Predicting post‐operative pancreatic fistulae using preoperative pancreatic imaging: a systematic review

Peripancreatic fluid collections following distal pancreatectomy and splenectomy-when is intervention warranted?

BACKGROUND

Peripancreatic fluid collections after distal pancreatectomy and splenectomy are commonly identified on postoperative cross-sectional imaging. This study aimed to determine the incidence, natural history, and indications for intervention.

METHODS

We conducted a retrospective review of patients with peripancreatic fluid collections after distal pancreatectomy with or without splenectomy between 2013 and 2018, approved by our institutional review board. The chi-square test was used for categorical variables, the Mann-Whitney U test for continuous variables, and Fisher's exact test was used for values in which the sample size was less than 5 to compare data.

RESULTS

During the study period, 235 patients underwent distal pancreatectomy with or without splenectomy, and 182 patients with postoperative imaging were included. In the cohort of patients with postoperative imaging, 83 (46%) had peripancreatic fluid collections, of which 46 (55%) were symptomatic fluid collections (SFCs) and 37 (45%) were asymptomatic fluid collections (AFCs). Those with SFC had a higher incidence of postoperative morbidity (46% vs 8%; P = .0002), most commonly postoperative pancreatic fistula (90%). Of patients with SFC, 34 (74%) underwent treatment via percutaneous drainage (n = 26), endoscopic drainage (n = 7), or antibiotics alone (n = 1). AFCs (n = 37) were observed. Collections that were intervened upon resolved significantly faster than those observed, 3.5 months vs 13.2 months (P < .0001), respectively.

CONCLUSION

Asymptomatic patients may be observed with or without serial imaging and the AFC will typically resolve spontaneously with time. Patients who develop symptoms should generally be intervened upon with drainage if deemed feasible, given that this reduces the time to resolution.

Estimating Fatty Pancreas-A Preoperative Bedside Assessment by Bioelectric Impedance Analysis: Implications for Pancreatic Surgery

OBJECTIVE

The aim of the study was to evaluate whether fatty pancreas could be estimated by fat mass measurement by preoperative bioelectric impedance analysis. Preoperative computed tomography scan and pathologic evaluation were used as validation methods. Moreover, the 3 methodologies were tested for their ability in predicting postoperative pancreatic fistula.

METHODS

Seventy-five patients who underwent pancreatic resection were analyzed. Preoperative computed tomography attenuation in Hounsfield unit (CT-HU) was used to assess fatty pancreas. Bioelectric impedance analysis was performed the day before surgery and fat mass index (FMI) was calculated. Pancreatic steatosis was assessed by pathologists at the line of surgical transection. The ability of the methods in predicting postoperative pancreatic fistula was evaluated by the area under the receiver operating characteristics curves.

RESULTS

There was a strong correlation between CT-HU values and grade of pancreatic steatosis evaluated at histology ( r = -0.852, P < 0.001) and a moderate correlation between FMI and histologic pancreatic steatosis ( r = 0.612, P < 0.001) and between CT-HU value and FMI ( r = -0.659, P < 0.001) values. The area under the curve (95% confidence interval) was 0.942 (0.879-1) for histology, 0.924 (0.844-1) for CT-HU, and 0.884 (0.778-0.990) for FMI.

CONCLUSIONS

Bioelectric impedance analysis represents a valid alternative to assess pancreatic steatosis.

Impact of Fatty Pancreas on Postoperative Pancreatic Fistulae: A Meta-Analysis

Background

Soft pancreas is widely recognized as an important risk factor for the development of postoperative pancreatic fistula (POPF). Although fatty pancreas (FP) has not been formally defined as a cause of pancreatic fistula, existing research has shown that it can increase the incidence of POPF by increasing pancreatic tenderness; therefore, it may be a potential risk factor. This study aimed to discern whether FP was associated with POPF.

Method

Two reviewers independently performed literature searches from five electronic databases. According to the established inclusion criteria, we extracted necessary data from the studies that met the criteria for further analysis. We pooled the odds ratios (ORs) from individual studies using a random-effects model to investigate the associations between POPF and the prognosis of FP.

