Publications (4)18.41 Total impact
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Article: Onset and maintenance of angiogenesis in biomaterials: in vivo assessment by dynamic contrast-enhanced MRI.
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ABSTRACT: To describe dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) as a practical tool for longitudinal assessment of angiogenesis in biomaterials. There is a lack of suitable methods for in vivo evaluation of the integration of biomaterials in a clinical setting. In oncology, DCE-MRI is used for the longitudinal monitoring of altered tumor angiogenesis during therapy. Thus, we investigated whether DCE-MRI enables to assess the integration of biomaterials over time. The tested material was bovine bone matrix applied in a bilateral sinus lift procedure in combination with concentrated mononuclear cells, including mesenchymal stem cells and autologous thrombin. To assess the development of new blood vessels inside the biomaterial, DCE-MRI was carried out before and 11, 25, 53, and 104 days after surgery. Perfusionparameters were calculated according to the model of Tofts. Analysis of the data revealed increasing parameters for perfusion and blood supply within the transplant over time. It was possible to determine the values for each transplantation site and each point of time separately. DCE-MRI is appropriate to repetitively survey angiogenesis and integration of biomaterials in patients. It seems appropriate as a valuable indicator of treatment response or failure, with consecutive adaption of the therapy regime.Tissue Engineering Part C Methods 05/2009; 15(3):455-62. · 4.64 Impact Factor -
Article: Detection of pulmonary nodules with move-during-scan magnetic resonance imaging using a free-breathing turbo inversion recovery magnitude sequence.
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ABSTRACT: Detection of pulmonary metastases is still a challenging task for magnetic resonance imaging (MRI). It was the aim of this study to evaluate the potential of a free-breathing move-during-scan turbo inversion recovery magnitude sequence for the detection of pulmonary nodules. The sensitivities and positive-predictive values of 2 radiologists to detect pulmonary nodules in 41 move-during-scan MRI examinations of 38 patients with different malignancies were calculated and subgroup analyses according to lesion size and localization were performed. Multidetector computed tomography served as the standard of reference. Additionally, 6 radiologists rated the confidence for the presence of nodular lesions in 212 regions-of-interest, which were randomly selected to represent lesions of various sizes as well as negative findings. Receiver-operator-characteristic was performed. Three hundred twenty-one nodules were found in 30 patients by multidetector computed tomography. Sensitivity and specificity of MRI to detect pulmonary nodules larger than 3 mm on a per-patient basis were 81.8% and 94.7%, respectively. On a per-lesion basis, MRI revealed a sensitivity of 79.0% to 80.7% for lesions larger than 3 mm, if high conspicuity ratings were counted as positive, and 84.6%, if medium and high conspicuity ratings were counted as positive. Sensitivity increased uniformly with lesion size, and all lesions larger than 12 mm were detected. Receiver-operator-characteristic analysis revealed a mean accuracy of 0.90 and sensitivities over 90% for lesions larger than 3 mm with a specificity of 96.1%. For lesions larger than 6 mm the accuracy was 0.99. Detection of pulmonary nodules with a move-during-scan turbo inversion recovery magnitude sequence is feasible. Excellent detection of lesions larger than 6 mm is achievable with free-breathing moving-table MRI.Investigative Radiology 07/2008; 43(6):359-67. · 4.59 Impact Factor -
Article: Comparison of the detectability of high- and low-contrast details on a TFT screen and a CRT screen designed for radiologic diagnosis.
