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  • DKFZ Publication Database  (181)
  • COMPUTED-TOMOGRAPHY
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  • DKFZ Publication Database  (181)
Keywords
  • 1
    Keywords: COMPUTED-TOMOGRAPHY ; RESPIRATORY-DISTRESS-SYNDROME ; GENERAL-ANESTHESIA ; CONDUCTIVITY ; reconstruction algorithm ; REGULARIZATION ; REGIONAL VENTILATION ; ELECTRICAL-IMPEDANCE TOMOGRAPHY ; VENTILATION DISTRIBUTION ; ATELECTASIS
    Abstract: INTRODUCTION: Electrical impedance tomography (EIT) is an emerging clinical tool for monitoring ventilation distribution in mechanically ventilated patients, for which many image reconstruction algorithms have been suggested. We propose an experimental framework to assess such algorithms with respect to their ability to correctly represent well-defined physiological changes. We defined a set of clinically relevant ventilation conditions and induced them experimentally in 8 pigs by controlling three ventilator settings (tidal volume, positive end-expiratory pressure and the fraction of inspired oxygen). In this way, large and discrete shifts in global and regional lung air content were elicited. METHODS: We use the framework to compare twelve 2D EIT reconstruction algorithms, including backprojection (the original and still most frequently used algorithm), GREIT (a more recent consensus algorithm for lung imaging), truncated singular value decomposition (TSVD), several variants of the one-step Gauss-Newton approach and two iterative algorithms. We consider the effects of using a 3D finite element model, assuming non-uniform background conductivity, noise modeling, reconstructing for electrode movement, total variation (TV) reconstruction, robust error norms, smoothing priors, and using difference vs. normalized difference data. RESULTS AND CONCLUSIONS: Our results indicate that, while variation in appearance of images reconstructed from the same data is not negligible, clinically relevant parameters do not vary considerably among the advanced algorithms. Among the analysed algorithms, several advanced algorithms perform well, while some others are significantly worse. Given its vintage and ad-hoc formulation backprojection works surprisingly well, supporting the validity of previous studies in lung EIT.
    Type of Publication: Journal article published
    PubMed ID: 25110887
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  • 2
    Keywords: SYSTEM ; PATIENT ; IMRT ; VERIFICATION ; FLUENCE ; PART
    Type of Publication: Book chapter
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  • 3
    Keywords: PART ; BM ; ALGORITHM ; computed tomography ; COMPUTED-TOMOGRAPHY ; tomography
    Type of Publication: Book chapter
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  • 4
    Keywords: computed tomography ; ACCURACY ; validation ; QUANTIFICATION ; INFORMATION ; IMAGES ; MODEL ; human ; Germany ; tomography ; IMAGE REGISTRATION ; VESSELS ; TRACKING ; COMPUTED-TOMOGRAPHY ; CONTRAST ; RECOGNITION ; PATTERN ; SCALE ; PATTERN-RECOGNITION ; EXTRACTION ; intensity ; pattern recognition ; Aorta ; MEDICAL IMAGES ; USA ; function ; 3-D cylindrical model ; 3-D MRA data ; 3-D parametric intensity model ; 3-D vessel segmentation ; ANGIOGRAPHIC IMAGES ; Kalman filtering ; TUBULAR STRUCTURES ; SHAPE ; ERROR ; MRA ; image processing
    Type of Publication: Book chapter
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  • 5
    Keywords: PERFUSION ; CT ; DIAGNOSIS ; FOLLOW-UP ; imaging ; VENTILATION ; VISUALIZATION ; EFFICIENCY ; computed tomography ; PATIENT ; MR ; MRI ; magnetic resonance ; MAGNETIC-RESONANCE ; tomography ; EMBOLISM ; COMPUTED-TOMOGRAPHY ; DIAGNOSTIC-TESTS ; MAGNETIC-RESONANCE ANGIOGRAPHY ; MR-ANGIOGRAPHY ; ANGIOGRAPHY ; CONTRAST-ENHANCED MRI ; MR angiography ; MR imaging ; MANAGEMENT ; AIRWAY-OBSTRUCTION ; DEEP VENOUS THROMBOSIS ; LUNG PERFUSION ; MOLECULAR-WEIGHT HEPARIN ; NONTRAUMATIC THORACIC EMERGENCIES ; pulmonary embolism ; SINGLE BREATH-HOLD ; SPIN-LABELING TECHNIQUES ; thrombus imaging ; VEIN THROMBOSIS