Result

A total of 11 studies involving 2484 individuals were included. The pooled prevalence of POPF was 18% (95% CI: 12-24%). Body mass index (BMI) was associated with a significantly increased risk of POPF (OR=3.55; 95% CI: 1.83, 6.86; P=0.0002; I²=0). FP was obviously associated with the occurrence of POPF (OR=3.75; 95% CI: 1.64, 8.58; P=0.002; I²=78).

Conclusion

FP is closely associated with the development of POPF, and the early identification of these high-risk patients can help to reduce the incidence of POPF.

Systematic Review Registration

The Registration URL link is (https://www.crd.york.ac.uk/PROSPERO/). The ID is "CRD42021265141".

Role of extracellular matrix structural components and tissue mechanics in the development of postoperative pancreatic fistula

Radical resection remains the only curative treatment option in pancreatic cancer. Postoperative pancreatic fistulas (POPF) occur in up to 30% of patients leading to prolonged hospital-stay, increased cost of care and morbidity and mortality. Mechanical properties of the pancreas are associated with POPF. The aim of this study is to analyze the role of extracellular matrix (ECM) and tissue mechanics in the risk of POPF. Biopsies of 41 patients receiving a partial pancreas-resection are analyzed. Clinical data, ECM components and mechanical properties are correlated with POPF. Preoperative cholestasis is correlated with reduced risk of POPF, which comes along with a dilatation of the pancreatic duct and significantly higher content of collagen I. Patients developing POPF exhibited a degenerated tissue integrity, with significantly lower content of fibronectin and a trend for lower collagen I, III, IV and hyaluronic acid. This correlated with a soft tactile sensation of the surgeon during the intervention. However, this was not reflected with tissue mechanics evaluated by ex vivo uniaxial compression testing, where a significantly higher elastic modulus and no effect on the stress relaxation time were found. In conclusion, patients with cholestasis seem to have a lower risk for POPF, and an increase in collagen I. A degenerated matrix with lower content of structural ECM components correlates with increased risk of POPF. However, ex vivo uniaxial compression testing failed to clearly explain the link of ECM properties and POPF.

Preoperative prediction of clinically relevant postoperative pancreatic fistula after pancreaticoduodenectomy

OBJECTIVES

To develop a radiomics model and a combined model for preoperative prediction of clinically relevant postoperative pancreatic fistula (CR-POPF) in patients undergoing pancreaticoduodenectomy and to compare the predictive performance of the two models with the traditional Fistula Risk Score system.

METHODS

A total of 250 patients who underwent pancreaticoduodenectomy (PD) with preoperative computed tomography (CT) were divided into a training set (n = 175) and validation set (n = 75). The pancreatic area was automatically segmented on the portal venous phase CT images using a 3D U-Net segmentation model. A radiomics model was developed using radiomics features extracted from the volume of interest (VOI) and a combined model was developed using radiomics features, demographic information and radiological features. The FRS was also used to predict POPF. The predictive performance of the prediction models was assessed using receiver operating characteristic (ROC) curves, calibration curves and decision curve analysis (DCA).

RESULTS

Eleven and 18 features were extracted for the radiomics model and combined model, respectively. The combined model showed excellent predictive value, with an AUC of 0.871 (95 %CI 0.816,0.926) and 0.869 (95 %CI 0.779,0.958) in the training cohort and validation cohort, respectively. Calibration curves and DCA showed that the combined model outperformed the traditional FRS system and radiomics model.

CONCLUSION

The combined model exhibited excellent predictive performance and outperformed the traditional FRS system and radiomics model in the preoperative prediction of CR-POPF.

Pancreatic ductal adenocarcinoma and distal cholangiocarcinoma: a proposal of preoperative diagnostic score for differential diagnosis

PURPOSE

The differential diagnosis between primary adenocarcinoma of the pancreas head and distal cholangiocarcinoma remains a clinical challenge. Recent studies have shown important differences in terms of survival between these tumors. Therefore, different treatments should be considered, but the preoperative histological diagnosis is still difficult. Aim of this study is to create a preoperative diagnostic score for differential diagnosis between primary pancreatic adenocarcinoma and primary distal cholangiocarcinoma.

