Book contents
- Frontmatter
- Contents
- Contributors
- Case studies
- Preface to the second edition
- Preface to the first edition
- Abbreviations
- Introduction
- Section 1 Physiological MR techniques
- Section 2 Cerebrovascular disease
- Section 3 Adult neoplasia
- Section 4 Infection, inflammation and demyelination
- Section 5 Seizure disorders
- Chapter 33 Seizure disorders
- Chapter 34 Magnetic resonance spectroscopy in seizure disorders
- Chapter 35 Diffusion and perfusion MR imaging in seizure disorders
- Section 6 Psychiatric and neurodegenerative diseases
- Section 7 Trauma
- Section 8 Pediatrics
- Section 9 The spine
- Index
- References
Chapter 35 - Diffusion and perfusion MR imaging in seizure disorders
from Section 5 - Seizure disorders
Published online by Cambridge University Press: 05 March 2013
- Frontmatter
- Contents
- Contributors
- Case studies
- Preface to the second edition
- Preface to the first edition
- Abbreviations
- Introduction
- Section 1 Physiological MR techniques
- Section 2 Cerebrovascular disease
- Section 3 Adult neoplasia
- Section 4 Infection, inflammation and demyelination
- Section 5 Seizure disorders
- Chapter 33 Seizure disorders
- Chapter 34 Magnetic resonance spectroscopy in seizure disorders
- Chapter 35 Diffusion and perfusion MR imaging in seizure disorders
- Section 6 Psychiatric and neurodegenerative diseases
- Section 7 Trauma
- Section 8 Pediatrics
- Section 9 The spine
- Index
- References
Summary
Introduction
Conventional, anatomical MR imaging (MRI) has been widely used for the detection of brain tissue volume changes caused by chronic seizures, and for diagnosis of brain lesions that result in seizure activity. However, seizures are often not associated with lesions or volume changes visible in conventional MRI. In contrast, diffusion and perfusion MRI are sensitive to the physiological changes that take place in brain tissue ictally, postictally, and interictally. This chapter provides an in-depth discussion of the application of both diffusion and perfusion MRI in seizure disorders. The changes in perfusion (cerebral blood flow [CBF], cerebral blood volume [CBV]) and diffusion (apparent diffusion coefficient [ADC], fractional anisotropy [FA]) that occur in ictogenic regions or globally in the brain are described, and diffusion and perfusion MRI are evaluated as methods to localize seizure focus. Finally, mechanisms that may be responsible for the changes that occur in perfusion and diffusion of brain tissue in seizure disorders are examined.
Perfusion MRI in seizure disorders
The techniques
Positron emission tomography (PET) and single-photon emission computed tomography (SPECT) have been used to identify focal changes in regional CBF in patients with epilepsy.[1,2] However, the low spatial and temporal resolution of PET and SPECT and the ionizing radiation emitted from the nuclear medicine tracers are major concerns. The development of MR perfusion techniques has offered higher spatial and temporal resolution without the use of ionizing radiation.[3,4] Perfusion MRI has been applied in several studies of cerebral ischemia,[5] brain tumors,[6] and functional brain mapping.[7] The techniques are based on exogenous or endogenous tracers. In the method based on exogenous tracers, a paramagnetic agent such as gadolinium-diethylenetriaminepentaacetic acid (Gd-DTPA) is injected, and the resulting decrease and subsequent recovery of the MR signal is used to estimate perfusion.[8,9] In the method using endogenous tracers, the spins of arterial water are non-invasively labeled using radiofrequency pulses, and the regional accumulation of the label is measured by comparison with an image acquired without labeling (arterial spin-labeling, [ASL]).[10]
- Type
- Chapter
- Information
- Clinical MR NeuroimagingPhysiological and Functional Techniques, pp. 546 - 560Publisher: Cambridge University PressPrint publication year: 2009