    Abstract: Pulmonary embolism (PE) is one of the most frequently encountered clinical emergencies. The diagnosis often involves multiple diagnostic tests, which need to be carried out rapidly to assist in the safe management of the patient. Recent strides in computed tomography (CT) have made big improvements in patient management and efficiency of diagnostic imaging. This review article describes the developments in magnetic resonance (MR) techniques for the diagnosis of acute PE. Techniques include MR angiography (MRA) and thrombus imaging for direct clot visualization, perfusion MR, and combined perfusion-ventilation MR. As will be demonstrated, some of these techniques are now entering the clinical arena, and it is anticipated that MR imaging (MRI) will have an increasing role in the initial diagnosis and follow-up of patients with acute PE
    Type of Publication: Journal article published
    PubMed ID: 14635147
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  • 6
    Keywords: measurement ; ANGIOGENESIS ; Germany ; PERFUSION ; CLASSIFICATION ; CT ; imaging ; INFORMATION ; QUANTIFICATION ; liver ; TISSUE ; TUMORS ; computed tomography ; PATIENT ; BLOOD-FLOW ; INDEX ; primary ; INJECTION ; SIGNAL ; LESIONS ; PATTERNS ; DIFFERENCE ; metastases ; US ; tomography ; COMPUTED-TOMOGRAPHY ; LIVER METASTASES ; POWER DOPPLER SONOGRAPHY ; VASCULARIZATION ; contrast-enhanced ultrasound,liver metastases,arterial perfusion,low-MI imaging,SonoVue ; MICROBUBBLE CONTRAST ; SHU 508A
    Abstract: Rationale and Objectives: We investigated whether observing the arterial vascularization of liver metastases by contrast-enhanced ultrasound with low mechanical index (low-MI) imaging offers additional diagnostic information for the characterization of the liver lesions.Methods: Twenty nine patients with untreated liver metastases of different primaries were examined. Measurements were performed using a low frame rate, low-MI pulse inversion technique after injection of 2.4 mL SonoVue. The relative maximum signal intensity of the liver lesions related to the normal liver tissue was quantified. Ultrasound findings were compared with contrast-enhanced, dual-phase computed tomography (CT) using a pattern-based classification scheme.Results: Compared with contrast-enhanced CT, this modality better detects arterial perfusion. Metastases, even those usually considered hypovascularized, often showed homogeneous enhancement (66%) and higher arterial vascularization than normal liver tissue. CT did not show a comparable vascularization pattern (P 〈 0.001) or any similarly early signal intensity (P 〈 0.001).Conclusions: Contrast-enhanced CT may not be able to visualize short-lasting but large differences of the arterial perfusion of liver metastases, as does contrast-enhanced low-MI ultrasound. This offers new methods for their characterization and for monitoring of therapeutic effects
    Type of Publication: Journal article published
    PubMed ID: 15021325
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  • 7
    Keywords: evaluation ; Germany ; THERAPY ; CLASSIFICATION ; CT ; DIAGNOSIS ; FOLLOW-UP ; imaging ; SPIRAL CT ; DISEASE ; NEW-YORK ; RISK ; computed tomography ; BLOOD-FLOW ; primary ; RISK-FACTORS ; MR ; MRI ; treatment ; MAGNETIC-RESONANCE ; magnetic resonance imaging ; risk factors ; RISK FACTOR ; tomography ; SCINTIGRAPHY ; COMPUTED-TOMOGRAPHY ; ORGANIZATION ; BREATH-HOLD TECHNIQUE ; MR imaging ; HELICAL CT ; DIFFERENTIAL-DIAGNOSIS ; ARTERIAL-HYPERTENSION ; LEFT-VENTRICULAR DYSFUNCTION ; CHEST-X-RAY ; CHRONIC THROMBOEMBOLISM ; pulmonary hypertension,computed tomography,magnetic resonance imaging,echocardiography,angiography,E ; RADIOLOGIC FEATURES
    Abstract: In the recent World Health Organization (WHO) classification the group of pulmonary arterial hypertension (PH) comprises the classic primary pulmonary hypertension and several conditions with definite or very high risk factors to develop pulmonary arterial hypertension. Therapeutic advances drive the need for a comprehensive pre-therapeutic evaluation for optimal treatment. Furthermore, follow-up examinations need to be performed to monitor changes in disease status and response to therapy. Up to now, the diagnostic imaging work-up of PH comprises mainly echocardiography, invasive right heart catheterization and ventilation/perfusion scintigraphy. Due to technical advances helical computed tomography (CT) and magnetic resonance imaging (MRI) became more important in the evaluation and for differential diagnosis of pulmonary arterial hypertension. Both modalities are reviewed and recommendations for clinical use are given
