METHODS

Retrospective ethical review-board-approved study of 106 patients (2008-2019) with histopathological diagnosis of BD- and mixed-type IPMN (without solid masses) and preoperative MRI available. Standard imaging and clinical features were collected, and the novel imaging features cyst-volume and elongation value [EV = 1 - (width/length)] calculated on T2-weighted images. Logistic regression analysis was performed. Statistical significance set at two-tails, p < 0.05.

RESULTS

Neither volume (odds ratio (OR) = 1.01, 95% CI: 0.99-1.02, p = 0.12) nor EV (OR = 0.38, 95% CI: 0.02-5.93, p = 0.49) was associated with malignancy. Contrast-enhancing mural nodules (MN), main pancreatic duct (MPD) ≥ 5 mm, and elevated carbohydrate antigen (CA) 19-9 serum levels (> 37 μmol/L) were associated with malignancy (MN OR: 4.32, 95% CI: 1.18-15.76, p = 0.02; MPD ≥ 5 mm OR: 4.2, 95% CI: 1.34-13.1, p = 0.01; CA19-9 OR: 6.72; 95% CI: 1.89 - 23.89, p = 0.003).

CONCLUSIONS

Volume and elongation value cannot predict malignancy in BD- and/or mixed-type IPMN. Mural nodules, MPD ≥ 5 mm and elevated CA19-9 serum levels are associated with higher malignancy risk even after the exclusion of solid masses.

KEY POINTS

• Novel and well-established resection criteria for IPMN have been evaluated after excluding solid masses. • BD-IPMN volume and elongation value cannot predict malignancy. • Main pancreatic duct ≥ 5 mm, mural nodules, and elevated carbohydrate antigen 19-9 levels are associated with malignancy.

Pancreatic cystic neoplasms: a review of current recommendations for surveillance and management

Pancreatic cystic neoplasms (PCN) comprise of a diverse array of pancreatic cysts, including intraductal papillary mucinous neoplasms (IPMN), mucinous cystic neoplasms (MCN), serous cystic neoplasms (SCN), cystic neuroendocrine tumors (cNET), and many others. Increasing use of cross-sectional imaging has resulted in greater numbers of PCNs discovered incidentally. The overall risk of malignancy is low, but can vary considerably between different classes of PCNs. Furthermore, many pancreatic cysts are indeterminate on imaging, and the inability to reliably predict the course of disease remains a challenge for radiologists. Due to the variability in disease course and a lack of high-quality studies on PCNs, there is no universal consensus when it comes to balancing optimal surveillance while avoiding the risk for overtreatment. Currently, there are three widely accepted international guidelines outlining guidelines for surveillance and management of PCNs: the American Gastroenterological Association (AGA) in 2015, the International Association of Pancreatology (IAP) last revised in 2017, and the European Study Group on Cystic Tumours of the Pancreas (European) last revised in 2018. In 2017, the American College of Radiology released its own comprehensive set of recommendations for managing indeterminate pancreatic cysts that are detected incidentally on CT or MRI. The purpose of this paper is to describe the key differences between the ACR recommendations and the aforementioned three sets of guidelines regarding cyst management, imaging surveillance, performance, and cost-effectiveness.

Intraductal papillary mucinous neoplasm (IPMN) of the pancreas: recommendations for Standardized Imaging and Reporting from the Society of Abdominal Radiology IPMN disease focused panel

There have been many publications detailing imaging features of malignant transformation of intraductal papillary mucinous neoplasms (IPMN), management and recommendations for imaging follow-up of diagnosed or presumed IPMN. However, there is no consensus on several practical aspects of imaging IPMN that could serve as a clinical guide for radiologists and enable future data mining for research. These aspects include how to measure IPMN, define reporting terminology, standardize reporting and unify guidelines for surveillance. The Society of Abdominal Radiology (SAR) created multiple Disease-Focused Panels (DFP) comprised multidisciplinary panel members who focus on a particular disease, with the goal to develop ways for radiologists to improve patient care, education, and research. DFP members met to identify the current controversies and limitations of imaging pancreatic IPMN. This paper aims to provide a practical review of the key imaging characteristics of IPMN for trainees and practicing radiologists, to guide uniformity of performance and interpretation of surveillance imaging studies, and to improve communication with clinicians by providing a lexicon and reporting template based on the experience of the SAR-DFP panel members.

