Value of Contrast-Enhanced Ultrasound Combined with Percutaneous Ultrasound-Guided Fine-Needle Aspiration in the Diagnosis of Solid Pancreatic Lesions
Pancreatic carcinomas are among the most aggressive tumors, with high mortality rates and an overall 5-year survival rate of only 7%. Most solid pancreatic lesions are malignant, but other conditions such as focal pancreatitis can complicate the diagnosis. Accurate differentiation of solid pancreatic masses is crucial for determining the appropriate treatment strategy, as the decision to proceed with surgery or other interventions largely depends on whether the lesion is malignant or benign. Percutaneous ultrasound (US)-guided fine-needle aspiration (FNA) is a widely used diagnostic method for pancreatic lesions, offering high accuracy and fewer complications compared to core needle biopsy (CNB). However, conventional US has limitations in identifying detailed features of lesions, such as necrosis, fibrosis, or areas hidden within inflammatory regions. Contrast-enhanced ultrasound (CEUS) has emerged as a valuable tool to address these limitations by providing enhanced visualization of microvascular perfusion and lesion characteristics.
This study aimed to evaluate the diagnostic accuracy of percutaneous US-guided FNA for solid pancreatic lesions with or without CEUS assessment. The research retrospectively analyzed clinical, imaging, and pathologic data from 181 patients with solid pancreatic masses who underwent percutaneous US-FNA and ThinPrep cytologic test (TCT) between January 2014 and December 2018. Patients were divided into two groups: the CEUS group, which underwent CEUS before biopsy, and the US group, which did not. The diagnostic performance of both groups was compared based on sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy.
The study included 107 male and 74 female patients, with an average age of 60 years. Among the 181 patients, 123 were in the CEUS group, and 58 were in the US group. No significant differences were observed in age, gender, or lesion size between the two groups. The final diagnosis was confirmed by pathology or clinical and radiological follow-up for at least 12 months. Pathological samples were obtained through biopsy or surgery, and malignancy was confirmed in 123 cases (76.4%) based on pathological results. The remaining 38 cases (23.6%) were confirmed as malignant based on clinical and radiographic progression or death. Among the 20 patients with benign diagnoses, 4 were confirmed by surgical pathology, and the remaining 16 had clinical courses consistent with benign disease.
The cytological diagnoses were classified into six categories: non-diagnostic, negative (for malignancy), atypical, neoplastic (benign or others), suspicious (for malignancy), and positive/malignant. For analysis, non-diagnostic, neoplastic, and negative cases were combined into a negative category, while malignant, suspicious, and atypical cases were classified as positive. The diagnostic accuracy of the CEUS group was 95.1% (117/123), significantly higher than the 86.2% (50/58) observed in the US group. The sensitivity, specificity, PPV, and NPV of the CEUS group were increased by 7.5%, 16.7%, 3.4%, and 18.8%, respectively, compared to the US group, although these differences were not statistically significant.
CEUS was particularly useful in identifying necrotic areas, severe fibrosis, and lesions hidden within inflammatory regions, which are often missed by conventional US. By providing detailed information on lesion characteristics, CEUS helped guide the biopsy procedure, ensuring that viable tissue was sampled and reducing the likelihood of false-negative or non-diagnostic results. For example, in one case, CEUS revealed a hypo-enhanced area within a lesion, which was later confirmed as pancreatic adenocarcinoma. In another case, CEUS identified a small hypo-enhanced area in the edge of a lesion, which was diagnosed as a solid pseudo-papillary neoplasm (SPN) after biopsy.
The study also highlighted the challenges in diagnosing metastatic tumors of the pancreas (MTPs). Three cases with negative cytological diagnoses were later confirmed as metastatic renal carcinoma. CEUS played a crucial role in these cases by demonstrating rapid hyper-enhancement in the arterial phase and slight reduction in the venous phase, which is characteristic of metastatic lesions. This information, combined with the patient’s clinical history, led to the correct diagnosis despite the limited number of tumor cells in the biopsy sample.
The complication rate was low in both groups, with only one case of acute pancreatitis reported in each group. Both patients recovered after conservative treatment, and no severe complications or deaths were associated with the biopsy procedures. The study concluded that CEUS is a valuable tool for improving the accuracy of percutaneous US-guided FNA in diagnosing solid pancreatic lesions, particularly in complex cases where conventional US may fail to provide sufficient information.
The findings of this study have important implications for clinical practice. CEUS can enhance the diagnostic accuracy of percutaneous US-guided FNA by providing detailed information on lesion characteristics and guiding the biopsy procedure. This reduces the need for repeat biopsies and improves the overall efficiency of the diagnostic process. While CEUS-FNA is more expensive and time-consuming than conventional US-FNA, the higher accuracy rate and lower repeat biopsy rate make it a cost-effective option for diagnosing solid pancreatic lesions.
The study also addressed the limitations of conventional US in evaluating pancreatic diseases. Conventional US is convenient, safe, and cost-effective but lacks the ability to provide detailed information on lesion perfusion and microvascular architecture. CEUS overcomes these limitations by enhancing the visualization of tumor characteristics, such as necrosis, fibrosis, and areas hidden within inflammatory regions. This information is critical for identifying the best biopsy route and ensuring that viable tissue is sampled.
In conclusion, CEUS is a valuable tool for improving the diagnostic accuracy of percutaneous US-guided FNA in solid pancreatic lesions. By providing detailed information on lesion characteristics and guiding the biopsy procedure, CEUS reduces the likelihood of false-negative or non-diagnostic results and avoids the need for repeat biopsies. The study recommends the use of CEUS in evaluating solid pancreatic masses, particularly in complex cases where conventional US may fail to provide sufficient information. Further multicenter prospective studies are needed to confirm these findings and establish standardized guidelines for the use of CEUS in pancreatic lesion diagnosis.
doi.org/10.1097/CM9.0000000000001638
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