    Type of Publication: Journal article published
    PubMed ID: 14740163
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  • 8
    Keywords: evaluation ; Germany ; IN-VIVO ; LUNG ; CT ; DENSITY ; EMPHYSEMA ; imaging ; VOLUME ; DISEASE ; computed tomography ; PATIENT ; INDEX ; TRANSPLANTATION ; CONTRAST ; FLOW ; MRI ; magnetic resonance imaging ; FORM ; GAS ; tomography ; COMPUTED-TOMOGRAPHY ; HEALTHY ; HYPERPOLARIZED HE-3 ; DIFFUSION ; AIRWAY ; HRCT ; resonance imaging ; HIGH-RESOLUTION ; OBSTRUCTION ; lung transplantation ; FUNCTIONAL-CHARACTERIZATION ; AIRWAYS DISEASE ; apparent diffusion coefficient ; COEFFICIENT ; hyperpolarized (3)Helium ; lung function ; PULMONARY-FUNCTION TESTS
    Abstract: Purpose: To assess the emphysematous enlargement of distal airspaces and concomitant large and small airway disease using diffusion-weighted (3)Helium-magnetic resonance imaging (MRI), high-resolution computed tomography (HRCT), and lung function tests (LFT). Methods: Seven patients were examined after single lung transplantation (LTx) and 1 before double LTx for various forms of emphysema. Five patients after double LTx served as controls. Patients were assessed by (3)Helium-MRI (apparent diffusion coefficient [ADC]), HRCT (mean lung density [MLD], emphysema index [EI]), and LFT. Results: Transplanted lungs: mean ADC = 0.17 cm(2)/s, MLD -848 H, EI 22%. Emphysematous lungs: mean ADC = 0.33 cm(2)/s, MLD -922 H; EI = 54%. Good correlations were found between ADC and MLD (r = 0.6), EI (r = 0.8), intrathoracic gas volume (r = 0.7), forced expiratory volume in 1 second (r = 0.7), and forced expiratory flows (r = 0.7). In contrast, HRCT only provided moderate correlations with LFT (EI: r = 0.5; MLD: r [1e] 0.4). Conclusion: In this initial study, He-3-MRI yield good correlations with HRCT and agrees better than HRCT with the functional characterization of emphysema regarding hyperinflation, large and small airway disease as provided by LFT
    Type of Publication: Journal article published
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  • 9
    Keywords: CANCER ; tumor ; carcinoma ; Germany ; LUNG ; PERFUSION ; THERAPY ; CT ; DENSITY ; LUNG-CANCER ; NEW-YORK ; TUMORS ; PATIENT ; CONTRAST ; INJECTION ; treatment ; DIFFERENCE ; REGION ; REGIONS ; LOCALIZATION ; PARAMETERS ; tomography ; CARCINOMAS ; COMPUTED-TOMOGRAPHY ; PET ; lung neoplasms ; PULMONARY ; DYNAMIC CT ; X-ray computed
    Abstract: Advanced bronchial carcinomas by means of perfusion and peak enhancement using dynamic contrast-enhanced multislice CT are characterized. Twenty-four patients with advanced bronchial carcinoma were examined. During breathhold, after injection of a contrast-medium (CM), 25 scans were performed (I scan/s) at a fixed table position. Density-time curves were evaluated from regions of interest of the whole tumor and high- and low-enhancing tumor areas. Perfusion and peak enhancement were calculated using the maximum-slope method of Miles and compared with size, localization (central or peripheral) and histology. Perfusion of large tumors (〉50 cm(3)) averaged over both the whole tumor (P=0.001) and the highest enhancing area (P=0.003) was significantly lower than that of smaller ones. Independent of size, central carcinomas had a significantly (P=0.04) lower perfusion (mean 27.9 ml/min/100 g) than peripheral ones (mean 66.5 ml/min/100 9). In contrast, peak enhancement of central and peripheral carcinomas was not significantly different. Between non-small-cell lung cancers and small-cell lung cancers, no significant differences were observed in both parameters. In seven tumors, density increase after CM administration started earlier than in the aorta, indicating considerable blood supply from pulmonary vessels. Tumor perfusion was dependent on tumor size and localization, but not on histology. Furthermore, perfusion CT disclosed blood supply from both pulmonary and/or bronchial vessels in some tumors
