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15. Renal pelvis pressure and flowrate with a multi-channel ureteroscope: invoking the concept of outflow resistance.

Author

Bonzagni, Anthony F., Hall, Timothy L., Ghani, Khurshid R., and Roberts, William W.

Subjects
*OPTICAL fiber detectors, *KIDNEY pelvis, *TECHNOLOGICAL innovations, *SENSOR placement, *IRRIGATION (Medicine)
Abstract

Understanding renal pelvis pressure (PRP) during ureteroscopy (URS) has become increasingly important. High irrigation rates, desirable to maintain visualization and limit thermal dose, can increase PRP. Use of a multi-channel ureteroscope (m-ureteroscope) with a dedicated drainage channel is one strategy that may facilitate simultaneous low PRP and high flowrate. We sought to define the relationship between PRP and flowrate across a range of different outflow resistance scenarios with an m-ureteroscope versus a single-channel ureteroscope (s-ureteroscope). The m- or s-ureteroscope was placed into the pelvis of a validated silicone kidney-ureter model. Trials were conducted at irrigation pressures (50–150 cmH20) and five different outflow resistance scenarios simulated with catheters of different lengths and diameters. PRP was measured with a fiber optic pressure sensor positioned in the renal pelvis. Flowrate was determined by measuring the mass of drainage fluid over 60 s. PRP was lower with the m-ureteroscope than the s-ureteroscope when equivalent flowrates were delivered (i.e. 34 vs. 82 cmH20 respectively with 15 ml/min irrigation in a high outflow resistance scenario). Flowrate was higher with the m-ureteroscope than the s-ureteroscope when equivalent irrigation pressures were applied (i.e. 28 vs. 14 ml/min respectively with irrigation pressure 150 cmH20 in a high outflow resistance scenario). The m-ureteroscope has improved pressure-flow dynamics imparting important clinical benefits. More importantly, this approach to framing ureteroscopy in the context of pressure-flow relationships related by resistance values allows quantification of ureteroscopy within a deterministic system, which can be used to streamline future device development and technological innovation. [ABSTRACT FROM AUTHOR]

Published
2025
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16. A pre-clinical MRI-guided all-in-one focused ultrasound system for murine brain studies.

Author

Kaovasia, Tarana Parvez, Duclos, Sarah, Gupta, Dinank, Kalayeh, Kourosh, Fabiilli, Mario, Noll, Douglas C., Sukovich, Jonathan, Pandey, Aditya, Xu, Zhen, and Hall, Timothy L.

Subjects
MAGNETIC resonance imaging, BLOOD-brain barrier, ULTRASONIC therapy, FEVER, TRANSDUCERS, HIGH-intensity focused ultrasound
Abstract

This paper describes the design and initial proof-of-concept of a single pre-clinical transcranial focused ultrasound (FUS) system capable of performing histotripsy (mechanical ablation), hyperthermia, blood-brain barrier opening (BBBO), sonodynamic therapy, or neuromodulation in a murine brain. We have termed it the All-in-One FUS system for murine brain studies, which is the first FUS system of its kind. The 1.5 MHz ultrasound transducer was fabricated and driven using a custom electronic driver to produce 3-cycle pulses with a focal peak-negative pressure (P-) of up to 87 MPa at a low duty cycle (< 0.1%) for histotripsy as well as 50% duty cycle pulsed-ultrasound with a spatial-peak temporal-average intensity (Ispta) of up to 251 W/cm2 for the other FUS modalities. This All-in-One system can be guided by MRI or stereotactically to maximize its flexibility. To validate the design of the system, histotripsy, BBBO, and hyperthermia were performed in naïve brains of two mice for each modality. Histotripsy and BBBO were performed using MRI-based stereotactic co-registration. The therapeutic effect was confirmed using T2-weighted MR-images for histotripsy, and T1-weighted Gadolinium contrast-enhanced MR-images for BBBO. For hyperthermia, an MRI-compatible insert was designed to fit inside the 80 mm imaging coil of a 7-Tesla small-animal MRI-system, with T2-weighted MR-images used to confirm targeting, and MR-thermometry used to monitor the thermal dose delivered. [ABSTRACT FROM AUTHOR]

Published
2025
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23. In Vivo Cavitation-Based Aberration Correction of Histotripsy in Porcine Liver

Author

Yeats, Ellen, Lu, Ning, Stocker, Greyson, Komaiha, Mahmoud, Sukovich, Jonathan R., Xu, Zhen, and Hall, Timothy L.

