Figure 4 - uploaded by Philipp J Stolka
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2D needle detection: Canny edges, Hough transform lines, “twin peaks” in the transform, cropped input for possible 2nd pass (left to right)
Source publication
Handheld ultrasound is useful for intra-operative imaging, but requires additional tracking hardware to be useful in navigated intervention settings, such as biopsies, ablation therapy, injections etc. Unlike common probe-andneedle tracking approaches involving global or local tracking, we propose to use a bracket with a combination of very low-cos...
Context in source publication
Context 1
... Find needle candidates: In spite of the required general, unconstrained environment, the (any) needle can be found by looking for the longest, most prominent, straight line segment in the image. Strategies to find those features are well-established; the most straightforward might be edge-detection on the rectified grey-scale image, computation of the Hough transform on the resulting binary image, and selection of the n strongest peaks in the transform as needle candidates. This process is performed on both left and right images separately. Using the probabilistic Hough transform, one finds the presumed end points of detected 2D lines. In addition, Fig. 4 indicates ways to improve the line detection result in future work. For a well-visible needle, its image in the edge detection frame consists of two nearly-parallel lines (corresponding to the edges of said needle’s image, they extend in parallel over at least part of the length of the needle). This can be used to increase the robustness against false-positive needle detections. Furthermore, limited to the vicinity of the two peaks of the Hough transform corresponding to these parallel lines, the transform can be robustly recomputed with a higher resolution, thus increasing the final precision of the needle tracking. 2. Prune candidate set: The procedure above results in a potentially large number of line segments all over the two rectified stereo images, most of which do not correspond to any actual needle. In the next step, this set is pruned to find probable needle line candidates for further processing. Iterating over all combinations ( i, j ) of line segments L s i and R s j from the left and right images I L and I R , in a first step the combinations with horizontally non-overlapping segments (i.e. the segment in the left image is completely above or below the one in the right) are rejected. Second, combinations with line segments shorter than a threshold l min (heuristically set to l min = 30 px ) are rejected as well. In the third step, stereo information is used for further checks (Fig. 5). For each pixel L p i ( y ) on one line segment L s in the left image I , the corresponding pixel R p ( y ) on the line segment R s at the same ...
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Citations
... These methods incorporate an inertial sensor (e.g., three orthogonally mounted gyroscopes, or a Nintendo Wii™ remote's three-axis accelerometer) to detect angular rate of change and an optical mouse sensor to track translation along the body surface, resulting in 5 degree-offreedom tracking. [35][36][37] However, these studies have noted bias and drift in the inertial and optical mouse sensor readings; these effects can degrade the accuracy of the reconstruction and may limit the allowable scan duration. Attempts have been made to correct for bias and drift errors by comparing and combining inertial and optical tracking with ultrasound signal decorrelation. ...
... Attempts have been made to correct for bias and drift errors by comparing and combining inertial and optical tracking with ultrasound signal decorrelation. [37][38][39] Ultimately, these previous sensor-based 3D ultrasound acquisition and reconstruction methods have not proven to be cost-effective or practical for most clinical uses of ultrasound. 25 ...
Conventional two-dimensional (2D) ultrasound imaging is a powerful diagnostic tool in the hands of an experienced user, yet 2D ultrasound remains clinically underutilized and inherently incomplete, with output being very operator dependent. Volumetric ultrasound systems can more fully capture a three-dimensional (3D) region of interest, but current 3D systems require specialized transducers, are prohibitively expensive for many clinical departments, and do not register image orientation with respect to the patient; these systems are designed to provide improved workflow rather than operator independence. This work investigates whether it is possible to add volumetric 3D imaging capability to existing 2D ultrasound systems at minimal cost, providing a practical means of reducing operator dependence in ultrasound. In this paper, we present a low-cost method to make 2D ultrasound systems capable of quality volumetric image acquisition: we present the general system design and image acquisition method, including the use of a probe-mounted orientation sensor, a simple probe fixture prototype, and an offline volume reconstruction technique. We demonstrate initial results of the method, implemented using a Verasonics Vantage research scanner.
