title: Deep bleeder acoustic coagulation (DBAC)-Part I: development and in vitro testing of a research prototype cuff system.
abstract: BACKGROUND
  Bleeding from limb injuries is a leading cause of death on the battlefield, with deep wounds being least accessible. High-intensity focused ultrasound (HIFU) has been shown capable of coagulation of bleeding (cautery). This paper describes the development and refereed in vitro evaluation of an ultrasound (US) research prototype deep bleeder acoustic coagulation (DBAC) cuff system for evaluating the potential of DBAC in the battlefield. The device had to meet quantitative performance metrics on automated operation, therapeutic heating, bleeder detection, targeting accuracy, operational time limits, and cuff weight over a range of limb sizes and bleeder depths. These metrics drove innovative approaches in image segmentation, bleeder detection, therapy transducers, beam targeting, and dose monitoring. A companion (Part II) paper discusses the in vivo performance testing of an animal-specific DBAC system.
  
  
  METHODS
  The cuff system employed 3D US imaging probes ("Ix") for detection and localization (D&L) and targeting, with the bleeders being identified by automated spectral Doppler analysis of flow waveforms. Unique high-element-count therapeutic arrays ("Tx") were developed, with the final cuff prototype having 21 Tx's and 6 Ix's. Spatial registration of Ix's and Tx's was done with a combination of image-registration, acoustic time-of-flight measurement, and tracking of the cuff shape via a fiber optic sensor. Acoustic radiation force impulse (ARFI) imaging or thermal strain imaging (TSI) at low-power doses were used to track the HIFU foci in closed-loop targeting. Recurrent neural network (RNN) acoustic thermometry guided closed-loop dosing. The cuff was tested on three phantom "limb" sizes: diameters = 25, 15, and 7.5 cm, with bleeder depths from 3.75 to 12.5 cm. "Integrated Phantoms" (IntP) were used for assessing D&L, closed-loop targeting, and closed-loop dosing. IntPs had surrogate arteries and bleeders, with blood-mimicking fluids moved by a pulsatile pump, and thermocouples (TCs) on the bleeders. Acoustic dosing was developed and tested using "HIFU Phantoms" having precisely located TCs, with end-of-dose target ∆T = 33-58 °C, and skin temperature ∆T ≤ 20 °C, being required.
  
  
  RESULTS
  Most DBAC cuff performance requirements were met, including cuff weight, power delivery, targeting accuracy, skin temperature limit, and autonomous operation. The automated D&L completed in 9 of 15 tests (65 %), detecting the smallest (0.6 mm) bleeders, but it had difficulty with the lowest flow (3 cm/sec) bleeders, and in localizing bleeders in the smallest (7.5 cm) phantoms. D&L did not complete within the 9-min limit (results ranged 10-21 min). Closed-loop targeting converged in 20 of 31 tests (71 %), and closed-loop dosing power shut-off at preset ∆Ts was operational.
  
