Browsing by Author "Paun, Marla"

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    Comparison of Tissue Injury from Focused Ultrasonic Propulsion of Kidney Stones Versus Extracorporeal Shock Wave Lithotripsy
    (Elsevier, 2014-01) Connors, Bret A.; Evan, Andrew P.; Blomgren, Philip M.; Hsi, Ryan S.; Harper, Jonathan D.; Sorensen, Mathew D.; Wang, Yak-Nam; Simon, Julianna C.; Paun, Marla; Starr, Frank; Cunitz, Bryan W.; Bailey, Michael R.; Lingeman, James E.; Department of Anatomy & Cell Biology, IU School of Medicine
    Purpose Focused ultrasonic propulsion is a new non-invasive technique designed to move kidney stones and stone fragments out of the urinary collecting system. However, the extent of tissue injury associated with this technique is not known. As such, we quantitated the amount of tissue injury produced by focused ultrasonic propulsion under simulated clinical treatment conditions, and under conditions of higher power or continuous duty cycles, and compared those results to SWL injury. Materials and Methods A human calcium oxalate monohydrate stone and/or nickel beads were implanted (with ureteroscopy) into 3 kidneys of live pigs (45–55 kg) and repositioned using focused ultrasonic propulsion. Additional pig kidneys were exposed to SWL level pulse intensities or continuous ultrasound exposure of 10 minutes duration (ultrasound probe either transcutaneous or on the kidney). These kidneys were compared to 6 kidneys treated with an unmodified Dornier HM3 Lithotripter (2400 shocks, 120 SWs/min and 24 kV). Histological analysis was performed to assess the volume of hemorrhagic tissue injury created by each technique (% functional renal volume, FRV). Results SWL produced a lesion of 1.56±0.45% FRV. Ultrasonic propulsion produced no detectable lesion with the simulated clinical treatment. A lesion of 0.46±0.37% FRV or 1.15±0.49% FRV could be produced if excessive treatment parameters were used while the ultrasound probe was placed on the kidney. Conclusions Focused ultrasonic propulsion produced no detectable morphological injury to the renal parenchyma when using clinical treatment parameters and produced injury comparable in size to SWL when using excessive treatment parameters.
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    Focused Ultrasonic Propulsion of Kidney Stones
    (Mary Ann Liebert, Inc., 2013-12-09) Sorensen, Mathew D.; Bailey, Michael R.; Hsi, Ryan S.; Cunitz, Bryan W.; Simon, Julianna; Wang, Yak-Nam; Dunmire, Barbrina L.; Paun, Marla; Starr, Frank; Lu, Wei; Evan, Andrew P.; Harper, Jonathan D.; Anatomy and Cell Biology, School of Medicine
    Introduction: Our research group is studying a noninvasive transcutaneous ultrasound device to expel small kidney stones or residual post-treatment stone fragments from the kidney.1-3 The purpose of this study was to evaluate the efficacy and safety of ultrasonic propulsion in a live porcine model. Materials and Methods: In domestic female swine (50-60 kg), human stones (calcium oxalate monohydrate) and metalized glass beads (2-8 mm) were ureteroscopically implanted.4 Target stones and beads were placed in the lower half of the kidney and a reference bead was placed in the upper pole. Ultrasonic propulsion was achieved through a single ultrasound system that allowed targeting, stone propulsion, and ultrasound imaging using a Philips HDI C5-2 commercial imaging transducer and a Verasonics diagnostic ultrasound platform. Stone propulsion was achieved through the delivery of 1-second bursts of focused, ultrasound pulses, which consist of 250 finely focused pulses 0.1 milliseconds in duration. Stone propulsion was then observed using fluoroscopy, ultrasound, and visually with the ureteroscope. The kidneys were then perfusion-fixed with glutaraldehyde, embedded in paraffin, sectioned, and stained. Samples were histologically scored for injury by a blinded independent expert. Using the same pulsing scheme, while varying acoustic intensities, an injury threshold and patterns of injury were determined in additional pigs.5,6 Results: Stones were successfully implanted in 14 kidneys. Overall, 17 of 26 (65)% stones/beads were moved the entire distance to the renal pelvis, ureteropelvic junction (UPJ), or proximal ureter. The average procedure time for successfully repositioned stones was 14.2±7.9 minutes with 23±16 push bursts. No gross or histologic damage was identified from the ultrasound propulsion procedure. Under this pulsing scheme, a maximum exposure of 2400 W/cm2 was delivered during each treatment. An intensity threshold of 16,620 W/cm2 was determined at which, above this level, tissue injury consistent with emulsification, necrosis, and hemorrhage appeared to be dose dependent. Conclusions: Ultrasonic propulsion is effective with most stones being relocated to the renal pelvis, UPJ, or proximal ureter in a timely fashion. The procedure appears safe with no evidence of injury. The acoustic intensities delivered at maximum treatment settings are well below the threshold at which injury is observed. The angle and alignment of directional force are the most critical factors determining the efficacy of stone propulsion. We are now pursuing FDA approval for a human feasibility study. No competing financial interests exist. Runtime of video: 5 mins 44 secs.
