Acoustic radiation force impulse imaging of the pancreas for estimation of pathologic fibrosis and risk of postoperative pancreatic fistula

Severity of hyperechoic pancreas on preoperative ultrasonography: high potential as a clinically useful predictor of a postoperative pancreatic fistula

PURPOSE

This study aimed to evaluate the effectiveness of using the severity of hyperechoic pancreas (HP) observed on preoperative ultrasonography (US) as a predictor of clinically relevant postoperative pancreatic fistula (CR-POPF).

METHODS

A retrospective study was conducted with 94 patients who underwent pancreatectomy between April 2006 and March 2021. The severity of HP on US was classified into two categories (normal to mild vs. moderate to severe [obvious HP]). Multiple preoperative and intraoperative parameters were analyzed to predict CR-POPF.

RESULTS

Out of the 94 patients, CR-POPF occurred in 21 (22%) patients, and obvious HP was observed in 30 (32%). Univariate analysis revealed that moderate to severe HP (obvious HP) was significantly associated with an increased incidence of CR-POPF (P<0.001). Factors such as the absence of pancreatitis, a small main pancreatic duct (<3 mm), intraoperative soft pancreas, increased body mass index, and lower pancreatic attenuation and attenuation index were also associated with CR-POPF (all P<0.05). Multivariate analysis showed that obvious HP and soft pancreatic texture were independent predictors of CR-POPF, with odds ratios of 11.53 (P=0.001) and 14.12 (P=0.003), respectively. The combination of obvious HP and soft pancreatic texture provided the most accurate prediction for CR-POPF.

CONCLUSION

The severity of HP, as observed on preoperative US, was significantly associated with CR-POPF. Severe HP may serve as a clinically useful predictor of POPF, especially when evaluated alongside the intraoperative pancreatic texture.

Proposal of the novel predictive model for postoperative pancreatic fistula in distal pancreatectomy for pancreatic tumor based on preoperative imaging parameters and stapler handling

BACKGROUND

Distal pancreatectomy (DP) using linear staplers is widely performed; however, postoperative pancreatic fistulas (POPF) remain an issue. This study aimed to analyze preoperative risk factors for POPF and assess stapler handling.

METHODS

We retrospectively analyzed consecutive patients who underwent DP for pancreatic tumors using a linear stapler between 2014 and 2022. Preoperative measurements included pancreas-to-muscle signal intensity ratio (SIR) on fat-suppressed T1-weighted magnetic resonance imaging (MRI). The main outcome was clinically relevant POPF of the 2016 International Study Group of Pancreatic Fistulas definition. The predictive ability of the model was compared with the distal fistula risk score (D-FRS) by using the area under the receiver operating characteristic curve (AUROC).

RESULTS

Among the 81 patients, POPF occurred in 31 (38.2%). Multivariate analysis identified computed tomography-measured pancreatic thickness (odds ratio [OR] 1.30, 95% confidence interval [CI] 1.05-1.61, p = 0.009) and SIR on T1-weighted MRI (OR 6.85, 95% CI 1.71-27.4, p = 0.002) as preoperative predictors. A novel preoperative model, "Thickness × MRI (TM)"-index, was established by multiplying these two variables. The TM-index exhibited the highest predictability preoperatively (AUROC 0.757, 95% CI 0.649-0.867). In the intraoperative variable analyses, TM-index (p < 0.001), thin cartridge application (p = 0.032), and short pre-firing compression (p = 0.047) were identified as significant risk factors for POPF. The model's AUROC combined with these two stapler handling methods was higher than D-FRS (0.851 vs. 0.660, p = 0.006).

CONCLUSIONS

The novel preoperative model exhibited excellent predictability. Thick cartridge use and long pre-firing compression were protective factors against POPF. This model may facilitate preventive surgical strategy development to reduce POPF.

Tomoelastography and Pancreatic Extracellular Volume Fraction Derived From MRI for Predicting Clinically Relevant Postoperative Pancreatic Fistula

BACKGROUND

Pancreatic stiffness and extracellular volume fraction (ECV) are potential imaging biomarkers for pancreatic fibrosis. Clinically relevant postoperative fistula (CR-POPF) is one of the most severe complications after pancreaticoduodenectomy. Which imaging biomarker performs better for predicting the risk of CR-POPF remains unknown.

PURPOSE

To evaluate the diagnostic performance of ECV and tomoelastography-derived pancreatic stiffness for predicting the risk of CR-POPF in patients undergoing pancreaticoduodenectomy.

STUDY TYPE

Prospective.

POPULATION

Eighty patients who underwent multiparametric pancreatic MRI before pancreaticoduodenectomy, among whom 16 developed CR-POPF and 64 did not.

FIELD STRENGTH/SEQUENCE

3 T/tomoelastography and precontrast and postcontrast T1 mapping of the pancreas.

ASSESSMENT

Pancreatic stiffness was measured on the tomographic c-map, and pancreatic ECV was calculated from precontrast and postcontrast T1 maps. Pancreatic stiffness and ECV were compared with histological fibrosis grading (F0-F3). The optimal cutoff values for predicting CR-POPF were determined, and the correlation between CR-POPF and imaging parameters was evaluated.

STATISTICAL TESTS

The Spearman's rank correlation and multivariate linear regression analysis was conducted. The receiver operating characteristic curve analysis and logistic regression analysis was performed. A double-sided P < 0.05 indicated a statistically significant difference.

RESULTS

Pancreatic stiffness and ECV both showed a significantly positive correlation with histological pancreatic fibrosis (r = 0.73 and 0.56, respectively). Patients with advanced pancreatic fibrosis had significantly higher pancreatic stiffness and ECV compared to those with no/mild fibrosis. Pancreatic stiffness and ECV were also correlated with each other (r = 0.58). Lower pancreatic stiffness (<1.38 m/sec), lower ECV (<0.28), nondilated main pancreatic duct (<3 mm) and pathological diagnosis other than pancreatic ductal adenocarcinoma were associated with higher risk of CR-POPF at univariate analysis, and pancreatic stiffness was independently associated with CR-POPF at multivariate analysis (odds ratio: 18.59, 95% confidence interval: 4.45, 77.69).

DATA CONCLUSION

Pancreatic stiffness and ECV were associated with histological fibrosis grading, and pancreatic stiffness was an independent predictor for CR-POPF.

LEVEL OF EVIDENCE

1 TECHNICAL EFFICACY STAGE: 5.

Radiological parameters to predict pancreatic texture: Current evidence and future perspectives

Preoperative prediction of the postoperative pancreatic fistula risk is critical in the current era of minimally invasive pancreatic surgeries to tailor perioperative management, thereby minimizing postoperative morbidity. Pancreatic duct diameter can be readily measured by any routine imaging used to diagnose pancreatic disease. However, radiological evaluation of pancreatic texture, an important determinant of pancreatic fistula, has not been widely used to predict the risk of postoperative pancreatic fistula. Qualitative and quantitative assessment of pancreatic fibrosis and fat fraction provides the basis for predicting pancreatic texture. Traditionally computed tomography has been utilized in identifying and characterizing pancreatic lesions and background parenchymal pathologies. With the increasing utilisation of endoscopic ultrasound and magnetic resonance imaging for evaluating pancreatic pathologies, elastography is emerging as a promising tool for predicting pancreatic texture. Also, recent studies have shown that early surgery for chronic pancreatitis is associated with better pain relief and preservation of pancreatic function. Pancreatic texture assessment can allow early diagnosis of chronic pancreatitis, facilitating early intervention. The present review outlines the current evidence in utilizing various imaging modalities for determining the pancreatic texture based on different parameters and image sequences. However, multidisciplinary investigations using strong radiologic-pathologic correlation are needed to standardize and establish the role of these non-invasive diagnostic tools in predicting pancreatic texture.

Pancreatoduodenectomy for suspected malignancy: nonmalignant histology confers increased risk of serious morbidity

BACKGROUND/AIMS

A tissue diagnosis is not always obtained prior to pancreatoduodenectomy (PD) and a proportion of patients are found to have noncancerous histology postoperatively. It is unknown if these patients have different outcomes when compared with those who have malignancy confirmed.

