VT vs SPI: ARDMS Exam Comparison
This page compares the ARDMS Vascular Technology (VT) and Sonography Principles & Instrumentation (SPI) exams side by side. They differ in clinical scope, content focus, career setting, and 2025 pass-rate data.
VT vs SPI: Exam Comparison
| Factor | Vascular Technology (VT) | Sonography Principles & Instrumentation (SPI) |
|---|---|---|
| Credential earned | RVT | RDMS/RVT prerequisite |
| Question count | 170 | 110 |
| Exam duration | 3 hours | 2 hours |
| Passing score | 555/700 | 555/700 |
| 2025 first-time pass rate | 70% | 74% |
| 2025 repeat pass rate | 45% | 47% |
| 2025 overall pass rate | 63% | 68% |
| Difficulty level | Hard | Hard |
Source: ARDMS/APCA Global Exam Performance Summary Report, 2025. First-time and repeat rates describe different candidate groups and do not by themselves establish exam difficulty.
About the Vascular Technology (VT) Exam
The ARDMS Vascular Technology (VT) specialty exam earns the Registered Vascular Technologist (RVT) credential. It has the lowest first-time pass rate among all seven specialties (70% in 2025) and tests a deep understanding of hemodynamics, Doppler physics, carotid stenosis criteria, DVT protocols, peripheral arterial disease, and abdominal vascular assessment.
About the Sonography Principles & Instrumentation (SPI) Exam
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.
Key Topics Compared
VT Key Topics
- Carotid duplex
- Vertebral artery assessment
- DVT evaluation
- Arterial duplex
- ABI and segmental pressures
- Venous insufficiency
- Abdominal aorta
- Renal artery stenosis
- Mesenteric arteries
- Hemodialysis access
- Hemodynamic principles
- Doppler physics
SPI 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
Among 2025 candidates, VT first-time and repeat pass rates were 70% and 45% (a 25-point gap); SPI rates were 74% and 47% (a 27-point gap). These are separate groups, not a measure of individual improvement.
Which Exam Should You Take First?
The right choice depends on your clinical background, your current employer's needs, and your long-term career goals. Sonographers with strong clinical experience in vascular technology imaging should consider the VT exam first, as applied clinical knowledge transfers directly to board performance. Similarly, those working predominantly in sonography principles & instrumentation settings will find the SPI exam more immediately supported by their daily practice.
- Career goals: The SPI is the physics exam every ARDMS credential shares; the VT exam decides which specialty your RVT covers. Consider whether that specialty aligns with your desired work environment.
- Where to start: SPI is required for every RDMS and RVT credential, and most candidates take it first. Pass rates compare separate candidate groups, not the inherent difficulty of an exam.
- Clinical experience: Take the exam that aligns with your strongest clinical rotations or work experience. Hands-on scanning experience impacts exam readiness.
- Prerequisite: The SPI physics exam is a prerequisite for earning the RVT specialty credential. If you have not passed SPI, plan for it before completing the specialty registration.
Both exams reward structured, domain-aligned preparation. The VT first-time pass rate is 70% compared with 74% for SPI; use these cohort results as context rather than a prediction of your individual outcome.