... Efforts to combine optical and acoustic imaging has spurred the development of needle tracking devices such as the Clear Guide ONE (Clear Guide Medical) which uses stereo and US imaging to guide the cannula via trajectory predictions 75,76 . Specifically, the Clear Guide ONE overlays the needle and end point target on an external US monitor to provide real-time data on the location and depth of the needle, and thus simplifies the insertion process for the clinician. ...
... For visual guidance, we use a Clear Guide ONE (Clear Guide Medical, Inc., Baltimore MD; Fig. 1), which adds instrument guidance capabilities to regular ultrasound machines for needle-based interventions. Instrument and ultrasound probe tracking is based on computer vision, using wide-spectrum stereo cameras mounted on a standard clinical ultrasound transducer [14]. Instrument guidance is displayed as a dynamic overlay on live ultrasound imaging. ...
Ultrasound-based interventions require experience and good hand-eye coordination. Especially for non-experts, correctly guiding a handheld probe towards a target, and staying there, poses a remarkable challenge. We augment a commercial vision-based instrument guidance system with haptic feedback to keep operators on target. A user study shows significant improvements across deviation, time, and ease-of-use when coupling standard ultrasound imaging with visual feedback, haptic feedback, or both.
... To address this issue, the Clear Guide ONE system (Clear Guide Medical, USA) 1 uses a similar augmentation approach, but does not require customized needles; instead, it uses a device mounted directly onto the US probe, which includes a structured light system to 1 Not yet approved for clinical use. track the needle and a combination of optical and inertial sensors for tracking the US probe (Stolka et al. 2011). ...
... Several methods to establish the transformation C M US from camera to US image coordinates were explored. One well-known approach [13,9] involves the presentation of linear objects (such as needles) to the cameras and the US imager, and to solve the resulting equation system of 3D camera lines and 2D intersection points with the US plane. ...
... The basic method to reconstruct needle poses from the left and right camera images in real time and in 4DoF (degrees of freedom) has been described in [13]. We now track the needle tip by directly measuring insertion depth as well, leaving only the long-axis DoF untracked. ...
With real-time instrument tracking and in-situ guidance projection directly integrated in a handheld ultrasound imaging probe, needle-based interventions such as biopsies become much simpler to perform than with conventionally-navigated systems. Stereo imaging with needle detection can be made sufficiently robust and accurate to serve as primary navigation input. We describe the low-cost, easy-to-use approach used in the Clear Guide ONE generic navigation accessory for ultrasound machines, outline different available guidance methods, and provide accuracy results from phantom trials.
Objective:
This article presents two haptic guidance systems designed to help a clinician keep an ultrasound probe steady when completing ultrasound-assisted needle insertion tasks. These procedures demand spatial reasoning and hand-eye coordination because the clinician must align a needle with the ultrasound probe and extrapolate the needle trajectory using only a 2D ultrasound image. Past research has shown that visual guidance helps the clinician align the needle, but does not help the clinician keep the ultrasound probe steady, sometimes resulting in a failed procedure.
Methods:
We created two separate haptic guidance systems to provide feedback if the user tilts the ultrasound probe away from the desired setpoint using (1) vibrotactile stimulation provided by a voice coil motor or (2) distributed tactile pressure provided by a pneumatic mechanism.
Results:
Both systems significantly reduced probe deviation and correction time to errors during a needle insertion task. We also tested the two feedback systems in a more clinically relevant setup and showed that the perceptibility of the feedback was not affected by the addition of a sterile bag placed over the actuators and gloves worn by the user.
Conclusion:
These studies show that both types of haptic feedback are promising for helping the user keep the ultrasound probe steady during ultrasound-assisted needle insertion tasks. Survey results indicated that users preferred the pneumatic system over the vibrotactile system.
Significance:
Haptic feedback may improve user performance in ultrasound-based needle-insertion procedures and shows promise in training for needle-insertion tasks and other medical procedures where guidance is required.
