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991.
Gadi Horev M.D. Leora Kornreich M.D. Herzeliah Hadar M.D. Kalman Katz M.D. 《Skeletal radiology》1991,20(7):479-482
Children suffering from Gaucher's disease were examined by magnetic resonance imaging (MRI) during a characteristic episode of bone crisis. An unexpectedly high intramedullary as well as subperiosteal signal was observed on both the T1 and T2-weighted sequences in 5 patients, suggesting a subacute hemorrhage or hematoma. It is conceivable that such a painful hemorrhage is an important component of the bone crisis phenomenon. Furthermore, in these cases this is a specific sign which may enable differentiation of bone crises from other types of bone pain associated with Gaucher's disease. 相似文献
992.
Marc D. Liang M.D. Krishna Narayanan M.D. Peter L. Davis M.D. J. William Futrell M.D. 《Aesthetic plastic surgery》1991,15(1):313-319
Magnetic resonance imaging (MRI) provides noninvasive images of facial and neck fat for a variety of conditions. It accurately maps the soft tissues pre- and postoperatively, enabling surgeons to precisely and objectively assess results of soft tissue facial contouring and fat transplantation. The risks of MRI are few. It has the potential to provide aesthetic surgeons with a more scientific means of comparing various techniques of fat contouring. 相似文献
993.
von Bibra H Stempfle HU Poll A Scherer M Blüml G Blömer H 《Echocardiography (Mount Kisco, N.Y.)》1991,8(6):633-642
There is little awareness of the limitations of flow detection with the commercially available color Doppler flow mapping system. The influence of flow velocity, ultrasound attenuation, and penetration depth on flow detection in color Doppler (Toshiba SSH 65A) were therefore studied in vitro and compared with conventional Doppler. The flow model had physiological flow volumes and laminar flow with parabolic velocity profile in a horizontal tube of Lucite with less than 3 degrees of coincidence. Conventional Doppler flow velocity measurements correlated highly with laser Doppler anemometry results (r = 0.99, SEE = 3 cm/sec). Signal strength of color Doppler and pulsed Doppler was semi-quantitatively graded using a scale from 0 to 5. Scale 1 (sparse signals) was useless for any assessment in color Doppler but just allowed velocity measurement in pulsed Doppler. Using 19-dB attenuation, flow velocities greater than 100 cm/sec had good scores with moderate gain, 60-100 cm/sec needed increasing gain, and velocities less than 40 cm/sec were not detectable with color Doppler but readily so with pulsed Doppler. With increasing attenuation (1-29 dB) and also with increasing penetration depth, flow detection was reduced significantly (P less than 0.001) more in color Doppler than in the pulsed technique (P less than 0.01). In conclusion, low flow velocities, high attenuation, and greater than 8 cm penetration depth may hamper flow detection in color Doppler and, thus, diagnostic accuracy. Conventional Doppler with its superior accuracy and sensitivity should therefore consolidate diagnostic ultrasound assessment. 相似文献
994.
995.
Cortical activation during retrieval of arithmetical facts and actual calculation: a functional magnetic resonance imaging study 总被引:5,自引:0,他引:5
By using functional magnetic resonance imaging (fMRI), the neural substrates involved in mental recitation of the single-digit multiplication table and serial subtraction were studied. The former depends mostly on well-learned arithmetical facts, while the latter requires arithmetic processing. Activation during each task was compared with that in a number counting control. During the recitation of single-digit multiplication, the activated regions included the area lying along the left intraparietal sulcus, the premotor and supplementary motor areas, and the posterior portion of the left inferior frontal gyrus. The areas activated during serial subtraction included these areas as well as the bilateral prefrontal and right parietal areas. From the results obtained during retrieval of the multiplication table in this study and previous studies, it was concluded that semantic memory of the multiplication table is stored in the area lying along the intraparietal sulcus and that the frontal areas play an executive role in utilizing the semantic memory of arithmetical facts. It was assumed that the arithmetical facts requiring actual calculation are also stored in the same region. The additional activation during serial subtraction compared with the activation during retrieval of the multiplication table is probably due to the processes of actual calculation. These processes include proper alignment of digits, which may have caused the right parietal activation, and maintaining digits needed for the mental serial subtractions, which may have caused the bilateral prefrontal activation. 相似文献
996.
The tick-borne encephalitis (TBE) virus gives rise to epidemic encephalitis. Mild forms usually manifest as influenza-like
episodes or are clinically silent. MRI is usually normal in TBE. We describe severe TBE in a patient who presented with fever
and altered mental status after a tick bite and a specific antibody response to TBE. MRI revealed pronounced signal abnormalities
in the basal ganglia and thalamus, without contrast enhancement. These findings coincide well with neuropathological studies
of severe nerve cell degeneration with inflammatory cell infiltrates, neuronophagia and reactive astrocytosis in the deep
grey matter. We review the literature and discuss the relevant differential diagnosis.
