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Page 152 Kimbowa et al. Art Int Surg 2024;4:149-69 https://dx.doi.org/10.20517/ais.2024.20

REVIEW RESULTS
We categorized all the literature based on the challenges being solved and whether they are hardware-based
or software-based [Figure 2]. In this section, we briefly describe the different approaches, providing their
motivation, strengths, limitations, and how they have evolved.

Needle alignment
A main challenge with ultrasound needle-guided procedures is aligning the needle with the ultrasound
beam. Most solutions are hardware-based methods and can be broken down into two categories: (1) guided
insertion of the needle in the ultrasound plane; and (2) increasing the field view of the ultrasound probe.

Hardware-based methods
Guided insertion
The simplest guided insertion solution is to use needle guides that attach to the transducer to keep the
needle within the ultrasound plane , or to attach a laser on the ultrasound probe which projects a line on
[19]
[20]
the skin to indicate the ultrasound plane . In central venous catheterization, needle guides have been
shown to increase success rate under ultrasound . However, the needle can still deviate from the
[21]
ultrasound plane once inside the skin. In addition, a fixed system limits the degrees of freedom of the
[9]
needle . Robotic systems have been used clinically to perform ultrasound-guided needle insertion either
[22]
autonomously or semi-autonomously under the control of the surgeon . The first semi-autonomously
robotic ultrasound-guided nerve block in humans was conducted in 2013 with a 100% success rate and a
decrease in procedure time . Autonomous systems have been utilized in phantom models, successfully
[23]
maneuvering the ultrasound probe and needle simultaneously using Kalman and Random Sample
Consensus (RANSAC) algorithms with a 1 mm accuracy . Recent handheld robotic devices can guide
[24]
non-expert ultrasound users in probe localization and needle insertion, enabling them to achieve procedure
times and success rates similar to those of experts . However, the cost of implementing robotic technology
[25]
is high, and autonomous systems are still at the proof-of-concept phase.

Probe choice
Another approach to align the needle with the ultrasound beam is to maximize the field of view for a given
procedure, such as 3D imaging. A 3D image can be constructed by sweeping a 2D transducer over a region
of interest to capture numerous images. These 2D images are then processed with segmentation algorithms
to reconstruct the 3D view. 3D rendered images have been useful in analyzing anatomical structures and
guiding catheters for spreading local anesthetics after peripheral nerve blocks in patients . However, 3D
[26]
imaging and needle tracking in real time are not simultaneously possible using a 2D transducer. In contrast,
an electronic beam steering matrix array transducer can emit and receive sound waves in 3D, allowing for
real-time or 4D imaging. In a mid-line epidural lumbar spine needle placement study, the distance between
the puncture site identified by the 3D probe and standard palpitation was within 3 mm . Therefore, 3D
[27]
transducers show promise in aligning the needle within the ultrasound image. However, their resolution
[28]
and screen refresh rate (i.e., visible feed pauses) are inferior to 2D transducers .
Needle visualization and localization
Even when the needle is aligned with the ultrasound beam, it can often be challenging to visualize it and
then localize it. This section briefly highlights the various approaches that have been proposed to enhance
needle visualization and localization.