  
  CONCLUSIONS
  The main performance objectives of the prototype DBAC cuff were met, however the designs required a number of challenging new technology developments. The novel Tx arrays exhibited high power with significant beam steering and focusing flexibility, while their integrated electronics enabled the required compact, lightweight configurability and simplified driving controls and cable/connector architecture. The compounded 3D imaging, combined with sophisticated software algorithms, enabled automated D&L and initial targeting and closed-loop targeting feedback via TSI. The development of RNN acoustic thermometry made possible feedback-controlled dosing. The lightweight architecture required significant design and fabrication effort to meet mechanical functionalities. Although not all target specifications were met, future engineering solutions addressing these performance deficiencies are proposed. Lastly, the program required very complex limb test phantoms and, while very challenging to develop, they performed well.
authors.affiliation: Siemens Ultrasound Business Unit, 22010 S.E. 51st Street, Issaquah, WA 98029-1271 USA ; Medical Device and Technology Development and Commercialization (concultancy) , 8808 Points Dr. N.E, Yarrow Point, WA 98004 USA.
authors.forename: K Michael
authors.initials: KM
authors.lastname: Sekins
authors.affiliation: Siemens Ultrasound Business Unit, 22010 S.E. 51st Street, Issaquah, WA 98029-1271 USA.
authors.forename: Stephen R
authors.initials: SR
authors.lastname: Barnes
authors.affiliation: Siemens Ultrasound Business Unit, 22010 S.E. 51st Street, Issaquah, WA 98029-1271 USA.
authors.forename: Liexiang
authors.initials: L
authors.lastname: Fan
authors.affiliation: Siemens Ultrasound Business Unit, 22010 S.E. 51st Street, Issaquah, WA 98029-1271 USA.
authors.forename: Jerry D
authors.initials: JD
authors.lastname: Hopple
authors.affiliation: Siemens Ultrasound Business Unit, 22010 S.E. 51st Street, Issaquah, WA 98029-1271 USA.
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Hsu
authors.affiliation: Siemens Ultrasound Business Unit, 22010 S.E. 51st Street, Issaquah, WA 98029-1271 USA.
authors.forename: John
authors.initials: J
authors.lastname: Kook
authors.affiliation: Siemens Ultrasound Business Unit, 22010 S.E. 51st Street, Issaquah, WA 98029-1271 USA.
authors.forename: Chi-Yin
authors.initials: CY
authors.lastname: Lee
authors.affiliation: Siemens Ultrasound Business Unit, 22010 S.E. 51st Street, Issaquah, WA 98029-1271 USA.
authors.forename: Caroline
authors.initials: C
authors.lastname: Maleke
authors.affiliation: Siemens Ultrasound Business Unit, 22010 S.E. 51st Street, Issaquah, WA 98029-1271 USA.
authors.forename: A R
authors.initials: AR
authors.lastname: Ramachandran
authors.affiliation: Siemens Ultrasound Business Unit, 22010 S.E. 51st Street, Issaquah, WA 98029-1271 USA.
authors.forename: Xiaozheng Jenny
authors.initials: XJ
authors.lastname: Zeng
authors.affiliation: Siemens Corporate Research and Technology, 755 College Road East, Princeton, NJ 08540 USA.
authors.forename: Romain
authors.initials: R
authors.lastname: Moreau-Gobard
authors.affiliation: Siemens Corporate Research and Technology, 755 College Road East, Princeton, NJ 08540 USA.
authors.forename: Alexis
authors.initials: A
authors.lastname: Ahiekpor-Dravi
authors.affiliation: Siemens Corporate Research and Technology, 755 College Road East, Princeton, NJ 08540 USA.
authors.forename: Gareth
authors.initials: G
authors.lastname: Funka-Lea
authors.affiliation: Center for Industrial and Medical Ultrasound, Applied Physics Laboratory, University of Washington, 1013 NE 40th Street, Seattle, WA 98105-6698 USA.
authors.forename: Stuart B
authors.initials: SB
authors.lastname: Mitchell
authors.affiliation: Center for Industrial and Medical Ultrasound, Applied Physics Laboratory, University of Washington, 1013 NE 40th Street, Seattle, WA 98105-6698 USA.
authors.forename: Barbrina
authors.initials: B
authors.lastname: Dunmire
authors.affiliation: Center for Industrial and Medical Ultrasound, Applied Physics Laboratory, University of Washington, 1013 NE 40th Street, Seattle, WA 98105-6698 USA.
authors.forename: John C
authors.initials: JC
authors.lastname: Kucewicz
authors.affiliation: ETN LLC, 1150 Guinda St., Palo Alto, CA 94301 USA.
authors.forename: John
authors.initials: J
authors.lastname: Eaton
authors.affiliation: ETN LLC, 1150 Guinda St., Palo Alto, CA 94301 USA.
authors.forename: Keith
authors.initials: K
authors.lastname: Wong
authors.affiliation: Siemens Corporate Research and Technology, 755 College Road East, Princeton, NJ 08540 USA.
authors.forename: Scott
authors.initials: S
authors.lastname: Keneman
authors.affiliation: Center for Industrial and Medical Ultrasound, Applied Physics Laboratory, University of Washington, 1013 NE 40th Street, Seattle, WA 98105-6698 USA.
authors.forename: Lawrence A
authors.initials: LA
authors.lastname: Crum
keywords: ARFI; Acoustic coagulation; Acoustic hemostasis; Acoustic thermometry; Bleeding; Cautery; Combat bleeding; HIFU; Image compounding; Neural network; Phantom; Recurrent neural network; Ultrasound