Inplane Spatial Resolution
The in-plane spatial resolution is determined by the matrix size and the size of the FOV that is how many voxels we divide the area we are imaging into. A typical matrix in clinical practice is 256 x 256, which means that the whole image is divided, in two dimensions, into an array of this many compartments or picture elements pixels . The actual size of the pixels will depend on the FOV. If we know the third dimension of the slice thickness as well we can determine the voxel volume, i.e. the...
Info Fgm
FIG. 3.7. Frontal pole, anterior aspect. 3,3' Middle frontal gyrus F2 , superior and inferior parts 4 Middle frontal sulcus reaching 5 5 Frontomarginal sulcus 6,6',6 Superior, middle, and inferior transverse frontopolar gyri 7 Frontomarginal gyrus FIG. 3.8. Lateral aspect of the right frontal lobe. 3 Inferior postcentral sulcus ascending portion 4' Posterior subcentral sulcus 4 Anterior subcentral sulcus 5 Lateral fissure, middle segment 6 Lateral fissure, anterior segment a vertical and b...
Parahippocampal Gyrus Abnormalities
Other indirect features of mesial sclerosis commonly seen in these patients are the presence of parahippocampal gyrus atrophy and sometimes signal change. These changes are difficult to visualize but with optimized images one can evaluate the presence of thinning of the underlying white matter and blurring of the gray white matter pattern. This usually depends on having images that assess signal change well Fig. 4.41 . Similarly, changes of the collateral white matter, which is located between...
Info Wth
FIG. 3.18. Intraventricular aspect of the right hippocampus. The temporal horn of the lateral ventricle has been opened and the choroid plexuses have been removed. FIG. 3.18. Intraventricular aspect of the right hippocampus. The temporal horn of the lateral ventricle has been opened and the choroid plexuses have been removed. 2 Hippocampal head digltationes hippocampi 6 Splenium of the corpus callosum 7 Calcar avis in the occipital horn 10 Uncal recess of the temporal horn the amygdala...
Table 45 MRI Characteristics of Astrocytic Neoplasms
adult Homogeneous intensity Variable adult Cystic Demarcated Common dense adult Heterogeneous Common irregular Oligodendrogliomas are histologically characterized by the presence of compact groups of large, rounded cells with empty cytoplasm Fig. 4.65 . In almost half the cases, the tumors are mixed with glial components. Calcifications are frequent, with calcium deposits in the intrinsic blood vessels 393, 397-399 . These tumors are less frequent than astrocytomas and also infrequent in our...
Hippocampal Dysplasia
Hippocampal dysplasia is a nonspecific term that is used to mean a developmental abnormality of the hippocampus see Chapter 6 for a full discussion of malformations of cortical development . In this context it is defined by the presence of distinct architectural and cellular abnormalities in the hippocampus. Although there is debate as to what the role of development is in the origins of HS, we do not include HS as dysplasia. We include hippocampal dysplasia here because of the imaging issues,...
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1 Hippocampal head, cornu ammonis 2 Hippocampal head, gyrus deniatus 3 Temporal horn of the lateral ventricle 9 Band of Giacomini arrows indicate the hippocampal sulcus
Coronal Sections Of The Hippocampus
The coronal views show eight sections moving progressively from anterior to posterior levels. FIG. 3.24. Coronal section of the hippocampal head. A. Three-dimensional drawing. B. T1 -weighted MR image. C. Anatomic section posterior view . FIG. 3.24. Coronal section of the hippocampal head. A. Three-dimensional drawing. B. T1 -weighted MR image. C. Anatomic section posterior view . 1 Anterior apex of the hippocampal head cornu ammonis 2' Amygdala, lateral nucleus 2 Amygdala, basal nucleus 2'...
List of Contributors
David F. Abbott, Ph.D. Brain Research Institute, Melbourne, Victoria, Australia A. James Barkovich, M.D. Department of Radiology, Neuroradiology Section, University of California San Francisco, San Francisco, CA, USA Samuel F. Berkovic, M.D. Epilepsy Research Collaborative Centre, University of Melbourne, Melbourne, Victoria, Australia Andrea Bernasconi, M.D. Montreal Neurological Institute, McGill University, Montreal, Qu bec, Canada Jeffrey R. Binder, M.D. Department of Neurology, Medical...
A Jex
FIG. 4.31. Measurement of T2-relaxometry times T2 relaxometry was acquired with a CPMG sequence with eight images per location 7 e 29-231 ms, TR 5000ms on a 3T GE LX Horizon scanner Milwaukee, USA . A. All eight acquired images are shown, with echo times between 29 and 231 ms, on one slice at the level of the hippocampus. Note the changing brightness of the images, reflecting the T2 decay. In the region within the red circle, the signal was measured on each image. This decay is shown...
Observing Hippocampal Sclerosis Development
Acute Changes in Patients with Epilepsy Progressing to Hippocampal Sclerosis The presence of short-term, seizure-associated changes is an important issue. There is debate about whether seizures cause damage to the brain or whether all or a portion of the abnormalities seen in the brains of patients with epilepsy are due to pre-existing factors. A change in T2 relaxometry after a seizure would favor the idea that seizure-associated damage can occur. An early study suggested that recent seizures...