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991.
Mortality rate, prognosis, and treatment outcome of cancer patients depend strongly on the detection of malignancy at an early
stage and efficient monitoring of the disease. Multimodality diagnostic approaches are now widely applied for tumor detection,
staging, and follow-up. However, the introduction of whole-body imaging modalities into clinical practice has substantially
expanded diagnostic options. PET-CT has increased diagnostic accuracy by providing “anatometabolic” information by fusing
tumor glucose-uptake measures from the PET examination and accurate delineation of anatomical structures given by spiral CT.
Since PET-CT is associated with high doses of ionizing radiation, it is used in mainly tumor staging and screening within
the scope of tertiary prevention. Here promising results have been reported for various tumor entities. MRI provides excellent
tissue contrast, detailed morphological information and lack of ionizing radiation. MRI has been employed for the assessment
of focal pathologies in specific anatomical regions. Whole-body MRI scanners using multiple receiver channels with parallel
acquisition techniques now allow tumor screening from head to toe within substantially shorter examination times and without
compromises in image resolution. We report our experience with these two novel techniques and discuss their benefits and drawbacks
in terms of systemic tumor screening. 相似文献
992.
Coppenrath E Meindl T Herzog P Khalil R Mueller-Lisse U Krenn L Reiser M Mueller-Lisse UG 《European radiology》2006,16(9):1982-1989
A novel ureter phantom was developed for investigations of image quality and dose in CT urography. The ureter phantom consisted of a water box (14 cm×32 cm×42 cm) with five parallel plastic tubes (diameter 2.7 mm) filled with different concentrations of contrast media (1.88–30 mg iodine/ml). CT density of the tubes and noise of the surrounding water were determined using two multidetector scanners (Philips MX8000 with four rows, Siemens Sensation 16 with 16 rows) with varying tube current–time product (15–100 mAs per slice), voltage (90 kV, 100 kV, 120 kV), pitch (0.875–1.75), and slice thickness (1 mm, 2 mm, 3.2 mm). Contrast-to-noise ratio as a parameter of image quality was correlated with dose (CTDI) and was compared with image evaluation by two radiologists. The CT densities of different concentrations of contrast media and contrast-to-noise ratio were significantly higher when low voltages (90 kV versus 120 kV, 100 kV versus 120 kV) were applied. Smaller slice thickness (1 mm versus 2 mm) did not change CT density but decreased contrast-to-noise ratio due to increased noise. Contrast phantom studies showed favourable effects of low tube voltage on image quality in the low dose range. This may facilitate substantial dose reduction in CT urography. 相似文献
993.
994.
Dr. O. Dietrich C. Losert U. Attenberger C. Reuter U. Fasol M. Peller K. Nikolaou M. F. Reiser S. O. Schoenberg 《Der Radiologe》2006,46(4):300-308
Background
In oxygen-enhanced lung MRI, difference maps of acquisitions during inhalation of room air and pure oxygen are calculated to assess lung function. The purpose of this study was to analyze how the calculation of these difference maps depends on the delayed signal change after switching the gas supply.Methods
Ten healthy volunteers were examined with an ECG and respiratory-triggered T1-weighting inversion recovery HASTE sequence with parallel imaging. Four blocks with 20 repetitions of up to 6 coronal slices were continuously acquired; in blocks 1 and 3 room air was supplied, in blocks 2 and 4 oxygen. Data were postprocessed, discarding between 0 and 19 repetitions after each change of gas supply before calculating the relative signal difference.Results
The averaged relative signal difference increases from 9.4 to 17.4% when the number of discarded acquisitions increases; the ratio of signal difference and spatial standard deviation reaches a maximum at 5–8 discarded acquisitions.Conclusions
An optimized ratio of signal difference and statistical error is found if about 5–8 of 20 respiratory-triggered repetitions are discarded after each change of gas supply for the calculation of difference maps. 相似文献995.