METHODS

A retrospective paired case matched control study was undertaken. Patients who underwent PD for suspected malignancy but ultimately had nonmalignant histology were identified. Each was matched to a confirmed malignant control using the following criteria: age, gender, body mass index, American Society of Anesthesiologists grade, neoadjuvant treatment, preoperative serum bilirubin, preoperative biliary stenting and type of pancreatic anastomosis. Matching was blinded to the measured outcomes, which included perioperative morbidity and mortality.

RESULTS

Forty-five cases were compared with 45 well-matched controls. There was no difference in 30- or 90-day mortality, or length of stay. While overall morbidity rates were the same, patients with nonmalignant disease were more likely to experience major (Clavien-Dindo grade III-IV) morbidity (40.0% versus 17.8%, p = 0.0352). Independently, rates of clinically relevant pancreatic fistula (CR-POPF) were higher in the nonmalignant group (22.2% versus 4.44%, p = 0.0131).

CONCLUSIONS

In our study, PD patients with nonmalignant histology had significantly higher incidence of major morbidity and CR-POPF when compared with those who had malignancy confirmed. This should be considered when planning the management of patients with known or presumed benign/premalignant disease.

Ultrasound Shear Wave Elastography of Normal Pancreas in Adult Subjects

Background and Purpose Transabdominal ultrasound (US)-based shear wave elastography (SWE) provides an attractive method of estimating pancreatic stiffness. There is limited data on the SWE values of the healthy pancreas in Indian subjects. The current study aimed to evaluate SWE of the normal pancreas.

Methods We performed a study from January 2019 to March 2019. We included adult patients who presented for the US of the upper abdomen for vague abdominal symptoms, unrelated to the pancreas. The SWE values were obtained from the pancreatic head and body. The association of pancreatic SWE with age, gender, fatty liver, chronic liver disease, and cholelithiasis was recorded.

Results During the study period, 205 subjects underwent SWE of the pancreas. The mean age of subjects was 41.3 (standard deviation [SD] 15.3) years. There were 93 males and 112 females. The mean SWE value in the head of the pancreas was 8.98 (SD 2.46 kPa), and that in the body region was 8.67 (SD 2.67 kPa). There was a positive correlation of SWE with age. The SWE of the pancreatic body was significantly higher in patients who had a fatty liver on US (p < 0.05). There was no significant association of SWE of the pancreas with gender, presence of chronic liver disease, or gallstones.

Conclusion The normal values of pancreatic SWE are correlated with age and fatty change in the liver.

Histological pancreatic findings correlate with computed tomography attenuation and predict postoperative pancreatic fistula following pancreatoduodenectomy

BACKGROUND

Although a soft pancreas is a widely-accepted reliable risk factor for postoperative pancreatic fistula (POPF) after pancreatoduodenectomy (PD), there is no established preoperative evaluation of pancreatic texture.

METHODS

Two hundred thirty-seven patients who underwent PD with histological pancreatic assessment were retrospectively enrolled. The degree of fibrosis and fatty infiltration was scored histologically as seven grades and five grades, respectively. Computed tomography (CT) attenuation of the pancreas was measured on preoperative unenhanced CT images. Correlations between the CT attenuation of the pancreas and the histological pancreatic findings, and the development of POPF were analyzed.

RESULTS

The fibrosis grade was significantly higher for hard pancreas than for soft pancreas (p < 0.001), whereas the fatty infiltration grade was similar between the two types (p = 0.161). CT attenuation of the pancreas was inversely correlated with both fibrosis grade (Spearman's rank correlation coefficient ([r] = -0.609, p < 0.001) and fatty infiltration grade (r = -0.382, p < 0.001). Multivariate analysis showed that body mass index ≥25 kg/m² (odds ratio [OR]: 5.64, p < 0.001) and fibrosis grade ≤2 (OR: 18.0, p < 0.001) were independent risk factors for clinically significant POPF.

CONCLUSION

Histological pancreatic texture can be evaluated with CT attenuation and might be helpful in preoperatively predicting the development of POPF after PD.

Evaluation of the Elasticity of the Pancreas Using Acoustic Radiation Force Impulse Elastography in Patients with Acute Pancreatitis: A Systematic Review and Meta-Analysis

Acoustic radiation force impulse (ARFI) elastography has been used to diagnose acute pancreatitis (AP). The present study aimed to assess the effectiveness of ARFI elastography in the diagnosis of AP. Studies examining the efficacy of ARFI elastography in AP were selected by searching MEDLINE, EMBASE, CENTRAL, ICTRP, and ClinicalTrial.gov. until September 2021. Meta-analyses were performed using random effects models. The Grading of Recommendations, Assessment, Development, and Evaluation approach was used to assess the certainty of the evidence. Eight case-control studies (994 patients) were included in the meta-analysis. The ARFI-Virtual Touch Quantification value (or ARFI shear wave propagation velocity) of the AP patient group was 0.83 m/s higher (95% confidence interval [CI]: 0.36-1.3) than that in the control group (95% CI: 1.0-1.28). The sensitivity and specificity of ARFI elastography for diagnosing AP were 98.3% (95% CI: 92.6-96.6%) and 95.5% (95% CI: 87.5-98.5%), respectively. The results showed that physicians could use ARFI elastography to accurately diagnose patients with AP. Additional well-designed studies are necessary to validate the efficacy of ARFI elastography in patients with AP.

Pancreatic Steatosis Is Associated with Both Metabolic Syndrome and Pancreatic Stiffness Detected by Ultrasound Elastography

INTRODUCTION

There is increasing evidence that pancreatic steatosis (PS) is associated with metabolic syndrome (MS). However, it is not known whether it is associated with PS grade and pancreatic stiffness, or not. We aimed to evaluate the relationship between PS and its grade detected by transabdominal ultrasound, and pancreatic stiffness determined by two-dimensional shearwave elastography (2D-SWE), whether it has clinical significance and its relationship with MS.

METHODS

Patients with and without PS were evaluated prospectively.

RESULTS

Patients with PS had higher odds ratio for MS (OR 5.49). Also, ultrasonographic grade of PS was associated with MS parameters and hepatosteatosis. Pancreatic SWE value was significantly higher in PS group and positively correlated with PS grade, liver fat, MS, number of MS criteria.

DISCUSSION/CONCLUSION

PS and its grade were associated with MS. In this first comprehensive PS-SWE study, we found that pancreas stiffness increased in the presence of PS, in correlation with PS grade and MS.

A modified alternative fistula risk score (a-FRS) obtained from the computed tomography enhancement pattern of the pancreatic parenchyma predicts pancreatic fistula after pancreatoduodenectomy

BACKGROUND

Alternative fistula risk score (a-FRS) is useful to predict clinically relevant postoperative pancreatic fistula (CR-POPF) after pancreatoduodenectomy (PD).

METHODS

Clinical data from 239 patients undergoing PD were collected. The CT value of the pancreatic parenchyma was measured in the nonenhanced (N), arterial (A), portal venous (P), and late (L) phases. The A/N, A/P, P/L and A/L ratios were calculated and their correlation with CR-POPF were analyzed. By replacing pancreatic texture with the best CT attenuation ratio, a modified a-FRS was developed.

RESULTS

Forty-seven patients developed CR-POPF. The A/P ratio (P < 0.001), P/L ratio (P = 0.002) and A/L ratio (P < 0.001) were significantly higher in the CR-POPF group. The A/L ratio performed best in predicting CR-POPF (AUC: 0.803) and the cut-off value is 1.36. A/L ratio >1.36 (P < 0.001), body mass index (P = 0.005) and duct diameter (P = 0.037) were independently associated with CR-POPF. By replacing soft texture with an A/L ratio >1.36, a modified a-FRS was developed and performed better than the a-FRS (AUC: 0.823 vs 0.748, P = 0.006) in predicting CR-POPF.

CONCLUSIONS

The modified a-FRS is an objective and preoperative model for predicting the occurrence of CR-POPF after PD.

