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1.
The human visual system is amenable to a number of adaptive processes; one such process, or collection of processes, is the adaptation to blur. Blur adaptation can be observed as an improvement in vision under degraded conditions, and these changes occur relatively rapidly following exposure to blur. The potential important future directions of this research area and the clinical implications of blur adaptation are discussed. 相似文献
2.
3.
Floriana S Luppino Edward Grooters Francisca T de Bru?ne Aeilko H Zwinderman Andel G L van der Mey 《Otology & neurotology》2006,27(7):962-968
OBJECTIVE: Conservative treatment in vestibular schwannomas is mainly dependent on optimal tumor size determination. The first objective of this study was to establish interobserver and intraobserver variability and the accuracy and reproducibility of three different measurement methods: one bidimensional and two volumetrical. The second objective was to evaluate the influence of the use of different magnetic resonance imaging (MRI) slice thickness and the influence of patient's repositioning on the measurements' outcome. STUDY DESIGN: Two consecutive studies have been prospectively performed, both mainly concerning volumetrical measurements. SETTING: Both studies were performed in a tertiary academic, multidisciplinary center. PATIENTS: In the first study, 19 patients were included between March 1996 and May 2002, with a total of 52 scans. The second study comprised 14 patients. All patients in the first study had at least two MRI examinations performed according to a standard protocol (T1-weighted gadolinium-enhanced, slice thickness of 3 mm, and interslice gap of 0.3 mm). The population in the second study underwent a conservative wait and scan (W&S) treatment. METHODS: Both studies are discussed separately. In the first study, all scans were measured by four investigators, two of whom performed the measurements twice using three different methods. The first method concerns a manually performed bidimensional surface measurement along the petrous pyramid. The second method concerns a semiautomatic volumetrical measurement on a computer, relying on contour detection, and the last method concerns a fully automatic volume reconstruction also performed on a computer using different gray shade scales.All 14 patients included in the second study underwent three magnetic examinations. Three different T1-weighted gadolinium-enhanced sequences were used: the first using a slice thickness of 1 mm, the second again with 1-mm slice thickness but after having repositioned the patient. In the third sequence, a slice thickness of 3 mm was used. All scans were measured by two investigators using the three different methods, as described previously. RESULTS: The manual surface method shows large intraobserver variability, and its reproducibility is significantly lower compared with volume measurements. Because of a relatively large systematic error in small tumors, sensitivity of growth detection is low. Both volumetrical methods are hardly interobserver- and intraobserver-dependent, and the gray shade method turned out to be the most accurate. Radiologic progression is only significant at a volume increase of at least 50%. The influence of patient repositioning is negligible, whereas the use of 1-mm slice thickness seems to be superior to a 3-mm slice thickness. CONCLUSION: The volumetrical gray shade method is the most accurate method to detect early tumor progression. As tumor increase of at least 50% is needed to be able to speak of statistically significant tumor growth, the absence of radiologic progression does not mean that there is no tumor growth. Repositioning of the patient has no influence on the measurements' outcome, whereas for optimal magnetic resonance imaging examinations, a 1-mm slice thickness protocol seems to be superior. 相似文献
4.
Marcel Stokkel Aeilko Zwinderman Jaap Zwartendijk Ernest Pauwels Berthe van Eck-Smit 《European journal of nuclear medicine and molecular imaging》1997,24(10):1215-1220
Between 10% and 25% of patients with newly diagnosed prostate cancer without bone metastases at the time of diagnosis will
develop metastases during follow-up. To determine the value of clinical and biochemical parameters for assessment of prognosis
at the time of diagnosis, a retrospective study was performed in 124 consecutive patients with newly diagnosed prostate cancer
without bone metastases. The mean follow-up was 41 months, during which time 36 patients died and 15 patients developed metastases.
Bone scans were classified from 0 (=normal) through 2 (=abnormal, but not typical for metastases) and were correlated with
age, alkaline phosphatase (AP), prostate-specific antigen (PSA), tumour grade, T-stage and N-stage. In patients with a class
2 scan, additional roentgenograms and follow-up were used to exclude metastases at initial stage. All parameters, including
therapy, were finally correlated with the development of metastases and survival. For survival 38 patients with proven metastases
were used as controls. For all parameters tested, no statistically significant differences were found between the three bone
scan classifications. The interval between diagnosis and the development of metastases ranged from 12 to 72 months. For the
risk of development of metastases only PSA was found to be a significant correlate (P=0.0075). However, when tumour stages were clustered in limited disease (T0–2) and extensive disease (T3–4), the incidence
of metastases was significantly higher in patients with extensive disease than in those with limited disease (P=0.0021). Finally, age, PSA and Anderson classification were found to be significant correlates of survival, but in stepwise
analysis PSA was selected as the most prognostic variable (P<0.0001). In contrast with a typical pattern of metastases on bone scintigraphy, an abnormal scan (class 1 and 2) at the time
of diagnosis is not a poor prognostic parameter of the risk of death. In conclusion, in patients with prostate cancer without
bone metastases at the time of diagnosis, pretreatment PSA and tumour stage can be used for the assessment of risk of development
of metastases during follow-up and survival. For this purpose, tumour stage should be clustered in limited and extensive disease.
Received 14 April and in revised form 9 June 1997 相似文献
5.
