Author
H. von Tengg-Kobligk
Other affiliations: University Hospital Heidelberg, National Institutes of Health, Ohio State University
Bio: H. von Tengg-Kobligk is an academic researcher from German Cancer Research Center. The author has contributed to research in topics: Thoracic aorta & Aorta. The author has an hindex of 18, co-authored 39 publications receiving 2053 citations. Previous affiliations of H. von Tengg-Kobligk include University Hospital Heidelberg & National Institutes of Health.
Papers
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15 May 2010
TL;DR: Medical application of rapid prototyping is feasible for specialized surgical planning and prosthetics applications and has significant potential for development of new medical applications.
Abstract: Generation of graspable three-dimensional objects applied for surgical planning, prosthetics and related applications using 3D printing or rapid prototyping is summarized and evaluated. Graspable 3D objects overcome the limitations of 3D visualizations which can only be displayed on flat screens. 3D objects can be produced based on CT or MRI volumetric medical images. Using dedicated post-processing algorithms, a spatial model can be extracted from image data sets and exported to machine-readable data. That spatial model data is utilized by special printers for generating the final rapid prototype model. Patient–clinician interaction, surgical training, medical research and education may require graspable 3D objects. The limitations of rapid prototyping include cost and complexity, as well as the need for specialized equipment and consumables such as photoresist resins. Medical application of rapid prototyping is feasible for specialized surgical planning and prosthetics applications and has significant potential for development of new medical applications.
1,362 citations
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TL;DR: Recent developments in contrast agents for magnetic resonance angiography (MRA) are outlined and it is likely that two different types of contrast agent will soon be available: extracellular agents for first‐pass MRA and intravascular agents mainly for steady‐state MRA.
Abstract: The purpose of this review is to outline recent developments in contrast agents for magnetic resonance angiography (MRA) and to give some idea of what the future might hold. Up to now, non-binding gadolinium (Gd) chelates have been the agents used for MRA. Modified paramagnetic Gd-based agents with varying degrees of protein interaction have been developed, and these, together with new superparamagnetic compounds, are currently under clinical evaluation. It is likely that two different types of contrast agent will soon be available: extracellular agents for first-pass MRA and intravascular agents mainly for steady-state MRA. Several agents also exhibit certain tissue specific properties in addition to conventional extracellular properties. This will lead to more comprehensive imaging approaches.J. Magn. Reson. Imaging 10:314–316, 1999. © 1999 Wiley-Liss, Inc.
87 citations
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TL;DR: Hybrid aortic arch repair is technically challenging but feasible and may be an alternative to standard open procedures in high-risk patients and emergency cases, however, the promising early results need to be confirmed by longer follow-up and larger series.
Abstract: The aim of this study was to report our clinical experience with and review current literature on endoluminal aortic hybrid techniques and to evaluate outcome in high-risk patients treated for complex aortic arch lesions combining conventional supra-aortic debranching bypasses with subsequent or staged thoracic endovascular grafting. Of 172 patients treated with thoracic endografts for different thoracic aortic pathologies within the last 8 years, the mid-aortic arch was involved in 25, i.e. at least the left common carotid artery had to be overstented and revascularized to provide a proper proximal landing zone. These debranching bypasses were performed as a simultaneous or a staged procedure. All patients were at high-risk and were excluded by cardiac surgeons as ineligible for conventional arch repair. After partial (n=16) or complete (n=9) supra-aortic transposition, 4 different commercially available endografts (80% TAG, WL Gore) were implanted transfemorally or via iliac conduit. Deployment success was 100% in 25 patients after simultaneous or staged supra-aortic transposition; in 32% an emergency procedure was performed due to contained rupture; in 36% more than 1 endograft system was implanted (2 in 20%, 3 in 8% und 4 in 8%). The overall perioperative thirty-day mortality was 5 of 25 (20%) due to interoperative proximal bare stent perforation (n=1), transfusion related acute lung injury (TRALI n=1), cardiac failure (n=1), embolic stroke (n=1) and pneumonia (n=1). The mean follow-up was 21 months. All endoleaks type I (n=3) were corrected with another endograft; the 2 endoleaks type II sealed spontaneously. The major adverse events were: prolonged ventilation in 5 (20%), temporary renal insufficiency with hemodialysis (n=2), bypass infection (n=1), without any complications (n=9). No cases of paraplegia were recorded. Hybrid aortic arch repair is technically challenging but feasible. This novel approach may be an alternative to standard open procedures in high-risk patients and emergency cases. However, the promising early results need to be confirmed by longer follow-up and larger series.
