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Browsing by Subject "Doppler ultrasound"
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Item Contrast-Enhanced Ultrasound Versus Doppler Ultrasound for Detection of Early Vascular Complications of Pancreas Grafts(American Roentgen Ray Society, 2020-11) Swensson, Jordan; Hill, Danielle; Tirkes, Temel; Fridell, Jonathan; Patel, Aashish; Radiology and Imaging Sciences, School of MedicineOBJECTIVE. The purpose of this study is to compare conventional duplex ultrasound and contrast-enhanced ultrasound (CEUS) for identifying vascular abnormalities in pancreas allografts in the immediate posttransplant setting. Identification of pancreas allografts at risk of failure may impact patient care because early intervention for vascular insufficiency can lead to graft salvage. MATERIALS AND METHODS. Two radiologists who were blinded to patient outcomes performed a retrospective analysis of the postoperative Doppler ultrasound and CEUS images of 34 pancreas grafts from transplants performed between 2017 and 2019. A total of 28 patients who did not require surgical reexploration were considered the control group. Six patients had surgically proven arterial or venous abnormalities on surgical reexploration. Each radiologist scored grafts as having normal or abnormal vascularity on the basis of image sets obtained using Doppler ultrasound only and CEUS only. Comparisons of both the diagnostic performance of each modality and interobserver agreement were performed. RESULTS. Both readers showed that CEUS had increased sensitivity for detecting vascular abnormalities (83.3% for both readers) compared with Doppler ultrasound (66.7% and 50.0%). For both readers, the specificity of CEUS was similar to that of Doppler imaging (81.6% and 78.9% for reader 1 and reader 2 versus 76.3% and 84.2% for reader 1 and reader 2). For both readers, the negative predictive value of CEUS was higher than that of Doppler ultrasound (96.9% and 96.8% for reader 1 and reader 2 versus 93.5% and 91.4% for reader 1 and reader 2). Interobserver agreement was higher for CEUS than for Doppler ultrasound (κ = 0.54 vs κ = 0.28). CONCLUSION. CEUS may provide radiologists and surgeons with a means of timely and effective evaluation of pancreas graft perfusion after surgery, and it may help identify grafts that could benefit from surgical salvage.Item The role of trapped bubbles in kidney stone detection with the color Doppler ultrasound twinkling artifact(IOP Publishing, 2018-01-09) Simon, Julianna C.; Sapozhnikov, Oleg A.; Kreider, Wayne; Breshock, Michael; Williams, James C.; Bailey, Michael R.; Anatomy and Cell Biology, IU School of MedicineThe color Doppler ultrasound twinkling artifact, which highlights kidney stones with rapidly changing color, has the potential to improve stone detection; however, its inconsistent appearance has limited its clinical utility. Recently, it was proposed stable crevice bubbles on the kidney stone surface cause twinkling; however, the hypothesis is not fully accepted because the bubbles have not been directly observed. In this paper, the micron or submicron-sized bubbles predicted by the crevice bubble hypothesis are enlarged in kidney stones of five primary compositions by exposure to acoustic rarefaction pulses or hypobaric static pressures in order to simultaneously capture their appearance by high-speed photography and ultrasound imaging. On filming stones that twinkle, consecutive rarefaction pulses from a lithotripter caused some bubbles to reproducibly grow from specific locations on the stone surface, suggesting the presence of pre-existing crevice bubbles. Hyperbaric and hypobaric static pressures were found to modify the twinkling artifact; however, the simple expectation that hyperbaric exposures reduce and hypobaric pressures increase twinkling by shrinking and enlarging bubbles, respectively, largely held for rough-surfaced stones but was inadequate for smoother stones. Twinkling was found to increase or decrease in response to elevated static pressure on smooth stones, perhaps because of the compression of internal voids. These results support the crevice bubble hypothesis of twinkling and suggest the kidney stone crevices that give rise to the twinkling phenomenon may be internal as well as external.