3D MRI of the membranous labyrinth. An age related comparison of MR findings in patients with labyrinthine fibrosis and in persons without inner ear symptoms.
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PURPOSE: We compared MRI of the membranous labyrinth in patients with chronic non-neoplastic inner ear disease and MR signs of labyrinthine fibrosis and controls depending on their age, in order to establish whether there were any MR differences regarding patient age groups, control age groups and between the patients and controls themselves. MATERIALS AND METHODS: Clinical ENT examinations as well as a T2* weighted 3D CISS (Constructive Interference in Steady State) sequence with a slice thickness of 0.7 mm were performed. Our collective was subdivided as follows: 0-19 years (10 controls, 3 patients with chronic non-neoplastic inner ear disease), 20-49 years (55 controls, 8 patients), 50 years and older (40 controls, 22 patients). Detectability of labyrinthine structures (e.g. cochlea, vestibule, semicircular canals) and filling defects were evaluated. RESULTS: In the 3 age-groups of the control collective no significant differences were observed in the membranous labyrinth. However differences concerning labyrinthine detectability emerged between controls and patients in both the 20-49 years and 50 years and older age groups. In the patient collective the 3 age groups showed no significant discrepancy in the mean number of lesions. CONCLUSION: Filling defects of the membranous labyrinth on 3D CISS MR images are pathological even in older persons. We would therefore recommend high resolution T2* weighted MRI in the case of suspected labyrinthine fibrosis. (+info)
Cortical lesions in multiple sclerosis.
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Although previous studies have shown that the lesions of multiple sclerosis may involve the cerebral cortex, there is little published research on the prevalence and distribution of such lesions. Using neuropathological techniques and MRI, a series of studies has been undertaken in order to assess this, in particular to identify their relationship to cortical veins. A serial MRI study showed that the use of gadolinium proffered an increase in cortical lesion detection of 140% and showed that 26% of active lesions arose within or adjacent to the cortex. In a post-mortem study, MRI under-reported lesions subsequently analysed neuropathologically, particularly those arising within the cortex. In a further 12 cases examined, 478 cortical lesions were identified, of which 372 also involved the subcortical white matter. Seven different lesion types were identified; the majority arose within the territory of the principal cortical veins, whilst the remaining quarter arose within the territory of the small branch or superficial veins. Small cortical lesions are common in multiple sclerosis and are under-reported by MRI. Investigation of the cortical venous supply shows how such lesions may arise, and why the majority also involve the underlying white matter. (+info)
Differential spatial memory impairment after right temporal lobectomy demonstrated using temporal titration.
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In this study a temporal titration method to explore the extent to which spatial memory is differentially impaired following right temporal lobectomy was employed. The spatial and non-spatial memory of 19 left and 19 right temporal lobectomy (TL) patients was compared with that of 16 normal controls. The subjects studied an array of 16 toy objects and were subsequently tested for object recall, object recognition and memory for the location of the objects. By systematically varying the retention intervals for each group, it was possible to match all three groups on object recall at sub-ceiling levels. When memory for the position of the objects was assessed at equivalent delays, the right TL group revealed disrupted spatial memory, compared with both left TL and control groups (P < 0.05). MRI was used to quantify the extent of temporal lobe resection in the two groups and a significant correlation between hippocampal removal and both recall of spatial location and object name recall in the right TL group only was shown. These data support the notion of a selective (but not exclusive) spatial memory impairment associated with right temporal lobe damage that is related to the integrity of the hippocampal functioning. (+info)
Reduced cytosolic acidification during exercise suggests defective glycolytic activity in skeletal muscle of patients with Becker muscular dystrophy. An in vivo 31P magnetic resonance spectroscopy study.
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Becker muscular dystrophy is an X-linked disorder due to mutations in the dystrophin gene, resulting in reduced size and/or content of dystrophin. The functional role of this subsarcolemma protein and the biochemical mechanisms leading to muscle necrosis in Becker muscular dystrophy are still unknown. In particular, the role of a bioenergetic deficit is still controversial. In this study, we used 31p magnetic resonance spectroscopy (31p-MRS) to investigate skeletal muscle mitochondrial and glycolytic ATP production in vivo in 14 Becker muscular dystrophy patients. Skeletal muscle glycogenolytic ATP production, measured during the first minute of exercise, was similar in patients and controls. On the other hand, during later phases of exercise, skeletal muscle in Becker muscular dystrophy patients was less acidic than in controls, the cytosolic pH at the end of exercise being significantly higher in Becker muscular dystrophy patients. The rate of proton efflux from muscle fibres of Becker muscular dystrophy patients was similar to that of controls, pointing to a deficit in glycolytic lactate production as a cause of higher end-exercise cytosolic pH in patients. The maximum rate of mitochondrial ATP production was similar in muscle of Becker muscular dystrophy patients and controls. The results of this in vivo 31P-MRS study are consistent with reduced glucose availability in dystrophin-deficient muscles. (+info)
Absent pituitary gland and hypoplasia of the cerebellar vermis associated with partial ophthalmoplegia and postaxial polydactyly: a variant of orofaciodigital syndrome VI or a new syndrome?