    Type of Publication: Journal article published
    PubMed ID: 15029450
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  • 10
    Keywords: evaluation ; human ; IN-VIVO ; LUNG ; DENSITY ; HIGH-RESOLUTION CT ; imaging ; INFORMATION ; VENTILATION ; DYNAMICS ; MRI ; FIELD ; PROTON ; GAS ; PARENCHYMA ; COMPUTED-TOMOGRAPHY ; THIN-SECTION CT ; functional MRI ; OXYGEN ; hyperpolarized ; helium-3 ; DIFFUSION ; AIRWAY ; PULMONARY ; pulmonary function ; TRANSPLANT RECIPIENTS ; HE-3 GAS ; lung diseases ; CYSTIC-FIBROSIS ; LASER-POLARIZED XE-129 ; NOBLE-GAS ; NUCLEAR-MAGNETIC-RESONANCE ; ultrafast imaging
    Abstract: Lung imaging has traditionally relied on x-ray methods, since proton MRI is limited to some extent by low proton density in the lung parenchyma and static field inhomogeneities in the chest. The relatively recent introduction of MRI of hyperpolarized noble gases has led to a rapidly evolving field of pulmonary MRI, revealing functional information of the lungs, which were hitherto unattainable. This review article briefly describes the physical background of the technology, and subsequently focuses on its clinical applications. Four different techniques that have been used in various human investigations are discussed: ventilation distribution, ventilation dynamics, and small airway evaluation using diffusion imaging and oxygen uptake assessment
    Type of Publication: Journal article published
    PubMed ID: 15390146
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  • 11
    Keywords: measurement ; tumor ; Germany ; LUNG ; CT ; IMAGES ; DISEASE ; NEW-YORK ; TUMORS ; PATIENT ; REDUCTION ; CONTRAST ; MRI ; CYCLE ; SEQUENCE ; NO ; DIFFERENCE ; REGION ; LOCALIZATION ; LENGTH ; COMPUTED-TOMOGRAPHY ; CURVES ; 3-DIMENSIONAL RECONSTRUCTION ; MOTION ; HEALTHY ; ORIENTATION ; LOCATION ; dynamic MRI ; ADULT ; ADULTS ; STRENGTH ; TRUEFISP ; HEALTHY-VOLUNTEERS ; PULMONARY-FUNCTION ; HEART-FAILURE ; EXPIRATION ; LUNG-VOLUMES ; breathing cycle ; diaphragmatic function
    Abstract: The purpose of this study was to assess diaphragmatic length and shortening during the breathing cycle in healthy volunteers and patients with a lung tumor using dynamic MRI (dMRI). In 15 healthy volunteers and 28 patients with a solitary lung tumor, diaphragmatic motion and length were measured during the breathing cycle using a trueFISP sequence (three images per second in the coronal and sagittal plane). Time-distance curves and maximal length reduction (= shortening) of the diaphragm were calculated. The influence of tumor localization on diaphragmatic shortening was examined. In healthy volunteers maximal diaphragmatic shortening was 30% in the coronal and 34% in the sagittal orientation, with no difference between both hemithoraces. Tumors of the upper and middle lung region did not affect diaphragmatic shortening. In contrast, tumors of the lower lung region changed shortening significantly (P〈0.05). In hemithoraces with a tumor in the lower region, shortening was 18% in the coronal and 19% in the sagittal plane. The ratio of diaphragmatic length change from inspiration to expiration changed significantly from healthy subjects (inspiration length &MGT; expiratory length, P〈0.05) to patients with a tumor in the lower lung region (inspiratory length = expiratory length). dMRI is a simple, non-invasive method to evaluate diaphragmatic motion and shortening in volunteers and patients during the breathing cycle. Tumors of the lower lung region have a significant influence on shortening of the diaphragm
    Type of Publication: Journal article published
    PubMed ID: 15127220
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  • 12
    Keywords: CANCER ; IRRADIATION ; radiotherapy ; Germany ; LUNG ; MODEL ; CT ; DENSITY ; FOLLOW-UP ; DISEASE ; MORTALITY ; computed tomography ; MICE ; MOUSE ; NO ; MOBILITY ; PARAMETERS ; tomography ; leukocyte ; MOUSE MODEL ; COMPUTED-TOMOGRAPHY ; THIN-SECTION CT ; HIGH-RESOLUTION ; WEIGHT ; lung function ; AMIFOSTINE ; INDUCED PULMONARY FIBROSIS ; lung fibrosis ; MOUSE LUNG ; STRAIN-DEPENDENT DIFFERENCES