Abstract

Histotripsy is a noninvasive ablation technique that focuses ultrasound pulses into the body to destroy tissues via cavitation. Heterogeneous acoustic paths through tissue introduce phase errors that distort and weaken the focus, requiring additional power output from the histotripsy transducer to perform therapy. This effect, termed phase aberration, limits the safety and efficacy of histotripsy ablation. It has been shown in vitro that the phase errors from aberration can be corrected by receiving the acoustic signals emitted by cavitation. For transabdominal histotripsy in vivo, however, cavitation-based aberration correction (AC) is complicated by acoustic signal clutter and respiratory motion. This study develops a method that enables robust, effective cavitation-based AC in vivo and evaluates its efficacy in the swine liver. The method begins with a high-speed pulsing procedure to minimize the effects of respiratory motion. Then, an optimal phase correction is obtained in the presence of acoustic clutter by filtering with the singular value decomposition (SVD). This AC method reduced the power required to generate cavitation in the liver by 26% on average (range: 0%–52%) and required ~2 s for signal acquisition and processing per focus location. These results suggest that the cavitation-based method could enable fast and effective AC for transabdominal histotripsy.

Published
2024
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35. An Ultrasound Array of Emitter-Receiver Stacks for Microbubble-Based Therapy

Author

Jiang, Zheng, Cudeiro-Blanco, Javier, Ilbilgi Yildiz, Betul, Sujarittam, Krit, Dickinson, Robert J., Guasch, Lluis, Tang, Mengxing, Hall, Timothy L., and Choi, James J.

Abstract

Most therapeutic ultrasound devices place emitters and receivers in separate locations, so that the long therapeutic pulses (>1 ms) can be emitted while receivers monitor the procedure. However, with such placement, emitters and receivers are competing for the same space, producing a trade-off between emission efficiency and reception sensitivity. Taking advantage of recent studies demonstrating that short-pulse ultrasound can be used therapeutically, we aimed to develop a device that overcomes such trade-offs. The array was composed of emitter-receiver stacks, which enabled both emission and reception from the same location. Each element was made of a lead zirconate titanate (PZT)–polyvinylidene fluoride (PVDF) stack. The PZT (frequency: 500 kHz, diameter: 16 mm) was used for emission and the PVDF (thickness: 28 μm, diameter: 16 mm) for broadband reception. 32 elements were assembled in a 3D-printed dome-shaped frame (focal length: 150 mm; ${\bm{f}}$-number: 1) and was tested in free-field and through an ex-vivo human skull. In free-field, the array had a 4.5 × 4.5 × 32 mm focus and produced a peak-negative pressure (PNP) of 2.12 MPa at its geometric center. The electronic steering range was ±15 mm laterally and larger than ±15 mm axially. Through the skull, the array produced a PNP of 0.63 MPa. The PVDF elements were able to localize broadband microbubble emissions across the skull. We built the first multi-element array for short-pulse and microbubble-based therapeutic applications. Stacked arrays overcome traditional trade-offs between the transmission and reception quality and have the potential to create a step change in treatment safety and efficacy.

Published
2024
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44. An X-Ray C-Arm Guided Automatic Targeting System for Histotripsy

Author

Wagner, Martin G., primary, Periyasamy, Sarvesh, additional, Kutlu, Ayca Z., additional, Pieper, Alexander A., additional, Swietlik, John F., additional, Ziemlewicz, Tim J., additional, Hall, Timothy L., additional, Xu, Zhen, additional, Speidel, Michael A., additional, Jr, Fred T. Lee, additional, and Laeseke, Paul F., additional

Published
2023
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