Lumbar punctures (LPs) are interventional procedures used to collect cerebrospinal fluid (CSF), a bodily fluid needed to
diagnose central nervous system disorders. Most lumbar punctures are performed blindly without imaging guidance.
Because the target window is small, physicians can only accurately palpate the appropriate space about 30% of the time
and perform a successful procedure after an average of three attempts. Although various forms of imaging based
guidance systems have been developed to aid in this procedure, these systems complicate the procedure by including
independent image modalities and requiring image-to-needle registration to guide the needle insertion. Here, we propose
a simple and direct needle insertion platform utilizing a single ultrasound element within the needle through dynamic
sensing and imaging. The needle-shaped ultrasound transducer can not only sense the distance between the tip and a
potential obstacle such as bone, but also visually locate structures by combining transducer location tracking and back
projection based tracked synthetic aperture beam-forming algorithm. The concept of the system was validated through
simulation first, which revealed the tolerance to realistic error. Then, the initial prototype of the single element
transducer was built into a 14G needle, and was mounted on a holster equipped with a rotation tracking encoder. We
experimentally evaluated the system using a metal wire phantom mimicking high reflection bone structures and an actual
spine bone phantom with both the controlled motion and freehand scanning. An ultrasound image corresponding to the
model phantom structure was reconstructed using the beam-forming algorithm, and the resolution was improved
compared to without beam-forming. These results demonstrated the proposed system has the potential to be used as an
ultrasound imaging system for lumbar puncture procedures.
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