Introduction:

Endoscopic ultrasonography with fine-needle aspiration allows performing a diagnosis of solid pancreatic lesions with an approximate 85% sensitivity, as referenced in specialized literature, and even lower sensitivity as per local research. To yield better sensitivity and to improve the results, it is required to examine new elements (needles) and techniques like elastography. Elastography helps in the quantification of tissue stiffness with a high level of accuracy. Since 2001, elastography has been applied in diagnosing solid forms of cancer (tumors) that affect organs like breasts, the thyroid, and some muscles. This method which has been used to diagnose solid pancreatic lesions (SPL) since 2006 has proved to be useful as a complementary method to the existing diagnostic techniques. It improves the accuracy of the endoscopic ultrasound-guided fine-needle aspiration biopsy (EUS-FNA) by selecting the more suspicious area to be punctured, and it also guides the clinical treatment after getting a negative EUS-FNA or a non-conclusive result.

Objective:

To evaluate the diagnostical performance of the strain ratio (SR) quantitative elastography by ecoendoscopy in solid pancreatic lesions, considering the cytopathologic diagnostic as the gold standard.

Methods:

71 patients (age range: 35-89 years old, mean: 62.2 years old); out of those 71 patients, The EUS to diagnose SPL, was performed on 35 women. This was a single-center, prospective cross-sectional study design. The EUS was performed with a Pentax linear endoscope and a Hitachi-Noblus ultrasound. The lesion (area A) and a reference area B were selected to calculate the deformation ratio (B/A, SR expressed as a percentage). SR > 22 was selected as a cut-off point to determine the malignant lesions (solid lesions), considering the evidence currently available. The results were compared with their cytopathology interpretation once that the EUS was performed. After the exclusion criteria was applied, a statistical analysis of 56 patients was performed, considering p < 0,05. The sensitivity, the specificity, the positive predictive value (PPV), the negative predictive value (NPV) and the diagnostic accuracy, were calculated, comparing the elastography SR with the final diagnostics with the cytopathology interpretation.

Results:

Quantitative elastography SR (%) allows to detect the malignant SPL with sensitivity 94.6% (95% confidence interval [CI]: 85.4%-98.2%), specificity of 89.3% (CI 95%: 78,5 %-95,0 %), PPV of 89.8% (CI 95 %: 79,5 %-95,3 %); NPV of 94.3% (IC 95 %: 84,6 %-98,1 %) and an accuracy of 92.0% (CI 95 %: 85,4 %-95,7 %).

Conclusion:

SR quantitative elastography by Endoscopic Ultrasound, EUS is a suitable complement method that improves the EUS-FNA accuracy, by selecting the most suspicious area to be punctured, and it also guides clinical treatment after getting a negative EUS-FNA or a non-conclusive result, due to its high sensitivity and specificity levels to diagnose malignant SPL.

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