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magnetic_resonance_imaging

Magnetic resonance imaging (MRI)

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Magnetic resonance imaging represents a imaging technique that does not use ionizing radiation.

Preoperative magnetic resonance images are typically coregistered to provide intraoperative navigation, the accuracy of which can be significantly compromised by brain deformation.

Types

MRI analysis techniques

Freely available automated MRI analysis techniques are being increasingly used to investigate neuroanatomical abnormalities in patients with neurological disorders. It is important to assess the specificity and validity of automated measurements of structure volumes with respect to reliable manual methods that rely on human anatomical expertise. The thalamus is widely investigated in many neurological and neuropsychiatric disorders using MRI, but thalamic volumes are notoriously difficult to quantify given the poor between-tissue contrast at the thalamic gray-white matter interface. In a study Keller et al. investigated the reliability of automatically determined thalamic volume measurements obtained using FreeSurfer software with respect to a manual stereological technique on 3D T1-weighted MR images obtained from a 3 T MR system. Further to demonstrating impressive consistency between stereological and FreeSurfer volume estimates of the thalamus in healthy subjects and neurological patients, we demonstrate that the extent of agreeability between stereology and FreeSurfer is equal to the agreeability between two human anatomists estimating thalamic volume using stereological methods. Using patients with juvenile myoclonic epilepsy as a model for thalamic atrophy, we also show that both automated and manual methods provide very similar ratios of thalamic volume loss in patients. This work promotes the use of FreeSurfer for reliable estimation of global volume in healthy and diseased thalami 1).


Many researchers in the field of ultrahigh-field magnetic resonance have become accustomed to bracing themselves for an oft-repeated question. This question may arise during lulls in conversation with clinical colleagues, or during interviews with interested visitors from the press or the lay public, or, more delicate still, during reviews of our applications for research funding. The question is brief, and to the point: ‘When will 7 Tesla scanners be ready for clinical use?’

Pediatric Patient

Its practical utility has been limited due to the near-uniform requirement for sedation or general anesthesia in children. Magnetic resonance imaging without sedation is often futile because of the movement artifact produced by the nonsedated pediatric patient.

fast-sequence MRI (fsMRI)studies were shown to have an excellent overall quality and a statistically significant high degree of interrater reliability. Consequently, Patel et al, propose that fsMRI is a sufficiently effective modality that eliminates the need for sedation and the use of ionizing radiation and that it should supplant CT for routine surveillance imaging in hydrocephalus 2).

Tumor

Magnetic resonance imaging (MRI) has become the gold standard for the assessment of intracerebral lesions and is thus the primary tool for diagnosis and follow up examination of neurological cancers as it is more sensitive than CT for small tumors and offers better visualization of the posterior fossa. The contrast provided between grey and white matter make it the optimal choice for many conditions of the central nervous system including demyelinating diseases, dementia, cerebrovascular disease, infectious diseases and epilepsy.

Magnetic resonance imaging (MRI) is a method of choice for follow-up of irradiated brain metastases.

Cervical spinal cord injury

Magnetic resonance imaging (MRI) has become an important tool in the evaluation of cervical spinal cord injury. In the acute posttraumatic period, intramedullary signal abnormalities on MRI may signify disruption of the intramedullary microstructure, sensory tracts, and motors tracts as previously demonstrated with diffusion tensor imaging (DTI). Such disruption often results in edema and posttraumatic inflammation manifesting as T2 hyperintensity 3).

Japan has the highest number of magnetic resonance imaging units in the world,

1)
Keller SS, Gerdes JS, Mohammadi S, Kellinghaus C, Kugel H, Deppe K, Ringelstein EB, Evers S, Schwindt W, Deppe M. Volume estimation of the thalamus using freesurfer and stereology: consistency between methods. Neuroinformatics. 2012 Oct;10(4):341-50. doi: 10.1007/s12021-012-9147-0. PubMed PMID: 22481382; PubMed Central PMCID: PMC3464372.
2)
Patel DM, Tubbs RS, Pate G, Johnston JM Jr, Blount JP. Fast-sequence MRI studies for surveillance imaging in pediatric hydrocephalus. J Neurosurg Pediatr. 2014 Feb 21. [Epub ahead of print] PubMed PMID: 24559278.
3)
Song T, Chen WJ, Yang B, et al. Diffusion tensor imaging in the cervical spinal cord. Eur Spine J. 2011;20(3):422-428.
magnetic_resonance_imaging.txt · Last modified: 2017/06/27 12:07 by administrador