Safety Indices of Ultrasound: Adherence to Recommendations and Awareness During Routine Obstetric Ultrasound Scanning

Abstract

Purpose To analyze bioeffect safety indices and assess how often operators look at these indices during routine obstetric ultrasound.

Materials and Methods Automated analysis of prospectively collected data including video recordings of full-length ultrasound scans coupled with operator eye tracking was performed. Using optical recognition, we extracted the Mechanical Index (MI), Thermal Index in soft tissue (TIs), and Thermal Index in bone (TIb) values and ultrasound mode. This allowed us to report the bioeffect safety indices during routine obstetric scans and assess adherence to professional organization recommendations. Eye-tracking analysis allowed us to assess how often operators look at the displayed bioeffect safety indices.

Results A total of 637 ultrasound scans performed by 17 operators were included, of which 178, 216, and 243 scans were first, second, and third-trimester scans, respectively. During live scanning, the mean and range were 0.14 (0.1 to 3.0) for TIb, 0.2 (0.1 to 1.2) for TIs, and 0.9 (0.1 to 1.3) for MI. The mean and standard deviation of TIb were 0.15 ± 0.03, 0.23 ± 0.09, 0.32 ± 0.24 in the first, second, and third trimester, respectively. For B-mode, the highest TIb was 0.8 in all trimesters. The highest TIb was recorded for pulsed-wave Doppler mode in all trimesters. The recommended exposure times were maintained in all scans. Analysis of eye tracking suggested that operators looked at bioeffect safety indices in only 27 (4.2 %) of the scans.

Conclusion In this study, recommended bioeffect indices were adhered to in all routine scans. However, eye tracking showed that operators rarely assessed safety indices during scanning.

Zusammenfassung

Ziel Analyse der Bioeffekt-Sicherheitsindizes und Bewertung, wie häufig Anwender diese Indizes beim Routine-Ultraschall in der Geburtshilfe betrachten.

Material und Methoden Durchführung einer automatisierten Analyse prospektiv gesammelter Daten einschließlich der Videoaufnahmen von Ultraschalluntersuchungen in voller Länge, gekoppelt mit einem Eye-Tracking des Anwenders. Mithilfe optischer Erkennung wurden die Werte des mechanischen Index (MI), thermischen Index im Weichteilgewebe (TIs) und thermischen Index im Knochen (TIb) sowie der Ultraschallmodus extrahiert. Dadurch konnten wir die Bioeffekt-Sicherheitsindizes bei geburtshilflichen Routineuntersuchungen angeben und die Einhaltung der Empfehlungen der Berufsorganisation beurteilen. Die Analyse des Eye-Trackings ermöglichte es uns zu beurteilen, wie oft die Anwender die angezeigten Bioeffekt-Sicherheitsindizes betrachten.

Ergebnis Insgesamt wurden 637 Ultraschalluntersuchungen von 17 Anwendern eingeschlossen, von denen 178 im ersten, 216 im zweiten und 243 Untersuchungen im dritten Schwangerschaftstrimenon durchgeführt wurden. Bei der Live-Untersuchung lagen Mittelwert und Bereich des TIb bei 0,14 (0,1 bis 3,0), des TIs bei 0,2 (0,1 bis 1,2) und des MI bei 0,9 (0,1 bis 1,3). Mittelwert und Standardabweichung des TIb betrugen 0,15 ± 0,03 im ersten, 0,23 ± 0,09 im zweiten und 0,32 ± 0,24 im dritten Trimenon. Für den B-Modus lag der höchste TIb in allen Trimenons bei 0,8. Der höchste TIb wurde für den gepulsten Doppler-Modus in allen Trimenons gemessen. Die empfohlenen Expositionszeiten wurden bei allen Scans eingehalten. Die Analyse des Eye-Trackings ergab, dass die Anwender nur bei 27 Scans (4,2 %) auf die Bioeffekt-Sicherheitsindizes achteten.

