Pedro et al developed an "activity" index to evaluate the appearance of carotid plaque material using color-flow duplex ultrasonography. This score correlates with symptoms and can help identify those patients who may benefit from therapy. The authors are from the Instituto Cardiovascular de Lisbon in Portugal.
Color-flow duplex ultrasonography was performed of the carotid arteries with a 7-10 MHz probe and a 60 dB dynamic range.
|
Ultrasonographic Appearance of Plaque |
Plaque Type |
|
regular and uniform |
homogenous |
|
areas of different echogenicity |
heterogenous |
Parameters used to evaluate the plaque:
(1) type of plaque
(2) plaque surface disruption
(3) degree (percent) of stenosis
(4) GSM (grey-scale median of the histogram representing the distribution of plaque image pixels)
(5) P40 (percentile 40, which is the percent black or echolucent pixels; this is a measure of the echogenicity of the plaque)
(6) location of echolucent region (if heterogenous plaque)
|
Parameter |
Finding |
Points if Homogenous |
Points if Heterogenous |
|
type of plaque |
|
9 |
12 |
|
disruption of plaque surface |
no |
5 |
8 |
|
|
yes |
22 |
14 |
|
degree of stenosis |
< 50% |
4 |
0 |
|
|
50 - 69% |
5 |
3 |
|
|
70 - 79% |
6 |
8 |
|
|
80 - 89% |
16 |
11 |
|
|
>= 90% |
20 |
19 |
|
GSM |
< 20 |
31 |
19 |
|
|
20 - 32 |
15 |
11 |
|
|
33 - 40 |
7 |
8 |
|
|
> 40 |
4 |
2 |
|
P40 |
< 43 |
3 |
4 |
|
|
43 - 55 |
7 |
9 |
|
|
56 - 63 |
11 |
10 |
|
|
> 63 |
18 |
19 |
|
location of echolucent region |
central with echo-genic cap |
NA |
3 |
|
|
juxta-luminal without echogenic cap |
NA |
14 |
Interpretation:
• The cutoff separating symptomatic from asymptomatic patients irregardless of plaque type was 52 (symptomatic > 52) based on ROC curve analysis.
• As indicated by the performance data, different cutoffs could be used depending on the plaque type.
Performance:
• For homogenous plaques, a cutoff > 52 had a sensitivity of 56% and specificity of 88% (the Youden index was slightly better using a cutoff of > 53, with sensitivity of 56% and specificity of 92%).
• For heterogenous plaques, a cutoff > 52 had a sensitivity of 89% and specificity of 43% (the Youden index was slightly better using a cutoff of > 60, with sensitivity of 89% and specificity of 67%).
Specialty: Neurology
ICD-10: ,
