Role of endoscopic ultrasound in pancreatic cancer

Pancreatic Mass Characterization Using IVIM-DKI MRI and Machine Learning-Based Multi-Parametric Texture Analysis

Non-invasive characterization of pancreatic masses aids in the management of pancreatic lesions. Intravoxel incoherent motion-diffusion kurtosis imaging (IVIM-DKI) and machine learning-based texture analysis was used to differentiate pancreatic masses such as pancreatic ductal adenocarcinoma (PDAC), pancreatic neuroendocrine tumor (pNET), solid pseudopapillary epithelial neoplasm (SPEN), and mass-forming chronic pancreatitis (MFCP). A total of forty-eight biopsy-proven patients with pancreatic masses were recruited and classified into pNET (n = 13), MFCP (n = 6), SPEN (n = 4), and PDAC (n = 25) groups. All patients were scanned for IVIM-DKI sequences acquired with 14 b-values (0 to 2500 s/mm2) on a 1.5T MRI. An IVIM-DKI model with a 3D total variation (TV) penalty function was implemented to estimate the precise IVIM-DKI parametric maps. Texture analysis (TA) of the apparent diffusion coefficient (ADC) and IVIM-DKI parametric map was performed and reduced using the chi-square test. These features were fed to an artificial neural network (ANN) for characterization of pancreatic mass subtypes and validated by 5-fold cross-validation. Receiver operator characteristics (ROC) analyses were used to compute the area under curve (AUC). Perfusion fraction (f) was significantly higher (p < 0.05) in pNET than PDAC. The f showed better diagnostic performance for PDAC vs. MFCP with AUC:0.77. Both pseudo-diffusion coefficient (D*) and f for PDAC vs. pNET showed an AUC of 0.73. ADC and diffusion coefficient (D) showed good diagnostic performance for pNET vs. MFCP with AUC: 0.79 and 0.76, respectively. In the TA of PDAC vs. non-PDAC, f and combined IVIM-DKI parameters showed high accuracy ≥ 84.3% and AUC ≥ 0.84. Mean f and combined IVIM-DKI parameters estimated that the IVIM-DKI model with TV texture features has the potential to be helpful in characterizing pancreatic masses.

Future role of endoscopic ultrasound in personalized management of pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) is aggressive and lethal with the majority of cases presenting with advanced unresectable disease due to delayed diagnosis. Despite improvement in surgery, chemotherapies, and intensive care medicine, the outcome of PDAC remains poor, which may relate to the tumor biology. Recent data suggest that PDAC is a "systemic cancer" with complex molecular or genomics derangement with marked heterogeneity. The ability to characterize the PDAC better by detailed evaluation of tissue biomarkers or genomics allows for improved prediction of prognosis and stratification of treatment, a concept known as "personalized cancer therapy." Using tissue from resected PDAC specimens has several weaknesses and is only possible in 20% of patients with PDAC. Endoscopic ultrasound (EUS)-guided biopsy overcomes these weaknesses, and with recent advancements in needle technology, tissue can be obtained for personalized cancer therapy for all patients with PDAC. This review aims to outline our current understanding of the molecular biology of PDAC specifically focusing on how EUS-guided biopsy may play a fundamental role in tissue acquisition, allowing for assessment and stratify therapy according to the individual cancer biology as we move toward the era of precision medicine.

Contrast-enhanced ultrasound in the differential diagnosis of exocrine versus neuroendocrine pancreatic tumors

OBJECTIVES

Contrast-enhanced ultrasound (CEUS) has been developed to better characterize the microvasculature of solid masses in several organs, including the pancreas. In this study, we assessed CEUS accuracy in differentiating exocrine from endocrine pancreatic tumors.

METHODS

A total of 127 patients with single, undetermined pancreatic masses were prospectively examined with transabdominal ultrasound and CEUS, before surgical resection or percutaneous biopsy.

