Fate of small pancreatic cysts (<3 cm) after long-term follow-up: analysis of significant radiologic characteristics and proposal of follow-up strategies

Comparison of intra- and inter-reader agreement of abbreviated versus comprehensive MRCP for pancreatic cyst surveillance

OBJECTIVE

To retrospectively compare inter- and intra-reader agreement of abbreviated MRCP (aMRCP) with comprehensive MRI (cMRCP) protocol for detection of worrisome features, high-risk stigmata, and concomitant pancreatic cancer in pancreatic cyst surveillance.

METHODS

151 patients (104 women, mean age: 69[10] years) with baseline and follow-up contrast-enhanced MRIs were included. This comprised 138 patients under cyst surveillance with 5-year follow-up showing no pancreatic ductal adenocarcinoma (PDAC), 6 with pancreatic cystic lesion-derived malignancy, and 7 with concomitant PDAC. The aMRCP protocol used four sequences (axial and coronal Half-Fourier Single-shot Turbo-spin-Echo, axial T1 fat-saturated pre-contrast, and 3D-MRCP), while cMRCP included all standard sequences, including post-contrast. Three blinded abdominal radiologists assessed baseline cyst characteristics, worrisome features, high-risk stigmata, and PDAC signs using both aMRCP and cMRCP, with a 2-week washout period. Intra- and inter-reader agreement were calculated using Fleiss' multi-rater kappa and Intra-class Correlation Coefficient (ICC). 95% confidence intervals (CI) were calculated.

RESULTS

Cyst size, growth, and abrupt main pancreatic duct transition had strong intra- and inter-reader agreement. Intra-reader agreement was ICC = 0.93-0.99 for cyst size, ICC = 0.71-1.00 for cyst growth, and kappa = 0.83-1.00 for abrupt duct transition. Inter-reader agreement for cyst size was ICC = 0.86 (aMRCP) and ICC = 0.83 (cMRCP), and for abrupt duct transition was kappa = 0.84 (aMRCP) and kappa = 0.69 (cMRCP). Thickened cyst wall, mural nodule and cyst-duct communication demonstrated varying intra-reader agreements and poor inter-reader agreements.

CONCLUSION

aMRCP showed high intra- and inter-reader agreement for most pancreatic cyst parameters that highly rely on T2-weighted sequences.

Imaging for Early Detection of Pancreatic Ductal Adenocarcinoma: Updates and Challenges in the Implementation of Screening and Surveillance Programs

Pancreatic ductal adenocarcinoma (PDA) is one of the most aggressive cancers. It has a poor 5-year survival rate of 12%, partly because most cases are diagnosed at advanced stages, precluding curative surgical resection. Early-stage PDA has significantly better prognoses due to increased potential for curative interventions, making early detection of PDA critically important to improved patient outcomes. We examine current and evolving early detection concepts, screening strategies, diagnostic yields among high-risk individuals, controversies, and limitations of standard-of-care imaging.

Optimal Follow-up of Incidental Pancreatic Cystic Lesions without Worrisome Features: Clinical Outcome after Long-term Follow-up

Background/Aims

: The optimal duration and interval of follow-up for cystic lesions of the pancreas (CLPs) is not well established. This study was performed to investigate the optimal duration and interval of follow-up for CLPs in clinical practice.

Methods

: Patients with CLPs without worrisome features or high-risk stigmata underwent follow-up with computed tomography at 6, 12, 18, and 24 months and then every 12 months thereafter. A retrospective analysis of prospectively collected data was performed.

Results

: A total of 227 patients with CLPs detected from 2000 to 2008 (mean initial diameter, 1.3±0.6 cm) underwent follow-up for a median of 120 months. Twenty-two patients (9.7%) underwent surgery after a median of 47.5 months. Malignancies developed in four patients (1.8%), one within 5 years and three within 10 years. One hundred and fourteen patients (50.2%) were followed up for more than 10 years. No malignancy developed after 10 years of follow-up. During surveillance, 37 patients (16.3%) experienced progression to surgical indication. In patients with CLPs less than 2 cm in diameter, development of surgical indications did not occur within 24 months of follow-up.

Conclusions

: CLPs should be continuously monitored after 5 years because of the persistent potential for malignant transformation of CLPs. An interval of 24 months for initial follow-up might be enough for CLPs with initial size of less than 2 cm in clinical practice.

Clinical Feasibility of Abbreviated Magnetic Resonance With Breath-Hold 3-Dimensional Magnetic Resonance Cholangiopancreatography for Surveillance of Pancreatic Intraductal Papillary Mucinous Neoplasm

OBJECTIVES

To determine the clinical feasibility of abbreviated magnetic resonance image (MRI) using breath-hold 3-dimensional magnetic resonance cholangiopancreatography (3D-MRCP) (aMRI-BH) for pancreatic intraductal papillary mucinous neoplasm (IPMN) surveillance.

