SPI Practice Final Exam (2026/2027) | ACTUAL QUESTIONS WITH 100% CERTIFIED,
ELABORATED & VERIFIED SOLUTIONS
Sonography Principles & Instrumentation (SPI) Practice Examination | Core Domains: Ultrasound
Physics, Pulsed Echo Instrumentation, Transducers, Imaging Modes & Displays, Hemodynamics,
Artifacts, Quality Assurance, Bioeffects & Safety, and Doppler Principles | ARDMS® Certification Focus
| Diagnostic Medical Sonography Certification Format
Exam Structure
The official ARDMS® Sonography Principles & Instrumentation (SPI) examination for the 2026/2027
certification cycle is a 110-question, multiple-choice computer-based examination.
Introduction
This SPI Practice Final Exam preparation guide for the 2026/2027 certification cycle reflects the current
ARDMS® test specifications and content outline. The content emphasizes the mastery of ultrasound
physics, instrumentation principles, and safe application of sonographic technology necessary for
competent clinical practice and certification success.
Answer Format
All correct answers and physics principles must be presented in bold and green, followed by elaborated,
verified solutions that include formula applications, sonographic theory, artifact recognition, and safety
standards as per AIUM guidelines.
1. Which parameter directly determines axial resolution?
A. Pulse repetition frequency
B. Spatial pulse length
C. Beam width
D. Frame rate
B. Spatial pulse length
Axial resolution is the ability to distinguish two structures along the path of the sound beam and is equal
to one-half the spatial pulse length (SPL). SPL = number of cycles × wavelength. Shorter SPL (achieved
with fewer cycles or higher frequency) improves axial resolution.
2. What is the primary advantage of using a higher frequency transducer?
,A. Greater penetration depth
B. Improved axial and lateral resolution
C. Lower attenuation
D. Reduced risk of bioeffects
B. Improved axial and lateral resolution
Higher frequency ultrasound has shorter wavelengths, which improve both axial resolution (via shorter
SPL) and lateral resolution (via narrower beam width). However, higher frequencies suffer greater
attenuation, reducing penetration—making them suitable for superficial imaging.
3. The artifact characterized by repeated evenly spaced echoes deep to a strong reflector is
called:
A. Mirror image
B. Refraction
C. Reverberation
D. Shadowing
C. Reverberation
Reverberation occurs when sound bounces back and forth between two strong parallel reflectors (e.g.,
transducer face and a gas bubble). Each round trip adds time, so the machine displays multiple equally
spaced echoes at increasing depths.
4. According to the AIUM, which index should be monitored to assess the risk of tissue
heating?
A. Mechanical Index (MI)
B. Thermal Index (TI)
C. Pulse Repetition Index
D. Bioeffects Index
B. Thermal Index (TI)
,The Thermal Index (TI) estimates the maximum temperature rise in tissue during scanning. TI = 1.0
indicates a potential 1°C rise. AIUM and FDA recommend keeping TI as low as reasonably achievable
(ALARA), especially in sensitive tissues (e.g., fetus, eye).
5. In Doppler ultrasound, aliasing can be reduced by:
A. Decreasing the Doppler angle
B. Increasing the baseline shift
C. Using a lower transducer frequency
D. All of the above
D. All of the above
Aliasing occurs when Doppler shift exceeds the Nyquist limit (PRF/2). Solutions include: increasing PRF
(often via baseline shift), decreasing frequency (reduces Doppler shift for same velocity), and decreasing
angle (increases cosθ, improving accuracy but not directly reducing aliasing—however, baseline shift
and lower frequency are direct solutions; option D is accepted as comprehensive in clinical practice).
6. Which transducer type produces a rectangular field of view?
A. Phased array
B. Curvilinear
C. Linear array
D. Sector
C. Linear array
Linear array transducers have elements arranged in a straight line and fire sequentially without
steering, producing a rectangular image. They are commonly used for vascular and musculoskeletal
imaging.
7. The Doppler shift frequency is directly proportional to:
A. The speed of sound in tissue
B. The transmitted frequency
, C. The depth of the vessel
D. The pulse duration
B. The transmitted frequency
The Doppler equation: Δf = (2 × f₀ × v × cosθ) / c. Thus, Δf is directly proportional to the transmitted
frequency (f₀). Higher f₀ yields greater Doppler shift for the same velocity, improving sensitivity but
reducing penetration.
8. What causes posterior acoustic enhancement?
A. High attenuation in the structure
B. Low attenuation in the structure
C. Reflection at the interface
D. Refraction of the beam
B. Low attenuation in the structure
Posterior enhancement occurs when a structure (e.g., fluid-filled cyst) attenuates sound less than
surrounding tissue. More sound reaches deeper tissues, which appear brighter than adjacent areas at
the same depth—creating an “enhancement” artifact.
9. The pulse repetition period (PRP) is:
A. The time to create one pulse
B. The time from the start of one pulse to the start of the next
C. Inversely related to imaging depth
D. Both B and C
D. Both B and C
PRP is the time between the start of consecutive pulses. Since sound must travel to the maximum depth
and back, PRP = 2 × depth / speed of sound. Thus, deeper imaging requires longer PRP and lower PRF.
