Medical Needle Design

Franseen Needle For Fine Needle Biopsy are composed of different materials, including aluminum, stainless steel, chromium-cobalt, and nitinol, offering various degrees of hardness and tensile properties. Nitinol needles, for example, are more flexible and preferred in cases where the echoendoscope is fully angulated, for example, with lesions in the uncinate process. Furthermore, all needles undergo postproductional modifications (by polymer coating, laser etching, mechanical dimpling, or sandblasting) in order to enhance the visualization of the needle tip during TA. The echogenicity of the currently available needles is dissimilar, but the difference has not been shown to impact neither tissue quality nor quantity.

Performance of different needle designs has been tested in several randomized controlled trials (RCT) and meta-analyses as well as numerous low-quality studies. The reversed bevel design has been most thoroughly examined in several RCTs and two meta-analyses evaluating needle performance in various solid lesions and lymph nodes. Compared to the FNA-needle, no overall difference was observed in sample adequacy, histologic core procurement rate, and adverse event rate. However, in order to reach a diagnostic sample, fewer passes were needed with the reversed bevel FNB needle compared to FNA needle. Subgroup analysis of nonpancreatic lesions, for example, submucosal tumors, are lacking in the aforementioned studies, and FNB needles may be useful in these cases. A meta-analysis by Facciorusso et al. evaluating diagnostic accuracy in subepithelial lesions, further strengthened the superiority of the FNB sampling in these lesions. In an interesting cost-analysis model originating from an RCT, FNB sampling was shown to have an overall lower cost compared to FNA, mainly caused by a higher diagnostic yield of these needles and lack of rapid on-site evaluation (ROSE) in the FNB group. As ROSE is not systematically utilized outside US, results from this study may not apply to other countries. As for the third-generation FNB needles, no difference between the fork-tip and Franseen needles was observed in terms of diagnostic accuracy and histologic core procurement rate. Furthermore, comparison of the two needles with the standard FNA needle was only reported for sample diagnostic adequacy, an outcome with no clearly established clinical significance, where both needles outperformed the FNA needle. Even though many studies have shown that different needle designs seem to have similar rates of diagnostic accuracy and histologic procurement, only a few studies have evaluated the actual size of the tissue obtained.