title: Comparison of Thresholds for Pulmonary Capillary Hemorrhage Induced by Pulsed-wave and B-mode Ultrasound.
abstract: Pulsed ultrasound was found to induce pulmonary capillary hemorrhage (PCH) in mice about 25 years ago but remains a poorly understood risk factor for pulmonary diagnostic ultrasound. In early research using laboratory fixed beam ultrasound, thresholds for PCH had frequency variation from 1-4 MHz similar to the Mechanical Index. In recent research, thresholds for B mode diagnostic ultrasound from 1.5-12 MHz had little dependence on frequency. To compare the diagnostic ultrasound method to laboratory pulsed exposure, thresholds for fixed beam ultrasound were determined using comparable methods at 1.5 and 7.5 MHz. PCH thresholds were lower for simple fixed-beam pulse modes than for B mode and in approximate agreement with early research. However, for comparable timing parameters, PCH thresholds had little dependence on ultrasonic frequency. These findings suggest that the MI may not be directly useful as a dosimetric parameter for safety guidance in pulmonary ultrasound.
authors.affiliation: Department of Radiology, Universtiy of Michigan, Ann Arbor MI 48109 USA.
authors.forename: Douglas L
authors.initials: DL
authors.lastname: Miller
authors.affiliation: Department of Radiology, Universtiy of Michigan, Ann Arbor MI 48109 USA.
authors.forename: Chunyan
authors.initials: C
authors.lastname: Dou
authors.affiliation: Department of Surgery, University of Michigan, Ann Arbor MI 48109 USA.
authors.forename: Krishnan
authors.initials: K
authors.lastname: Raghavendran
keywords: Mechanical Index; Pulmonary ultrasound; bioeffects of ultrasound; comet tail artifact; ultrasound dosimetry
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