The design of a single-insertion multiple specimen biopsy instrument

Abstract

Background: When a suspicious lesion is detected, a thorough examination is essential for the diagnostics of the lesion. Information about the nature and character of the lesion is crucial for the determination of the disease and an appropriate corresponding treatment plan. Taking a biopsy plays an important role in this examination. A biopsy is the removal of a tissue sample from a living organism. The aim of the biopsy is to provide a sufficient and representative part of a lesion, which will enable a thorough examination. Unfortunately,
the diagnostics of a biopsy is not always as accurate as desired. Core-needle biopsy is a commonly used minimally invasive biopsy technique. This technique uses a needle, with a varying size between 1.3mm to 2.1 mm, to cut away a tissue sample from a lesion. Biopsies taken with core-needle instruments do not
always represent the lesion sufficiently. It is often hard to determine the exact lesion site, and to know if the needle has indeed taken a biopsy from the lesion. To prevent non-diagnostic results from the biopsy, multiple samples should be taken from the lesion site. Common core-needle methods currently obtain a single biopsy sample per insertion. As multiple specimens must be obtained, multiple insertions of the biopsy instrument are required. The aim of this research is to design a single-insertion multiple specimen biopsy instrument.
This design will be developed and evaluated on its performance and functionality.
Methods: A list of requirements was setup to determine the conditions which comprise the design. Next to the requirements, a functional analysis was carried out which divided the functions of the design into three main functions. A, the insertion of the device into the lesion, B, the actions required to obtain a multitude of samples, and C, the retraction of the instrument from the body. The actions to obtain a multitude of samples, are subdivided into five actions: (1) the instrument must collect a tissue sample, and (2) enclose this tissue
sample into a container. (3) This container must be transported through the instrument. And subsequently stored inside the instrument, (4). Finally, (5) the instrument must be reloaded. This sequence of actions can be repeated until a number of specimens have been obtained. Using these five actions as a lead of the design process, conceptual designs were created. During the design process inspiration was found in firearms. The storing of bullets and reloading mechanisms found in guns could help find solutions to the storing and
reloading functions of the biopsy instrument. For each action a conceptual design is developed, and finally these five conceptual designs are combined and elaborated, resulting into one final design. A prototype of the final design was developed and evaluated. The prototype was validated on three different aspects: the ability to obtain multiple biopsy samples through a single insertion, the ability to use the prototype in accordance to the intended use, and a comparison between the prototype and an existing biopsy instrument in terms of
procedure duration. For each of these aspects the prototype was validated in three different proof of concept experiments.
Results: The prototype proved to successfully be able to take a multitude of biopsy specimens through a single insertion. Next to this initial evaluation, the intended use of the instrument is also successfully performed by the prototype. The last evaluation of the prototype, has shown that the procedure time of the
prototype to take a multitude of samples is longer than the procedure time to take a multitude of samples using and existing biopsy instrument (TruCore II). The prototype took 5 minutes and 7 seconds, whereas the existing biopsy instrument took 3 minutes and 50 seconds to obtain multiple tissue samples.
Discussion and Conclusion: The fabricated prototype has proven that it is able to take multiple tissue samples through a single insertion. This multitude of samples can be used to improve the diagnosis accuracy of core-needle biopsy. The functionality of the prototype is in accordance to the intended use. This
intended use provides an indication of the possibilities of use of the prototype. The procedure time of the prototype can be decreased by further improving the usability of the design. Future research can focus on a more elaborate evaluation on the accuracy of the instrument. Furthermore, future work can be carried out
on decreasing the instrument length of the current design. Another research can be done on possible ways to implement a semi-, or even a fully-automatic reloading and transportation mechanism on the now manual operable instrument. With these additional future improvements, this initial proof of concept prototype has the potential to become a fully functioning biopsy instrument.