    Abstract: Rationale and Objectives: To identify characteristics of lung fibrosis in a mouse model after radiotherapy (RT) using thin-section computed tomography (CT), histology and clinical parameters. Materials and Methods: Using a multislice CT-scanner, follow-up chest CT scans of 10 out of 72 included mice (C57BL/6J, 36 control mice, 36 mice (20Gy)) were performed every 2 weeks until week 26 after RT. Hounsfield units (HU) and cardiothoracic ratio (CTR) were measured, and a multireader analysis on characteristic lung changes was performed and correlated with histology and clinical parameters. Results: From weeks 4 to 8 after RT changes in histology (leukocyte count, extraalveolar edema, P 〈 0.01) and from week 12 changes in CT were detected (increase in HU, intralobular opacity and fibrotic strandings, P 〈 0.05). From week 14 clinical manifestations occurred (loss of weight, mobility, breathing, increased mortality, P 〈 0.01). CTR showed no significant changes. Three readers showed excellent interobserver agreement (kappa 〉 0.84). Conclusion: Thin-section CT in a mouse model is capable of detecting the development of lung fibrosis after RT prior to the onset of clinical deterioration
    Type of Publication: Journal article published
    PubMed ID: 15377939
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  • 13
    Keywords: brain ; OPTIMIZATION ; BLOOD ; Germany ; CT ; DENSITY ; IMAGES ; EXPOSURE ; radiation ; CONTRAST ; X-RAYS ; COMPUTED-TOMOGRAPHY ; CT ANGIOGRAPHY ; contrast media ; BLOOD-VESSELS ; ENHANCEMENT ; cerebral angiography ; IMAGE QUALITY ; spiral computed tomography
    Abstract: Purpose: We sought to intraindividually compare computed tomography angiographies (CTAs) acquired at 80 kVp and 120 kVp with respect to vessel contrast, noise level, and radiation dose. Material and Methods: CTA was performed on a single-slice CT scanner using tube voltages of 80 kVp and 120 kVp in 29 patients with arteriovenous malformations. Mean Hounsfield Units (HU) were evaluated for different vessels and brain parenchyma. To determine contrast-to-noise ratios (CNRs), noise levels were estimated from phantom measurements. Results: The calculated effective dose to male/female patients was 0.4/0.5 mSv for 80 kVp and 0.7/0.8 mSv for 120 kVp. CT density in blood vessels was between 297 and 458 HU for 80 kVp and 152 and 229 HU for 120 kVp (P 〈 0.0001). Despite an increased noise level in the low-voltage images, the CNR was 26-59% higher at 80 kVp than at 120 kVp (P 〈 0.05). Conclusion: The use of a reduced tube potential leads to improved CNR in CTA of the cerebral vasculature and a markedly reduced radiation exposure to patients
    Type of Publication: Journal article published
    PubMed ID: 15770141
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  • 14
    Keywords: RECEPTOR ; CANCER ; EXPRESSION ; GROWTH ; GROWTH-FACTOR ; INHIBITOR ; IRRADIATION ; radiotherapy ; SURVIVAL ; FACTOR RECEPTOR ; Germany ; KINASE ; LUNG ; TYROSINE KINASE ; DISEASE ; MICE ; radiation ; PHOSPHORYLATION ; TYROSINE KINASE INHIBITOR ; MOUSE ; EFFICACY ; chemotherapy ; COMPUTED-TOMOGRAPHY ; imatinib ; inflammation ; FACTOR-BETA ; TGF-BETA ; lung fibrosis ; MOUSE LUNG ; STRAIN-DEPENDENT DIFFERENCES ; IMATINIB MESYLATE ; KINASE INHIBITORS ; PDGF
    Abstract: Pulmonary fibrosis is the consequence of a variety of diseases with no satisfying treatment option. Therapy-induced fibrosis also limits the efficacy of chemotherapy and radiotherapy in numerous cancers. Here, we studied the potential of platelet-derived growth factor (PDGF) receptor tyrosine kinase inhibitors (RTKIs) to attenuate radiation-induced pulmonary fibrosis. Thoraces of C57BL/6 mice were irradiated (20 Gy), and mice were treated with three distinct PDGF RTKIs (SU9518, SU11657, or Imatinib). Irradiation was found to induce severe lung fibrosis resulting in dramatically reduced mouse survival. Treatment with PDGF RTKIs markedly attenuated the development of pulmonary fibrosis in