A loop-shaped minimally invasive brush for improved cytology sampling of pancreatic cysts during EUS-FNA

Pancreatic cancer is the fourth leading cause of cancer-related deaths in the West and has a 5-year survival rate of only 2%–9%. Pancreatic cystic lesions are precursors of pancreatic cancers and a prime target for early diagnosis. Endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) enables collection of cystic fluid aiming for the diagnosis of malign and premalign cysts. However, this fluid is acellular or paucicellular in 20% of cases, hampering a proper diagnosis. Here, we introduce a minimally invasive Nitinol brush that can be operated through the 413 µm lumen of a 22G FNA needle. During operation, the brush is rotated against the inner wall of the cyst, removing cells and dispersing them in the cystic fluid, where they can be aspirated through the needle. We demonstrate the brush function using three models. An in vitro cyst model was used to visualize the brushing procedure and the mechanical interaction between the brush and the wall of a spherical cavity. Ex vivo porcine intestine and bovine ovary cyst models were used to demonstrate how brushing increases the number of harvested cells with more than one order of magnitude. These results indicate the potential of cystic brushing for the minimally invasive early diagnosis of pancreatic adenocarcinoma.