Dr. M. Treitl A. Panteleon M. Körner C. Becker-Gaab M. Reiser S. Wirth 《Der Radiologe》2006,46(8):677-688
Purpose
The aim of this study was to evaluate typical magnetic resonance imaging (MRI) findings in early rheumatic diseases manifesting at the soft tissues of the hand using a retrospective analysis.Material and methods
A total of 186 MRI examinations of patients with clinical suspicion of a rheumatic disease were evaluated in a consensus reading by two experienced radiologists. All imaging patterns were assessed with respect to their type and localization. Under blinded and non-blinded conditions diagnoses were correlated with final clinical diagnosis.Results
The most frequent diagnoses were rheumatoid arthritis (RA, 45.7%) and psoriatic arthritis (PsA, 15.6%). The mean correlation between clinical and MRI diagnosis (r) was 0.75 in blinded and 0.853 in non-blinded reading (p <0.001). The following extra-articular imaging patterns were found: synovitis (59.1%), tendovaginitis (91.4%), dactylitis (14.5%), and bone marrow edema (18.3%). Only dactylitis was specific for a particular rheumatic disease (PsA; r=0.934; sensitivity 84.9%, specificity 82.4%).Conclusion
Inflammatory conditions of the hand can be reliably detected with MRI. In many cases the definite diagnosis can only be made when taking clinical, serological, and radiographic results into account (+13.7% increase of significance). 相似文献996.
Aggressive risk factor modification, change of eating habits, exercise programs, and forceful antiplatelet therapy are the most important tools for the treatment of PAOD in symptomatic patients suffering from intermittent claudication. There are however no guidelines for revascularization at this stage. Endovascular treatment has been increasingly utilized over the last decade and increasingly displaced vascular surgery. Amongst numerous endovascular techniques beside PTA, stents meanwhile play the most important role due to constant technical progress. Results regarding the rate of restenosis or patency rates still remain worse compared to other vascular beds. This paper gives a review over recent results, currently available stent techniques, and possible indications for the endovascular therapy of an artery, which has turned out to be the biggest ordeal for material and construction of stents. 相似文献
997.
Rist C von Ziegler F Nikolaou K Kirchin MA Wintersperger BJ Johnson TR Knez A Leber AW Reiser MF Becker CR 《Academic radiology》2006,13(12):1465-1473
RATIONALE AND OBJECTIVES: Restenosis remains a major limitation of coronary catheter-based stent placement. Therefore, a reliable noninvasive diagnostic method for the evaluation of stented coronary arteries would be highly desirable. Our aim was to evaluate the diagnostic accuracy of high-resolution 64-slice computed tomography (64SCT) in a pilot study for the assessment of the lumen of coronary artery stents. MATERIALS AND METHODS: Twenty-five patients underwent 64SCT of the coronary arteries and quantitative x-ray coronary angiography (QCA) after coronary artery stent placement. 64SCT coronary angiography was performed with the following parameters: spatial resolution = 0.4 x 0.4 x 0.4 mm; temporal resolution = 83-165 milliseconds; contrast agent = 80 mL at a flow rate of 5 mL/second; retrospective electrocardiogram gating. The 64SCT scans were evaluated for image quality and for the presence of significant in-stent and peri-stent (proximal and distal) stenoses. Determinations were made of the sensitivity, specificity, diagnostic accuracy, and positive and negative predictive values (PPV and NPV) of 64SCT for the detection or exclusion of stenoses. RESULTS: A total of 46 stents were evaluated, of which 45 (98%) were of diagnostic image quality. Significant in-stent restenosis or occlusion was detected on QCA in 8/45 cases (>/=50% stenosis = 6; occlusion = 2). The sensitivity, specificity, accuracy, PPV, and NPV of 64SCT for the detection of significant in-stent disease was 75%, 92%, 89%, 67%, and 94%, respectively. Both occluded coronary artery stents were correctly identified. The sensitivity, specificity, and accuracy values of 64SCT for the detection of significant proximal peri-stent stenoses were 75%, 95%, and 93%, respectively, whereas the values for detection of significant distal peri-stent stenoses were 67%, 85%, and 84%, respectively. CONCLUSION: The high spatial and temporal resolution of 64SCT may permit improved assessment of stent occlusion and peri-stent disease, although detection of in-stent stenosis remains difficult. 相似文献
998.