excellent correlation with clinical, histological, and computed tomography results. Importantly, RTKIs also prolonged the life span of irradiated mice. We found that radiation up-regulated expression of PDGF (A-D) isoforms leading to phosphorylation of PDGF receptor, which was strongly inhibited by RTKIs. Our findings suggest a pivotal role of PDGF signaling in the pathogenesis of pulmonary fibrosis and indicate that inhibition of fibrogenesis, rather than inflammation, is critical to antifibrotic treatment. This study points the way to a potential new approach for treating idiopathic or therapy-related forms of lung fibrosis
    Type of Publication: Journal article published
    PubMed ID: 15781583
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  • 15
    Keywords: brain ; CANCER ; BLOOD ; Germany ; LUNG ; MODEL ; MODELS ; PERFUSION ; THERAPY ; chest ; CT ; imaging ; lung cancer ; LUNG-CANCER ; SYSTEM ; SYSTEMS ; TOOL ; VISUALIZATION ; VOLUME ; DISEASE ; liver ; TISSUE ; computed tomography ; RESOLUTION ; MICE ; kidney ; RAT ; PROGRESSION ; EFFICACY ; tomography ; COMPUTED-TOMOGRAPHY ; STROKE ; ANIMAL-MODELS ; fibrosis ; TUMOR-GROWTH ; monitoring ; HIGH-RESOLUTION ; PNEUMONITIS ; lung fibrosis ; LEVEL ; IMAGE QUALITY ; ABILITY ; SIZE ; TECHNOLOGY ; ANIMAL-MODEL ; contrast-enhanced ; DISEASE PROGRESSION ; flat-panel detector ; lung carcinoma
    Abstract: Noninvasive radiologic imaging has recently gained considerable interest in basic and preclinical research for monitoring disease progression and therapeutic efficacy. In this report, we introduce flat-panel volumetric computed tomography (fpVCT) as a powerful new tool for noninvasive imaging of different organ systems in preclinical research. The three-dimensional visualization that is achieved by isotropic high-resolution datasets is illustrated for the skeleton, chest, abdominal organs, and brain of mice. The high image quality of chest scans enables the visualization of small lung nodules in an orthotopic lung cancer model and the reliable imaging of therapy side effects such as lung fibrosis. Using contrast-enhanced scans, fpVCT displayed the vascular trees of the brain, liver, and kidney down to the subsegmental level. Functional application of fpVCT in dynamic contrast-enhanced scans of the rat brain delivered physiologically reliable data of perfusion and tissue blood volume. Beyond scanning of small animal models as demonstrated here, fpVCT provides the ability to image animals up to the size of primates
    Type of Publication: Journal article published
    PubMed ID: 16207475
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  • 16
    Keywords: Germany ; VISUALIZATION ; computed tomography ; arteries ; tomography ; COMPUTED-TOMOGRAPHY ; CHILDREN ; PULMONARY ; HIGH-RESOLUTION ; STENOSIS ; PULMONARY-ARTERIES
    Type of Publication: Journal article published
    PubMed ID: 16235778
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  • 17
    Keywords: CANCER ; GROWTH ; tumor ; Germany ; PATHWAY ; PATHWAYS ; CT ; imaging ; SYSTEM ; SYSTEMS ; TOOL ; VISUALIZATION ; VOLUME ; liver ; RESOLUTION ; SURGERY ; ACQUISITION ; EFFICACY ; RESECTION ; tomography ; SAFETY ; COMPUTED-TOMOGRAPHY ; SEGMENTS ; ultrasound ; inflammation ; pancreas ; review ; TUMOR-GROWTH ; HIGH-RESOLUTION ; SOFTWARE ; CLINICAL-RELEVANCE ; 3D ; surgical planning ; 3-dimensional ; liver and pancreas ; liver surgery ; organ movements ; volumetry
    Abstract: Cross-sectional imaging based on navigation and virtual reality planning tools are well - established in the surgical routine in orthopedic surgery and neurosurgery. In various procedures, they have achieved a significant clinical relevance and efficacy and have enhanced the discipline's resection capabilities. In abdominal surgery, however, these tools have gained little attraction so far. Even with the advantage of fast and high resolution cross-sectional liver and pancreas imaging, it remains unclear whether 3D planning and interactive planning tools might increase precision and safety of liver and pancreas surgery. The inability to simply transfer the methodology from orthopedic or neurosurgery