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Active ultrasound pattern injection system (AUSPIS) for interventional tool guidance.

Guo X, Kang HJ, Etienne-Cummings R, Boctor EM - PLoS ONE (2014)

Bottom Line: Accurate tool tracking is a crucial task that directly affects the safety and effectiveness of many interventional medical procedures.Compared to CT and MRI, ultrasound-based tool tracking has many advantages, including low cost, safety, mobility and ease of use.We performed ex vitro and in vivo experiments, showing significant improvements of tool visualization and accurate localization using different US imaging platforms.

View Article: PubMed Central - PubMed

Affiliation: Dept. of Electrical and Computer Engineering, Johns Hopkins University, Baltimore, MD, United States of America.

ABSTRACT
Accurate tool tracking is a crucial task that directly affects the safety and effectiveness of many interventional medical procedures. Compared to CT and MRI, ultrasound-based tool tracking has many advantages, including low cost, safety, mobility and ease of use. However, surgical tools are poorly visualized in conventional ultrasound images, thus preventing effective tool tracking and guidance. Existing tracking methods have not yet provided a solution that effectively solves the tool visualization and mid-plane localization accuracy problem and fully meets the clinical requirements. In this paper, we present an active ultrasound tracking and guiding system for interventional tools. The main principle of this system is to establish a bi-directional ultrasound communication between the interventional tool and US imaging machine within the tissue. This method enables the interventional tool to generate an active ultrasound field over the original imaging ultrasound signals. By controlling the timing and amplitude of the active ultrasound field, a virtual pattern can be directly injected into the US machine B mode display. In this work, we introduce the time and frequency modulation, mid-plane detection, and arbitrary pattern injection methods. The implementation of these methods further improves the target visualization and guiding accuracy, and expands the system application beyond simple tool tracking. We performed ex vitro and in vivo experiments, showing significant improvements of tool visualization and accurate localization using different US imaging platforms. An ultrasound image mid-plane detection accuracy of ±0.3 mm and a detectable tissue depth over 8.5 cm was achieved in the experiment. The system performance is tested under different configurations and system parameters. We also report the first experiment of arbitrary pattern injection to the B mode image and its application in accurate tool tracking.

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The prototype AUSPIS setup.a) The block diagram of the AUSPIS. b) The pulser and logic unit board. c) One of the prototype catheters; it has an active echo element very close to the tip.
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pone-0104262-g003: The prototype AUSPIS setup.a) The block diagram of the AUSPIS. b) The pulser and logic unit board. c) One of the prototype catheters; it has an active echo element very close to the tip.

Mentions: Figure 3a shows the block diagram of the AUSPIS prototype. A piezoelectric element for both ultrasound receiving and transmitting is integrated with a catheter. The element is connected to a customized electronic circuit, which consists of a transmit/receive (T/R) switch, a variable gain amplifier (VGA) with analog filters, triggering circuit, analog to digital converter (ADC), an embedded microprocessor, and a pulser. Figure 3b and 3c show the circuit board and the catheter tip. The T/R switch circuit is built with a TX810 8 channel integrated switch to protect the receiving circuit from the transmission driving voltage, which can go up to a hundred volts. Analog filters have a low and high cutoff frequency of 0.1 MHz and 20 MHz. The trigger circuit compares the absolute value of the signal amplitude and the threshold, and sends pulses out when it is higher than the threshold. Since the receiver and emitter are the same element, the trigger circuit has a latch and reset function to prevent oscillating triggering. The ADC converts the analog signal to digital. The control program runs on an embedded processor, which controls all the peripherals on the AUSPIS circuit. To drive the element, the pulser is able to generate pulses with a minimum duration of 12.5 ns and variable voltage from zero to ±150 V. The active echo element is a customized small tube made of PZT5-H material with an outer diameter of 2.08 mm, inner diameter of 1.47 mm, and length of 2 mm. The catheter has a sealing layer around the element, which makes the overall diameter of the catheter tip close to 3.0 mm. A Sonix RP and a Sonix Touch ultrasound systems (UltraSonix Co.) with L14-5W (128 element) linear probe and 4DL14-5/38 (128 element) 3D probe is used in the experiment. We've also tested the AUSPIS with SonoSite portable ultrasound system to verify the cross platform operation performance.