背景 一般估计英国医院每年约有85万件医疗事故发生,而且多数包括患者辨识错误。虽然在许多国家现在的医疗规程上患者的安全性是高的,但或许临床的医疗事故仍未被重视及报告,而且也没有做深层次的研究以找出可能的解决方案。 错误可发生在医疗中的许多方面,包括输血和注射药物、外科、诊断过程、实验室检查。在这些和其他的过程进行中必须 相似文献
999.
Saturated very long chain fatty acids (VLCFAs; > or =C22:0) accumulate in X-linked adrenoleukodystrophy (X-ALD, OMIM 300100), a severe hereditary neurodegenerative disease, due to peroxisomal impairment. Previous studies analysed the development of X-ALD in humans and gene knockout animal models. However, the toxic effect of VLCFA leading to severe symptoms with progressive and multifocal demyelination, adrenal insufficiency and inflammation still remains unclear. To understand the toxic effects of VLCFA in the brain, here we exposed neural cells to VLCFA and analysed the cellular consequences. We found that oligodendrocytes and astrocytes challenged with docosanoic- (C22:0), tetracosanoic- (C24:0) and hexacosanoic acids (C24:0) die within 24 h. VLCFA-induced depolarization of mitochondria in situ and increased intracellular Ca2+ level in all three brain cell types provides indications about the mechanism of toxicity of VLCFA. Interestingly, VLCFAs affect to the largest degree the myelin-producing oligodendrocytes. In isolated mitochondria, VLCFAs exert a detrimental effect by affecting the inner mitochondrial membrane and promoting the permeability transition. In conclusion, we suggest that there is a potent toxic activity of VLCFA due to dramatic cell physiological effects with mitochondrial dysfunction and Ca2+ deregulation. This provides the first evidence for mitochondrial-based cell death mechanisms in neurodegenerative disease with peroxisomal defects and subsequent VLCFA accumulation. 相似文献
1000.
Stefan Wirth Markus Körner Marcus Treitl Ulrich Linsenmaier Bernd A. Leidel Thomas Jaschkowitz Maximilian F. Reiser Karl G. Kanz 《European radiology》2009,19(8):1857-1866
The purpose of the study was to evaluate both CT image quality in a phantom study and feasibility in an initial case series
using automated chest compression (A-CC) devices for cardiopulmonary resuscitation (CPR). Multidetector CT (MDCT) of a chest/heart
phantom (Thorax-CCI, QRM, Germany) was performed with identical protocols of the phantom alone (S), the phantom together with
two different A-CC devices (A: AutoPulse, Zoll, Germany; L: LUCAS, Jolife, Sweden), and the phantom with a LUCAS baseplate,
but without the compression unit (L-bp). Nine radiologists evaluated image noise quantitatively (n = 244 regions, Student’s
t-test) and also rated image quality subjectively (1–excellent to 6–inadequate, Mann-Whitney U-test). Additionally, three
patients during prolonged CPR underwent CT with A-CC devices. Mean image noise of S was increased by 1.21 using L-bp, by 3.62
using A, and by 5.94 using L (p < 0.01 each). Image quality was identical using S and L-bp (1.64 each), slightly worse with
A (1.83), and significantly worse with L (2.97, p < 0.001). In all patient cases the main lesions were identified, which led
to clinical key decisions. Image quality was excellent with L-bp and good with A. Under CPR conditions initial cases indicate
that MDCT diagnostics supports either focused treatment or the decision to terminate efforts. 相似文献