MATERIALS AND METHODS

In this retrospective study, 123 patients with 158 pancreatic IPMNs (pathologically proven [n = 73] and typical image feature with ≥2-year stability [n = 85]) who underwent conventional MRI (cMRI) consisting of contrast-enhanced pancreatobiliary MRI with conventional and BH-3D-MRCP were included. Two readers independently evaluated aMRI-BH protocols consisting of heavily T2-weighted, precontrast T1-weighted, and BH-3D-MRCP sequences. The diagnostic performance of aMRI-BH for detecting malignant IPMNs was assessed using the following criteria: category 3, presence of mural nodule 5 mm or bigger and/or main pancreatic duct (MPD) 10 mm or bigger; category 2, more than one of the following: cyst size 30 mm or greater, mural nodule smaller than 5 mm, thickened cyst walls, MPD of 5 to 9 mm, lymphadenopathy, and an abrupt MPD caliber change with distal atrophy; and category 1, none of the above. Categories 2 or 3 were considered positive results of surveillance. Interreader agreement of image features by intraclass correlation and κ statistics were analyzed.

RESULTS

The total acquisition times of cMRI and aMRI-BH were 32.7 ± 8 and 5.5 ± 2.1 minutes, respectively (P < 0.01). Among 158 IPMNs, 33 lesions were malignant. The aMRI-BH presented a sensitivity of 100% and a negative predictive value of 100% for evaluating malignant IPMNs in both readers, with substantial interreader agreements (intraclass correlation or к values, range: 0.73-0.93 for cMRI and 0.57-0.94 for aMRI-BH) in significant imaging features based on revised Fukuoka guidelines, except for thickened cyst walls and lymphadenopathy (к values: 0.10 and 1.00 for cMRI and 0.13 and 0.49 for aMRI-BH, respectively).

CONCLUSIONS

The aMRI-BH provided high sensitivity and negative predictive value to evaluate malignant IPMNs by using predetermined criteria, and aMRI-BH might be a potential tool for pancreatic IPMN surveillance with significantly lower acquisition time.

A Review of the Diagnosis and Management of Premalignant Pancreatic Cystic Lesions

Pancreatic cystic lesions are an increasingly common clinical finding. They represent a heterogeneous group of lesions that include two of the three known precursors of pancreatic cancer, intraductal papillary mucinous neoplasms (IPMN) and mucinous cystic neoplasms (MCN). Given that approximately 8% of pancreatic cancers arise from these lesions, careful surveillance and timely surgery offers an opportunity for early curative resection in a disease with a dismal prognosis. This review summarizes the current evidence and guidelines for the diagnosis and management of IPMN/MCN. Current pre-operative diagnostic tests in pancreatic cysts are imperfect and a proportion of patients continue to undergo unnecessary surgical resection annually. Balancing cancer prevention while preventing surgical overtreatment, continues to be challenging when managing pancreatic cysts. Cyst fluid molecular markers, such as KRAS, GNAS, VHL, PIK3CA, SMAD4 and TP53, as well as emerging endoscopic technologies such as needle-based confocal laser endomicroscopy and through the needle microbiopsy forceps demonstrate improved diagnostic accuracy. Differences in management and areas of uncertainty between the guidelines are also discussed, including indications for surgery, surveillance protocols and if and when surveillance can be discontinued.

Long-term follow-up of branch-duct intraductal papillary mucinous neoplasms with No change in first 5 Years of diagnosis

BACKGROUND

Discontinuation of branch-duct intraductal papillary mucinous neoplasm (BD-IPMN) surveillance after 5 years of no change remains controversial. Long-term outcomes of BD-IPMN without significant changes in the first 5 years were evaluated.

METHODS

We performed a multi-center retrospective analysis of patients with BD-IPMN diagnosis from 2005 to 2011 (follow-up until 2017). Significant changes were defined as pancreatic cancer (PC), pancreatectomy, high-risk stigmata (HRS), worrisome features (WF) and worrisome EUS features (WEUS).

RESULTS

Of 982 patients who had no significant changes, 5 (0.5%), 7 (0.7%), 99 (10.1%), 4 (0.4%) patients developed PC, HRS, WF, WEUS, respectively, post-5 years. PC and HRS/WF/WEUS incidences at 12 years were 1.0% and 29.0%, respectively. Patients that developed HRS/WF/WEUS had larger cyst size in first 5 years compared to those that did not [16 (12-23) vs. 12 (9-17) mm, p = 0.0001], cyst size of >15 mm having higher cumulative incidence of HRS/WF/WEUS. PC mortality was 0.8%; all-cause mortality was 32%. Incidence of mortality due to PC was higher in HRS/WF/WEUS group, p < 0.0001. The mortality rate at 12 years for ACCI (age-adjusted Charlson Comorbidity Index) of ≤3, 4-6, and ≥7 were 3.5%, 19.9%, and 57.6% (p < 0.0001), respectively.