Validation of European evidence-based guidelines and American College of Gastroenterology guidelines as predictors of advanced neoplasia in patients with suspected mucinous pancreatic cystic neoplasms

BACKGROUND AND AIM

The European evidence-based guidelines (EEG) and American College of Gastroenterology Guidelines (ACGG) have been published to guide the management of pancreatic cystic lesions. We aim to evaluate the value of both guidelines in predicting advanced pancreatic cystic lesions (A-PCLs) with preoperatively imaging-suspected cystic mucinous pancreatic neoplasms (cMNs).

METHODS

One hundred ninety-eight patients who underwent resections from 2013 to 2019 for suspected cMNs were retrospectively reviewed. Receiver operating characteristic curves were calculated and compared with measure diagnostic value.

RESULTS

Sixty-two patients were diagnosed with A-PCLs pathologically. Cross-imaging modalities had comparable diagnostic accuracy to endoscopic ultrasound in type classification and A-PCLs prediction. Receiver operating characteristic curve comparison analyses showed that EEG absolute + MCN (EEG^AM ) and EEG relative + MCN (EEG^RM ) having at least one indications criteria were comparable to the ACGG (P = 0.21 and P = 0.45). For the criteria having at least two indications, ACGG was superior to EEG^AM (P = 0.001) but comparable to EEG^RM (P = 0.12). EEG^AM ≥ 1 indication criteria was superior to ≥ 2 indications criteria (P = 0.02). EEG^RM ≥ 1 indication criteria had comparable diagnostic performance with ≥ 2 indications criteria (P = 0.86). ACGG ≥ 2 indications criteria was superior to ≥ 1 indication criteria (P = 0.02).

CONCLUSION

On the basis of cross-imaging evaluations, both sets of guidelines were found to be helpful in identifying A-PCLs in suspected cMNs with comparable performance. EEG^AM  ≥ 1 indication criteria was superior to ≥ 2 indications criteria. ACGG ≥ 2 indications criteria was superior to ≥ 1 indication criteria.

Abdominal Imaging of Pancreatic Cysts and Cyst-Associated Pancreatic Cancer in BRCA1/2 Mutation Carriers: A Retrospective Cross-Sectional Study

BACKGROUND

Direct-to-consumer BRCA testing will increase BRCA diagnoses and subsequent abdominal imaging. It is unclear whether BRCA carriers are at higher risk of developing pancreatic cysts (PCs) or cyst-associated pancreatic ductal adenocarcinoma (PDAC). We investigated the prevalence of PCs in BRCA-tested patients, and whether BRCA-carriers have higher rates of PDAC when PCs are found.

STUDY DESIGN

This is a retrospective cross-sectional study of patients with BRCA testing and abdominal imaging between 1996 and 2018. Pancreatic cysts were identified on original imaging reports. Prevalence and risk characteristics of PCs, as well as incidence of PDAC, were compared between BRCA+, BRCA-, and BRCA-untested patients.

RESULTS

Pancreatic cysts were identified in 4,045 patients among 128,164 unique patients with abdominal imaging, including 33 patients with PCs in 1,113 BRCA-tested patients. There was no difference in PC prevalence between BRCA+, BRCA-, and untested patients (3.6%, 2.6%, 3.2%, respectively; p = 0.64). Pancreatic cysts were diagnosed in BRCA+ patients at a younger age (57.1 vs 65.3 years, p < 0.001); however, there was no difference in risk stratification compared with BRCA- or untested patients by consensus criteria. Across the population of imaged patients, patients with PCs had significantly higher rates of PDAC compared with those without PCs (18.2% vs 2.4%, p < 0.001). Incidence of cyst-associated PDAC was similar in BRCA+ and BRCA- patients (13.3% vs 22.2%, p = 0.84).

CONCLUSIONS

BRCA+ patients have similar rates of PCs, high-risk features in their cysts, and PDAC as BRCA- and untested patients. BRCA+ patients likely do not require dedicated abdominal imaging to evaluate for PCs and should follow management guidelines similar to those as the untested general population if an incidental PC is identified.

Development of a stratification tool to identify pancreatic intraductal papillary mucinous neoplasms at lowest risk of progression

BACKGROUND

Because most pancreatic intraductal papillary mucinous neoplasms (IPMNs) will never become malignant, currently advocated long-term surveillance is low-yield for most individuals.