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We report two sibs with features overlapping those of orofaciodigital syndrome type VI (Varadi syndrome). Both presented at birth with oculomotor abnormalities, dysmorphic facial features, and dysgenesis of the cerebellar vermis. There were minimal oral manifestations (high arched palate) in both of them and one had postaxial polydactyly of both hands and one foot. In addition, there was evidence of aplasia of the pituitary gland on MRI scan in both of them with evidence of hypopituitarism. Both responded well to hormone replacement therapy with improvement in their linear growth and mental ability. These cases may represent a new autosomal recessive midline defect syndrome with features overlapping OFDS VI. Alternatively the features in these children could represent variability within OFDS VI. (+info)
High-resolution intravascular magnetic resonance imaging: monitoring of plaque formation in heritable hyperlipidemic rabbits.
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BACKGROUND: The individual makeup of atherosclerotic plaque has been identified as a dominant prognostic factor. With the use of an intravascular magnetic resonance (MR) catheter coil, we evaluated the effectiveness of high-resolution MR in the study of the development of atherosclerotic lesions in heritable hyperlipidemic rabbits. METHODS AND RESULTS: Sixteen hyperlipidemic rabbits were investigated at the ages of 6, 12, 24, and 36 months. The aorta was studied with digital subtraction angiography and high-resolution MR with the use of a surface coil and an intravascular coil that consisted of a single-loop copper wire integrated in a 5F balloon catheter. Images were correlated with histological sections regarding wall thickness, plaque area, and plaque components. Digital subtraction angiography revealed no abnormalities in the 6- and 12-month-old rabbits and only mild stenoses in the 24- and 36-month-old rabbits. High-resolution imaging with surface coils resulted in an in-plane resolution of 234x468 microm. Delineation of the vessel wall was not possible in younger rabbits and correlated only poorly with microscopic measurements in the 36-month-old rabbits. Intravascular images achieved an in-plane resolution of 117x156 microm. Increasing thickness of the aortic wall and plaque area was observed with increasing age. In the 24- and 36-month-old animals, calcification could be differentiated from fibrous and fatty tissue on the basis of the T2-fast spin echo images, as confirmed by histological correlation. CONCLUSIONS: Atherosclerotic evolution of hyperlipidemic rabbits can be monitored with high-resolution intravascular MR imaging. Image quality is sufficient to determine wall thickness and plaque area and to differentiate plaque components. (+info)
Retinotopic mapping of lateral geniculate nucleus in humans using functional magnetic resonance imaging.
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Subcortical nuclei in the thalamus, which play an important role in many functions of the human brain, provide challenging targets for functional mapping with neuroimaging techniques because of their small sizes and deep locations. In this study, we explore the capability of high-resolution functional magnetic resonance imaging at 4 Tesla for mapping the retinotopic organization in the lateral geniculate nucleus (LGN). Our results show that the hemifield visual stimulation only activates LGN in the contralateral hemisphere, and the lower-field and upper-field visual stimulations activate the superior and inferior portion of LGN, respectively. These results reveal a similar retinotopic organization between the human and nonhuman primate LGN and between LGN and the primary visual cortex. We conclude that high-resolution functional magnetic resonance imaging is capable of functional mapping of suborganizations in small nuclei together with cortical activation. This will have an impact for studying the thalamocortical networks in the human brain. (+info)
Correlation of regional cerebral blood flow and change of plasma sodium concentration during genesis and satiation of thirst.
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Positron emission tomography studies were conducted during genesis of moderate thirst by rapid i.v. infusion of hypertonic saline (0.51 M) and after satiation of thirst by drinking water. The correlation of regional cerebral blood flow with the change in the plasma Na concentration showed a significant group of cerebral activations in the anterior cingulate region and also a site in the middle temporal gyrus and in the periaqueductal gray. Strongest deactivations occurred in the parahippocampal and frontal gyri. The data are consistent with an important role of the anterior cingulate in the genesis of thirst. (+info)