title: Measurement of Thermal Effects of Doppler Ultrasound: An In Vitro Study.
abstract: OBJECTIVE
  Ultrasound is considered a safe imaging modality and is routinely applied during early pregnancy. However, reservations are expressed concerning the application of Doppler ultrasound in early pregnancy due to energy emission of the ultrasound probe and its conversion to heat. The objective of this study was to evaluate the thermal effects of emitted Doppler ultrasound of different ultrasound machines and probes by means of temperature increase of in-vitro test-media.
  
  
  METHODS
  We investigated the energy-output of 5 vaginal and abdominal probes of 3 ultrasound machines (GE Healthcare, Siemens, Aloka). Two in-vitro test objects were developed at the Center for Medical Physics and Biomedical Engineering, Medical University Vienna (water bath and hydrogel bath). Temperature increase during Doppler ultrasound emission was measured via thermal sensors, which were placed inside the test objects or on the probes' surface. Each probe was emitting for 5 minutes into the absorbing test object with 3 different TI/MI settings in Spectral Doppler mode.
  
  
  RESULTS
  During water bath test, temperature increase varied between 0.1 and 1.0°C, depending on probe, setting and focus, and was found highest for spectral Doppler mode alone. Maximum temperature increase was found during the surface heating test, where values up to 2.4°C could be measured within 5 minutes of emission.
  
  
  CONCLUSIONS
  Activation of Doppler ultrasound in the waterbath model causes a significant increase of temperature within one minute. Thermally induced effects on the embryo cannot be excluded when using Doppler ultrasound in early pregnancy.
authors: Department of Obstetrics and Gynecology, Medical University Vienna, Vienna, Austria.
authors: Samir
authors: S
authors: Helmy
authors: Department of Gynecology, Obstetrics and Reproductive Medicine, University Clinic of Saarland, Homburg, Germany.
authors: Yvonne
authors: Y
authors: Bader
authors: Department of Obstetrics and Gynecology, Medical University Vienna, Vienna, Austria; Karl Landsteiner Society, Austria.
authors: Marianne
authors: M
authors: Koch
authors: Department of Obstetrics and Gynecology, Medical University Vienna, Vienna, Austria.
authors: Denise
authors: D
authors: Tiringer
authors: Center for Medical Physics and Biomedical Engineering, Medical University Vienna, Vienna, Austria.
authors: Christian
authors: C
authors: Kollmann
mesh_terms: D001831:Body Temperature; D005260:Female; D005333:Fetus; D006801:Humans; D011247:Pregnancy; D013696:Temperature; D018608:Ultrasonography, Doppler / Q000009:adverse effects* / Q000295:instrumentation; D016216:Ultrasonography, Prenatal / Q000009:adverse effects* / Q000295:instrumentation