AIM

To develop a score chart identifying IPMNs at lowest risk of developing worrisome features or high-risk stigmata.

METHODS

We combined prospectively maintained pancreatic cyst surveillance databases of three academic institutions. Patients were included if they had a presumed side-branch IPMN, without worrisome features or high-risk stigmata at baseline (as defined by the 2012 international Fukuoka guidelines), and were followed ≥ 12 months. The endpoint was development of one or more worrisome features or high-risk stigmata during follow-up. We created a multivariable prediction model using Cox-proportional logistic regression analysis and performed an internal-external validation.

RESULTS

875 patients were included. After a mean follow-up of 50 months (range 12-157), 116 (13%) patients developed worrisome features or high-risk stigmata. The final model included cyst size (HR 1.12, 95% CI 1.09-1.15), cyst multifocality (HR 1.49, 95% CI 1.01-2.18), ever having smoked (HR 1.40, 95% CI 0.95-2.04), history of acute pancreatitis (HR 2.07, 95% CI 1.21-3.55), and history of extrapancreatic malignancy (HR 1.34, 95% CI 0.91-1.97). After validation, the model had good discriminative ability (C-statistic 0.72 in the Mayo cohort, 0.71 in the Columbia cohort, 0.64 in the Erasmus cohort).

CONCLUSION

In presumed side branch IPMNs without worrisome features or high-risk stigmata at baseline, the Dutch-American Risk stratification Tool (DART-1) successfully identifies pancreatic lesions at low risk of developing worrisome features or high-risk stigmata.

The Surveillance Patterns of Incidentally Detected Pancreatic Cysts Vary Widely and Infrequently Adhere to Guidelines

OBJECTIVES

We aimed to determine incidental pancreatic cyst ("cyst") surveillance patterns, predictors of receiving surveillance, and guideline adherence.

METHODS

We performed a retrospective cohort study of all patients receiving longitudinal care at a single tertiary care center with a newly diagnosed incidental pancreatic cyst over a 2-year period (2010-2011). All follow-up care was abstracted over a 5-year period.

RESULTS

Of 3241 eligible imaging studies reviewed, 100 patients with newly diagnosed incidental cysts eligible for surveillance were identified. A majority (53%) received no follow-up. We identified 4 predictors of cyst surveillance: radiology report conclusion mentioning the cyst (odds ratio [OR], 14.9; 95% confidence interval [CI], 1.9-119) and recommending follow-up (OR, 5.5; 95% CI, 2.1-13.9), pancreas main duct dilation (OR, 10.7; 95% CI, 1.3-89), and absence of multiple cysts (OR, 2.5; 95% CI, 1.1-10.0). Of the 47 patients who received surveillance, 66% met minimum surveillance imaging intervals of at least one guideline. Conversely, 21% of patients met the criteria for overutilization in at least one guideline.

CONCLUSIONS

Although guidelines recommend that surgically fit patients with incidental cysts undergo surveillance, most patients receive no follow-up. When follow-up occurs, surveillance patterns vary widely and infrequently conform to guidelines. Interventions to reduce care variation require study.

Impact of endoscopic ultrasound on diagnosis and management of presumed mucinous neoplasms when done for pancreatic cyst morphology change on non-invasive surveillance imaging

Background and study aims  Guidelines for management of presumed neoplastic pancreatic cysts have encouraged noninvasive imaging for low-risk surveillance, while reserving endoscopic ultrasound for worrisome features including morphologic change. We aim to study the impact of endoscopic ultrasound on diagnosis and management compared with non-invasive imaging. Patients and methods  A single-institution pancreatic cyst database was retrospectively queried for patients who underwent endoscopic ultrasound for the indication of change in cyst morphology. Diagnoses were classified as presumed mucinous neoplasm with or without worrisome features or high-risk stigmata and non-mucinous lesions. Management decisions were defined a priori as surgical evaluation for patients with high-risk stigmata, positive cytology or mural nodule, or continued surveillance for all others. Results  Between January 2013 and October 2016, 709 pancreas cyst endoscopic ultrasounds were performed of which 89 were for cyst morphology change seen on noninvasive imaging including 10 presumed pseudocysts, nine presumed serous cystadenomas, and 70 presumed mucinous cystic neoplasms. Cyst morphologic changes included increase in caliber of the main pancreatic duct (7 cases), increase in cyst size (68 cases), cyst ≥ 30 mm (10 cases), and presence of a solid nodule (1 case). Median cyst size increase was 5 mm with interquartile range of 4 mm over 2.1 ± 1.9 years. Endoscopic ultrasound done for morphologic change resulted in a change in diagnosis and management in 16 % and 13 % of cases, respectively. Conclusion  Endoscopic ultrasound has a modest but clinically significant role in impacting diagnosis and management for presumed mucinous cystic neoplasms when performed for the indication of cyst morphology change.