Estimation of pancreatic fibrosis and prediction of postoperative pancreatic fistula using extracellular volume fraction in multiphasic contrast-enhanced CT

OBJECTIVE

To investigate the diagnostic performance of the extracellular volume (ECV) fraction in multiphasic contrast-enhanced computed tomography (CE-CT) for estimating histologic pancreatic fibrosis and predicting postoperative pancreatic fistula (POPF).

METHODS

Eighty-five patients (49 men; mean age, 69 years) who underwent multiphasic CE-CT followed by pancreaticoduodenectomy with pancreaticojejunal anastomosis between January 2012 and December 2018 were retrospectively included. The ECV fraction was calculated from absolute enhancements of the pancreas and aorta between the precontrast and equilibrium-phase images, followed by comparisons among histologic pancreatic fibrosis grades (F0‒F3). The diagnostic performance of the ECV fraction in advanced fibrosis (F2‒F3) was evaluated using receiver operating characteristic curve analysis. Multivariate logistic regression analysis was used to evaluate the associations of the risk of POPF development with patient characteristics, histologic findings, and CT imaging parameters.

RESULTS

The mean ECV fraction of the pancreas was 34.4% ± 9.5, with an excellent intrareader agreement of 0.811 and a moderate positive correlation with pancreatic fibrosis (r = 0.476; p < 0.001). The mean ECV fraction in advanced fibrosis was significantly higher than that in no/mild fibrosis (44.4% ± 10.8 vs. 31.7% ± 6.7; p < 0.001), and the area under the receiver operating characteristic curve for the diagnosis of advanced fibrosis was 0.837. Twenty-two patients (25.9%) developed clinically relevant POPF. Multivariate logistic regression analysis demonstrated that the ECV fraction was a significant predictor of POPF.

CONCLUSIONS

The ECV fraction can offer quantitative information for assessing pancreatic fibrosis and POPF after pancreaticojejunal anastomosis.

KEY POINTS

• There was a moderate positive correlation of the extracellular volume (ECV) fraction of the pancreas in contrast-enhanced CT with the histologic grade of pancreatic fibrosis (r = 0.476; p < 0.001). • The ECV fraction was higher in advanced fibrosis (F2‒F3) than in no/mild fibrosis (F0‒F1) (p < 0.001), with an AUC of 0.837 for detecting advanced fibrosis. • The ECV fraction was an independent risk factor for predicting subclinical (odds ratio, 0.81) and clinical (odds ratio, 0.80) postoperative pancreatic fistula.

The course and prognostic value of increased pancreas stiffness detected by ultrasound elastography during acute pancreatitis

BACKGROUND

In this study, we determined the pancreatic stiffness (PS) changes in the course of acute pancreatitis (AP) by ultrasound elastography and evaluated its relation with prognosis.

MATERIAL/METHODS

Pancreatic shear wave velocity measurements (SWM) were evaluated at the time of admission to the hospital, following clinical improvement, and one-month after for AP patients and compared to healthy volunteers. Its relationship with clinical severity indexes was evaluated.

RESULTS

The pancreatic SWM value in the healthy group was 7.72 ± 2.50 kPa, and in AP group was 10.97 ± 2.26 kPa (p = 0.000). There was no difference between mild and severe pancreatitis. The mean SWM was 8.96 ± 1.53 kPa after disease remission, and 8.83 ± 1.24 kPa after 1-month.

CONCLUSIONS

PS increases significantly during AP and decreases with clinical improvement, but this was still higher than controls, and it kept its elevation after 1-month. We think that larger, long-term studies are needed to determine the clinicopathological significance of this.

Proposal of a Preoperative CT-Based Score to Predict the Risk of Clinically Relevant Pancreatic Fistula after Cephalic Pancreatoduodenectomy

Background and Objectives: Postoperative pancreatic fistula after cephalic pancreatoduodenectomy (CPD) is still the leading cause of postoperative morbidity, entailing long hospital stay and costs or even death. The aim of this study was to propose the use of morphologic parameters based on a preoperative multisequence computer tomography (CT) scan in predicting the clinically relevant postoperative pancreatic fistula (CRPF) and a risk score based on a multiple regression analysis. Materials and Methods: For 78 consecutive patients with CPD, we measured the following parameters on the preoperative CT scans: the density of the pancreas on the unenhanced, arterial, portal and delayed phases; the unenhanced density of the liver; the caliber of the main pancreatic duct (MPD); the preoperatively estimated pancreatic remnant volume (ERPV) and the total pancreatic volume. We assessed the correlation of the parameters with the clinically relevant pancreatic fistula using a univariate analysis and formulated a score using the strongest correlated parameters; the validity of the score was appreciated using logistic regression models and an ROC analysis. Results: When comparing the CRPF group (28.2%) to the non-CRPF group, we found significant differences of the values of unenhanced pancreatic density (UPD) (44.09 ± 6.8 HU vs. 50.4 ± 6.31 HU, p = 0.008), delayed density of the pancreas (48.67 ± 18.05 HU vs. 61.28 ± 16.55, p = 0.045), unenhanced density of the liver (UDL) (44.09 ± 6.8 HU vs. 50.54 ± 6.31 HU, p = 0.008), MPD (0.93 ± 0.35 mm vs. 3.14 ± 2.95 mm, p = 0.02) and ERPV (46.37 ± 10.39 cm³ vs. 34.87 ± 12.35 cm³, p = 0.01). Based on the odds ratio from the multiple regression analysis and after calculating the optimum cut-off values of the variables, we proposed two scores that both used the MPD and the ERPV and differing in the third variable, either including the UPD or the UDL, producing values for the area under the receiver operating characteristic curve (AUC) of 0.846 (95% CI 0.694-0.941) and 0.774 (95% CI 0.599-0.850), respectively. Conclusions: A preoperative CT scan can be a useful tool in predicting the risk of clinically relevant pancreatic fistula.

Chronic pancreatitis for the clinician. Part 2: Treatment and follow-up. Interdisciplinary Position Paper of the Societat Catalana de Digestologia and the Societat Catalana de Pàncrees

Chronic pancreatitis is associated with impaired quality of life, high incidence of comorbidities, serious complications and mortality. Healthcare costs are exorbitant. Some medical societies have developed guidelines for treatment based on scientific evidence, but the gathered level of evidence for any individual topic is usually low and, therefore, recommendations tend to be vague or weak. In the present position papers on chronic pancreatitis from the Societat Catalana de Digestologia and the Societat Catalana de Pàncrees we aimed at providing defined position statements for the clinician based on updated review of published literature and on multidisciplinary expert agreement. The final goal is to propose the use of common terminology and rational diagnostic/therapeutic circuits based on current knowledge. To this end 51 sections related to chronic pancreatitis were reviewed by 21 specialists from 6 different fields to generate 88 statements altogether. Statements were designed to harmonize concepts or delineate recommendations. Part 2 of these paper series discuss topics on treatment and follow-up. The therapeutic approach should include assessment of etiological factors, clinical manifestations and complications. The complexity of these patients advocates for detailed evaluation in multidisciplinary committees where conservative, endoscopic, interventional radiology or surgical options are weighed. Specialized multidisciplinary units of Pancreatology should be constituted. Indications for surgery are refractory pain, local complications, and suspicion of malignancy. Enzyme replacement therapy is indicated if evidence of exocrine insufficiency or after pancreatic surgery. Response should be evaluated by nutritional parameters and assessment of symptoms. A follow-up program should be planned for every patient with chronic pancreatitis.

Intraoperative amylase level of pancreatic juice as a simple predictor of pancreatic fistula after pancreaticoduodenectomy

INTRODUCTION

A soft remnant texture of the pancreas is commonly accepted as a risk factor for postoperative pancreatic fistula (POPF) after pancreaticoduodenectomy (PD). However, its assessment is subjective. The aim of this study was to evaluate the significance of intraoperative amylase level of the pancreatic juice as a risk factor of POPF after PD.

METHOD

This study included 75 patients who underwent PD between November 2014 and April 2020 at Jikei University Hospital. We investigated the relationship between pancreatic texture, intraoperative amylase level of pancreatic juice, results of the pathological evaluations, and the incidence of POPF.