Received: 10 November 1999/Accepted: 4 February 2000 相似文献
997.
MRI of the intraorbital optic nerve in patients with autosomal dominant optic atrophy 总被引:3,自引:0,他引:3
Votruba M Leary S Losseff N Bhattacharya SS Moore AT Miller DH Moseley IF 《Neuroradiology》2000,42(3):180-183
Measurements of the intraorbital optic nerve were made using high-resolution coronal MRI in 10 adults with autosomal dominant
optic atrophy. Comparisons were made with previous studies of 10 normal adult subjects. The cross-sectional diameters of the
optic nerve and the perineural subarachnoid space were measured and a ratio of there diameters at anterior, mid and posterior
positions along the optic nerve was determined. We found a statistically significant difference in the mean optic nerve: sheath
ratio between the control group and patients with autosomal dominant optic atrophy. At anterior, mid and posterior locations
along the optic nerve it is significantly smaller in patients with optic atrophy. We have demonstrated that the loss of ganglion
cells, previously documented in dominant optic atrophy, is associated with a significant loss of optic nerve tissue and thinning
of the nerve along its length.
Received: 6 July 1999/Accepted: 22 July 1999 相似文献
998.
Chronological changes in nonhaemorrhagic brain Infarcts with short T1 in the cerebellum and basal ganglia 总被引:2,自引:0,他引:2
Our purpose was to investigate nonhaemorrhagic infarcts with a short T1 in the cerebellum and basal ganglia. We carried out
repeat MRI on 12 patients with infarcts in the cerebellum or basal ganglia with a short T1. Cerebellar cortical lesions showed
high signal on T1-weighted spin-echo images beginning at 2 weeks, which became prominent from 3 weeks to 2 months, and persisted
for as long as 14 months after the ictus. The basal ganglia lesions demonstrated slightly high signal from a week after the
ictus, which became more intense thereafter. Signal intensity began to fade gradually after 2 months. High signal could be
seen at the periphery until 5 months, and then disappeared, while low or isointense signal, seen in the central portion from
day 20, persisted thereafter.
Received: 1 February 1999 Accepted: 13 September 1999 相似文献
999.
Serial diffusion-weighted imaging in MELAS 总被引:7,自引:1,他引:6
Ohshita T Oka M Imon Y Watanabe C Katayama S Yamaguchi S Kajima T Mimori Y Nakamura S 《Neuroradiology》2000,42(9):651-656
Clinical features of mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes (MELAS) resemble those
of cerebral infarcts, but the pathogenesis of infarct-like lesions is not fully understood. To characterise these infarct-like
lesions, we studied two patients with MELAS using diffusion-weighted (DWI) MRI before and after stroke-like episodes and measured
the apparent diffusion coefficient (ADC) in the new infarct-like lesions. These gave high signal on DWI and had much higher
ADC than normal-appearing regions. The ADC remained high even 30 days after a stroke-like episode then decreased in lesions,
with or without abnormality as shown by conventional MRI. We speculate that early elevation of ADC in the acute or subacute
phase reflects vasogenic rather than cytotoxic edema. The ADC of the lesions, which disappeared almost completely with clinical
improvement, returned to normal levels, which may reflect tissue recovery without severe damage. To our knowledge, this is
the first study of DWI in MELAS.
Received: 13 September 1999/Accepted: 7 January 2000 相似文献
1000.
Cystic lesions of the pineal region – MRI and pathology 总被引:5,自引:0,他引:5
Pineal lesions are rare. Tumours in this location comprise 0.4–1 % of intracranial tumours. They grow mainly as solid-mass
lesions, and cystic tumours are not common. On MRI, a cystic configuration is associated usually with non-neoplastic pineal
lesions rather than with a tumour, but analysis does not allow cystic pineal tumours to be distinguished from glial cysts
with certainty. We compared neuroradiological and pathological data from 13 cystic pineal lesions, analysing preoperative
MRI. Formalin-fixed, paraffin-embedded surgical specimens were stained routinely and immunocytochemically, using the streptavidin-biotin-complex
method. Histology revealed six pineocytomas, four glial cysts, an arachnoid cyst, a low-grade astrocytoma and a teratoma.
Signal characteristics of pineocytomas were similar in many respects to those of glial pineal cysts. Histomorphological analysis
allowed unambiguous discrimination between pineocytomas and glial pineal cysts.
Received: 19 July 1999/Accepted: 3 September 1999 相似文献