Current Guideline Controversies in the Management of Pancreatic Cystic Neoplasms

Pancreatic cystic lesions are a common clinical entity. The majority are neoplastic and have the potential for malignant transformation. To assist with patient management, a number of clinical guidelines have been developed over the past decade. However, controversies exist in regards to the various guidelines and treatment strategies they offer. This article will review the various clinical guidelines for management of pancreatic cysts, describe the limitations of these guidelines, and present future directions for improvement in clinical decision making for patients diagnosed with a pancreatic cystic neoplasm.

Higher Growth Rate of Branch Duct Intraductal Papillary Mucinous Neoplasms Associates With Worrisome Features

BACKGROUND & AIMS

For patients with branch duct intraductal papillary mucinous neoplasms (BD-IPMNs, cysts), it is a challenge to identify those at high risk for malignant lesions. We sought to identify factors associated with development of pancreatic cancer, focusing on neoplasm growth rate.

METHODS

We performed a retrospective study of 189 patients with BD-IPMNs who underwent at least 2 contrast-enhanced cross-sectional imaging studies, 1 year or more apart, at a tertiary referral center from January 2003 through 2013. Patients with cysts that had Fukuoka worrisome or high-risk features were excluded. Two radiologists reviewed all images. Cyst size was recorded at the initial and final imaging studies and growth rate was calculated. We collected patient demographic data, cyst characteristics, and clinical outcomes; univariate logistic regression models were used to determine the odds of developing worrisome features. The primary outcomes were to determine growth rate of low-risk BD-IPMNs and to assess whether cyst growth rate correlates high-risk features of IPMNs.

RESULTS

Based on image analyses, cysts were initially a median 11 mm (range, 3-31 mm) and their final size was 12.5 mm (range, 3-42 mm). After a median follow-up time of 56 months (range, 12-163 months), the median cyst growth rate was 0.29 mm/year. Twelve patients developed worrisome features, no patients developed high-risk features, 4 patients had surgical resection, and no cancers developed. The rate of BD-IPMN growth was greater in patients who developed worrisome features than those who did not (2.84 mm/year vs 0.23 mm/year; P < .001). The odds of developing worrisome features increased for each unit (mm) increase in cyst size (odds ratio, 1.149; 95% CI, 1.035-1.276, P = .009).

CONCLUSION

In a retrospective analysis of images from patients with BD-IPMN, we found low-risk BD-IPMNs to grow at an extremely low rate (less than 0.3 mm/year). BD-IPMNs in only about 6% of patients developed worrisome features, and none developed high-risk features or invasive cancers. BD-IPMNs that developed worrisome features were associated with a significantly higher rate of growth than lesions with low-risk features. Low risk BD-IPMNs that grow more than 2.5 mm/year might require surveillance.

Mucinous cystic neoplasms of the pancreas: high-resolution cross-sectional imaging features with clinico-pathologic correlation

PURPOSE

To describe the high-resolution cross-sectional (MDCT/MRI) features of mucinous cystic neoplasms (MCN) of the pancreas with clinico-pathologic correlation; to identify imaging predictors of high-grade dysplasia/carcinoma; and to estimate MCN growth rate.

MATERIALS AND METHODS

Thirty-two women (mean age: 46; range, 25-79 years) with resected MCN who underwent preoperative MDCT (n = 20) or MRI (n = 12) examinations over a 14-year period were included. Two radiologists examined retrospectively in consensus the following MDCT/MRI features: MCN location, size/volume, presence of capsule and thickness of the capsule, and presence of mural nodules, enhancing septations, calcifications, chronic pancreatitis, and main pancreatic duct dilation. Imaging features were correlated with clinical symptoms, biochemistry results, and histopathologic features. A univariate model was analyzed for the prediction of high-grade dysplasia/carcinoma. Preoperative MCN growth rate was assessed using a subset of patients with more than one imaging study available (n = 6).

