Risk of ipsilateral ischemia according to MPRAGE signal intensity and stenosis after excluding patients with atrial fibrillation and prosthetic heart valves
| Stenosis | 0%–29% (n = 152) | 30%–69% (n = 114) | 70%–99% (n = 100) | Total (n = 366) | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| S | A | F (%) | S | A | F (%) | S | A | F (%) | S | A | F (%) | |
| MPRAGE | ||||||||||||
| High signal intensity | 6 | 26 | 18.8 | 18 | 44 | 29.0 | 27 | 36 | 42.9 | 51 | 106 | 32.5 |
| Low signal intensity | 9 | 111 | 7.5 | 2 | 50 | 3.8 | 8 | 29 | 21.6 | 19 | 190 | 9.1 |
| P | 0.0889 | 0.0004 | 0.0498 | <0.0001 | ||||||||
| Relative risk (95% CI) | 2.500 (0.9603–6.508) | 7.548 (1.836–31.041) | 1.982 (1.008–3.900) | 3.573 (2.201–5.801) | ||||||||
Note:—MPRAGE indicates magnetization-prepared rapid acquisition with gradient echo; S, symptomatic within previous 6 months; A, asymptomatic within previous 6 months; F, frequency of carotid arteries in patients with ipsilateral symptom; CI, confidence interval. P values were calculated using the Fisher exact test between MPRAGE high and low groups for symptoms (S) in each stenosis group. Relative risk of ischemic events was calculated for MPRAGE high carotid arteries compared with low carotid arteries in each stenosis group.