Imaging Cerebral Microbleeds Using Susceptibility Weighted Imaging: One Step Toward Detecting Vascular Dementia

The MRI Institute for Biomedical Research, Detroit, Michigan, USA.
Journal of Magnetic Resonance Imaging (Impact Factor: 3.21). 01/2010; 31(1):142-8. DOI: 10.1002/jmri.22001
Source: PubMed


To monitor changes in the number of cerebral microbleeds (CMBs) in a longitudinal study of healthy controls (HC) and mild-cognitively impaired (MCI) patients using susceptibility weighted imaging (SWI).
SWI was used to image 28 HC and 75 MCI patients annually at 1.5 Tesla over a 4-year period. Magnitude and phase data were used to visualize CMBs for the first and last scans of 103 subjects.
Preliminary analysis revealed that none of the 28 HC had more than three CMBs. In the 75 MCI patients, five subjects had more than three CMBs in both first and last scans, while one subject had more than three bleeds only in the last scan. In five of these six MCI patients, the number of CMBs increased over time and all six went on to develop progressive cognitive impairment (PCI). Of the 130 total CMBs seen in the last scans of the six MCI cases, most were less than 4 mm in diameter.
SWI can reveal small CMBs on the order of 1 mm in diameter and this technique can be used to follow their development longitudinally. Monitoring CMBs may be a means by which to evaluate patients for the presence of microvascular disease that leads to PCI.

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Available from: Wolff M Kirsch, Dec 17, 2013
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    • "However, visual screening is time-consuming, subjective and has low reproducibility between observers [6]. Moreover, it is prone to errors as small CMBs can be easily missed, or mistaken for vessel cross-sections, especially in MR Susceptibility Weighted Imaging (SWI) due to the high sensitivity of this sequence to magnetic susceptibility [7]. "
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    ABSTRACT: Recent developments of susceptibility weighted MR techniques have improved visualization of venous vasculature and underlying pathologies such as cerebral microbleed (CMB). CMBs are small round hypointense lesions on MRI images that are emerging as a potential biomarker for cerebrovascular disease. CMB manual rating has limited reliability, is time-consuming and is prone to errors as small CMBs can be easily missed or mistaken for venous cross-sections. This paper presents a computer-aided detection technique that utilizes a novel cascade of random forest classifiers which are trained on robust Radon-based features with an unbalanced sample distribution. The training samples and their associated bounding box were acquired from a multi-scale Laplacian of Gaussian technique with respect to their geometric characteristics. Validation results demonstrate that the current approach outperforms state of the art approaches with sensitivity of 92.04% and an average false detection rate of 16.84 per subject.
    2014 IEEE 11th International Symposium on Biomedical Imaging (ISBI 2014); 04/2014
    • "The same physics principle of susceptibility discussed above allows for thrombus to demonstrate susceptibility and hence SWI to show thrombus within an artery at the same time allow for venous imaging from the BOLD effect.[41115161718] "
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    ABSTRACT: To evaluate the additional information that susceptibility weighted sequences and datasets would provide in acute stroke. The aim of this study were to assess the value addition of susceptibility weighted magnetic resonance imaging (SWI) of brain in patients with acute arterial infarct. All patients referred for a complete brain magnetic resonance imaging (MRI) between March 2010 and March 2011 at our institution had SWI as part of routine MRI (T1, T2, and diffusion imaging). Retrospective study of 62 consecutive patients with acute arterial infarct was evaluated for the presence of macroscopic hemorrhage, petechial micro-bleeds, dark middle cerebral artery (MCA) sign and prominent vessels in the vicinity of infarct. SWI was found to detect hemorrhage not seen on other routine MRI sequences in 22 patients. Out of 62 patients, 17 (10 petechial) had hemorrhage less than 50% and 5 patients had greater than 50% area of hemorrhage. A "dark artery sign" due to thrombus within the artery was seen in 8 out of 62 patients. Prominent cortical and intraparenchymal veins were seen in 14 out of 62 patients. SWI has been previously shown to be sensitive in detecting hemorrhage; however is not routinely used in stroke evaluation. Our study shows that SWI, by virtue of identifying unsuspected hemorrhage, central occluded vessel, and venous congestion is additive in value to the routine MR exam and should be part of a routine MR brain in patients suspected of having an acute infarct.
    Annals of Indian Academy of Neurology 03/2014; 17(1):58-61. DOI:10.4103/0972-2327.128555 · 0.60 Impact Factor
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    • "SWI requires more time than does GRE, and also requires post-processing, but because SWI accentuates the magnetic properties of tissues, it enables visualization of areas such as CMBs containing deoxygenated blood substances.16 SWI permits visualization of a greater number of CMBs than can be seen with conventional GRE sequences, but the clinical implications of this increased sensitivity are not yet fully understood (Figure 1).17 "
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    ABSTRACT: Cerebral microbleeds (CMBs) are tiny, round dark-signal lesions that are most often detected on gradient-echo MR images. CMBs consist of extravasations of blood components through fragile microvascular walls characterized by lipohyalinosis and surrounding macrophages. The prevalence of CMBs in elderly subjects with no history of cerebrovascular disease is around 5%, but is much higher in patients with ischemic or hemorrhagic stroke. Development of CMBs is closely related to various vascular risk factors; in particular, lobar CMBs are thought to be associated with cerebral amyloid angiopathy. The presence of CMBs has been hypothesized to reflect cerebral-hemorrhage-prone status in patients with hypertension or amyloid microangiopathy. Stroke survivors with CMBs have been consistently found to have an elevated risk of subsequent hemorrhagic stroke or an antithrombotic-related hemorrhagic complication, although studies have failed to establish a link between CMBs and hemorrhagic transformation after thrombolytic treatment. A large prospective study is required to clarify the clinical significance of CMBs and their utility in a decision-making index.
    09/2013; 15(3):153-163. DOI:10.5853/jos.2013.15.3.153
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