RESULTS

Twenty-five (78%) patients presented with symptoms and 8 (25%) patients had abnormal serum biochemical values. Mean MCN maximum dimensions were 48 × 45 × 45 mm with a mean volume of 169 mL. MCN were located in the tail (n = 18), body (n = 10), neck (n = 2), and (head = 2); 30 (93.5%) MCN were encapsulated, 3 (9%) had calcifications, 4 (12%) showed enhancing nodules, 9 (28%) had enhancing septations, and 5 (15%) had main pancreatic duct dilation. Associated chronic pancreatitis was observed in 4 (12%) patients. The only predictors for high-grade dysplasia/carcinoma were MCN size and volume. Using a cut-off size greater than 8.5 cm, the specificity and sensitivity for high-grade dysplasia/carcinoma were 97 and 60%, respectively (p = 0.003; OR 81, 95% CI 3.9-1655.8). Mean MCN growth rate was estimated at 4.2 mm/year with a doubling time of 8.23 years.

CONCLUSION

MCN size (> 8.5 cm) and volume are the only features on MDCT/MR imaging that correlate with high-grade dysplasia/carcinoma. The average growth rate for MCNs is slow at approximately 4 mm per year.

Utility of transabdominal ultrasound for surveillance of known pancreatic cystic lesions: prospective evaluation with MRI as reference standard

OBJECTIVES

To prospectively assess the utility of transabdominal ultrasound in surveillance of known pancreatic cystic lesions (PCL) using same day MRI as reference standard.

METHODS

In an IRB-approved study with written informed consent, patients with known PCL underwent pancreas US on same day as surveillance MRI. US was performed blinded to same date MRI results. Transverse (TR), antero-posterior (AP), cranio-caudal (CC), and longest any plane diameter, were measured for each PCL at US and MRI. Visualization was correlated with patient (weight, abdominal diameter, thickness of abdominal fat, sex) and cyst (location, size, internal complexity) factors.

RESULTS

252 PCLs evaluated in 57 subjects (39 females; mean age 67 (range 39-86) yrs). Mean maximum PCL diameter 8.5 (range 2-92) mm. US identified 100% (5/5) of cysts ≥3 cm; 92% (12/13) ≥2 and <3 cm; 78% (43/55) ≥1 and <2 cm; 35% (27/78) ≥5 mm and <1 cm; and 16% (16/101) <5 mm. US visualization correlated with PCL location (<0.0001), size (p < 0.0001), patient gender (p = 0.005), participation of attending radiologist (p = 0.03); inversely with patient weight (p = 0.012) and AP abdominal diameter (p = 0.01).

CONCLUSION

Many PCLs are visualized and accurately measured at follow-up with transabdominal ultrasound. Visualization correlates with lesion size, location, patient sex, weight, and abdominal diameter.

ACG Clinical Guideline: Diagnosis and Management of Pancreatic Cysts

Pancreatic cysts are very common with the majority incidentally identified. There are several types of pancreatic cysts; some types can contain cancer or have malignant potential, whereas others are benign. However, even the types of cysts with malignant potential rarely progress to cancer. At the present time, the only viable treatment for pancreatic cysts is surgical excision, which is associated with a high morbidity and occasional mortality. The small risk of malignant transformation, the high risks of surgical treatment, and the lack of high-quality prospective studies have led to contradictory recommendations for their immediate management and for their surveillance. This guideline will provide a practical approach to pancreatic cyst management and recommendations for cyst surveillance for the general gastroenterologist.

MDCT vs. MRI for incidental pancreatic cysts: measurement variability and impact on clinical management

PURPOSE

To investigate incidental pancreatic cysts (IPCs) size discrepancy in a cohort of patients receiving both computed tomography (CT) and magnetic resonance imaging (MRI) and its impact on clinical management based on the 2010 American College of Radiology (ACR) guidelines.

METHODS

This was a HIPAA-compliant, retrospective, IRB-approved study. Informed consent was waived. Patients with known IPCs and at least one case-pair, consisting of an abdominal CT and MRI examination within 180 days between 05/1999 and 12/2011, were included. Maximum diameter of cysts was measured in both the CT and MR examinations. A subset of 30 patients was measured by three radiologists independently to assess inter-observer variability. Absolute difference in diameter measurements between CT and MRI was calculated. Influence of cyst size, cyst location, and patient characteristics such as weight, height, and body mass index (BMI) on variability of size measurements were evaluated. Clinical impact in terms of current ACR guidelines was assessed.