is mainly a result of intraoperative organ movements and shifting and corresponding technical difficulties in the on-line applicability of presurgical cross sectional imaging data. For the interactive planning of liver surgery, three systems partly exist in daily routine: HepaVision2 (MeVis GmbH, Bremen), LiverLive (Navidez Ltd, Slovenia) and OrgaNicer (German Cancer Research Center, Heidelberg). All these systems have realized a half- or full-automatic liver-segmentation procedure to visualize liver segments, vessel trees, resected volumes or critical residual organ volumes, either for preoperative planning or intraoperative visualization. Acquisition of data is mainly based on computed tomography. Three-dimensional navigation for intraoperative surgical guidance with ultrasound is part of the clinical testing. There are only few reports about the transfer of the visualization of the pancreas, probably caused by the difficulties with the segmentation routine due to inflammation or organ-exceeding tumor growth. With this paper, we like to evaluate and demonstrate the present status of software planning tools and pathways for future pre- and intraoperative resection planning in liver and pancreas surgery
    Type of Publication: Journal article published
    PubMed ID: 16123867
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  • 18
    Keywords: GROWTH ; radiotherapy ; tumor ; Germany ; PERFUSION ; CT ; FOLLOW-UP ; HEPATOCELLULAR-CARCINOMA ; liver ; TISSUE ; TUMORS ; PATIENT ; BLOOD-FLOW ; RADIATION-THERAPY ; metastases ; tomography ; COMPUTED-TOMOGRAPHY ; LIVER METASTASES ; contrast media ; APPEARANCE ; ultrasound ; RE ; TUMOR-GROWTH ; monitoring ; ENHANCEMENT ; MICROBUBBLE CONTRAST ; TUMOR PERFUSION ; ARTERIAL ; PHASE ; SIZE ; contrast-enhanced ; ARTERIAL PHASE ; KUPFFER CELLS ; liver neoplasms
    Abstract: The purpose of this study was to monitor liver metastases after radiotherapy using contrast-enhanced ultrasound (CEUS). In 15 patients, follow-up examinations after stereotactic, single-dose radiotherapy were performed using CEUS (low mechanical index (MI), 2.4-ml SonoVue) and computed tomography (CT). Besides tumor size, the enhancement of the liver and the metastases was assessed at the arterial, portal venous, and delayed phases. The sizes of the tumor and of a perifocal liver reaction after radiotherapy measured with CEUS significantly correlated with those measured at CT (r=0.93, p〈0.001). CEUS found a significant reduction of the arterial vascularization in treated tumors (p〈0.05). In the arterial phase, the perifocal liver tissue was hypervascularized compared to the treated tumor (p〈0.001); in the late phase, it was less enhanced than the liver (p〈0.001) and more than the tumor (p〈0.01). The perifocal liver reaction was also seen in CT, but with a variable enhancement at the arterial (50% hyperdense compared to normal liver tissue), venous, or delayed phase (each with 70% hyperdense reactions). CEUS allows for the assessment of tumor and liver perfusion, in addition to morphological tumor examination, which was comparable with CT. Thus, changes of tumor perfusion, which may indicate tumor response, as well as the perifocal liver reaction after radiotherapy, which must be differentiated from perifocal tumor growth, can be sensitively visualized using CEUS
    Type of Publication: Journal article published
    PubMed ID: 15729565
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  • 19
    Keywords: PEPTIDE ; CANCER ; CELLS ; IN-VITRO ; tumor ; AGENTS ; carcinoma ; Germany ; MICROSCOPY ; MODEL ; PERFUSION ; THERAPY ; VITRO ; DIAGNOSIS ; imaging ; TOOL ; GENE-EXPRESSION ; TISSUE ; TUMORS ; MICE ; RAT ; ANTIGEN ; BINDING ; MOUSE ; DESIGN ; CARCINOMA CELLS ; MEMBRANE ; NUMBER ; PROSTATE-CANCER ; NUDE-MICE ; LINE ; PEPTIDES ; BIODISTRIBUTION ; MONOCLONAL-ANTIBODIES ; positron emission tomography ; POSITRON-EMISSION-TOMOGRAPHY ; tomography ; CARCINOMAS ; COMPUTED-TOMOGRAPHY ; KINETICS ; sensitivity ; prostate carcinoma ; TRACER ; ultrasound ; PHAGE DISPLAY ; HUMAN TISSUES ; AGENT ; RE ; tumor imaging ; INTERNALIZATION ; HIGH-SENSITIVITY ; SOMATOSTATIN ANALOGS ; CYTOTOXIC ANALOGS ; EXTRACELLULAR DOMAIN ; HORMONE-RELEASING HORMONE ; MEMBRANE ANTIGEN-EXPRESSION ; RADIONUCLIDE THERAPY