Schlussfolgerung In dieser Studie wurden die empfohlenen Bioeffekt-Indizes bei allen Routine-Scans eingehalten. Die Eye-Tracking-Methode zeigte jedoch, dass die Anwender die Sicherheitsindizes während der Untersuchung nur selten analysieren.

Key words

ultrasound safety - doppler ultrasound - thermal index - output display standard - eye tracking

• References

• 1 Ang Jr ES, Gluncic V, Duque A. et al. Prenatal exposure to ultrasound waves impacts neuronal migration in mice. Proc Natl Acad Sci USA 2006; 103: 12903-12910
• 2 Abramowicz JS. Ultrasound and autism: association, link, or coincidence?. J Ultrasound Med 2012; 31: 1261-1269
• 3 Hoglund Carlsson L, Saltvedt S, Anderlid BM. et al. Prenatal ultrasound and childhood autism: long-term follow-up after a randomized controlled trial of first- vs second-trimester ultrasound. Ultrasound Obstet Gynecol 2016; 48: 285-288
• 4 Torloni MR, Vedmedovska N, Merialdi M. et al. Safety of ultrasonography in pregnancy: WHO systematic review of the literature and meta-analysis. Ultrasound Obstet Gynecol 2009; 33: 599-608
• 5 Salvesen KA. Ultrasound in pregnancy and non-right handedness: meta-analysis of randomized trials. Ultrasound Obstet Gynecol 2011; 38: 267-271
• 6 Holt R, Abramowicz JS. Quality and Safety of Obstetric Practices Using New Modalities- Ultrasound, MR, and CT. Clin Obstet Gynecol 2017; 60: 546-561
• 7 Nelson TR, Fowlkes JB, Abramowicz JS. et al. Ultrasound biosafety considerations for the practicing sonographer and sonologist. J Ultrasound Med 2009; 28: 139-150
• 8 Kollmann C, Jenderka KV, Moran CM. et al. EFSUMB Clinical Safety Statement for Diagnostic Ultrasound – (2019 revision). Ultraschall in Med 2019;
• 9 Ter HaarG. Guidelines and recommendations for the safe use of diagnostic ultrasound: the user's responsibilties. In The Safe use of Ultrasound in Medical Diagnosis 3rd edition, ter Haar G (eds). London: British Institute of Radiology; 2012: 142-157
• 10 Barnett SB, Ter Haar GR, Ziskin MC. et al. International recommendations and guidelines for the safe use of diagnostic ultrasound in medicine. Ultrasound Med Biol 2000; 26: 355-366
• 11 Marsal K. The output display standard: has it missed its target?. Ultrasound Obstet Gynecol 2005; 25: 211-214
• 12 Sheiner E, Abramowicz JS. Clinical end users worldwide show poor knowledge regarding safety issues of ultrasound during pregnancy. J Ultrasound Med 2008; 27: 499-501
• 13 American Institute of Ultrasound in Medicine. American Institute of Ultrasound in Medicine. Official Statement: Recommended Maximum Scanning Times for Displayed Thermal Index (TI) Values. 2016 https://www.aium.org/officialStatements/65 [Accessed May 2nd, 2019]
• 14 Safety Group of the British Medical Ultrasound Society. Guidelines for the safe use of diagnostic ultrasound equipment. 2009 https://www.bmus.org/static/uploads/resources/BMUS-Safety-Guidelines-2009-revision-FINAL-Nov-2009.pdf [Accessed May 2nd, 2019]
• 15 Royal College of Obstetricians and Gynaecologists. Royal College of Obstetricians and Gynaecologists, Small-for-Gestational-Age Fetus, Investigation and Management (Green-top Guideline No. 31). https://www.rcog.org.uk/globalassets/documents/guidelines/gtg_31.pdf [Accessed February 18th, 2019]
• 16 Sarris I, Ioannou C, Ohuma EO. et al. Standardisation and quality control of ultrasound measurements taken in the INTERGROWTH-21st Project. BJOG 2013; 120 (Suppl. 02) 33-37
• 17 Abramowicz JS. Benefits and risks of ultrasound in pregnancy. Semin Perinatol 2013; 37: 295-300
