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Diagnostic imaging modality | | |
| | CDU | CE-MRA | CTA | |
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Tends to overestimate moderate (50–69%) stenosis
(i) Good for screening tool
(ii) Prior to surgical intervention, obtain CE-MRA imaging for positive selection, especially in asymptomatic patients [21, 22] |
Tends to overestimate moderate (50–69%) stenosis
(i) Specificity in this category is improved when there is concordance with CDU |
Highest specificity and overall accuracy of the three imaging modalities [22, 23]
Combining data sets with submillimeter spatial resolution with dedicated MPR reconstructions obtained in oblique planes or parallel to the vessel lumen provides a better evaluation of percent stenosis | |
| % Stenosis | Consensus criteria (AbuRahma et al.) [24]: | Anzidei et al. [22]: | Anzidei et al. [22]: | |
| | % Stenosis | Sensitivity | Specificity | Accuracy | % Stenosis | Sensitivity | Specificity | Accuracy | % Stenosis | Sensitivity | Specificity | Accuracy | |
| | 50–69% | 93% | 68% | 85% | ≥70% | 93% | 97% | 95% | ≥70% | 95% | 98% | 97% | |
| | ≥70% | 99% | 86% | 95% | |
|
Selection of patients for intervention | | Plaque morphology |
Not routine in every vascular lab and requires specific protocols to assure standardization of results:
(i) B-mode (surface and structure characteristics)
(ii) Contrast [25]
(a) Neovascularization of adventitia (earliest stage of atherosclerosis) [25]
(b) Intraplaque neovascularization (vulnerable plaque)
(ii) Grayscale median (GSM) calculation (using Adobe Photoshop) [26]
(a) ≤25 increased risk for embolization |
When dedicated protocols are used, CE-MRA can demonstrate specific plaque components, including calcium, lipid, fibrocellular element, or thrombus. It can also distinguish between an intact (thick, thin) or ruptured fibrous cap [22] |
Able to discriminate between lipid components, fibrous components, and the calcium present in atheromas [22] | |
| Individual risk assessment | Intracranial |
(i) Integrity of CoW can be assessed with TCD/TCI (not routinely done in all vascular labs)
(ii) Unable to assess other intracranial pathology |
Well suited for delineating intracranial anatomy (CoW, aneurysms, tandem lesions) |
Well suited for delineating intracranial anatomy (CoW, aneurysms, tandem lesions) | |
| | Brain perfusion |
Time-intensity curves with TCD and contrast agent (not routine) [27] | With addition of MRI | Can be done at same time as CTA | |
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Surveillance following intervention | | CE |
Low cost and low risk of this imaging modality make it ideal for postprocedure follow-up.
Primary closure:
(i) <1 month, 6 months, yearly
Patch closure:
(i) 6 months (if normal, and there is no contralateral disease, routine follow-up may not be necessary)
(ii) Modified CDU criteria may be necessary |
May have role if restenosis detected by CDU or patient is symptomatic |
May have role if restenosis detected by CDU or patient is symptomatic | |
| CAS |
Low cost and low risk of this imaging modality make it ideal for postprocedure follow-up.
Modified CDU criteria are necessary (blood flow and vessel compliance are altered in stented arteries) [28, 29]
Strict follow-up and surveillance for in-stent restenosis (ISR):
(i) Baseline (before discharge), 3 months, and every 6 months for first 18 months
(ii) If no significant ISR at 2 years, then perform annually (with lifelong surveillance since long-term outcomes are not well defined) |
Varying stent designs and related artifacts limit widespread use [30] |
Need for frequent follow-up makes use of ionizing radiation and nephrotoxic contrast unsuitable | |
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