Coexisting large and small vessel disease in patients with ischemic stroke of undetermined cause

Background and Purpose: Large artery atherosclerosis (LAA) and small vessel disease (SVD) share common risk factors for stroke. We aimed at investigating the association of SVD with cerebral LAA as well as with atherosclerosis in patients with stroke likely to originate from aortic plaques. Methods: We investigated 71 consecutive patients (48 men, mean age 64.2 +/- 13 years) with ischemic stroke of undetermined cause according to the ASCO classification, who received ECG-triggered CT angiography for best available atherosclerotic plaque detection in the aorta. Results: Aortic atherosclerotic plaques were detected in 54 patients (76.1%). The presence of SVD significantly correlated with the presence of aortic plaques (p < 0.001), as well as LAA (p < 0.001) and risk factors such as arterial hypertension (p = 0.032) and diabetes mellitus (p = 0.017). Conclusions: Aortic plaques are common in patients with stroke of undetermined cause. If so, SVD and LAA are often coexisting, which demonstrates the close link of macro- and microangiopathy, at least in cases of severe risk factors of atherosclerosis. Copyright © 2012 S. Karger AG, Base

CT angiography of the aorta is superior to transesophageal echocardiography for determining stroke subtypes in patients with cryptogenic ischemic stroke

Background: The etiology of ischemic strokes remains cryptogenic in about one third of patients, even after extensive workup in specialized centers. Atherosclerotic plaques in the aorta can cause thromboembolic events but are often overlooked. They can elude standard identification by transesophageal echocardiography (TEE), which is invasive or at best uncomfortable for many patients. CT angiography (CTA) can be used as an alternative or in addition to TEE if this technique fails to visualize every part of the aorta and in particular the aortic arch. Methods: We prospectively studied 64 patients (47 men, age 60 8 13 years) classified as having cryptogenic stroke after standard and full workup [including brain MRI and 24-hour electrocardiogram (ECG)] with ECG-triggered CTA of the aorta in search of plaques and compared the results with those of TEE. Investigators were blinded to the results of both techniques

Noise Reduction and Image Quality Improvement of Low Dose and Ultra Low Dose Brain Perfusion CT by HYPR-LR Processing

To evaluate image quality and signal characteristics of brain perfusion CT (BPCT) obtained by low-dose (LD) and ultra-low-dose (ULD) protocols with and without post-processing by highly constrained back-projection (HYPR)–local reconstruction (LR) technique.Simultaneous BPCTs were acquired in 8 patients on a dual-source-CT by applying LD (80 kV,200 mAs,14×1.2 mm) on tube A and ULD (80 kV,30 mAs,14×1.2 mm) on tube B. Image data from both tubes was reconstructed with identical parameters and post-processed using the HYPR-LR. Correlation coefficients between mean and maximum (MAX) attenuation values within corresponding ROIs, area under attenuation curve (AUC), and signal to noise ratio (SNR) of brain parenchyma were assessed. Subjective image quality was assessed on a 5-point scale by two blinded observers (1:excellent, 5:non-diagnostic).Radiation dose of ULD was more than six times lower compared to LD. SNR was improved by HYPR: ULD vs. ULD+HYPR: 1.9±0.3 vs. 8.4±1.7, LD vs. LD+HYPR: 5.0±0.7 vs. 13.4±2.4 (both p<0.0001). There was a good correlation between the original datasets and the HYPR-LR post-processed datasets: r = 0.848 for ULD and ULD+HYPR and r = 0.933 for LD and LD+HYPR (p<0.0001 for both). The mean values of the HYPR-LR post-processed ULD dataset correlated better with the standard LD dataset (r = 0.672) than unprocessed ULD (r = 0.542), but both correlations were significant (p<0.0001). There was no significant difference in AUC or MAX. Image quality was rated excellent (1.3) in LD+HYPR and non-diagnostic (5.0) in ULD. LD and ULD+HYPR images had moderate image quality (3.3 and 2.7).SNR and image quality of ULD-BPCT can be improved to a level similar to LD-BPCT when using HYPR-LR without distorting attenuation measurements. This can be used to substantially reduce radiation dose. Alternatively, LD images can be improved by HYPR-LR to higher diagnostic quality

Mean attenuation values in a corresponding 60 s time series of the ultra low dose (ULD), the HYPR-LR-post-processed ultra low dose (ULD+HYPR), the low dose (LD) and the HYPR-LR-post-processed low dose (HYPR+LD) images.

<p>Mean attenuation values in a corresponding 60 s time series of the ultra low dose (ULD), the HYPR-LR-post-processed ultra low dose (ULD+HYPR), the low dose (LD) and the HYPR-LR-post-processed low dose (HYPR+LD) images.</p

Example images of ultra low dose (ULD), HYPR-LR-post-processed ultra low dose (ULD+HYPR), low dose (LD) and HYPR-LR-post-processed low dose (HYPR+LD) brain perfusion CT of a 58-years old male patient with no pathology.

<p>The images are all reconstructed with the same slice thickness (5 mm) and presented with identical window settings.</p

Correlation of mean attenuation between original and post-processed data sets.

<p>Correlation of mean attenuation between original and post-processed data sets.</p

Subjective image quality scores and and quantitative attenuation measurements of LD and ULD and HYPR-LR post-processed BPCT data sets.

<p>Note: Subjective quality score are reported as mean values.</p

Ultra low dose (ULD), HYPR-LR-post-processed ultra low dose (ULD+HYPR), low dose (LD) and HYPR-LR-post-processed low dose (HYPR+LD) brain perfusion CT of a 35-years old patient with no pathology.

<p>This patient has slightly moved his head several times starting after 8 seconds of the data acquisition. As the HYPR-algorithm is using information of all time frames in the composite image for the calculation of the individual images, this resulted in an artifact visible in all HYPR-LR-post-processed images of this patient with a double contour of the skull and the brain on the right side and a frontal right hypodensity. The frontal right hypodensity was also visible in some non-post-processed images. The subjective image quality of the LD+HYPR image (rated 3) was still preferred to LD and ULD+HYPR (both rated 4). The ULD image was subjectively non-diagnostic (5). In the case of motion artifacts image registration might further improve image quality if used before the HYPR-LR algorithm is applied.</p