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71.
To extend the signal longevity of magnetically excited spins in flowing fluids while in a state of global coherent free precession (GCFP), a refocusing radiofrequency (RF) pulse and bipolar gradient waveforms were combined with the GCFP sequence. The data demonstrate that RF refocusing in the presence of flowing blood is possible, but the improvement in signal amplitude depends on the static magnetic field homogeneity along the direction of motion and the displacement of the spins between the excitation and the RF refocusing pulse, as well as displacement during subsequent RF refocusing pulses. The least amount of phase dispersion and thus the longest lasting signal is obtained with the shortest echo spacing where only one line of data is recorded between two RF refocusing pulses. This approach was successfully used in a phantom and in vivo to image fast and slow blood flow. Depending on the experimental conditions, signal persistence is improved significantly compared to playing the same sequence without RF refocusing, but the improvement is limited by the product of blood flow velocity and the time between RF refocusing pulses.  相似文献   
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The loads needed to elicit a positive pivot shift test in a knee with an anterior cruciate ligament (ACL) rupture have not been quantified. The coupled anterior tibial translation (ATT), coupled internal tibial rotation (ITR), and the in situ force in the ACL in response to a valgus torque, an inherent component of the pivot shift test, were measured in 10 human cadaveric knee specimens. Using a robotic/universal force-moment sensor testing system, valgus torques ranging from 0.0 to 10.0 Nm were applied in nine increments on the intact and ACL-deficient knee in flexion ranging from 0 degrees to 90 degrees. At 15 degrees of knee flexion, the coupled ATT and ITR were significantly increased in the ACL-deficient knee when compared to the intact knee. Coupled ATT increased a maximum of 291% (6.7 mm, p<0.05), while coupled ITR increased a maximum of 85% (5.1 degrees, p<0.05). At 30 degrees, the increases in coupled ATT and ITR were significant at valgus loads of 3.3 Nm and greater with a maximum increase in coupled ATT of 137% (6.3 mm, p<0.05) and a maximum increase in coupled ITR of 38% (3.6 degrees, p<0.05). At 45 degrees, coupled ATT increased significantly (maximum of 69%, 4.4 mm, p<0.05), but only at torques > or =6.7 Nm. The in situ force in the ACL was less than 20 N for all flexion angles when a torque between 3.3 and 5.0 Nm was applied. Low valgus torque elicited tibial subluxation in the ACL-deficient knee with low in situ ACL forces, similar to a positive pivot shift test. Thus, application of a valgus torque may be suitable to evaluate ACL-deficient and ACL-reconstructed knees, since subluxation can be achieved with minimal harm to the ACL graft. This work is important in understanding one load component needed for the pivot shift examination; further studies quantifying other load components are essential for better comprehension of the in vivo pivot shift examination.  相似文献   
74.
Cerebral venous malformation complicated by spontaneous thrombosis   总被引:1,自引:0,他引:1  
A case of spontaneous thrombosis and infarction leading to death as complications of a cerebral venous malformation in a 13-yearold boy is reported. This is the first published report of this type of complication occurring in a case of venous angioma. While the biologic behavior of cerebral venous malformations has suggested that they are benign in nature, and the results of surgical management have encouraged a conservative approach, the present case illustrates a potential complication and argues against the assumption that these malformations are completely benign in nature.  相似文献   
75.
It is often difficult to make a clinical or histologic diagnosis of erythrodermic mycosis fungoides (MF) and Sézary syndrome (SS). Whereas the histologic parameters for making a diagnosis of MF with well-developed patch and plaque stage lesions are clearly defined, the same criteria appear to be less relevant for diagnosing MF in patients with erythroderma secondary to the disease. In order to better define the histologic features of erythrodermic MF and SS, we studied 28 routine histologic sections of 17 patients with known erythrodermic MF or SS. Sections were reviewed independently by 2 dermatopathologists. Each of 24 parameters was scored semi-quantitatively and the data were compared to data previously reported from a group of 64 patients with limited patch and plaque stage lesions of MF. When compared to biopsies from patients with limited patch/plaque lesions, biopsies taken from erythrodermic patients displayed more parakeratosis (p=0.0492) and acanthosis (p=0.0046), less disproportionate epidermotropism, fewer lymphocytes aligned within the basal layer (p=0.0045), fewer hyper-convoluted cells in the epidermis, more dermal hyperconvoluted cells (p=0.0191), more papillary dermal fibrosis (p=0.0002), more prominent teleangiectasias (p=0.0028) and more mitotic figures.
The histologic features of erythrodermic MF and Sézary syndrome are even more subtle than the features of patch and plaque stage MF, thus rendering the histologic diagnosis more difficult.  相似文献   
76.
Several areas related to the use of telescopes in low vision are reviewed. These include: contrast sensitivity function; eccentric viewing through a telescope; field of view; telescope used in reverse; and IOL-spectacle lens telescopic systems. Experimental data are included to support selected clinical observations routinely made by low vision clinicians.  相似文献   
77.
Abstract: Juvenile xanthogranuloma is a xanthomatous and granulomatous condition that frequently arises before 1 year of age and mainly occurs on the head and trunk. We report a rare solitary juvenile xanthogranuloma on the right palm of a 10-year-old girl, present for one year. This solitary involvement of the palm has been reported only twice before.  相似文献   
78.
In an attempt to develop a new anticancer platinum complex with greater or equivalent antitumor activity but reduced side effects compared with cisplatin (CDDP), a series of new platinum complexes having a glycolate leaving ligand was synthesized. Among them, five complexes were selected for further development on the basis of adequate water solubility, low nephrotoxicity and high antitumor activity in a murine system. The chemosensitivity of these five complexes was examined in MTT assay against two human pulmonary adenocarcinoma cell lines, PC-9 and PC-14, and two human stomach adenocarcinoma cell lines, MKN-45 and KATO III. Their IC50 and relative antitumor activity (RAA) values were compared with those of CDDP and 254-S, a second-generation platinum complex with a glycolate leaving ligand under phase III clinical trial. The lowest mean IC50 value was observed in CDDP, followed by SKI 2034R and SKI 2033R. In this study, the antitumor activity was evaluated in terms of RAA values and SKI 2034R showed the highest RAA value. The order of RAA values was SKI 2034R > CDDP > SKI 2032R > SKI 2033R > SKI 2030R > SKI 2029R > 254-S. Based on the RAA order, we have recommended SKI 2034R as the most promising candidate for further development of a clinically useful platinum complex.  相似文献   
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