Improving MRI differentiation of gray and white matter in epileptogenic lesions based on nonlinear feedback

Huang, Susie Y.; Wolahan, Stephanie M.; Mathern, Gary W.; Chute, Dennis J.; Akhtari, Massoud; Nguyen, Snow; Huynh, My N.; Salamon, Noriko; Lin, Yung‐Ya

doi:10.1002/mrm.20987

Cited by 20 publications

(30 citation statements)

References 39 publications

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“…Figure 7 demonstrates contrast enhancement due to small differences in resonance frequency under the joint feedback fields in a simple water/ethanol phantom. Additional experiments on tissue samples have confirmed the growth of contrast under the individual and joint feedback fields (41).…”

Section: Concepts In Magnetic Resonancementioning

confidence: 82%

Understanding spin turbulence in solution magnetic resonance through phase space dynamics and instability

Datta

Huang

Lin

2006

Concepts Magnetic Resonance

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ABSTRACT:The joint action of two feedback fields in solution magnetic resonance (MR), radiation damping and the distant dipolar field, are known to give rise to nonlinear evolution of the magnetization at high fields. The different stages of the resulting complex dynamics are explored here, and standard tools and terminology adopted from the theory of nonlinear dynamics are introduced to analyze the underlying dynamics. The nonlinear spin dynamics are shown to generate unexpected artifacts in routine MR experiments involving bulk solvents. Approaches to curtail the effects of the joint feedback fields are discussed, as well as applications exploiting these fields as new contrast enhancement mechanisms for MR imaging.

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Section: Concepts In Magnetic Resonancementioning

confidence: 82%

Understanding spin turbulence in solution magnetic resonance through phase space dynamics and instability

Datta

Huang

Lin

2006

Concepts Magnetic Resonance

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“…Such findings support the concept that CSF flow within the brain is probably altered related to the severe cortical and white matter disorganization in hemimegalencephaly cases rather than changes in brain compliance or due to blood and tissue debris since CD cases had lower rates of needing shunts despite similar ages at surgery, ventricular size, and expected blood loss during surgery. 1,2,11 Alternately, differences in etiology may contribute to the ability of the arachnoid granulations to remain open after resection-disconnection hemispherectomy. While acute changes in CSF osmolarity reflected by increased CSF RBC counts may also contribute to developing hydrocephalus, our data suggest that this is a minor association.…”

Section: Discussionmentioning

confidence: 99%

Etiology associated with developing posthemispherectomy hydrocephalus after resection-disconnection procedures

Phung

Krogstad

Mathern

2013

PED

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Object The authors sought to determine if clinical epilepsy variables, maximum daily temperature (Tmax), and blood and CSF findings were associated with the risk of developing hydrocephalus after first-time resection-disconnection hemispherectomy. Methods Patients who underwent cerebral hemispherectomy in whom a standardized perioperative protocol was used, including the use of ventriculostomies (n = 79), were classified into those who developed and those who did not develop hydrocephalus requiring CSF shunts. The authors compared these 2 groups for clinical variables, Tmax, and blood and CSF studies through postoperative Day 12. Results In this cohort, 30% of the patients required CSF shunts, of which 8% developed late hydrocephalus up to 3 years posthemispherectomy. Multivariate analysis found that etiology was associated with developing posthemispherectomy hydrocephalus. Higher shunt rates were observed for patients with hemimegalencephaly (40%; n = 15) and a history of CNS infection (100%; n = 4) compared with cortical dysplasia (17%; n = 23) and Rasmussen encephalitis (17%; n = 12). In univariate analysis, other factors associated with developing hydrocephalus were elevated maximum daily temperatures, elevated white blood cell counts, decreased CSF protein, and increased CSF red blood cell counts. Conclusions The findings of the study indicate that etiology was the factor most strongly associated with developing posthemispherectomy hydrocephalus. These findings suggest that there are variable mechanisms for developing hydrocephalus after cerebral hemispherectomy depending on the procedure, and in resection-disconnection operations the mechanism may involve changes in CSF bulk flow that varies by histopathology.

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“…Contrast enhancement based on nonlinear feedback interactions has been shown to reveal differences in tissue composition based on small resonance frequency variations arising from magnetic susceptibility differences (12,13). As an example, one such magnetization-dependent feedback field is radiation damping (RD).…”

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confidence: 99%

“…The phase ⌿ and amplitude of the RD field can also be modified to suppress or enhance the RD effect through active feedback to the induced free induction decay (FID) current in the RF coil (21,22). Under RD, different frequency components contribute to varying extents to the feedback field, resulting in sensitivity to microscopic field variations (12,13). The evolution of the magnetization under the RD field depends on the strength of the feedback field as well as the width and mean of the specified frequency distribution in a given voxel relative to that of all other voxels within the active region of the coil.…”

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confidence: 99%

“…The evolution of the magnetization under the RD field depends on the strength of the feedback field as well as the width and mean of the specified frequency distribution in a given voxel relative to that of all other voxels within the active region of the coil. RD has been shown to highlight pathologic features in fresh in vitro human brain tissue samples excised from epileptogenic lesions and malignant brain tumors based on subtle variations in magnetic susceptibility and/or resonance frequency that are not apparent in conventional T 1 -weighted, T * 2 -weighted, and proton density images (12), in agreement with microscopic susceptibility gradients characteristic of gray and white matter (23). Whether the high selectivity of such feedback-based contrast enhancement for small resonance frequency variations still holds even in the presence of macroscopic field inhomogeneity is important for transitioning this new methodology into in vivo animal models in imaging systems with lower field strengths and greater inhomogeneity.…”

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confidence: 99%

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Sensitivity of feedback‐enhanced MRI contrast to macroscopic and microscopic field variations

Huang¹,

Yang²,

Lin³

2009

Magnetic Resonance in Med

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Nonlinear feedback interactions have been shown to amplify contrast due to small differences in resonance frequency arising from microscopic susceptibility variations. Determining whether the selectivity of feedback-based contrast enhancement for small resonance frequency variations remains valid even in the presence of macroscopic field inhomogeneity is important for transitioning this new methodology into in vivo applications in imaging systems with lower field strengths and poorer homogeneity. This work shows that contrast enhancement under the radiation damping (RD) feedback field is sensitive to microscopic intravoxel frequency variations. Feedbackenhanced contrast provides superior signal differentiation from voxels with distinct microscopic frequency distributions compared with T* 2 -weighted imaging, while remaining robust to macroscopic field gradients, which frequently give rise to artifacts by other frequency-sensitive methods.

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Improving MRI differentiation of gray and white matter in epileptogenic lesions based on nonlinear feedback

Cited by 20 publications

References 39 publications

Understanding spin turbulence in solution magnetic resonance through phase space dynamics and instability

Understanding spin turbulence in solution magnetic resonance through phase space dynamics and instability

Etiology associated with developing posthemispherectomy hydrocephalus after resection-disconnection procedures

Sensitivity of feedback‐enhanced MRI contrast to macroscopic and microscopic field variations

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