RESULTS

Twenty-three patients (31%) developed POPF. The significant predictors of POPF were non-ductal adenocarcinoma (p < 0.01), soft pancreatic remnant (p < 0.01), high intraoperative blood loss (p < 0.01), high intraoperative amylase level of pancreatic juice (p < 0.01), and low pancreatic fibrosis (p < 0.01). Multivariate analysis revealed that the significant independent predictors of POPF were high intraoperative blood loss (p < 0.01) and high intraoperative amylase level of pancreatic juice (p = 0.02). Receiver operating characteristic (ROC) analysis showed that the cut-off value for the intraoperative amylase level of pancreatic juice was 2.17 × 10⁵ IU/L (area under the curve = 0.726, sensitivity = 95.7%, and specificity = 50.0%) CONCLUSIONS: The intraoperative amylase level of pancreatic juice is a reliable objective predictor for POPF after PD.

A deep pancreas is a novel predictor of pancreatic fistula after pancreaticoduodenectomy in patients with a nondilated main pancreatic duct

BACKGROUND

We investigated the risk factors for clinically relevant postoperative pancreatic fistula after pancreaticoduodenectomy in patients with a nondilated main pancreatic duct.

METHODS

We investigated a total of 354 patients who underwent pancreaticoduodenectomy. The diameter of the main pancreatic duct, the shortest distance from the body surface to the pancreas (the pancreatic depth), and the computed tomography attenuation index (the difference between the pancreatic and splenic computed tomography attenuation) were measured in preoperative computed tomography.

RESULTS

One hundred eighty-one (51.1%) patients had a nondilated main pancreatic duct, and 50 (27.6%) of the 181 patients with a nondilated main pancreatic duct developed a clinically relevant postoperative pancreatic fistula. Univariate analyses revealed that the calculated body mass index (≥21.8 kg/m²) (P = .004), deep pancreas (pancreatic depth ≥51.2 mm) (P = .001), and low computed tomography attenuation index (≤-3.8 Hounsfield units) (P = .02) were significant risk factors for clinically relevant postoperative pancreatic fistula. The multivariate logistic regression analysis revealed that deep pancreas (odds ratio 2.370; 95% confidence interval 1.0019-5.590; P = .049) was an independent risk factor for clinically relevant postoperative pancreatic fistula. Among patients with a nondilated main pancreatic duct, deep pancreas (in comparison to patients without deep pancreas) was associated with male sex (72.7% vs 54.9%; P = .016), higher body mass index (22.5 kg/m² vs 19.6 kg/m²; P < .001), a history of diabetes mellitus (24.5% vs 8.5%; P = .006), a lower computed tomography attenuation index (-9.6 Hounsfield units vs -4.6 Hounsfield units; P = .007), a longer operative time (454 minutes vs 420 minutes; P = .007), and a higher volume of intraoperative blood loss (723 mL vs 500 mL; P < .001), respectively.

CONCLUSION

Deep pancreas may be an important parameter associated with significant risk factors for clinically relevant postoperative pancreatic fistula after pancreaticoduodenectomy in patients with a nondilated main pancreatic duct.

Role of ultrasound shear wave elastography in preoperative prediction of pancreatic fistula after pancreaticoduodenectomy

BACKGROUND

Majority of predictors of postoperative pancreatic fistula (POPF) use intraoperative variables. We aimed to study the role of preoperative ultrasound shear wave elastography (USWE) to predict POPF.

METHODS

The consecutive patients who underwent pancreaticoduodenectomy (PD) between January 2019 to March 2020 were prospectively enrolled. All patients underwent USWE assessment at the pancreatic neck level. Intraoperative variables including pancreatic texture, pancreatic duct diameter, blood loss and histological grading of fibrosis were also recorded. Associations between USWE and intraoperative variables and histological grading with the development of POPF were analyzed.

RESULTS

Of the 62 patients assessed, 50 patients (mean age: 53 ± 14 years; 31 males) were included. POPF and clinically relevant POPF (CRPOPF) were observed in 22 (44%) and 7 (14%) patients respectively. Soft pancreas was an independent predictor of CRPOPF (p = 0.04). The mean USWE valve was significantly lower in patients with CRPOPF as compared to no CRPOPF (9.7 Kpa vs. 12.8Kpa, p = 0.016). At receiver operating characteristic curve analysis, USWE value of 12.65Kpa yielded sensitivity and specificity of 100% and 47%, respectively, for prediction of CRPOPF. USWE showed significant correlation with intraoperative pancreatic texture (Spearman's rank correlation coefficient (ρ) = 0.565, p = 0.001).

CONCLUSION

USWE helps in preoperative prediction of CRPOPF. This may further help to customize management strategy in high risk patients.

[Predictors of external pancreatic fistulae after pancreatic resection]

Despite a significant decrease in postoperative mortality after pancreatic resections in recent years (5.2-15% after pancreatoduodenectomy and about 5% after distal pancreatectomy), incidence of postoperative complications remains high (30-50% and 22-50%, respectively). Postoperative pancreatic fistula is one of the most common and formidable complications. Currently, most authors use the classification proposed by the International Study Group for Pancreatic Fistula (biochemical failure, fistula type B and C). Prediction of the risk of postoperative fistula is still a complex and unresolved problem of modern surgical pancreatology. According to the literature, the main risk factors of postoperative pancreatic fistulae are obesity and high body mass index, concomitant cardiovascular diseases, no neoadjuvant chemo- and radiotherapy, soft pancreatic texture, narrow pancreatic duct, no fibrotic changes in parenchyma, adipose infiltration of the pancreas, advanced intraoperative blood loss, as well as center experience. Most often, magnetic resonance imaging, computed tomography, ultrasound elastography and various multivariate risk assessment systems are used to estimate the risk of pancreatic fistulae. However, a generally accepted technique does not exist. This manuscript is devoted to analysis of risk factors of postoperative pancreatic fistulae and diagnostic methods for assessment of this risk.

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.

Acoustic radiation force impulse imaging of pancreas in patients with early onset idiopathic recurrent acute pancreatitis

BACKGROUND AND AIMS

Patients with recurrent acute pancreatitis (RAP) may progress to chronic pancreatitis (CP). A critical step in this progression is the development of fibrosis. Elastography has been used to assess degree of fibrosis by measurement of shear wave velocity (SWV). The aim of this study was to measure the stiffness of pancreas as a surrogate for pancreatic fibrosis in patients with RAP and compare it with a group of individuals without any history of pancreatic disorders.

MATERIAL AND METHODS

Using acoustic radiation force impulse (ARFI) imaging SWV was calculated in 31 patients with idiopathic RAP having disease onset ≤30 years. A control group of 31 individuals with no history pancreatic disorder and no features of CP on endosonography was selected for comparison. ARFI imaging was done by a single radiologist who was blinded to the cases and controls RESULTS:: Mean age of patients with RAP was 24.8 (SD 9.86) years, disease duration was 3.45 (interquartile range 1-5) years, mean number of episodes 4.9 (SD 2.72). There was a significant difference in SWV between patients (1.27 ± 0.50 m/s) and controls (1.00 ± 0.17 m/s) (P = 0.001)). There was a positive correlation between SWV and number of pain episodes (P = 0.026) and negative correlation with BMI (P = 0.002).

CONCLUSION

SWV was high in patients with RAP indicating a stiff pancreas. The stiffness increases with the number of episodes of pancreatitis.

Intraoperative Ultrasound Elastography Is Useful for Determining the Pancreatic Texture and Predicting Pancreatic Fistula After Pancreaticoduodenectomy

OBJECTIVES

Pancreatic fistula (PF) is one of the most common complications after pancreaticoduodenectomy (PD). The soft pancreatic texture is known to be an important predictive factor for PF after PD. However, its evaluation is dependent on the sense of touch by the operator during operation, thus not objective. The aim of this study was to investigate the relationship between mean elasticity via intraoperative ultrasound elastography and histological pancreatic hardness, as well as predictive factor of PF after PD.

METHODS

Forty-eight patients who underwent ultrasound elastography during PD and had pancreatic parenchyma histologically evaluated were included.