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    Focused ultrasound to displace renal calculi: threshold for tissue injury
    (Springer Nature, 2014-03-31) Wang, Yak-Nam; Simon, Julianna C.; Cunitz, Bryan W.; Starr, Frank L.; Paun, Marla; Liggitt, Denny H.; Evan, Andrew P.; McAteer, James A.; Liu, Ziyue; Dunmire, Barbrina; Bailey, Michael R.; Anatomy, Cell Biology and Physiology, School of Medicine
    Background: The global prevalence and incidence of renal calculi is reported to be increasing. Of the patients that undergo surgical intervention, nearly half experience symptomatic complications associated with stone fragments that are not passed and require follow-up surgical intervention. In a clinical simulation using a clinical prototype, ultrasonic propulsion was proven effective at repositioning kidney stones in pigs. The use of ultrasound to reposition smaller stones or stone fragments to a location that facilitates spontaneous clearance could therefore improve stone-free rates. The goal of this study was to determine an injury threshold under which stones could be safely repositioned. Methods: Kidneys of 28 domestic swine were treated with exposures that ranged in duty cycle from 0%-100% and spatial peak pulse average intensities up to 30 kW/cm(2) for a total duration of 10 min. The kidneys were processed for morphological analysis and evaluated for injury by experts blinded to the exposure conditions. Results: At a duty cycle of 3.3%, a spatial peak intensity threshold of 16,620 W/cm(2) was needed before a statistically significant portion of the samples showed injury. This is nearly seven times the 2,400-W/cm(2) maximum output of the clinical prototype used to move the stones effectively in pigs. Conclusions: The data obtained from this study show that exposure of kidneys to ultrasonic propulsion for displacing renal calculi is well below the threshold for tissue injury.
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    Shockwave lithotripsy with renoprotective pause is associated with renovascular vasoconstriction in humans
    (Institute of Electrical and Electronics Engineers, 2014-09-03) Bailey, Michael; Lee, Franklin; Hsi, Ryan; Paun, Marla; Dunmire, Barbrina; Liu, Ziyue; Sorensen, Mathew; Harper, Jonathan; Department of Biostatistics, Richard M. Fairbanks School of Public Health
    Animal studies have shown that shock wave lithotripsy (SWL) delivered with an initial course of low-energy shocks followed by a pause reduces renal injury. The pause correlates with increased arterial resistive index (RI) during SWL as measured by ultrasound. This suggests that renal vasoconstriction is associated with protecting the kidney from injury. This study explored whether a similar increase in RI is observed in humans. Patients were prospectively recruited from two hospitals. All received an initial dose of 250 lowest energy shocks followed by a two-minute pause. Shock power was then ramped up at the discretion of the physician; shock rate was maintained at 1 Hz. Spectral Doppler velocity measurements were taken from an interlobar artery at baseline after induction, during the pause at 250 shocks, after 750 shocks, after 1500 shocks, and at the end of the procedure. RI was calculated from the peak systolic and end diastolic velocities and a linear mixed-effects model was used to compare RIs. The statistical model accounted for age, gender, laterality, and body mass index (BMI). Measurements were taken from 15 patients. Average RI ± standard deviation pretreatment, after 250 shocks, after 750 shocks, after 1500 shocks, and post treatment was 0.68 ± 0.06, 0.71 ± 0.07, 0.73 ± 0.06, 0.75 ± 0.07 and 0.75 ± 0.06, respectively. RI was found to be significantly higher after 250 shocks compared to pretreatment (p = 0.04). RI did not correlate with age, gender, BMI, or treatment side. This is suggestive that allowing a pause for renal vascular vasoconstriction to develop may be beneficial, and can be monitored for during SWL, providing real-time feedback as to when the kidney is protected.
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    Ultrasonic propulsion of kidney stones: preliminary results of human feasibility study
    (Institute of Electrical and Electronics Engineers, 2014-09-03) Bailey, Michael; Cunitz, Bryan; Dunmire, Barbrina; Paun, Marla; Lee, Franklin; Ross, Susan; Lingeman, James; Coburn, Michael; Wessells, Hunter; Sorensen, Mathew; Harper, Jonathan; Department of Medicine, IU School of Medicine
    One in 11 Americans has experienced kidney stones, with a 50% average recurrence rate within 5-10 years. Ultrasonic propulsion (UP) offers a potential method to expel small stones or residual fragments before they become a recurrent problem. Reported here are preliminary findings from the first investigational use of UP in humans. The device uses a Verasonics ultrasound engine and Philips HDI C5-2 probe to generate real-time B-mode imaging and targeted "push" pulses on demand. There are three arms of the study: de novo stones, post-lithotripsy fragments, and the preoperative setting. A pain questionnaire is completed prior to and following the study. Movement is classified based on extent. Patients are followed for 90 days. Ten subjects have been treated to date: three de novo, five post-lithotripsy, and two preoperative. None of the subjects reported pain associated with the treatment or a treatment related adverse event, beyond the normal discomfort of passing a stone. At least one stone was moved in all subjects. Three of five post-lithotripsy subjects passed a single or multiple stones within 1-2 weeks following treatment; one subject passed two (1-2 mm) fragments before leaving clinic. In the pre-operative studies we successfully moved 7 - 8 mm stones. In four subjects, UP revealed multiple stone fragments where the clinical image and initial ultrasound examination indicated a single large stone.