METHODS

One hundred eighty consecutive patients who underwent pancreaticoduodenectomy at Sapienza University of Rome from January 2010 to December 2019 were retrospectively analyzed. Inclusion criteria were pancreatic or biliary histologic origin obtained by definitive postoperative histological examination. Exclusion criteria were diagnosis of ampullary carcinoma, non-ampullary duodenal adenocarcinoma, pancreatic metastasis, and benign disease. One hundred one patients were considered eligible for the retrospective study. Preoperative biological, clinical, and radiological parameters were considered.

RESULTS

CRP > 10 mg/dL (p = 0.001), modified Glasgow Prognostic Score 2 (p = 0.002), albumin < 35 g/L (p = 0.05), CA 19-9 > 230 U/mL (p = 0.001), and Wirsung diameter > 3 mm (p < 0.001) were significant at univariate logistic analysis. Multivariate logistic analysis has shown that parameters independently associated with primary pancreatic adenocarcinoma were CRP > 10 mg/dL (p = 0.012), CA 19-9 > 230 U/mL (p = 0.043), and diameter of the Wirsung > 3 mm (p = 0.005). Through these parameters, a diagnostic score has been developed to predict a primary pancreatic adenocarcinoma when > 1 and a primary distal cholangiocarcinoma when < 1.

CONCLUSION

This feasible and low-cost diagnostic score could have a potential impact to differentiate pancreatic cancer histologic origin and to improve target therapeutic strategy.

Is Ultrasound Elastography Useful in Predicting Clinically Relevant Pancreatic Fistula After Pancreatic Resection?: A Systematic Review and Meta-analysis

OBJECTIVES

Ultrasound (US) elastography has been proposed for the non-invasive prediction of clinically relevant pancreatic fistula (CR-POPF) in patients undergoing pancreatic resection. We aimed to perform a systematic review with meta-analysis to assess the diagnostic value of US elastography in predicting CR-POPF.

METHODS

MEDLINE via PubMed, Ovid Embase, Scopus, and Cochrane Library databases, and abstracts of international conference proceedings were searched up to April 20, 2020. Studies assessing the performance of abdominal US elastography in predicting CR-POPF in patients undergoing pancreatic resection were included. The quality of the studies was assessed using Quality Assessment of Diagnostic Accuracy Studies.

RESULTS

Five studies, including 247 patients who underwent partial pancreatic resection of whom 72 patients experiencing CR-POPF, were selected. All studies performed US elastography in different pancreatic sites. The pooled mean strain value was lower in pancreatic segments of patients experiencing CR-POPF than in those without, with a pooled weighted mean difference of -0.187 (95% confidence intervals, -0.303 to -0.071; P = 0.002). There was low heterogeneity between studies (I = 7.6%), and all studies were at "high risk" or "unclear risk" of bias.

CONCLUSIONS

This study provides evidence that US elastography values are statistically significantly lower in patients experiencing CR-POPF.

Relation of computed tomography features of the pancreatic tissue and development of pancreatic fistula after pancreaticoduodenectomy

BACKGROUND

Pancreatic density and steatosis detected in pre-operative computed tomography (CT) may be a risk factor for PF development after pancreatoduodenectomy (PD). There is insufficient data available on the relationship between PF and atherosclerosis in pancreatic vasculature of pancreatitis. This study aims to investigate whether PF development in patients undergoing PD can be predicted by preoperative CT findings.

MATERIAL-METHOD

Pancreas and spleen densities were measured on non-contrast CT images and pancreatic index (PI) was calculated to detect pancreatic steatosis. Pancreatic density and Wirsung diameter (WD) were measured on portal venous phase. Pancreatic fistulae were identified as biochemical leak (BL), grade B and grade C using ISGPF classification. The findings were compared between the fistula and non-fistula groups and ISGPF subgroups.

RESULTS

Of 148 patients, PF was detected on 31 (20.9%). In PF group, mean pancreatic density and PI were significantly lower than non-PF group, while pancreatic steatosis was detected at a higher rate. The WD was significantly narrower in the PF group. No significant relationship was found between the development of PF and the findings of atherosclerosis in the CT and SMA or acute pancreatitis. There was no significant difference between the PF subgroups for pancreas density.