RESULTS

Pancreatic fistula was noted in 20 patients. There were significant differences in the histological pancreatic fibrosis rate between soft pancreas group (8.2%) and hard pancreas group (28.4%, P < 0.05) and in the mean elasticity between soft pancreas group (1.94 m/s) and hard pancreas group (3.17 m/s, P < 0.05). The mean elasticity was significantly correlated with pancreatic fibrosis rate (P < 0.05). A multivariate analysis revealed that the mean elasticity of less than 2.2 m/s was a significant predictor of PF after PD (P = 0.003).

CONCLUSIONS

Intraoperative ultrasound elastography could predict pancreatic texture objectively. The mean elasticity of less than 2.2 m/s was a significant predictor of PF after PD.

Pancreatic ultrasound elastography is not useful to predict the risk of pancreatic fistulas after pancreatic resection

The clinical usefulness of pancreatic elastography (PE) in the assessment of the pancreatic texture before pancreatic resection still remains uncertain. The aims are: to evaluate the value of pancreatic stiffness in both healthy volunteers and patients affected by pancreatic tumor; to evaluate the ability of PE in predicting clinically relevant postoperative pancreatic fistula (CR-POPF). Pancreatic stiffness of healthy subjects was compared with those of pancreatic tumors measuring shear wave velocity (SWV). In the last group, the ability of preoperative SWV in predicting CR-POPF was evaluated using linear regression. Ninety subjects were consecutively enrolled. No difference was found in SWV in the two groups (1.33 ± 0.31 vs 1.26 ± 0.30, p = 0.337). Multivariate analyses showed that male gender was associated with a softer pancreas (OR 0.74, CI 0.55-0.98, p = 0.035). In the 45 patients suitable for a secondary endpoint, the presence of soft pancreas assessed by surgeon's palpation (OR 61.21; CI 2.14- > 1000; p = 0.016) and preoperative risk score (OR 1.72; CI 1.01-2.96; p = 0.049) was predictors of CR-POPF. SWV showed a trend in predicting CR-POPF. The pancreatic stiffness far to the pancreatic neoplasm is the same as healthy controls. SWV showed a trend in predicting CR-POPF but the clinical utility is limited.

Meta-analysis of modified Blumgart anastomosis and interrupted transpancreatic suture in pancreaticojejunostomy after pancreaticoduodenectomy

Postoperative pancreatic fistula (POPF) remains the main cause of surgery related mortality after pancreaticoduodenectomy. Various pancreatoenteric anastomosis methods have been developed to reduce the POPF rate. However, the optimum choice has not been clarified. A literature search is performed in electronic databases, including PubMed, Medline, Embase, CNKI and the Cochrane Library. Studies comparing modified Blumgart anastomosis with interrupted transpancreatic suture are included in this meta-analysis. Grade B/C POPF, overall POPF rate and overall sever complication rate (Clavien-Dindo classification IIIa or more) are measured as primary outcomes. Revman 5.3 was used to perform the analysis. Five retrospective comparative studies and 1 randomized controlled trial with a total number of 1409 patients are included in our analysis. Meta-analysis revealed that modified Blumgart anastomosis is associated with lower rate of grade B/C POPF [Odds Ratio (OR) 95% confidence interval (CI),0.32 (0.12-0.84); P = 0.02] and intra-abdominal abscess [OR 95%CI, 0.43 (0.29-0.65); P < 0.01] comparing with interrupted transpancreatic suture. However, this procedure could not reduce overall POPF [OR 95%CI,0.70 (0.34-1.44); P = 0.34] and overall sever complication rate [OR 95%CI,0.91 (0.48-1.72); P = 0.77]. At current level of evidence, modified Blumgart anastomosis is superior to interrupted transpancreatic suture in terms of grade B/C POPF and intra-abdominal abscess. However, high-grade evidence will be necessary to confirm these results.

Quantification of pancreatic elasticity in type 2 diabetes: A new potential imaging marker for evaluation of microangiopathy

PURPOSE

The aim of this study was to noninvasively explore pancreatic morphological and mechanical changes in diabetic patients with or without microangiopathy and to investigate the clinical correlations of pancreatic stiffness or size with diabetic microangiopathy.

METHODS

A total of 213 type 2 diabetic patients with / without microangiopathy (91/122) were prospectively enrolled. Microangiopathy included diabetic retinopathy, diabetic nephropathy and diabetic peripheral neuropathy. Each subject underwent pancreatic ultrasonography and elastography. The shear wave velocity (SWV) and thickness of the head, body and tail were measured and compared. Receiver operating characteristic (ROC) curves was performed in the diagnosis of microangiopathy. Risk factors of the occurrence of more microvascular complications were explored.

RESULTS

The SWV in pancreas increased significantly in patients with microangiopathy (P < 0.01) while the thickness was similar in all patients. The area under ROC curve for the SWV in pancreatic body was greatest (0.747) and the sensitivity, specificity were 73.0, 70.9 %. There was a significant shift towards the occurrence of more microvascular complications for patients with increasing of the SWV in pancreatic body (OR 39.25), long duration of diabetes (OR 1.077), aging (OR 1.039) and elevation of microalbuminuria (OR 1.004).

CONCLUSIONS

The SWV in pancreatic body was significantly high in diabetic patients with microangiopathy and was prominently correlated with the number of microvascular complications. The SWV in pancreatic body may be considered as a potential marker for diabetic microangiopathy and its occurrence.

Pancreatic attenuation on computed tomography predicts pancreatic fistula after pancreaticoduodenectomy

BACKGROUND

Some parameters using preoperative computed tomography (CT) have been evaluated to predict the development of pancreatic fistula (PF) after pancreaticoduodenectomy (PD). The present retrospective study evaluated the predictive value of pancreatic attenuation for PF after PD.

METHODS

A retrospective review was conducted of the patients who underwent PD between January 2010 and December 2014. The pancreatic attenuation was measured in unenhanced preoperative CT images. Pre- and intraoperative variables were analyzed for the risk of PF after PD.

RESULTS

Of the 346 consecutive patients, PF occurred in 116 (34%). The pancreatic attenuation was significantly greater in patients with PF than in those without PF (median, 40.0 vs. 33.3 Hounsfield units [HU], P < 0.001). A multivariate analysis showed that a pancreatic attenuation ≥30.0 HU (odds ratio [OR], 3.72; P < 0.001), a body mass index ≥25.0 kg/m² (OR, 3.67; P < 0.001) and a diameter of the main pancreatic duct <3.0 mm (OR, 1.84; P = 0.034) were independent risk factors for PF after PD.

CONCLUSION

The degree of pancreatic attenuation on preoperative CT images was significantly associated with PF, and a pancreatic attenuation ≥30.0 HU was an independent risk factor of PF after PD.

The Propagation Display Method Improves the Reproducibility of Pancreatic Shear Wave Elastography

Evaluation of the pancreatic elastic modulus (PEM) using shear wave elastography (SWE) requires at least 5 measurements to ensure reproducibility. The aim of this study was to evaluate improvement in reproducibility of SWE, using the propagation display method in normal pancreas ([NP] phase 1) and to examine the differences in PEM between NP and chronic pancreatitis (CP), intraductal papillary mucinous neoplasm (IPMN) and autoimmune pancreatitis ([AIP] phase 2). In phase 1, the measurement success rate, median PEM in repeated measurements and appropriate number of SWE measurements were determined in 109 cases with NP. In phase 2, PEM was measured in CP (n = 10), IPMN (n = 31) and AIP (n = 5), using the required number of SWE measurements determined in phase 1. In phase 1, the measurement success rate was 93.9% (92/109 cases). The median PEM for NP was 14.6 kPa and the appropriate number of SWE measurements was at least 3. In phase 2, the median PEMs in CP, IPMN and AIP were 19.6, 18.1 and 17.2 kPa, respectively, with significant differences between NP and CP (p = 0.0133) and between NP and IPMN (p = 0.0436). Use of the propagation display method in SWE improves the reproducibility of measurement of PEM.

Elastography of the Pancreas, Current View

Ultrasound elastography (USE) of the pancreas allows pancreatic tissue stiffness assessment by virtual palpation. Two main types of USE are used. For the pancreas strain elastography applying by endoscopic ultrasound has been established for the characterisation of small solid pancreatic lesions (SPL). In larger SPL >30 mm the results are less convincing mainly due to the heterogenicity of the lesions but also by concomitant changes of the surrounding pancreatic parenchyma. The current role of shear wave elastography has to be determined. This article reviews the current use of elastography of the pancreas.