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ABSTRACT: To evaluate the detection rate of fine details of a new thin-film transistor (TFT) grayscale monitor designed for radiologic diagnosis, compared with a type of cathode ray tube (CRT) screen used routinely for diagnostic radiology. Fifteen radiographs of a statistical phantom presenting low- and high-contrast details were obtained and read out with an Agfa ADC compact storage phosphor system. Each radiograph presented 60 high-density (high-contrast) and 60 low-density (low-contrast) test bodies. Approximately half the test bodies contained holes with different diameters. Observers were asked to detect the presence or absence of a hole in the test body on a 5-point confidence range. The total of 1800 test bodies was reviewed by 5 radiologists on the TFT monitor (20.8 inches; 1536 x 2048 pixels; maximum luminance, 650 cd/m2; contrast, 600:1) and the CRT monitor (21 inches; P45 Phosphor; 2048 x 2560 pixels operated at 1728 x 2304 pixels; maximum luminance, 600 cd/m2; contrast, 300:1). The data were analyzed by receiver-operator characteristic analysis. For high-contrast details, the mean area under the curve rated 0.9336 for the TFT monitor and 0.9312 for the CRT monitor. For low-contrast details, the mean area under the curve rated 0.9189 for the TFT monitor and 0.9224 for the CRT monitor. At P <or= 0.05, no statistically significant difference could be detected between the 2 observational modalities for both (holes in high- and low-contrast disks) types of artifacts. The TFT screen performs as well as CRT monitors for the detection of fine details in both high- and low-contrast environments. Further studies with images derived from clinical routine are necessary before safely using TFT monitors in clinical practice.Investigative Radiology 11/2003; 38(11):719-24. · 4.59 Impact Factor -
Article: Comparison of the Detectability of High- and Low-Contrast Details on a TFT Screen and a CRT Screen Designed for Radiologic Diagnosis
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ABSTRACT: Rationale and Objectives: To evaluate the detection rate of fine details of a new thin-film transistor (TFT) grayscale monitor designed for radiologic diagnosis, compared with a type of cathode ray tube (CRT) screen used routinely for diagnostic radiology. Methods: Fifteen radiographs of a statistical phantom presenting low- and high-contrast details were obtained and read out with an Agfa ADC compact storage phosphor system. Each radiograph presented 60 high-density (high-contrast) and 60 low-density (low-contrast) test bodies. Approximately half the test bodies contained holes with different diameters. Observers were asked to detect the presence or absence of a hole in the test body on a 5-point confidence range. The total of 1800 test bodies was reviewed by 5 radiologists on the TFT monitor (20.8 inches; 1536 × 2048 pixels; maximum luminance, 650 cd/m2; contrast, 600:1) and the CRT monitor (21 inches; P45 Phosphor; 2048 × 2560 pixels operated at 1728 × 2304 pixels; maximum luminance, 600 cd/m2; contrast, 300:1). The data were analyzed by receiver-operator characteristic analysis. Results: For high-contrast details, the mean area under the curve rated 0.9336 for the TFT monitor and 0.9312 for the CRT monitor. For low-contrast details, the mean area under the curve rated 0.9189 for the TFT monitor and 0.9224 for the CRT monitor. At P ≤ 0.05, no statistically significant difference could be detected between the 2 observational modalities for both (holes in high- and low-contrast disks) types of artifacts. Conclusions: The TFT screen performs as well as CRT monitors for the detection of fine details in both high- and low-contrast environments. Further studies with images derived from clinical routine are necessary before safely using TFT monitors in clinical practice. During the last 5 years, picture archiving and communication systems have been implemented in many radiology departments. In these departments, radiologic diagnosis is made from monitor displays rather than from laser film hard copies or conventional films. In this context, special attention must be paid to the quality of monitors used for diagnosis. Although the needs for monitor quality for sectional imaging modalities are easily met with today's monitors, the monitor displays used for projectional imaging must meet exceedingly high-quality requirements, especially in terms of spatial resolution, brightness, contrast resolution, and uniformity of the display.1 Many radiology departments make use of high-quality cathode ray tube (CRT) monitors with a spatial resolution of approximately 2500 × 2000 pixels and a capability of very high maximum luminance of 550 cd/m2 or more. Although soft-copy reading with this type of monitor has been proved to be equivalent to hard-copy reading from laser film, CRT monitors suffer from several drawbacks. First, they are very bulky, and a pair of CRT monitors needs a lot of space in the reading room. Second, CRT monitors are not completely flicker free. Third, at very high resolutions, CRT pixels often suffer a certain degree of fuzziness. Fourth, CRT monitors have a very limited life span, because their overall brightness decreases rapidly and pixels may be burned into the phosphor coating of the CRT. Fifth, CRT monitors usually present some degree of geometric distortion. Lastly, CRT monitors produce a large amount of heat that is usually transported by fans, creating acoustical noise. Active matrix thin-film transistor (TFT) displays avoid many of these inconveniences (Table 1). There has been a lot of progress in production technology during the last few years, resulting in larger TFT panels with higher spatial resolutions, fewer dropout pixels, and lower prices for TFT panels. Moreover, today's TFT displays can be observed at larger viewing angles, nearly comparable with that of CRT monitors. Since the year 2000, prototypes of TFT monitors that are specifically designed for diagnostic purposes in radiology have been shown at radiologic conferences and are making their entrance to the market at the time of writing.Investigative Radiology 10/2003; 38(11):719-724. · 4.59 Impact Factor