CONCLUSION

In preoperative CT examinations, measuring the pancreatic density, PI index and WD can be used as a noninvasive quantitative method to predict the possibility of postoperative PF development.

Comparison of three fistula risk scores after pancreatoduodenectomy: A single-institution retrospective study

BACKGROUND

Postoperative pancreatic fistula (POPF) after pancreatoduodenectomy greatly influences patients' postoperative course. Several evaluation methods have been used to assess the risk of clinically relevant POPF (CR-POPF) after pancreatoduodenectomy namely, the original, alternative, and updated alternative fistula risk scores (o-FRS, a-FRS, and ua-FRS, respectively).

METHODS

We enrolled 106/179 patients who underwent pancreatoduodenectomy in our institution between April 2013 and Mar 2018. CR-POPF was defined as grade B and C POPF according to the 2016 definitions of the International Study Group on Pancreatic Surgery.

RESULTS

Pancreatic gland texture was the only significant risk factor for CR-POPF (p = 0.007). The CR-POPF incidence increased significantly according to the risk groups defined by both o-FRS (p = 0.004) and a-FRS (p = 0.004). The area under the curve for o-FRS, a-FRS, and ua-FRS was 0.693, 0.693, and 0.671, respectively.

CONCLUSION

o-FRS, a-FRS, and ua-FRS were almost equally useful for risk evaluation for CR-POPF after pancreatoduodenectomy. Further studies, especially for preoperative objective evaluation of pancreatic gland texture, are needed for more useful and accurate risk evaluation.

The efficacy of the 3-dimensional vibe-caipirinha-dixon technique in the evaluation of pancreatic steatosis

Background/aim

CAIPIRINHA is a new technique in abdominal imaging. Pancreatic steatosis (PS) is a subject of increasing scientific interest. The aim of this study was to investigate the efficacy of the isotropic 3D-VIBE- CAIPIRINHA -DIXON technique on a new generation 3-tesla MR unit in the evaluation of PS.

Materials and methods

In this retrospective study, the imaging findings of 49 patients with PS and 41 control subjects were examined. The pancreas-to-spleen ratio (PSR), pancreas-to-muscle ratio (PMR), and pancreatic signal intensity index (PSII) were defined as 3 new parameters and these indexes were calculated from the in-phase/out of phase 3D-VIBE- CAIPIRINHA-DIXON images.

Results

The PSR, PMR, and PSII values were significantly different between the patient and control groups (P = 0.001, P = 0.009, P < 0.001, respectively). Statistically significant differences were observed between patient and control groups for ROI measurements of fatty areas on these sequences/images: subtraction (in-out) (P < 0.001), T2W HASTE (P < 0.001), DIXON-fat (P < 0.001), fat-suppressed T1W (P = 0.002), and subtraction (out-in) (P = 0.010).

Conclusion

Evaluation of PS with the 3D-VIBE-CAIPIRINHA-DIXON technique can be made rapidly and effectively.

Non-alcoholic fatty pancreas disease - practices for clinicians

Obesity is a growing health burden worldwide, increasing the risk for several diseases featuring the metabolic syndrome - type 2 diabetes mellitus, dyslipidemia, non-alcoholic fatty liver disease and cardiovascular diseases. With the increasing epidemic of obesity, a new pathologic condition has emerged as a component of the metabolic syndrome - that of non-alcoholic fatty pancreas disease (NAFPD). Similar to non-alcoholic fatty liver disease (NAFLD), NAFPD comprises a wide spectrum of disease - from deposition of fat in the pancreas - fatty pancreas, to pancreatic inflammation and possibly pancreatic fibrosis. In contrast with NAFLD, diagnostic evaluation of NAFPD is less standardized, consisting mostly in imaging methods. Also the natural evolution of NAFPD and its association with pancreatic cancer is much less studied. Not least, the clinical consequences of NAFPD remain largely presumptions and knowledge about its metabolic impact is limited. This review will cover epidemiology, pathogenesis, diagnostic evaluation tools and treatment options for NAFPD, with focus on practices for clinicians.