RESULTS

Overall, 267 case-pairs of cysts in 113 patients were included in this study. 59/267 cysts were visualized on MRI but not on CT (22.1%, 95% CI 17.1%-27.1%; 32 patients, 64.6 ± 11.7 years, BMI 28.5 ± 4.8 kg/m²), with a median MRI cyst size of 7.8 mm, IQR 6.0-9.0 mm, range 2-17.8 mm. 208 case-pairs in 113 patients with a mean BMI of 26.9 ± 5.1 kg/m² (range 16.9-39.5 kg/m²) and mean cysts size of 13.4 ± 8.1 mm (range 3-49 mm) were seen in both CT and MRI. The mean absolute size difference for IPCs measured on MRI and CT was 2.1 ± 1.8 mm (median 1.5 mm, IQR 0.9-2.9 mm, range 0-9 mm). Absolute size difference between CT and MRI measurements increased with size of the cyst (r = 0.31, p < 0.001), whereas location of the cyst did not influence the absolute difference between CT and MRI measurements (p = 0.44). Patient weight and BMI had a negative correlation with the difference in cyst size between CT and MRI (weight r = -0.17, p = 0.023; BMI r = -0.17, p = 0.027), with cyst measurements being larger on MRI in thin patients and on CT in obese patients. Inter-reader variability was excellent (ICC = 0.99). In 12/208 (5.7%, 95% CI 2.7%-9.1%), variability between CT and MRI would have changed ACR-based follow-up recommendation.

CONCLUSION

There was a median difference of 1.5 mm between measurements of IPCs on CT vs. MRI. If imaging modality was switched during follow-up, variability of measurements may lead to inappropriate change of follow-up regimen in 6% of all cases. A single follow-up CT for incidental IPCs does not seem sufficient due to a high number (22%) of missed IPCs on CT.

Evolution of incidental branch-duct intraductal papillary mucinous neoplasms of the pancreas: A study with magnetic resonance imaging cholangiopancreatography

AIM

To investigate the type and timing of evolution of incidentally found branch-duct intraductal papillary mucinous neoplasms (bd-IPMN) of the pancreas addressed to magnetic resonance imaging cholangiopancreatography (MRCP) follow-up.

METHODS

We retrospectively evaluated 72 patients who underwent, over the period 2006-2016, a total of 318 MRCPs (mean 4.4) to follow-up incidental, presumed bd-IPMN without signs of malignancy, found or confirmed at a baseline MRCP examination. Median follow-up time was 48.5 mo (range 13-95 mo). MRCPs were acquired on 1.5T and/or 3.0T systems using 2D and/or 3D technique. Image analysis assessed the rates of occurrence over the follow-up of the following outcomes: (1) imaging evolution, defined as any change in cysts number and/or size and/or appearance; and (2) alert findings, defined as worrisome features and/or high risk stigmata (e.g., thick septa, parietal thickening, mural nodules and involvement of the main pancreatic duct). Time to outcomes was described with the Kaplan-Meir approach. Cox regression model was used to investigate clinical or initial MRCP findings predicting cysts changes.

RESULTS

We found a total of 343 cysts (per-patient mean 5.1) with average size of 8.5 mm (range 5-25 mm). Imaging evolution was observed in 32/72 patients (44.4%; 95%CI: 32-9-56.6), involving 47/343 cysts (13.7%). There was a main trend towards small (< 10 mm) increase and/or decrease of cysts size at a median time of 22.5 mo. Alert findings developed in 6/72 patients (8.3%; 95%CI: 3.4-17.9) over a wide interval of time (13-63 mo). No malignancy was found on endoscopic ultrasound with fine-needle aspiration (5/6 cases) or surgery (1/6 cases). No clinical or initial MRCP features were significantly associated with changes in bd-IPMN appearance (P > 0.01).

CONCLUSION

Changes in MRCP appearance of incidental bd-IPNM were frequent over the follow-up (44.4%), with relatively rare (8.3%) occurrence of non-malignant alert findings that prompted further diagnostic steps. Changes occurred at a wide interval of time and were unpredictable, suggesting that imaging follow-up should be not discontinued, though MRCPs might be considerably delayed without a significant risk of missing malignancy.