DMSO 1110: history of sono Study Notes on Medical Ultrasound and Sonography

Introduction to Medical Ultrasound

  • Overview of lecture: Development of medical ultrasound, sonographic specialties, and advances in sonography.

  • Reference: Information covered correlates with "Intro to Sonography" by Stephen Penny.

Early Investigation of Sound

  • Overview of historical developments in sound investigations.

    • 6th Century BC: Pythagoras studied pitch and frequency.

    • 1500s: Leonardo da Vinci and Galileo explored sound interactions.

    • 1600s: Robert Boyle established sound propagation requires a medium for travel.

    • Late 1700s: Spallanzani observed bats and their echolocation abilities.

    • 1842: Christian Doppler observed the effect of motion on sound pitch (Doppler Effect).

    • 1880s: Jacques and Pierre Curie noted the piezoelectric effect (electricity from crystal pressure and heat).

Development of Medical Ultrasound

  • Development timeline during and after World War II.

    • World War I: Sonar technology first utilized in submarines.

    • Post World War II: Military technology adapted for medical diagnosis.

    • Geographic contributions from: United States, Sweden, Scotland, Japan, Australia, and England.

    • Innovations in the 1940s-1950s:

    • Pulse echo technique: Images from sound waves reflecting off tissues.

    • 1960s: M Mode imaging developed to measure left ventricular size by doctors like Feigebaum and Dodge.

Definition of Sonography

  • Sonography: Combination of "sono" (sound) and "graphy" (writing/drawing) translating to sound images.

    • Utilizes high-frequency sound waves (20 kHz to several GHz) to create images.

    • Synonyms include: ultrasonography, ultrasound, diagnostic medical ultrasound, and echography.

    • The term "ultrasound techs" does not adequately represent the depth of skill and knowledge required of sonographers.

Applications of Ultrasound

  • Wide-ranging applications of ultrasound technology:

    • Natural phenomena in animals: echolocation in bats and dolphins.

    • Food industry applications.

    • Manual cleaning (jewelry and medical instruments).

    • Therapeutic uses by chiropractors and physical therapists for deep tissue heating.

    • Emphasized that ultrasound does not sterilize but deep cleans instruments.

Historical Evolution of Ultrasound Equipment

  • 1940s-1950s: Early medical ultrasound machines composed of repurposed electronic components.

    • Example: Gun turret from a tank utilized in imaging.

  • 1970s: Innovation led to more compact units, featured complex multi-component machines.

  • 1980s: Advances toward real-time scanning. Equipment became more portable (mobile units, laptops).

  • 1990s into 2000s: Development of lighter, highly maneuverable machines with diverse transducers, enabling broad applications regardless of clinical setting.

Scanning Techniques in Sonography

  • Static Scans: Early imaging limited to specific body areas (neck, abdomen, pelvis). Required multiple passes and was time-intensive.

  • Real-time Scans: Allowed for quicker imaging of moving organs. Transitioned from mechanical movements to electronically activated crystals, enhancing organ visualization.

Modes of Ultrasound

  • B Mode: Two-dimensional images created from a linear array of transducers, displaying shades of gray. Used in both static and real-time imaging.

  • M Mode: Represents motion over a single line of sound, primarily used in cardiac imaging. Displays movement of heart valves and walls in a waveform format.

  • Doppler Ultrasound: Utilizes the Doppler effect to assess tissue movement, primarily blood flow:

    • Color Doppler: Displays velocity with a color scale, commonly used in duplex imaging.

    • Spectral Doppler: Quantifies velocities to create waveforms representing flow over time.

    • Power Doppler: Highlights blood flow in small vessels.

    • Continuous Wave Doppler: Uses two elements for sound transmission and reception to visualize blood movement, good for measuring flow velocities.

Sonography Specialties

  • Overview of specialties:

    • Abdominal and Superficial Structures: Imaging performed using B Mode and Doppler techniques for areas like the thyroid, breast, and vascular evaluations.

    • Adult Cardiac: Utilizes Doppler techniques alongside M Mode and B Mode for robust cardiac imaging.

    • Obstetrics and Gynecology: Employs both B Mode and Doppler techniques to assess fetal development and female reproductive health.

    • Vascular Technology: Incorporates Doppler for detailed evaluation of blood flow and vascular structures.

Emerging Technologies in Ultrasound

  • Elastography: Measures organ stiffness to assess diseases like liver fibrosis. Utilizes low-frequency vibrations to visualize tissue elasticity.

    • Types: Strain imaging (mechanical) and shear wave imaging (2D and 1D).

  • Contrast Enhanced Ultrasound (CEUS): Injection of ultrasound contrast agents (microbubbles) enhances imaging clarity and vascular assessment in various organs.

  • Point of Care Ultrasound (POCUS): Immediate scanning for clinical decision-making by healthcare professionals outside typical imaging settings.

    • Applications for trauma, emergency settings, and specific medical specialties like OBGYN.

  • Tissue Motion Measurement: Advanced Doppler techniques for assessing tissue movement and cardiac velocities.

  • Lung and Chest Sonography: Increased application during COVID-19 for monitoring patients on mechanical ventilation.

  • Automated Breast Ultrasound: Uses machines to scan entire breasts for tumors.

  • CMUT Technology: Capacitive micromachined ultrasonic transducer, offering advantages such as miniaturization, high spatial resolution, and simpler manufacturing compared to traditional piezoelectric transducers.

Conclusion

  • Summary of historical progression in medical ultrasound, its current state, and where future advancements may lead.

  • Importance of foundational knowledge in ultrasound systems, physics, and specialties for advancing in the sonography field.