| Background Intraductal papillary mucinous neoplasm(IPMN)was classified into three sub-groups:Main duct type(MD),Side Branch or Branch duct(SB or BD)type,and mixed type.Pathology is divided into mild or moderate dysplasia,high-Grade Dysplasia(HGD),and invasive carcinoma.The SB-IPMN is the most common on clinical,and its follow-up strategies are still remaining controversy has been controversial.Objectives To analyze the characteristics of the risk factors(cyst size,cyst septation or mural nodules)on a serial magnetic resonance imaging(MRI)or computed tomography(CT)imaging retrospectively,and evaluate the risk stratification of SB-IPMN,and discuss how to develop a more appropriate long-term surveillance strategy,based on the results of a long-term follow-up(12-98 months)of the pancreatic SB-IPMN patients.Material and methods This study is consistent with the Health Insurance Portability and Accountability Act(HIPAA)compliant and have been approved by the authors' institutional review board.327 pancreatic SB-IPMN patients were included in this retrospective study with the image and clinical data over at least 1 year follow up.The natural history of SB-IPMN was observed during the follow-up period.The risk factors of the lesions were analyzed in a serial MRI or CT imaging follow-up,and correlated with the risk stratification by the pathological results of endoscopic retrograde cholangiopancreatography(ERCP),endoscopic ultrasonography(EUS)and clinical surgery.Paired T test and Variance Analysis were used for statistical analysis.The non-parameter Mann-Whitney U test is adopted for the comparison of the two groups;Kruskal-Wallis H test was used in three or more groups.The interobserver and intraobserver agreement of the SB-IPMN cyst measurement was evaluated by the Bland-Altman plot and the correlation coefficient(ICC).McNemar test and Kappa coefficient were used to evaluate the differences between MRI and EUS/ERCP/surgery on SB-IPMN septation or mural nodules determination.Results There were 327 SB-IPMN patients(214 females and 113 males)with a mean of(66±3)years on initial examination,ranged between 25 and 90 years old.The follow-up period ranged from 12 to 98 months,with an average of 41 months.On the initial MRI/CT study,the maximum diameter of cyst was(12± 9.0)mm,and the final mean cyst size was(14 ±10)mm on the follow-up studies,the average cyst growth was(2 ±7)mm.? SB-IPMN was divided for 4 groups by initial measurement size(? 10 mm,11 mm?20 mm,21 mm?30 mm,>30 mm):The smaller group(Cysts ? 10mm)showed the greatest mean cyst growth rate,with a 34%(58/171)patients by increase size ? 20%(P<0.001),but no patient was diagnosed as SB-IPMN associated with HGD in this group.The percent of HGD SB-IPMN in>30 mm group was 40%(4/10).? SB-IPMN was divided for 3 groups by the changes of cyst size(increased,decrease or no change):47%(155/327)patients with an increase in the maximum diameter of the lesion by the follow-up,and 5%(8/155)patients was diagnosed as SB-IPMN associated with HGD.21%(68/327)patients with a decrease in the maximum diameter of the lesion during the follow-up,and 4%(3/68)patients was diagnosed as SB-IPMN associated with high-grade dysplasia(HGD)by the pathological aspiration.32%(104/327)SB-IPMN patient remained unchanged with 1%(1/104)HGD SB-IPMN.? SB-IPMN was divided for 2 groups by with or without septation and/or mural nodule:The group with septation and/or mural nodule was more common in elderly patients average age(72 ± 9)years,and the average growth rate faster than the other without septation and/or mural nodule(P<0.05).SB-IPMN with HGD group had larger initial and final cyst size,with a mean of(29 ± 15)mm and(36 ± 19)mm,than the low-or intermediate-grade group with a mean of(11 ± 8)mm and(13 ± 9)mm,respectively(P<0.001).The HGD group was all presented with septation and/or mural nodule.? SB-IPMN was divided for 5 groups by follow-up periods(12 months?24 months,25 months?36 months,37 months?48 months,49 months?60 months,>60 months):28%(93/327)patients with 12 months?24 months follow-up periods and 9%(7/93)was diagnosed as SB-IPMN associated with HGD.20%(66/327)patients in 25 months?36 months group and 19%(62/327)patients in 37 months?48 months group,with a 3%of HGD SB-IPMN respectively.The percent of HGD SB-IPMN in 49 months?60 months group was 2.5%(1/40).There is no patient diagnosed as SB-IPMN associated with HGD in>60 months group,and no one was found with septation and/or mural nodule in a long-term serial MRI/CT follow-up.Conclusions SB-IPMN with septation and/or mural nodule was higher risk factor of malignancy.The change of cyst size is not a reliable indicator for malignancy during the long-term surveillance.Objectives To analyze the characteristics of the risk factors(cyst size,cyst septation or mural nodules)on a serial MRI or CT imaging retrospectively,and to study the natural history of these lesions combined with MRI/CT and ERCP/EUS data,based on the results of pancreatic SB-IPMN patients with more than 5 years follow-up.Material and methods This study is consistent with the Health Insurance Portability and Accountability Act(HIPAA)compliant and have been approved by the authors' institutional review board.A retrospective study was conducted with 67 pancreatic SB-IPMN patients(27 males,40 females,mean age 64 years,range from 33 to 88 years)at least 5 years CT and/or MRI imaging follow-up and clinical data.All imaging exams along with patients' EUS and ERCP data,were evaluated by analyzing of cystic lesions(including initial and final absolute sizes,absolute cyst growth rates,percentage size differences,and growth rate percentages)during the natural history observation.The differences in the septation and mural nodule between MRI,CT and EUS were compared.Statistical analysis included the T test,analysis of variance,and McNemar test.Results The mean follow-up time of 67 SB-IPMN patients was 72 months(ranging from 61 to 98 months).An initial cyst size was averaged(9.6 ± 6)mm,and the final mean cyst size was(12 ± 7)mm on the follow-up studies,the average cyst growth was(2 ± 5)mm.Lesions were divided for 4 groups according to initial cyst size(?10 mm,11 mm?20 mm,21 mm?30 mm,>30 mm),the smallest group(Cysts(10 mm)showed greater mean cyst growth rate(P<0.001).When lesions were divided for 4 groups by the changes of cyst size(<0 mm,0 mm?1.9 mm,2 mm?3.9 mm,? 4mm),there were no significant differences among the groups in age,initial size and follow-up period(P<0.05).Cyst with septation or mural nodule,and malignant cyst were not observed by the cross-sectional images and ERCP or EUS results.Conclusions SB-IPMN with a less than 30 mm size,and without septation or mural nodule can remain stable during more than 5 years follow-up.It would be more appropriate to prolong the follow-up period to 24 months. |
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