Sonography Principles & Instrumentation (SPI) Specialty Exam Prep

The ARDMS Sonography Principles and Instrumentation (SPI) exam is the physics prerequisite required before earning any ARDMS specialty credential. It tests sound wave physics, transducer construction, image formation, ultrasound artifacts, Doppler principles, quality assurance, bioeffects, and ALARA safety principles. Unlike specialty exams, the SPI rewards an academic rather than clinical approach.

What the SPI Exam Covers

The Sonography Principles & Instrumentation registration is a 110-question, 2-hour examination administered by the ARDMS. Work through every content domain in proportion to its published weight rather than reviewing only familiar topics.

Who This Exam Is For

The SPI credential suits both sonography students sitting for their first registration and practicing sonographers adding a new specialty. The outline covers material that may not come up in every clinical setting. Mapping each study block to a specific domain helps you review the published scope.

Exam Facts

• Credential earned: RDMS/RVT prerequisite
• Exam format: 110-question, 2-hour examination
• Passing score: 555/700

2025 Pass Rates

First-time candidates: 74%; repeat candidates: 47%; overall: 68%. This 27-percentage-point difference compares separate candidate groups; it does not measure changes in exam difficulty or the effectiveness of a study strategy.

Source: ARDMS/APCA Global Exam Performance Summary Report, 2025.

High-Yield Focus Areas

• Sound wave physics and propagation
• Transducer construction and beam characteristics
• Image artifacts and their causes
• Doppler principles and hemodynamics
• Bioeffects and safety (ALARA principle)

Common Mistakes to Avoid

• Confusing axial and lateral resolution and their determinants
• Misidentifying artifact types on clinical images
• Incorrectly applying the Doppler equation components
• Confusing near field and far field beam characteristics
• Misunderstanding the relationship between frequency and penetration

Study Tips

• Start with the fundamental equation: wavelength = propagation speed / frequency
• Create a master chart of all artifact types, their causes, and clinical examples
• Study transducer types and their specific applications systematically
• Practice Doppler equation calculations until they become second nature
• Review bioeffects indices (TI and MI) and their clinical significance

Sample Question Types

Illustrative prompts, not actual registry questions.

• What determines axial resolution in an ultrasound system?
• A hyperechoic curved line deep to a strong reflector is an example of what artifact?
• If the Doppler angle increases from 45 to 60 degrees, what happens to the measured velocity?
• What is the propagation speed of sound in soft tissue?

Key Topics

• Sound wave physics
• Transducer technology
• Image formation
• Spatial resolution
• Artifacts
• Doppler principles
• Hemodynamics
• Bioeffects and safety
• ALARA principle
• Image quality optimization
• Digital signal processing
• Harmonic imaging

How to Prepare

Take specialty quizzes or a timed exam and review missed concepts using domain-level analytics. Platform question-bank inventory and mock exams are separate from official exam-format facts.

Related Specialties & Resources

Explore these related specialties when planning another registration:

• Abdomen (AB) exam prep — SPI vs AB comparison
• Vascular Technology (VT) exam prep — SPI vs VT comparison
• Obstetrics & Gynecology (OB/GYN) exam prep — SPI vs OB/GYN comparison

Browse the seven ARDMS specialties we cover, weigh your options on the specialty comparison hub, or read study guides on the Ultrasound Analytics blog.