Hausegger KA; Cragg AH; Lammer J; Lafer M; Fluckiger F; Klein GE; Sternthal MH; Pilger E 《Radiology》1994,190(1):199
6.
Serum ionic fluoride levels in haemodialysis and continuous ambulatory peritoneal dialysis patients 总被引:1,自引:1,他引:0
al-Wakeel JS; Mitwalli AH; Huraib S; al-Mohaya S; Abu-Aisha H; Chaudhary AR; al-Majed SA; Memon N 《Nephrology, dialysis, transplantation》1997,12(7):1420-1424
High serum fluoride (F-) in patients with chronic renal failure (CRF) and
end-stage renal disease (ESRD) is associated with risk of renal
osteodystrophy and other bone changes. This study was done to determine F-
in normal healthy controls and patients with ESRD on haemodialysis (HD) or
peritoneal dialysis (PD). Seventeen healthy controls (12 males, 5 females)
and 39 ESRD patients on dialysis (17 males, 22 females) were recruited in
the study in a community with 47.4 +/- 3.28 microM/l (range 44-51 microM/l)
of F- content in drinking water. Control subjects showed a mean serum F-
concentration of 1.08 +/- 0.350 microM/l. Males in control group showed
slightly higher F- levels (1.15 +/- 0.334, range 0.55-1.9 microM/l) than
females (0.92 +/- 0.370, range 0.6-1.5 microM/l). Mean serum F-
concentration did not correlate significantly with age and sex among
control subjects, whereas such correlation was observed in patients with
ESRD on dialysis. Mean serum F- concentration was significantly higher in
patients on dialysis (2.67 +/- 1.09, range 0.8-5.2 microM/l) than normal
controls. When grouped according to sex, the mean serum F- concentration in
males (3.05 +/- 1.04, range 1.8-5.2 microM/l) was significantly higher than
females (2.38 +/- 1.08, range 0.8-5.2 microM/l). When patients were grouped
according to age, it was observed that F- concentration was significantly
higher in patients with age groups 21-70 (2.86 +/- 1.05) than those with
age group 13-20 years (1.42 +/- 0.531). Thus F- concentration correlated
with age and sex, being higher in males and above 20 years. Despite
appreciable clearance of F- (39-90%) across the peritoneum, patients on
CAPD showed higher serum F- concentration than those on HD (3.1 +/- 1.97 vs
2.5 +/- 1.137 microM/l). Of the total 39 patients on dialysis 39% had their
serum F- concentration above 3.0 microM/l, posing the risk of renal
osteodystrophy.
相似文献
7.
Clinical significance of rheumatoid factors in early rheumatoid arthritis: results of a follow up study. 总被引:8,自引:0,他引:8 下载免费PDF全文
D van Zeben J M Hazes A H Zwinderman A Cats E A van der Voort F C Breedveld 《Annals of the rheumatic diseases》1992,51(9):1029-1035
Serum rheumatoid factors (RF) were measured yearly in 135 women with rheumatoid arthritis by the Waaler-Rose and latex fixation tests and IgM, IgA, and IgG RF were measured by enzyme linked immunosorbent assays (ELISAs). The patients were followed up from an early phase of the disease for a mean duration of six years. Patients with a persistently positive RF test, irrespective of the type of test used, had more radiological abnormalities, more disease activity, worse functional ability, more extra-articular manifestations, and needed more treatment with second line drugs than patients with persistently negative or variably positive and negative test results during the follow up. Increased RF levels, especially a high level of IgA RF within three years of the onset of symptoms, was prognostic for a more severe disease outcome six years after the onset of symptoms. 相似文献
8.
Focal liver lesions: characterization with triphasic spiral CT 总被引:15,自引:1,他引:14
9.
Metabolic adaptation of the chick embryo to chronic hypoxia 总被引:1,自引:0,他引:1
10.
The CTLA-4 gene region of chromosome 2q33 is linked to, and associated with, type 1 diabetes. Belgian Diabetes Registry 总被引:8,自引:1,他引:8
Nistico L; Buzzetti R; Pritchard LE; Van der Auwera B; Giovannini C; Bosi E; Larrad MT; Rios MS; Chow CC; Cockram CS; Jacobs K; Mijovic C; Bain SC; Barnett AH; Vandewalle CL; Schuit F; Gorus FK; Tosi R; Pozzilli P; Todd JA 《Human molecular genetics》1996,5(7):1075-1080
Susceptibility to autoimmune insulin-dependent (type 1) diabetes mellitus
is determined by a combination of environmental and genetic factors, which
include variation in MHC genes on chromosome 6p21 (IDDM1) and the insulin
gene on chromosome 11p15 (IDDM2). However, linkage to IDDM1 and IDDM2
cannot explain the clustering of type 1 diabetes in families, and a role
for other genes is inferred. In the present report we describe linkage and
association of type 1 diabetes to the CTLA-4 gene (cytotoxic T lymphocyte
associated-4) on chromosome 2q33 (designated IDDM12). CTLA-4 is a strong
candidate gene for T cell- mediated autoimmune disease because it encodes a
T cell receptor that mediates T cell apoptosis and is a vital negative
regulator of T cell activation. In addition, we provide supporting evidence
that CTLA-4 is associated with susceptibility to Graves' disease, another
organ- specific autoimmune disease.
相似文献