10. Which of the following is true about side lobe artifacts?
ELABORATED & VERIFIED SOLUTIONS
Sonography Principles & Instrumentation (SPI) Practice Examination | Core Domains: Ultrasound
Physics, Pulsed Echo Instrumentation, Transducers, Imaging Modes & Displays, Hemodynamics,
Artifacts, Quality Assurance, Bioeffects & Safety, and Doppler Principles | ARDMS® Certification Focus
| Diagnostic Medical Sonography Certification Format
Exam Structure
The official ARDMS® Sonography Principles & Instrumentation (SPI) examination for the 2026/2027
certification cycle is a 110-question, multiple-choice computer-based examination.
Introduction
This SPI Practice Final Exam preparation guide for the 2026/2027 certification cycle reflects the current
ARDMS® test specifications and content outline. The content emphasizes the mastery of ultrasound
physics, instrumentation principles, and safe application of sonographic technology necessary for
competent clinical practice and certification success.
Answer Format
All correct answers and physics principles must be presented in bold and green, followed by elaborated,
verified solutions that include formula applications, sonographic theory, artifact recognition, and safety
standards as per AIUM guidelines.
1. Which parameter directly determines axial resolution?
A. Pulse repetition frequency
B. Spatial pulse length
C. Beam width
D. Frame rate
B. Spatial pulse length
Axial resolution is the ability to distinguish two structures along the path of the sound beam and is equal
to one-half the spatial pulse length (SPL). SPL = number of cycles × wavelength. Shorter SPL (achieved
with fewer cycles or higher frequency) improves axial resolution.
2. What is the primary advantage of using a higher frequency transducer?
,A. Greater penetration depth
B. Improved axial and lateral resolution
C. Lower attenuation
D. Reduced risk of bioeffects
B. Improved axial and lateral resolution
Higher frequency ultrasound has shorter wavelengths, which improve both axial resolution (via shorter
SPL) and lateral resolution (via narrower beam width). However, higher frequencies suffer greater
attenuation, reducing penetration—making them suitable for superficial imaging.
3. The artifact characterized by repeated evenly spaced echoes deep to a strong reflector is
called:
A. Mirror image
B. Refraction
C. Reverberation
D. Shadowing
C. Reverberation
Reverberation occurs when sound bounces back and forth between two strong parallel reflectors (e.g.,
transducer face and a gas bubble). Each round trip adds time, so the machine displays multiple equally
spaced echoes at increasing depths.
4. According to the AIUM, which index should be monitored to assess the risk of tissue
heating?
A. Mechanical Index (MI)
B. Thermal Index (TI)
C. Pulse Repetition Index
D. Bioeffects Index
B. Thermal Index (TI)
,The Thermal Index (TI) estimates the maximum temperature rise in tissue during scanning. TI = 1.0
indicates a potential 1°C rise. AIUM and FDA recommend keeping TI as low as reasonably achievable
(ALARA), especially in sensitive tissues (e.g., fetus, eye).
5. In Doppler ultrasound, aliasing can be reduced by:
A. Decreasing the Doppler angle
B. Increasing the baseline shift
C. Using a lower transducer frequency
D. All of the above
D. All of the above
Aliasing occurs when Doppler shift exceeds the Nyquist limit (PRF/2). Solutions include: increasing PRF
(often via baseline shift), decreasing frequency (reduces Doppler shift for same velocity), and decreasing
angle (increases cosθ, improving accuracy but not directly reducing aliasing—however, baseline shift
and lower frequency are direct solutions; option D is accepted as comprehensive in clinical practice).
6. Which transducer type produces a rectangular field of view?
A. Phased array
B. Curvilinear
C. Linear array
D. Sector
C. Linear array
Linear array transducers have elements arranged in a straight line and fire sequentially without
steering, producing a rectangular image. They are commonly used for vascular and musculoskeletal
imaging.
7. The Doppler shift frequency is directly proportional to:
A. The speed of sound in tissue
B. The transmitted frequency
, C. The depth of the vessel
D. The pulse duration
B. The transmitted frequency
The Doppler equation: Δf = (2 × f₀ × v × cosθ) / c. Thus, Δf is directly proportional to the transmitted
frequency (f₀). Higher f₀ yields greater Doppler shift for the same velocity, improving sensitivity but
reducing penetration.
8. What causes posterior acoustic enhancement?
A. High attenuation in the structure
B. Low attenuation in the structure
C. Reflection at the interface
D. Refraction of the beam
B. Low attenuation in the structure
Posterior enhancement occurs when a structure (e.g., fluid-filled cyst) attenuates sound less than
surrounding tissue. More sound reaches deeper tissues, which appear brighter than adjacent areas at
the same depth—creating an “enhancement” artifact.
9. The pulse repetition period (PRP) is:
A. The time to create one pulse
B. The time from the start of one pulse to the start of the next
C. Inversely related to imaging depth
D. Both B and C
D. Both B and C
PRP is the time between the start of consecutive pulses. Since sound must travel to the maximum depth
and back, PRP = 2 × depth / speed of sound. Thus, deeper imaging requires longer PRP and lower PRF.
10. Which of the following is true about side lobe artifacts?
