DEBI: a new mechanical device for safer needle insertions

Over 1 million core-needle breast biopsies are performed every year in the US alone [1], while gastrointestinal and prostate biopsies are estimated in similar numbers. The cost of core-needle breast biopsies ranges between $500 for manual procedures to $6,000 for image-guided procedures [2]. A retrospective study indicated that approximately 2.5% of breast biopsies fail [3]. Needle bending has been identified as a significant cause of error in biopsies and is particularly likely to occur at the insertion stage [2]. The associated risks include: i) biopsy of the wrong site leading to misdiagnosis; ii) puncture of sensitive areas in proximity of the insertion path; iii) repeated insertions, thus longer procedure du- ration and increased patient discomfort. Biopsy needles are also prone to buckling, which can damage the needle permanently. Common techniques for correcting needle bending in clinical settings include repeating the inser- tion (which can be time-consuming) or using a needle guide (which reduces the maximum insertion depth). In research, axial rotation is typically employed for steering bevel-tip needles, but it is less effective for needles with an axial-symmetric tip [4]. Additionally, straight insertions require continuous axial rotation, which can damage soft tissue due to the spinning of the bevel tip [5]. Alternative approaches employ steerable needles, which are not yet part of clinical practice [6]. We have developed a mechanical device that detects needle bending as soon as it occurs and that immediately reduces the insertion force thus helping to avoid deep insertions with deflected needles and the associated risks. Unlike existing solutions, our design does not require actuators or sensors hence it can be made MRI- safe, sterilisable or disposable. Finally, our device can be used with a variety of standard needles, including multi-bevel needles (e.g. diamond tip or conical tip).