Active ultrasound pattern injection system (AUSPIS) for interventional tool guidance.

Guo X, Kang HJ, Etienne-Cummings R, Boctor EM - PLoS ONE (2014)

The prototype AUSPIS setup.a) The block diagram of the AUSPIS. b) The pulser and logic unit board. c) One of the prototype catheters; it has an active echo element very close to the tip.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4206269&req=5

pone-0104262-g003: The prototype AUSPIS setup.a) The block diagram of the AUSPIS. b) The pulser and logic unit board. c) One of the prototype catheters; it has an active echo element very close to the tip.
Mentions: Figure 3a shows the block diagram of the AUSPIS prototype. A piezoelectric element for both ultrasound receiving and transmitting is integrated with a catheter. The element is connected to a customized electronic circuit, which consists of a transmit/receive (T/R) switch, a variable gain amplifier (VGA) with analog filters, triggering circuit, analog to digital converter (ADC), an embedded microprocessor, and a pulser. Figure 3b and 3c show the circuit board and the catheter tip. The T/R switch circuit is built with a TX810 8 channel integrated switch to protect the receiving circuit from the transmission driving voltage, which can go up to a hundred volts. Analog filters have a low and high cutoff frequency of 0.1 MHz and 20 MHz. The trigger circuit compares the absolute value of the signal amplitude and the threshold, and sends pulses out when it is higher than the threshold. Since the receiver and emitter are the same element, the trigger circuit has a latch and reset function to prevent oscillating triggering. The ADC converts the analog signal to digital. The control program runs on an embedded processor, which controls all the peripherals on the AUSPIS circuit. To drive the element, the pulser is able to generate pulses with a minimum duration of 12.5 ns and variable voltage from zero to ±150 V. The active echo element is a customized small tube made of PZT5-H material with an outer diameter of 2.08 mm, inner diameter of 1.47 mm, and length of 2 mm. The catheter has a sealing layer around the element, which makes the overall diameter of the catheter tip close to 3.0 mm. A Sonix RP and a Sonix Touch ultrasound systems (UltraSonix Co.) with L14-5W (128 element) linear probe and 4DL14-5/38 (128 element) 3D probe is used in the experiment. We've also tested the AUSPIS with SonoSite portable ultrasound system to verify the cross platform operation performance.

Bottom Line: Accurate tool tracking is a crucial task that directly affects the safety and effectiveness of many interventional medical procedures.Compared to CT and MRI, ultrasound-based tool tracking has many advantages, including low cost, safety, mobility and ease of use.We performed ex vitro and in vivo experiments, showing significant improvements of tool visualization and accurate localization using different US imaging platforms.

View Article: PubMed Central - PubMed

Affiliation: Dept. of Electrical and Computer Engineering, Johns Hopkins University, Baltimore, MD, United States of America.

ABSTRACT
Accurate tool tracking is a crucial task that directly affects the safety and effectiveness of many interventional medical procedures. Compared to CT and MRI, ultrasound-based tool tracking has many advantages, including low cost, safety, mobility and ease of use. However, surgical tools are poorly visualized in conventional ultrasound images, thus preventing effective tool tracking and guidance. Existing tracking methods have not yet provided a solution that effectively solves the tool visualization and mid-plane localization accuracy problem and fully meets the clinical requirements. In this paper, we present an active ultrasound tracking and guiding system for interventional tools. The main principle of this system is to establish a bi-directional ultrasound communication between the interventional tool and US imaging machine within the tissue. This method enables the interventional tool to generate an active ultrasound field over the original imaging ultrasound signals. By controlling the timing and amplitude of the active ultrasound field, a virtual pattern can be directly injected into the US machine B mode display. In this work, we introduce the time and frequency modulation, mid-plane detection, and arbitrary pattern injection methods. The implementation of these methods further improves the target visualization and guiding accuracy, and expands the system application beyond simple tool tracking. We performed ex vitro and in vivo experiments, showing significant improvements of tool visualization and accurate localization using different US imaging platforms. An ultrasound image mid-plane detection accuracy of ±0.3 mm and a detectable tissue depth over 8.5 cm was achieved in the experiment. The system performance is tested under different configurations and system parameters. We also report the first experiment of arbitrary pattern injection to the B mode image and its application in accurate tool tracking.

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