CONCLUSIONS

Incidence of PC in patients with BD-IPMN without significant changes in first 5 years of diagnosis remains low at 1.0%. Incidence of HRS/WF/WEUS was higher at 29.0%. PC-related mortality was higher in HRS/WF/WEUS group. These risks should be weighed against patients' overall mortality (utilizing scoring systems such as ACCI) when making surveillance decision of BD-IPMN beyond 5 years.

Risk of malignancy in small pancreatic cysts decreases over time

BACKGROUND

Pancreatic cysts <15 mm without worrisome features have practically no risk of malignancy at the time of diagnosis but this can change over time. Optimal duration of follow-up is a matter of debate. We evaluated predictors of malignancy and attempted to identify a time to safely discontinue surveillance.

METHODS

Bi-centric study utilizing prospectively collected databases of patients with pancreatic cysts measuring <15 mm and without worrisome features who underwent surveillance at the Massachusetts General Hospital (1988-2017) and at the University of Verona Hospital Trust (2000-2016). The risk of malignant transformation was assessed using the Kaplan-Meier method and parametric survival models, and predictors of malignancy were evaluated using Cox regression.

RESULTS

806 patients were identified. Median follow-up was 58 months (6-347). Over time, 58 (7.2%) cysts were resected and of those, 11 had high grade dysplasia (HGD) or invasive cancer. Three additional patients had unresectable cancer for a total rate of malignancy of 1.7%. Predictors of development of malignancy included an increase in size ≥2.5 mm/year (HR = 29.54, 95% CI: 9.39-92.91, P < 0.001) and the development of worrisome features (HR = 9.17, 95% CI: 2.99-28.10, P = 0.001). Comparison of parametric survival models suggested that the risk of malignancy decreased after three years of surveillance and was lower than 0.2% after five years.

CONCLUSIONS

Pancreatic cysts <15  mm at the time of diagnosis have a very low risk of malignant transformation. Our findings indicate the risk decreases over time. Size increase of ≥2.5 mm/year is the strongest predictor of malignancy.

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.

Progression of pancreatic cystic lesions without any risk features is associated with initial cyst size and obesity

BACKGROUND AND AIM

The clinical significance of incidental pancreatic cystic lesions (PCLs) remains unclear in those that are not accompanied by worrisome features or high-risk stigmata. We aimed to investigate the natural course of PCLs without any risk features and examine the clinical factors associated with their progression.

METHODS

We conducted a retrospective cohort study of 427 patients with PCLs, which were incidentally detected by computed tomography between January 2003 and December 2012. Progression of PCLs without any risk features and the clinical factors associated with their progression were investigated. The length of time to significant growth was also evaluated.

RESULTS

Ninety-four (22.0%) of the 427 patients had asymptomatic PCLs that showed significant growth after a median surveillance period of 5.3 years; approximately 27.7% of the patients showed significant size changes in the first 5 years, while the remaining 72.3% showed significant changes after 5 years. The cumulative rate of patients with significant growth was associated with initial cyst size and high body mass index. In the growth group, additional treatments were required for 12 patients, one of whom developed malignancy. Four patients in the stable group underwent additional treatment and showed no malignant change.

CONCLUSIONS

One-fifth of the asymptomatic PCLs significantly increased in size after a long-term follow-up period, which was associated with initial cyst size and obesity. The size of PCLs mostly increased after 5 years; although the malignancy risk of PCLs was low, it was still a concern.

Analyzing Intraductal Papillary Mucinous Neoplasms Using Artificial Neural Network Methodologic Triangulation

Intraductal papillary mucinous neoplasms (IPMN) are a type of mucinous pancreatic cyst. IPMN have been shown to be pre-malignant precursors to pancreatic cancer, which has an extremely high mortality rate with average survival less than 1 year. The purpose of this analysis is to utilize methodological triangulation using artificial neural networks and regression to examine the impact and effectiveness of a collection of variables believed to be predictive of malignant IPMN pathology. Results indicate that the triangulation is effective in both finding a new predictive variable and possibly reducing the number of variables needed for predicting if an IPMN is malignant or benign.

Progression of Pancreatic Branch Duct Intraductal Papillary Mucinous Neoplasm Associates With Cyst Size

BACKGROUNDS & AIMS

Most guidelines for management of patients with intraductal papillary mucinous neoplasms (IPMN) vary in proposed surveillance intervals and durations-these are usually determined based on expert opinions rather than substantial evidence. The progression of and optimal surveillance intervals for branch-duct IPMNs (BD-IPMN) has not been widely studied. We evaluated the progression of BD-IPMN under surveillance at a single center, and determined optimal follow-up intervals and duration.