A score model based on pancreatic steatosis and fibrosis and pancreatic duct diameter to predict postoperative pancreatic fistula after Pancreatoduodenectomy

Purposes

To establish a scoring model for the risk of postoperative pancreatic fistula (POPF) following pancreatoduodenectomy (PD).

Methods

PD Patients from 7 institutions in 2 independent sets: developmental (n = 457) and validation cohort (n = 152) were retrospectively enrolled and analyzed. Pancreatic Fibrosis (PF) and Pancreatic Steatosis (PS) were assessed by pathological examination of the pancreatic stump.

Results

Stepwise univariate and multivariate analysis indicated that pancreatic duct diameter ≤ 3 mm, increased PS and decreased PF were independent risk factors for POPF and Clinically Relevant Postoperative Pancreatic Fistula (CR-POPF). Based on the relative weight and odds ratio of each factor in the POPF, a simplified scoring model was developed. And patients were stratified into high-risk group (22~28 points), medium-risk group (15~21 points) and low-risk group (8~14 points). The receiver operating characteristic curve demonstrated that the Area under the curve for the predictive model was 0.868 and 0.887 in the model design group and the external validation group.

Conclusions

This study establishes a simplified scoring model based on accurately and quantitatively measuring the PS, PF and pancreatic duct diameter. The scoring model accurately predicted the risk of POPF.

Electronic supplementary material

The online version of this article (10.1186/s12893-019-0534-4) contains supplementary material, which is available to authorized users.

Assessment of acute obstructive pancreatitis by magnetic resonance imaging: Predicting the occurrence of pancreatic fistula following pancreatoduodenectomy

The aim of the present study was to assess the effect of preoperative acute obstructive pancreatitis on the risk of the occurrence of pancreatic fistula (PF) following pancreaticoduodenectomy. A total of 22 patients who developed postoperative PF were carefully matched with 22 control patients without PF according to demographic data, pancreatic pathology, presenting symptoms and other surgery-associated parameters. These parameters were compared between these two groups. The mean pancreatic apparent diffusion coefficient (ADC) values in the fistula group were 1.14±0.31×10^-3 mm²/s, which was significantly decreased compared with the non-fistula group (1.48±0.44×10^-3 mm²/s) (P=0.005). The pancreas-muscle signal intensity (SI) ratio on fat-suppressed T1 weighted image (rT1) in the fistula group was 1.71±0.25, which was significantly increased compared with the non-fistula group (1.25±0.29) (P<0.001). The pancreas-muscle SI ratios on fat-suppressed T2 weighted image (T2WI) in the fistula group and the non-fistula group were 0.72±0.08 and 0.62±0.07, respectively (P=0.79). There was no significant difference in pancreas-muscle SI ratio on fat-suppressed T2-weighted image (rT2) value between these two groups. Based on the receiver operating characteristic curve, the optimal cut-off value of ADC as a criterion for prediction of pancreatic fistula was 1.29×10^-3 mm²/s, which yielded a sensitivity of 77.3% and a specificity of 63.6%. In conclusion, the severity of acute obstructive pancreatitis was negatively associated with ADC values and pancreas-muscle SI ratio on rT1 images, which may be useful for predicting the occurrence of PF preoperatively.

Comparison of Duodenal Mucosal Chromogranin-A Expression in Non-Alcoholic Fatty Pancreas Dyspeptic Patients with and without Endosonography-Diagnosed Early Chronic Pancreatitis: A Case Series Study

Nonalcoholic fatty pancreas (NAFP) is hypothetically related to progressive fibro-inflammation of the pancreas whose exocrine function is controlled by enteroendocrine cells (EEC). There is little evidence of pancreatic fibrosis in fatty pancreas and of whether there are quantitative differences for EEC. This study aimed to prove the coexistence of NAFP and pancreatic fibrosis or early chronic pancreatitis (ECP) using acoustic radiation force impulse (ARFI) and endosonography. Besides, the expression of duodenal mucosal chromogranin-A, a surrogate for EEC, was analyzed. Dyspeptic patients were surveyed at the digestive clinic and received abdominal sonography, endosonography, and serology tests. Cases with organic causes of dyspepsia were excluded. Pancreatic fibrosis was defined as an ARFI value ≥1.3 m/s. ECP was defined by at least 2 scores of the Japan Pancreas Society endosonographic criteria. During endosonography, 4 biopsy samples of mucosa in the duodenal first part were obtained for analysis of chromogranin-A expression by Western blot. Mucosal biopsy was also performed at the gastric antrum for surveillance of Helicobacter pylori. Between January and June 2018, a total of 24 patients with NAFP were enrolled among 48 candidates and divided into 2 groups based on whether they had pancreatic fibrosis or not. In the pancreatic fibrosis group (n = 11, pancreatic ARFI: 1.76 ± 0.34 m/s), there was a higher endosonographic criteria score (2.45 vs. 1.61, p = 0.002), increased expression of chromogranin-A (p = 0.001), and more severe fatty pancreas that was defined by pancreatic duct blurring on abdominal sonography (91 vs. 46%, p = 0.062) as compared to the non-pancreatic fibrosis group (n = 13, pancreatic ARFI: 1.11 ± 0.09 m/s). A total of 54 endosonographic abnormalities of ECP was present in these 24 patients in the head (52%), body (31%), and tail (17%), an anatomic pattern similar to pancreatic adenocarcinoma. In conclusion, among dyspeptic patients with NAFP, the duodenal mucosa chromogranin-A showed increased expression in those with pancreatic fibrosis and endosonography-diagnosed ECP.

Computed Tomography Enhancement Pattern of the Pancreatic Parenchyma Predicts Postoperative Pancreatic Fistula After Pancreaticoduodenectomy

OBJECTIVE

The aim of this study was to assess the relationship between the computed tomography (CT) pancreatic parenchyma attenuation value and clinically relevant postoperative pancreatic fistula (POPF).

METHODS

The medical records of 115 patients who underwent pancreaticoduodenectomy and preoperative dynamic CT were retrospectively reviewed. The CT attenuation values of the nonenhanced (N), arterial (A), portal venous (P), and late (L) phase in the pancreatic parenchyma were determined via CT, and the A/N, A/P, and P/L ratios were calculated. The CT attenuation values and value ratios were compared between the POPF and non-POPF groups.

RESULTS

Thirty-two patients (28%) were categorized in the POPF group. On univariate analysis, the A/P ratio (P < 0.001) and P/L ratio (P = 0.018) were significantly higher in the POPF group. On receiver operating characteristic curve analysis, the A/P and P/L ratio cutoff values for predicting POPF were 1.19 and 1.17, respectively. Of the preoperative evaluable factors, A/P ratio of 1.19 or greater (P < 0.001; odds ratio, 10.3) and P/L ratio of 1.17 or greater (P = 0.049; odds ratio, 3.23) were independent predictive factors for POPF, and the combination of the 2 ratios was useful in detecting POPF preoperatively.

CONCLUSIONS

The enhancement pattern of the pancreatic parenchyma is associated with the development of clinically relevant POPF.

Magnetic Resonance Imaging as a Valid Noninvasive Tool for the Assessment of Pancreatic Fibrosis

OBJECTIVES

The aim of this study was to evaluate the utility of magnetic resonance imaging (MRI) for the noninvasive assessment of pancreatic fibrosis (PF).

METHODS

Fifty-two patients who underwent surgical resection of the pancreas, histological examination of resection margins, preoperative abdominal MRI, and fecal elastase-1 test were enrolled in the study. Pancreatic tissue was identified on the MRI T1-, T2-, and diffusion-weighted imaging sequences. Apparent diffusion coefficient (ADC) was measured at the expected resection margin of the pancreas.