RESULTS

Exocrine and endocrine pancreatic tumors showed different intralesional vascularization patterns: 98.9% (90/91) of exocrine tumors were hypoenhancing, whereas 95.8 % (23/24) of endocrine tumors had a hypervascular supply. A hypoenhancing pattern, indicative of ductal adenocarcinoma, had a significant (P < 0.001) diagnostic accuracy of 91.3% with a sensitivity of 96.8%, a specificity of 85.3%, a positive predictive value and a negative predictive value of 94.7% and 90.6%, respectively. The hyperenhancing pattern, indicative of endocrine tumors, had a significant (P = 0.031) diagnostic accuracy of 73.8% with a sensitivity of 83.3%, a specificity of 60.0%, a positive predictive value and negative predictive value of 83.3% and 60.0%, respectively.

CONCLUSIONS

Contrast-enhanced ultrasound has a valuable diagnostic accuracy in differentiating exocrine from endocrine pancreatic tumors, which is a fundamental step to address appropriate histological evaluation, therapeutic approach, and follow-up.

Imaging of focal autoimmune pancreatitis and differentiating it from pancreatic cancer

Autoimmune pancreatitis (AIP) is an inflammatory disorder of pancreas. Two types have been identified: the diffuse and the focal or mass forming. Clinical presentation of AIP overlaps that of pancreatic cancer (PC). Sometimes serum IgG4 and CA 19-9 levels are unable to differentiate AIP from PC. Various series have shown that 5%–21% of resected pancreatic masses for suspected malignancy turned out to be AIP. Accurate diagnosis of focal AIP can avoid unnecessary surgeries. This paper elaborates the various imaging modalities useful in differentiating focal AIP from PC.

Differentiation between pancreatic carcinoma and mass-forming chronic pancreatitis: usefulness of high b value diffusion-weighted imaging

OBJECTIVE

To investigate the value of high b value diffusion-weighted (DW) imaging in differentiating between pancreatic carcinoma and mass-forming chronic pancreatitis (MFCP).

METHODS

Fifty-one consecutive patients with pathology-proven pancreatic carcinoma (n = 37) or MFCP (n = 14) were evaluated with DW imaging (b value, 0 and 1000 s/mm(2)) at a 3-T MR system. Overall 20 healthy volunteers were evaluated as the control group. The apparent diffusion coefficient (ADC) values of normal pancreas, pancreatic carcinoma, MFCP, and mass-associated obstructive pancreatitis were measured.

RESULTS

On high b value (1000 s/mm(2) ) DW images, both pancreatic carcinoma and MFCP were hyperintense focal lesions; mass-associated obstructive pancreatitis occurred in 17 of 37 (45.9%) pancreatic carcinoma and 8 of 14 (57.1%) MFCP. The ADC (×10(-3) mm(2) /s) of the pancreatic carcinomas (1.06 ± 0.15) was significantly lower than that of normal pancreas (1.47 ± 0.18; P < 0.01), MFCP (1.35 ± 0.14; P < 0.01) and mass-associated chronic pancreatitis (1.44 ± 0.17; P < 0.01). The ADC of MFCP was also lower than that in the normal pancreas (P = 0.025), whereas the ADC of mass-associated obstructive pancreatitis was not different from those of the MFCP (P = 0.113) and normal pancreas (P = 0.544). When 1.195 was used as the optimal cut-off value, ADC quantification obtained a sensitivity of 85.7% and a specificity of 86.5% for differentiating pancreatic carcinomas from MFCP.

CONCLUSION

High b value DW imaging in combination with ADC quantification at a 3-T MR system is useful in differentiating between pancreatic carcinoma and MFCP.

Endoscopic ultrasonography findings in autoimmune pancreatitis

Endoscopic ultrasonography is an established diagnostic tool for pancreatic masses and chronic pancreatitis. In recent years there has been a growing interest in the worldwide medical community in autoimmune pancreatitis (AIP), a form of chronic pancreatitis caused by an autoimmune process. This paper reviews the current available literature about the endoscopic ultrasonographic findings of AIP and the role of this imaging technique in the management of this protean disease.