METHODS

We performed a retrospective analysis of 1369 patients with BD-IPMN seen at Seoul National University Hospital in Korea from January 2001 through December 2016. We included only patients whose imaging studies showed classical features of BD-IPMN, and collected data from each patient over time periods of at least 3 years. We reviewed radiologic and pathologic findings, and performed linear and binary logistic regressions to estimate cyst growth.

RESULTS

The median annual growth rate of the cyst was 0.8 mm over a median follow-up time of 61 months. During surveillance, 46 patients (3.4%) underwent surgery because of disease progression after a median follow-up time (in this group) of 62 months. Worrisome features were observed in 209 patients (15.3%) during surveillance, including cyst size of 3 cm or more (n = 109, 8.0%), cyst wall thickening (n = 51, 3.7%), main pancreatic duct dilatation (n = 77, 5.6%), and mural nodule (n = 43, 3.1%). Along with annual rate of cyst growth, incidences of main pancreatic duct dilatation and mural nodules associated with the sizes of cysts at detection (P < .001).

CONCLUSIONS

In a retrospective analysis of patients with BD-IPMN followed for more than 5 years, we found most cysts to be indolent, but some rapidly grew and progressed. Surveillance protocols should therefore be individualized based on initial cyst size and rate of growth.

Incidental, Small (< 3 cm), Unilocular, Pancreatic Cysts: Factors That Predict Lesion Progression during Imaging Surveillance

OBJECTIVE

To explore the features that predict size increase and development of potential malignant features in incidentally detected, unilocular cystic pancreatic lesions (CPLs) less than 3 cm in diameter, during subsequent follow-up.

MATERIALS AND METHODS

We retrieved data of patients diagnosed with unilocular CPLs less than 3 cm in diameter during the period from November 2003 through December 2014, using a computerized search. All serial CT and MR images were analyzed to identify the number, size, and location of CPLs; dilatation of the main pancreatic duct; and occurrence of worrisome features and high-risk stigmata of malignancy in the lesion. The characteristics of CPLs were compared between the increase (i.e., size increase during subsequent follow-up) and no-increase groups. For CPLs in the increase group, subgroup analysis was performed according to the lesion size at the last follow-up (< 3 cm vs. ≥ 3 cm).

RESULTS

Among 553 eligible patients, 132 (23.9%) had CPLs that increased in size, and 421 (76.1%) had CPLs that did not, during follow-up. Of the 132, 12 (9.1%) CPLs increased to diameters ≥ 3 cm at the final follow-up. Among the various factors, follow-up duration was a significant independent factor for an interval size increase of CPLs (p < 0.001). In the increase group, initial cyst size was a significant independent factor to predict later size increase to or beyond 3 cm in diameter (p < 0.001), and the initial cyst diameter ≥ 1.5 cm predicted such a growth with a sensitivity and specificity of 83% and 72%, respectively. No significant factors to predict the development of potential malignant features were identified.

CONCLUSION

Follow-up duration was associated with an interval size increase of CPLs. Among the growing CPLs, initial cyst size was associated with future lesion growth to and beyond 3 cm.

Validation of the American Gastroenterological Association guidelines on management of intraductal papillary mucinous neoplasms: more than 5 years of follow-up

OBJECTIVES

Recent guidelines suggest that imaging surveillance be conducted for 5 years for patients with at most one high-risk feature. If there were no significant changes, surveillance is stopped. We sought to validate this follow-up strategy.

METHODS

In study 1, data were analysed for 392 patients with intraductal papillary mucinous neoplasms (IPMNs) and at most one high-risk feature who were periodically followed up for more than 1 year with imaging tests. In study 2, data were analysed for 159 IPMN patients without worsening high-risk features after 5 years (stop surveillance group).

RESULTS

In study 1, pancreatic cancer (PC) was identified in 12 patients (27.3%) in the endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) indication group and none in the non-EUS-FNA indication group (P < 0.01). In the EUS-FNA indication group, 11 patients (25%) died, whereas 29 (8.3%) died in the non EUS-FNA indication group (P < 0.01). In study 2 (stop surveillance group), PC was identified in three patients (1.9%) at 84, 103 and 145 months.

CONCLUSIONS

PC risk and mortality for IPMNs not showing significant change for 5 years is likely to be low, and the non-EUS-FNA indication can provide reasonable decisions. However, three patients without worsening high-risk features for 5 years developed PC. The stop surveillance strategy should be reconsidered.

KEY POINTS

• The AGA guidelines provide reasonable clinical decisions for the EUS-FNA indication. • In stop surveillance group, PC was identified in 3 patients (1.9%). • In stop surveillance group, 2 of 3 PC patients died from PC. • Risk of pancreatic cancer in "stop surveillance" group is not negligible.