AJNR. American journal of neuroradiology
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AJNR Am J Neuroradiol · Feb 2009
ReviewSusceptibility-weighted imaging: technical aspects and clinical applications, part 2.
Susceptibility-weighted imaging (SWI) has continued to develop into a powerful clinical tool to visualize venous structures and iron in the brain and to study diverse pathologic conditions. SWI offers a unique contrast, different from spin attenuation, T1, T2, and T2* (see Susceptibility-Weighted Imaging: Technical Aspects and Clinical Applications, Part 1). In this clinical review (Part 2), we present a variety of neurovascular and neurodegenerative disease applications for SWI, covering trauma, stroke, cerebral amyloid angiopathy, venous anomalies, multiple sclerosis, and tumors. We conclude that SWI often offers complementary information valuable in the diagnosis and potential treatment of patients with neurologic disorders.
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AJNR Am J Neuroradiol · Feb 2009
Clinical TrialMR imaging detection of cerebral microbleeds: effect of susceptibility-weighted imaging, section thickness, and field strength.
The emergence of cerebral microbleeds (CMB) as common MR imaging findings raises the question of how MR imaging parameters influence CMB detection. To evaluate the effects of modified gradient recalled-echo (GRE) MR imaging methods, we performed an analysis of sequence, section thickness, and field strength on CMB imaging properties and detection in subjects with cerebral amyloid angiopathy (CAA), a condition associated with microhemorrhage. ⋯ The examined alternatives to conventional GRE MR imaging yield substantially improved CMB contrast and sensitivity for detection. Future studies based on these techniques will most likely yield even higher prevalence estimates for CMB.
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AJNR Am J Neuroradiol · Feb 2009
Variability of homotopic and heterotopic callosal connectivity in partial agenesis of the corpus callosum: a 3T diffusion tensor imaging and Q-ball tractography study.
Little is known about the anatomic connectivity of callosal axons in individuals with partial agenesis of the corpus callosum (pAgCC). We used tractography based on both diffusion tensor imaging (DTI) and high angular resolution diffusion imaging (HARDI) to investigate interhemispheric white matter connectivity in pAgCC. ⋯ Individuals with pAgCC demonstrate a remarkable diversity of callosal connectivity, including a number of heterotopic tracts that are absent in healthy subjects. The patterns of their callosal connections cannot be predicted from the appearance of their callosal fragments on conventional MR imaging. More tracts and more extensive fibers within tracts are recovered with HARDI than with DTI.
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AJNR Am J Neuroradiol · Feb 2009
Hypercapnia-induced cerebral hyperperfusion: an underrecognized clinical entity.
The incidence of cerebral hyperperfusion and hypoperfusion, respectively, resulting from hypercapnia and hypocapnia in hospitalized patients is unknown but is likely underrecognized by radiologists and clinicians without routine performance of quantitative perfusion imaging. Our purpose was to report the clinical and perfusion imaging findings in a series of patients confirmed to have hypercapnic cerebral hyperperfusion and hypocapnic hypoperfusion. ⋯ With the inception of ASL as a routine perfusion imaging technique, hypercapnic-associated cerebral hyperperfusion will be recognized more frequently and may provide an alternative cause of unexplained neuropsychiatric symptoms in hospitalized patients. In a similar fashion, hypocapnia may account for a subset of patients with normal MR imaging examinations with poor ASL perfusion signal.
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AJNR Am J Neuroradiol · Feb 2009
Clinical TrialCervical CT-guided, selective nerve root blocks: improved safety by dorsal approach.
Cervical transforaminal blocks are frequently performed as a treatment of cervical radicular pain. These blocks are performed mostly under fluoroscopy, but a CT-guided technique also has been described. We describe a modification that leads to a more extraforaminal than transforaminal and equally selective nerve root block.