• 18 Alldred SK, Takwoingi Y, Guo B. et al. First trimester ultrasound tests alone or in combination with first trimester serum tests for Down’s syndrome screening. Cochrane Database Syst Rev 2017; 3: CD012600
• 19 Salvesen K, Lees C, Abramowicz J. et al. ISUOG statement on the safe use of Doppler in the 11 to 13 +6-week fetal ultrasound examination. Ultrasound Obstet Gynecol 2011; 37: 628
• 20 Rempen A, Chaoui R, Hausler M. et al. Quality Requirements for Ultrasound Examination in Early Pregnancy (DEGUM Level I) between 4+0 and 13+6 Weeks of Gestation. Ultraschall in Med 2016; 37: 579-583
• 21 von Kaisenberg C, Chaoui R, Hausler M. et al. Quality Requirements for the early Fetal Ultrasound Assessment at 11–13+6 Weeks of Gestation (DEGUM Levels II and III). Ultraschall in Med 2016; 37: 297-302
• 22 Kollmann C, Jenderka KV, Moran CM. et al. EFSUMB Clinical Safety Statement for Diagnostic Ultrasound – (2019 revision). Ultraschall in Med 2019;
• 23 European Research Council (ERC). Advanced Grant Perception Ultrasound by Learning Sonographic Experience.. https://erc.europa.eu/projects-figures/erc-funded-projects/results?search_api_views_fulltext=Sonographic+
• 24 Chatelain P, Sharma H, Drukker L. et al. Evaluation of Gaze Tracking Calibration for Longitudinal Biomedical Imaging Studies. IEEE Trans Cybern 2020; 50: 153-163
• 25 Brysbaert M. Arabic number reading: On the nature of the numerical scale and the origin of phonological recoding. Journal of Experimental Psychology: General 1995; 124: 434-452
• 26 Bromley B, Spitz J, Fuchs K. et al. Do clinical practitioners seeking credentialing for nuchal translucency measurement demonstrate compliance with biosafety recommendations? Experience of the Nuchal Translucency Quality Review Program. J Ultrasound Med 2014; 33: 1209-1214
• 27 Sheiner E, Abramowicz JS. Acoustic output as measured by thermal and mechanical indices during fetal nuchal translucency ultrasound examinations. Fetal Diagn Ther 2009; 25: 8-10
• 28 Nemescu D, Berescu A, Onofriescu M. et al. Safety Indices during Fetal Echocardiography at the Time of First-Trimester Scan Are Machine Dependent. PLoS One 2015; 10: e0127570
• 29 Deane C, Lees C. Doppler obstetric ultrasound: a graphical display of temporal changes in safety indices. Ultrasound Obstet Gynecol 2000; 15: 418-423
• 30 Toms DA. The mechanical index, ultrasound practices, and the ALARA principle. J Ultrasound Med 2006; 25: 560-561 ; author reply 561–562
• 31 Abramowicz JS, Kossoff G, Marsal K. et al. Safety Statement, 2000 (reconfirmed 2003). International Society of Ultrasound in Obstetrics and Gynecology (ISUOG). Ultrasound Obstet Gynecol 2003; 21: 100
• 32 Sande RK, Matre K, Eide GE. et al. The effects of reducing the thermal index for bone from 1.0 to 0.5 and 0.1 on common obstetric pulsed wave Doppler measurements in the second half of pregnancy. Acta Obstet Gynecol Scand 2013; 92: 790-796
• 33 Houston LE, Allsworth J, Macones GA. Ultrasound is safe... right?: resident and maternal-fetal medicine fellow knowledge regarding obstetric ultrasound safety. J Ultrasound Med 2011; 30: 21-27
• 34 Retz K, Kotopoulis S, Kiserud T. et al. Measured acoustic intensities for clinical diagnostic ultrasound transducers and correlation with thermal index. Ultrasound Obstet Gynecol 2017; 50: 236-241
• 35 Drukker L, Droste R, Chatelain P. et al. Routine third-trimester growth scans: how common is expected value bias?. Ultrasound Obstet Gynecol 2019;