86 citations
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TL;DR: Fusion of morphologic and functional images is feasible before, during and after radiofrequency ablation of tumors in abdominal organs and may facilitate interventional procedures like RFA.
Abstract: The value of image processing and fusion has been investigated for diagnostic and prognostic purposes; still it has been a less studied tool for interventional radiological procedures. Registration and fusion of radiological images is by no means a new post processing technique [1–5]. There are numerous technical approaches described to coalesce imaging data from different modalities [6–8] and use them to provide better health care for the patient. Registration is defined as aligning the two imaging data sets spatially to each other. While fusion is defined as overlaying them and visualizing them as one image. Algorithms for registration of anatomical and functional data sets have been mostly studied in fixed or rigid organs such as the spine or brain [2, 4, 7, 9, 10]. But registration is somewhat more difficult in region with physiologic movements like the neck [11] or in moving organs such as lungs [12, 13]. Major challenges due to physiologic motion and the non-rigid nature of organs have limited the practical implementation of image fusion for abdominal interventional procedures for diagnostic and prognostic reasons.
Recent studies have shown that fusion of abdominal images from different modalities can improve diagnosis and monitoring of disease progression [14–16]. New hybrid-imaging systems combining positron emission tomography (PET) or single photon emission computed tomography (SPECT) with computed tomography (CT) offer a one-stop examination promoting the diagnostic and prognostic potentials for extra-cranial applications of image fusion in cancer [17–21]. Image fusion has proven useful for evaluation of patients with cancer supporting diagnosis, staging, treatment planning, monitoring the response to therapy including disease progression [22]. Minimally invasive image-guided therapy like radiofrequency thermal ablation is being routinely used, especially in the liver, lung, bone and kidney [23–26] and improves survival for certain patients [27].
Optimal outcomes of percutaneous radiofrequency ablation (RFA) are highly dependent upon accurate targeting of the neoplastic tissue and monitoring of the resulting thermal lesion. Success of treatment is intimately linked to the volumetric spatial relationship of neoplastic tissue to the thermal lesion margins. An accurate spatial understanding of this relationship that is readily accessible may provide feedback during pre-treatment planning, procedural navigation, early detection of re-growth improving prognosis. Ideal image guidance for RFA allows accurate probe placement for sphere-packing with sufficient overlap to avoid gaps of sub-lethal heating, and to treat a small margin of normal tissue beyond the neoplastic tissue borders. This is a challenging task and is prone to human error. The procedure is to be followed by repeated scanning and look for disease progression.
Image fusion was studied with an image processing software used before, during, and after RFA interventions. Fusion of morphologic and functional image data might improve spatial appreciation and visualization of tumor and its relation to thermal lesion margins.
78 citations
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TL;DR: Investigation of the feasibility of semi-automated volumetric analysis of lymph node metastases in patients with malignant melanoma found the software allows a fast and robust segmentation in up to 80% of all cases and the ease of use and time needed are acceptable.
Abstract: Therapy monitoring in oncological patient care requires accurate and reliable imaging and post-processing methods. RECIST criteria are the current standard, with inherent disadvantages. The aim of this study was to investigate the feasibility of semi-automated volumetric analysis of lymph node metastases in patients with malignant melanoma compared to manual volumetric analysis and RECIST. Multislice CT was performed in 47 patients, covering the chest, abdomen and pelvis. In total, 227 suspicious, enlarged lymph nodes were evaluated retrospectively by two radiologists regarding diameters (RECIST), manually measured volume by placement of ROIs and semi-automated volumetric analysis. Volume (ml), quality of segmentation (++/−−) and time effort (s) were evaluated in the study. The semi-automated volumetric analysis software tool was rated acceptable to excellent in 81% of all cases (reader 1) and 79% (reader 2). Median time for the entire segmentation process and necessary corrections was shorter with the semi-automated software than by manual segmentation. Bland-Altman plots showed a significantly lower interobserver variability for semi-automated volumetric than for RECIST measurements. The study demonstrated feasibility of volumetric analysis of lymph node metastases. The software allows a fast and robust segmentation in up to 80% of all cases. Ease of use and time needed are acceptable for application in the clinical routine. Variability and interuser bias were reduced to about one third of the values found for RECIST measurements.
70 citations
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TL;DR: In this paper, the authors give an overview on 3D printing techniques of polymer composite materials and the properties and performance of 3D printed composite parts as well as their potential applications in the fields of biomedical, electronics and aerospace engineering.
