J Neuroradiology
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Previous studies have reported increased cerebral blood flow (CBF) velocity after decompressive craniectomy in traumatic brain injury (TBI) patients. A 27-year-old man presented with clinical and tomographic signs of cerebral herniation secondary to TBI. Prior to decompressive craniectomy, hemodynamic study by perfusion computed tomography (CT) indicated diffuse cerebral hyperperfusion. ⋯ The patient's blood pressure levels were similar at both pre- and postoperative perfusion CT examinations. This finding provides indirect evidence that decompressive craniectomy may improve mechanisms of CBF regulation in TBI, providing pathophysiological insights in the cerebral hemodynamics of TBI patients. This is the first report analyzing the hemodynamic changes through perfusion CT (PCT) in a patient with decompressive craniotomy due to TBI.
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Spinal canal stenosis is often measured on anatomical magnetic resonance imaging (MRI) to estimate the degree of spinal cord compression. This study examined whether two quantitative measures of spinal canal stenosis taken from anatomical MRI are related to spinal cord white-matter integrity in patients with cervical spondylosis measured by diffusion tensor imaging (DTI). ⋯ Pavlov's ratio is a better predictor of spinal cord integrity than the SAC and, therefore, may be more relevant clinically for the evaluation of stenosis in patients with cervical spondylosis.
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Progressive multifocal leukoencephalopathy (PML) generally occurs in patients with impaired cellular immunity. Monoclonal antibodies also predispose the patient to PML as they depress the immune system. PML was classically characterized by a lack of inflammation and absence of gadolinium enhancement. ⋯ We present a case of gadolinium enhanced PML lesions occuring after natalizumab monotherapy of a relapsing multiple sclerosis. Radiologists must be aware of this particular feature, as confirmation of the diagnostic of PML becomes more challenging. Namely, distinction between starting PML and multiple sclerosis enhanced additional active lesion is difficult and diagnosis must be established by combined analysis of full clinical evolution, brain MRI scans, and polymerase chain reaction of cerebrospinal fluid.
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Susceptibility-weighted MR sequences, T2 star weighted angiography (SWAN, General Electric), Susceptibility weighted imaging (SWI, Siemens) and venous blood oxygen level dependant (VenoBOLD, Philips) are 3D spoiled gradient-echo sequence that provide a high sensitivity for the detection of blood degradation products, calcifications, and iron deposits. For all these sequences, an appropriate echo time allows for the visualization of susceptibility differences between adjacent tissues. However, each of these sequences presents a specific technical background. The purpose of this review was to describe 1/the technical aspects of SWAN, VenoBOLD and SWI sequences, 2/the differences observed in term of contrast within the images, 3/the key imaging findings in neuroimaging using susceptibility-weighted MR sequences.
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The radial nerve is a continuation of the posterior cord of the brachial plexus and one of the major nerves that provide motor and sensory innervations to the forearm. MR imaging evaluation of the radial nerve pathology has been described in scattered case reports. Current high-field MR scanners enable high resolution and high contrast imaging of the peripheral nerves. This article reviews the 3 Tesla magnetic resonance neurography imaging of radial nerve anatomy and various pathologies affecting it with relevant case examples.