Article Figures & Data
Figures
- fig 1.
The TCD device provides two sample volumes for insonation of the MCA. An embolus streaming down the MCA will be recorded first in the proximal sample volume (depth of insonation, 57 mm [D57]) and with a time delay in the distal sample volume (depth of insonation, 52 mm [D52]). Next to the color-coded decibel scale, the Doppler velocity spectrum after fast Fourier transformation (FFT) of each sample volume is shown. The blood flow direction in both sample volumes is indicated in the proximal sample volume beneath D57 by an arrow directed toward the probe symbol ([), which means that the velocity spectrum of the blood flow in the MCA usually directed toward the probe is imaged above the zero line; the background velocity spectrum can be seen more clearly in the distal sample volume as a band with a signal intensity of 9 to 15 dB (colored slightly blue to green). The signal of the embolus after FFT is overloaded, as indicated by its bidirectional appearance
- fig 2.
A–D, Pre- and postoperative T2-weighted images (A and C) and DWIs (B and D) of a patient in whom a territorial infarct was present on the postoperative images. The small white matter lesions on the preoperative T2-weighted (4000/99/3) image (A) are not present on the preoperative DWI (B) (episequence; 123/1 [TE/excitations]). The corresponding postoperative T2-weighted image (C) and DWI (D) show a medium-sized territorial infarct on the left side, and a small new lesion in the head of the caudate nucleus on the right side. This patient underwent surgery for a tight left-sided stenosis associated with occlusion of the contralateral internal carotid artery
- fig 3.
A–C, Pre- and postoperative images of a patient who had had an episode of amaurosis fugax. The preoperative DWI (A) shows no signal abnormality. The postoperative DWI (B) shows a small cortical lesion in the distribution of the posterior branches of the MCA; on the postoperative T2-weighted image (C), this lesion (arrow) can be seen only in light of the findings on the DWI
- fig 4.
A–D, Pre- and postoperative images of a patient who underwent carotid endarterectomy 14 days after the clinical event. The preoperative T2-weighted (A) and DWI (B) studies show four small cortical lesions and one subcortical lesion (arrow, B). The cortical lesions cannot be detected on the corresponding postoperative DWI (D). The subcortical lesion is still present, but there is a new, smaller territorial infarction nearby as shown on the T2-weighted (C) and DWI (D) studies. These findings may suggest that cortical lesions disappear sooner than subcortical lesions, probably because of the better collateral blood flow in cortical regions as compared with subcortical regions
- fig 5.
A–C, Preoperative CT scan (A) of a patient with an asymptomatic tight stenosis of the right internal carotid artery. In the right parasagittal area, the slight leukoencephalopathy is one aspect of the coincident microvascular disease, which is more clearly present on the other CT sections (not shown). Postoperatively, an infarct in the right precentral gyrus is seen on the axial T2-weighted (B) and DWI (C) studies
Tables
Types of hyperintense signal distribution on postoperative diffusion-weighted images in patients who had endarterectomies performed without and with shunting
In this issue
Jump to section
Related Articles
Cited By...
- Symptomatic Carotid Occlusion Is Frequently Associated With Microembolization
- Intracranial Hemodynamics Is Altered by Carotid Artery Disease and After Endarterectomy: A Dynamic Magnetic Resonance Angiography Study
- Cerebral Microemboli and Brain Injury During Carotid Artery Endarterectomy and Stenting
- Assessing Carotid Revascularization: Should We Abandon the Neurological Examination?
- New Brain Lesions After Carotid Stenting Versus Carotid Endarterectomy: A Systematic Review of the Literature
- Internal and Cortical Border-Zone Infarction: Clinical and Diffusion-Weighted Imaging Features
- Pathogenesis of deep white matter medullary infarcts: a diffusion weighted magnetic resonance imaging study
- The Pathophysiology of Watershed Infarction in Internal Carotid Artery Disease: Review of Cerebral Perfusion Studies
- Subcortical White Matter Infarcts: Comparison of Superficial Perforating Artery and Internal Border-Zone Infarcts Using Diffusion-Weighted Magnetic Resonance Imaging
- Brain diffusion changes in carotid occlusive disease treated with endarterectomy
- Protecting the brain:how do we measure success?
- Assessment of Silent Embolism from Carotid Endarterectomy by Use of Diffusion-weighted Imaging: Work in Progress
- Detection of Clinically Silent Infarcts after Carotid Endarterectomy by Use of Diffusion-weighted Imaging
- Systematic Review of Diffusion and Perfusion Imaging in Acute Ischemic Stroke