Carotid Plaque Characterization

Plaque Characterization/Morphology in B-mode

1. Always evaluate in sagittal and transverse imaging planes, with best overall assessment of plaque burden made in transverse images

2. Note location of plaque in report

3. Reporting terminology

a. Normal (no overt evidence of wall changes or plaque), minimal, moderate or severe may be used to describe impression of plaque burden or volume

b. Surface characteristics

i.   Smooth

ii. Irregular

c. Plaque composition, echo pattern

i.   Homogeneous: even echo pattern

ii.  Heterogeneous: mixed echo pattern

d. Echogenicity

i.   Hypoechoic/sonolucent: low level echoes

ii.  Hyperechoic/echogenic: brighter level echoes

iii. Calcific: bright area with associated shadowing of the deeper structures causing inadequate visualization; these plaques are not able to be further classified.

iv. Hypoechoic/sonolucent plaque or region within a plaque may be associated with intraplaque hemorrhage and/ or ulceration

e. Other pathology

i.   Thromboembolism: oscillating, pulsating, moving echogenic mass within the extracranial carotid vessels

ii.  Intimal dissection (tear or flap)

iii. Masses in the neck are described in terms of location, size and presence or absence of flow / discernable vessels within the encapsulated region

iv. Aneurysm: enlarged segment that measures 1.5 times the more proximal contiguous segment

v.  Pseudoaneurysm: contained bleed from a hole in the vessel wall

vi. Fibromuscular dysplasia may produce increased velocity and / or turbulence in the mid to distal segments of the ICA

Color Doppler

1. Color Doppler may be used to assess flow using mean velocity or in the power amplitude mode.

2. Color Doppler is not used as a diagnostic tool, but as a road map to guide sample volume placement for spectral Doppler velocity waveform assessment.

3. All color Doppler controls must be optimized, including PRF, gain and baseline.

4. In areas of color flow disturbances / abnormal flow patterns, the PW Doppler sample volume is “walked through’ the vessel segment to document highest velocities or display the particular waveform characteristics.

5. Absence of color Doppler signal is not sufficient to diagnose vessel occlusion; spectral Doppler confirmation is required.