RESULTS

There was a significant negative correlation between the ADC mean and histologically determined PF (r = -0.752, P = 0.001). For equal to or greater than 25% of PF, the ADC cutoff value was 1.331 or less, with a sensitivity of 77% and specificity of 88%. The unenhanced T1-weighted signal intensity ratio (T1SI) cutoff value was 172.1 or less. For equal to or greater than 50% of PF, the ADC cutoff value was 1.316 or less with a sensitivity of 85% and specificity of 88%. The highest sensitivity was obtained by combining ADC and T1SI values.

CONCLUSIONS

Combining both the ADC and T1SI measurement allows the detection of early PF with good sensitivity and specificity. Magnetic resonance imaging has the advantage of being noninvasive and widely used in the clinical setting, thus making our results easily transferable to routine clinical practice.

Ultrasound point shear wave elastography of the pancreas: comparison of patients with type 1 diabetes and healthy volunteers - results from a pilot study

Background

The aims of this study were to establish shear wave elastography of the pancreas by comparing measurements in patients with type 1 diabetes (T1D) and healthy volunteers and to consider whether this method could contribute to the screening or prevention of T1D.

Methods

This pilot study included 15 patients with T1D (10 men, 5 women) and 15 healthy volunteers (10 men, 5 women) as controls. Measurements were performed with a Siemens Acuson S3000 (Siemens Healthcare, Erlangen, Germany) using a 6C1 convex transducer and the Virtual Touch™ tissue quantification (VTQ) method.

Results

The mean shear wave velocity of the head of the pancreas was 1.0 ± 0.2 m/s (median: 1.1 m/s) for the study group and likewise 1.0 ± 0.2 m/s (median: 0.9 m/s) for the control group. Velocities of 1.2 ± 0.2 m/s (median: 1.2 m/s) were measured in the body of the pancreas in both groups. There was a significant difference between the values obtained in the tail of the pancreas: patients 1.1 ± 0.1 m/s (median: 1.0 m/s) versus controls 0.9 ± 0.1 m/s (median: 0.8 m/s) (p = 0.0474). The mean value in the whole pancreas of the study group was not significantly above that of the control group: 1.1 ± 0.1 m/s (median: 1.0 m/s) versus 1.0 ± 0.1 m/s (median: 1.0 m/s) (p = 0.2453).

Conclusions

Sonoelastography of the pancreas revealed no overall difference between patients with T1D and healthy volunteers. Patients with T1D showed higher values only in the tail segment. Future studies need to determine whether specific regional differences can be found in a larger study population.

Systematic review and meta-analysis of postoperative pancreatic fistula rates using the updated 2016 International Study Group Pancreatic Fistula definition in patients undergoing pancreatic resection with soft and hard pancreatic texture

BACKGROUND

In 2016, the International Study Group of Pancreatic Fistula (ISGPS) proposed an updated definition for postoperative pancreatic fistula (POPF). Pancreas texture (PT) is an established risk factor of POPF. The definition of soft vs. hard texture, however, remains elusive.

METHODS

A systematic search was performed to identify PT definitions and a meta-analysis linking POPF to PT using the updated ISGPS definition.

RESULTS

122 studies including 22 376 patients were identified. Definition criteria for PT varied among studies and most classified PT in hard and soft based on intraoperative subjective assessment. The total POPF rate (pooled grades B and C) after pancreatoduodenectomy was 14.5% (n = 10 395) and 15.5% (n = 3767) after distal pancreatectomy. In pancreatoduodenectomy, POPF rate was higher in soft compared to hard pancreas (RR, 4.4, 3.3 to 6.1; p < 0.001; n = 6393), where PT grouped as soft and hard. No data were available for intermediate PT.

CONCLUSION

The reported POPF rates may be used in planning future prospective studies. A widely accepted definition of PT is lacking and a correlation with the risk of POPF is based on subjective evaluation, which is still acceptable. Classification of PT into 2-groups is more reasonable than classification into 3-groups.

Evaluation of Pancreatic Fibrosis With Acoustic Radiation Force Impulse Imaging and Automated Quantification of Pancreatic Tissue Components

OBJECTIVES

The aim of this study was to determine whether computer-assisted digital analysis and acoustic radiation force impulse (ARFI) imaging were useful for assessing pancreatic fibrosis, and if ARFI imaging predicted postoperative pancreatic fistula (POPF).

METHODS

Seventy-eight patients scheduled to undergo pancreatic resection were enrolled. Shear wave velocity (SWV) at the pancreatic neck was measured preoperatively using ARFI imaging. Pancreatic tissue components on a whole slide image were quantified using an automatic image processing software. The relationship between SWV, fibrotic tissue content, and POPF incidence and clinical severity was analyzed.

RESULTS

The median collagen fiber, fatty tissue, and acinar cell contents were 11.6%, 8.5%, and 61.3%, respectively. Unlike fatty tissue, collagen fiber content and acinar cells were correlated with SWV (ρ = 0.440, P < 0.001 and ρ = -0.428, P < 0.001, respectively). Although collagen fiber content and SWV were associated with the overall incidence of POPF (P = 0.004 and 0.001, respectively), collagen fiber content and SWV had no statistical correlation with clinically relevant POPF (P = 0.268 and 0.052, respectively).

CONCLUSIONS

We objectively quantified the pancreatic tissue components using an automatic image processing software. Shear wave velocity was significantly related to collagen fiber content and suggests that ARFI imaging can be useful for evaluating pancreatic fibrosis.

Risk factors for pancreatic fistula following pancreaticoduodenectomy: A retrospective study in a Thai tertiary center

AIM

To analyze the risk factors of postoperative pancreatic fistula following pancreaticoduodenectomy in a Thai tertiary care center.

METHODS

We retrospectively analyzed 179 patients who underwent pancreaticoduodenectomy at our hospital from January 2001 to December 2016. Pancreatic fistula were classified into three categories according to a definition made by an International Study Group on Pancreatic Fistula. The risk factors for pancreatic fistula were analyzed by univariate analysis and multivariate logistic regression analysis.

RESULTS

Pancreatic fistula were detected in 88/179 patients (49%) who underwent pancreaticoduodenectomy. Fifty-eight pancreatic fistula (65.9%) were grade A, 22 cases (25.0%) were grade B and eight cases (9.1%) were grade C. Clinically relevant pancreatic fistula were detected in 30/179 patients (16.7%). The 30-d mortality rate was 1.67% (3/179 patients). Multivariate logistic regression analysis revealed that soft pancreatic texture (odds ratio = 3.598, 95%CI: 1.77-7.32) was the most significant risk factor for pancreatic fistula. A preoperative serum bilirubin level of > 3 mg/dL was the most significant risk factor for clinically relevant pancreatic fistula according to univariate and multivariate analysis.

CONCLUSION

Soft pancreatic tissue is the most significant risk factor for postoperative pancreatic fistula. A high preoperative serum bilirubin level (> 3 mg/dL) is the most significant risk factor for clinically relevant pancreatic fistula.

Usefulness of endoscopic ultrasonography-elastography as a predictive tool for the occurrence of pancreatic fistula after pancreatoduodenectomy

BACKGROUND

Pancreatic fistula (PF) is a major complication following pancreatoduodenectomy (PD). Pancreatic texture is a risk factor for PF, but its evaluation depends on the subjective judgment. The aim of this study was to investigate whether preoperative endoscopic ultrasonography-elastography (EUS-EG), which objectively assesses tissue elasticity, predict the development of PF following PD.

METHODS

Fifty-nine patients who underwent EUS-EG before PD and had pancreas parenchyma histologically evaluated were included. Using histogram analysis, mean elasticity (ME), which represents tissue elasticity and is inversely correlated with pancreatic fibrosis, was calculated.

RESULTS

Among 59 patients, 19 developed PF (32.2%). The ME in patients with PF was significantly higher than that in patients without PF (85.4 vs. 55.6, P < 0.001). Area under the receiver operating characteristic curve for the accuracy of pancreatic texture and ME for predicting PF were 0.718 and 0.846, respectively. When a ME of 70.0 was used as a cut-off value for predicting PF, the sensitivity and specificity were 84.2% and 80.0%, respectively. In a multivariate logistic regression analysis, only a ME of >70.0 was an independent predictor of PF (odds ratio 10.02, P = 0.008).

CONCLUSIONS

Endoscopic ultrasonography-elastography may be an accurate and objective method for predicting PF following PD.