Abstract: The use of 3D printing for rapid tooling and manufacturing has promised to produce components with complex geometries according to computer designs. Due to the intrinsically limited mechanical properties and functionalities of printed pure polymer parts, there is a critical need to develop printable polymer composites with high performance. 3D printing offers many advantages in the fabrication of composites, including high precision, cost effective and customized geometry. This article gives an overview on 3D printing techniques of polymer composite materials and the properties and performance of 3D printed composite parts as well as their potential applications in the fields of biomedical, electronics and aerospace engineering. Common 3D printing techniques such as fused deposition modeling, selective laser sintering, inkjet 3D printing, stereolithography, and 3D plotting are introduced. The formation methodology and the performance of particle-, fiber- and nanomaterial-reinforced polymer composites are emphasized. Finally, important limitations are identified to motivate the future research of 3D printing.
2,132 citations
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TL;DR: Future directions such as the "print-it-all" paradigm, that have the potential to re-imagine current research and spawn completely new avenues for exploration are pointed out.
Abstract: Additive manufacturing (AM) is poised to bring about a revolution in the way products are designed, manufactured, and distributed to end users. This technology has gained significant academic as well as industry interest due to its ability to create complex geometries with customizable material properties. AM has also inspired the development of the maker movement by democratizing design and manufacturing. Due to the rapid proliferation of a wide variety of technologies associated with AM, there is a lack of a comprehensive set of design principles, manufacturing guidelines, and standardization of best practices. These challenges are compounded by the fact that advancements in multiple technologies (for example materials processing, topology optimization) generate a "positive feedback loop" effect in advancing AM. In order to advance research interest and investment in AM technologies, some fundamental questions and trends about the dependencies existing in these avenues need highlighting. The goal of our review paper is to organize this body of knowledge surrounding AM, and present current barriers, findings, and future trends significantly to the researchers. We also discuss fundamental attributes of AM processes, evolution of the AM industry, and the affordances enabled by the emergence of AM in a variety of areas such as geometry processing, material design, and education. We conclude our paper by pointing out future directions such as the "print-it-all" paradigm, that have the potential to re-imagine current research and spawn completely new avenues for exploration. The fundamental attributes and challenges/barriers of Additive Manufacturing (AM).The evolution of research on AM with a focus on engineering capabilities.The affordances enabled by AM such as geometry, material and tools design.The developments in industry, intellectual property, and education-related aspects.The important future trends of AM technologies.
1,792 citations
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TL;DR: Additive manufacturing processes take the information from a computer-aided design (CAD) file that is later converted to a stereolithography (STL) file as discussed by the authors.
Abstract: Additive manufacturing processes take the information from a computer-aided design (CAD) file that is later converted to a stereolithography (STL) file. In this process, the drawing made in the CAD software is approximated by triangles and sliced containing the information of each layer that is going to be printed. There is a discussion of the relevant additive manufacturing processes and their applications. The aerospace industry employs them because of the possibility of manufacturing lighter structures to reduce weight. Additive manufacturing is transforming the practice of medicine and making work easier for architects. In 2004, the Society of Manufacturing Engineers did a classification of the various technologies and there are at least four additional significant technologies in 2012. Studies are reviewed which were about the strength of products made in additive manufacturing processes. However, there is still a lot of work and research to be accomplished before additive manufacturing technologies become standard in the manufacturing industry because not every commonly used manufacturing material can be handled. The accuracy needs improvement to eliminate the necessity of a finishing process. The continuous and increasing growth experienced since the early days and the successful results up to the present time allow for optimism that additive manufacturing has a significant place in the future of manufacturing.
1,777 citations
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TL;DR: Awareness of the field strength and solvent associated with relaxivity data is crucial for the comparison and evaluation of relaxivity values and should be replaced by relaxivities measured at 1.5 T and at 3 T in plasma at physiological temperature.
Abstract: Rationale and Objectives:To characterize and compare commercially available contrast media (CM) for magnetic resonance imaging (MRI) in terms of their relaxivity at magnetic field strengths ranging from 0.47 T to 4.7 T at physiological temperatures in water and in plasma. Relaxivities also were quan
1,464 citations
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TL;DR: The history of 3D printing is encompassed, various printing methods are reviewed, current applications are presented, and the future direction and impact this technology will have on laboratory settings as 3D printers become more accessible is offered.
Abstract: Nearing 30 years since its introduction, 3D printing technology is set to revolutionize research and teaching laboratories. This feature encompasses the history of 3D printing, reviews various printing methods, and presents current applications. The authors offer an appraisal of the future direction and impact this technology will have on laboratory settings as 3D printers become more accessible.
1,381 citations