Endoscopic ultrasound elastography for solid pancreatic lesions

Elastography is one of technologies assisting diagnosis of solid pancreatic lesions (SPL). This technology has been previously used for measuring the stiffness of various organs based on a principle of “harder the lesions, higher chance for malignancy”. Two elastography techniques; strain and shear wave elastography, are available. For endoscopic ultrasound (EUS), only the former is existing. To interpret results of EUS elastography for SPL, 3 methods are used: (1) pattern recognition; (2) strain ratio; and (3) strain histogram. Based on results of existing studies, these 3 techniques provide high sensitivity but low to moderate specificity and accuracy rate. This review will summarize all available information in order to update current situation of using elastography for an evaluation of SPLs to readers.

AMPK: a novel target for treating hepatic fibrosis

Fibrosis is a common process of excessive extracellular matrix (ECM) accumulation following inflammatory injury. Fibrosis is involved in the pathogenesis of almost all liver diseases for which there is no effective treatment. 5'-AMP-activated protein kinase (AMPK) is a cellular energy sensor that can ameliorate the process of hepatic fibrogenesis. Given the existing evidence, we first introduce the basic background of AMPK and hepatic fibrosis and the actions of AMPK in hepatic fibrosis. Second, we discuss the three phases of hepatic fibrosis and potential drugs that target AMPK. Third, we analyze possible anti-fibrosis mechanisms and other benefits of AMPK on the liver. Finally, we summarize and briefly explain the current objections to targeting AMPK. This review may aid clinical and basic research on AMPK, which may be a novel drug candidate for hepatic fibrosis.

Pancreatic Elastography From Acoustic Radiation Force Impulse Imaging for Evaluation of Diabetic Microangiopathy

OBJECTIVE

The purposes of this study were to compare pancreatic shear-wave velocity (SWV) in subjects with and those without diabetic microvascular complications and to investigate the feasibility of pancreatic SWV in evaluating diabetic microangiopathy.

SUBJECTS AND METHODS

SWV measurements were prospectively performed in 115 patients with diabetes mellitus and 115 healthy persons by use of acoustic radiation force impulse imaging. Patients with diabetes were divided into subgroups with and without microangiopathy. Pancreatic SWV was compared in three groups. Factors associated with increased SWV were studied.

RESULTS

Pancreatic SWV increased significantly in the subgroups with diabetes mellitus compared with the control group (p < 0.01). Especially, the SWV in the pancreatic body was significantly higher when microangiopathy was present (p < 0.01). In patients with diabetes, microangiopathy (standardized β = 0.208, p = 0.022), age (standardized β = 0.265, p = 0.004), and total cholesterol level (standardized β = 0.223, p = 0.011) were positively and markedly correlated with high SWV in the pancreatic body.

CONCLUSION

The increased SWV in the pancreatic body was significantly related to the presence of microangiopathy. It is feasible to use SWV in the pancreatic body to evaluate diabetic microangiopathy.

A novel preoperative predictor of pancreatic fistula using computed tomography after distal pancreatectomy with staple closure

PURPOSE

A thick pancreas has proven to be a conspicuous predictor of pancreatic fistula (PF) following distal pancreatectomy (DP) using staples. Other predictors for this serious surgical complication currently remain obscure. This study sought to identify novel predictors of PF following DP.

METHODS

One hundred and twenty-two patients were retrospectively assessed to determine the correlation between PF occurrence and the clinicopathological findings and radiologic data from preoperative computed tomography (CT). CT assessments included the thickness of the pancreas (TP) and pancreatic CT number (pancreatic index; PI), calculated by dividing the pancreatic CT by the splenic CT density.

RESULTS

Twenty-four patients (19.7%) developed a clinically relevant PF. TP was identified as an independent risk factor for PF in multivariate analyses (odds ratio 1.17; P = 0.0095). In subgroup analyses, a lower PI in a thick pancreas was a significant predictor of PF (P = 0.032). The combination of these two prediction parameters, known as the TP-to-PI ratio (TPIR), showed a significantly better prediction ability than TP alone (area under the receiver operating characteristic curve for the incidence of PF, TPIR 0.80 vs. TP 0.69; P = 0.037).

CONCLUSION

Combining the CT number with TP substantially improves the prediction ability for the incidence of PF following DP with staple use.

Quantitative evaluation of pancreatic tumor fibrosis using shear wave elastography

BACKGROUND & AIMS

There is no established non-invasive method for diagnosis of pancreatic fibrosis. Shear wave elastography (SW-EG) may be a candidate for this purpose. The aims of this study were to assess the reproducibility of SW-EG in the normal imaging pancreas (Phase 1) and to evaluate the diagnostic performance of SW-EG for pancreatic fibrosis classified histologically (Phase 2).

METHODS

Phase 1: This included 127 cases that underwent SW-EG of the normal imaging pancreas. SW-EG was measured at least five times in the pancreatic parenchyma and the median of repeated measurements was defined as the pancreatic elastic modulus (PEM). Phase 2: This included 53 cases that underwent SW-EG of the pancreatic parenchyma preoperatively and in which pancreas parenchyma were evaluated histologically. Histological fibrosis was graded in 4 stages: normal, mild, moderate, and severe.

RESULTS

Phase 1: Median PEM in the head, body, and tail of the pancreas were 3.23, 3.17, and 2.91 kPa, respectively, with no significant difference among regions (P = 0.554). The intraclass correlation coefficient showed good reproducibility (ρ = 0.71) after 5 measurements. Phase 2: There was a significant positive correlation between PEM and the histological pancreatic fibrosis stage (r_s = 0.63, P < 0.001). Areas under the receiver operating characteristic curve for the accuracy of SW-EG for diagnosis of pancreatic fibrosis were 0.85 (≥mild), 0.84 (≥moderate), and 0.87 (severe).

CONCLUSION

SW-EG can be used to determine the stage of pancreatic fibrosis non-invasively with high accuracy and reproducibility.

Indications and results of pancreatic stump duct occlusion after duodenopancreatectomy

Severe post-operative complications after pancreaticoduodenectomy (PD) are largely due to pancreatic fistula onset. The occlusion of the main pancreatic duct using synthetic glue may prevent these complications. Aim of this study is to describe this technique and to report short- and long-term results as well as the post-operative endocrine and exocrine insufficiency. Two hundred and four patients who underwent PD with occlusion of the main pancreatic duct in a period of 15 years were retrospectively analyzed. Post-operative complications and their management were the main aim of the study with particular focus on pancreatic fistula incidence and its treatment. At 1-year follow-up endocrine and exocrine functions were analyzed. We observed a 54 % pancreatic fistula incidence, most of which (77/204 patients) were a grade A fistula with little change in medical management. Twenty-eight patients developed a grade B fistula while only 2 % of patients (5/204) developed a grade C fistula. Nine patients required re-operation, 5 of whom had a post-operative grade C fistula. Post-operative mortality was 3.4 %. At 1-year follow-up, 31 % of patients developed a post-operative diabetes while exocrine insufficiency was encountered in 88 % of patients. The occlusion of the main pancreatic duct after PD can be considered a relatively safe and easy-to-perform procedure. It should be reserved to selected patients, especially in case of soft pancreatic texture and small pancreatic duct and in elderly patients with comorbidities, in whom pancreatic fistula-related complications could be life threatening.

ARFI: from basic principles to clinical applications in diffuse chronic disease-a review

Abstract

The many factors influencing the shear wave velocity (SWV) measured with Acoustic Radiation Force Impulse (ARFI) are examined in order to define the most correct examination technique. In particular, attention is given to the information achieved by experimental models, such as phantoms and animal studies. This review targets the clinical applications of ARFI in the evaluation of chronic diffuse disease, especially of liver and kidneys. The contribution of ARFI to the clinical workout of these patients and some possible perspectives are described.

Teaching Points

• Stiffness significantly varies among normal and abnormal biological tissues.

• In clinical applications physical, geometrical, anatomical and physiological factors influence the SWV.

• Elastographic techniques can quantify fibrosis, which is directly related to stiffness.

• ARFI can be useful in chronic diffuse disease of liver and kidney.