    Abstract: Purpose: Prostate carcinomas belong to the most widespread tumors, and their number is increasing. Imaging modalities used for diagnosis, such as ultrasound, computed tomography, and positron emission tomography, often produce poor results. Radiolabeled peptides with high sensitivity and specificity for prostate cancer would be a desirable tool for tumor diagnosis and treatment. Experimental Design: We used phage display and the prostate-specific membrane antigen -negative cell line DU-145 to identify a peptide. The isolated DUP-1 was tested in vitro for its binding specificity, kinetics, and affinity. Internalization of the peptide was evaluated with confocal microscopy. The tumor accumulation in a nude mouse model was analyzed with I-131-labeled DUP-1 in PC-3 and DU-145 prostate tumors as well as in the rat prostate tumor model AT-1. Results: The synthesized peptide showed rapid binding kinetics peaking at 10 minutes. It shows specific binding to prostate carcinoma cells but low binding affinity to non-tumor cells. Peptide binding is competed with unlabeled DUP-1, and a time-dependent internalization into DU-145 cells was shown. Biodistribution studies of DUP-1 in nude mice with s.c. transplanted DU-145 and PC-3 tumors showed a tumor accumulation of 5% and 7% injected dose per gram, and bound peptide could not be removed by perfusion. The rat prostate tumor model showed an increase of radioactivity in the prostate tumor up to 300% in comparison with normal prostate tissue. Conclusions: DUP-1 holds promise as a lead peptide structure applicable in the development of new diagnostic tracers or anticancer agents that specifically target prostate carcinoma
    Type of Publication: Journal article published
    PubMed ID: 15671538
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  • 20
    Keywords: CANCER ; GROWTH ; Germany ; human ; LUNG ; VIVO ; chest ; imaging ; segmentation ; computed tomography ; TIME ; LESIONS ; REPRODUCIBILITY ; tomography ; COMPUTED-TOMOGRAPHY ; RECONSTRUCTION ; SOFTWARE ; EX-VIVO ; analysis ; methods ; NUCLEAR ; volumetry ; PULMONARY NODULES ; lungs ; MULTISLICE CT ; CHEST CT ; DIAGNOSTIC PERFORMANCE ; DOSE SPIRAL CT ; FOLLOW-UP CT ; GROWTH-RATE ; lung nodule ; phantom ; SMALL PULMONARY NODULES ; THICKNESS
    Abstract: Objective: The main purpose of this study was to investigate the reproducibility of computed tomography (CT)-based volumetric measurements of small pulmonary nodules. Methods: We implanted 70 artificial pulmonary nodules in 5 ex vivo porcine lungs in a dedicated chest phantom. The lungs were scanned 5 times consecutively with multislice-CT (collimation 16 X 0.75 mm, slice thickness 1 mm, reconstruction increment 0.7 mm). A commercial software package was used for lesion volumetry. The authors differentiated between intrascan reproducibility, interscan reproducibility, and results from semiautomatic and postprocesse volumetry. Results: Analysis of intrascan reproducibility revealed a mean variation coefficient of 6.2% for semiautomatic volumetry and of 0.7% for human adapted volumetry. For interscan reproducibility a mean variation coefficient of 9.2% and for human adapted volumetry a mean of 3.7% was detected. Conclusion: The presented volumetry software showed a high reproducibility that can be expected to detect nodule growth with a high degree of certainty
    Type of Publication: Journal article published
    PubMed ID: 16355037
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    Keywords: Germany ; THERAPY ; FOLLOW-UP ; SYSTEM ; SYSTEMS ; MORTALITY ; RISK ; computed tomography ; SURGERY ; PATIENT ; treatment ; DESIGN ; AGE ; REPAIR ; RATES ; tomography ; COMPUTED-TOMOGRAPHY ; COMPLICATIONS ; DISSECTION ; STROKE ; THORACIC AORTA ; THROMBOSIS ; methods ; Male ; VARIABLES ; endovascular ; GRAFTS ; ANEURYSM REPAIR ; DISSECTIONS ; PHANTOMS ; PULSATILE FLOW ; SINGLE-CENTER ; STENT-GRAFT PLACEMENT ; TRUE-LUMEN COLLAPSE
    Abstract: Objective: To outline the complications after endovascular repair in patients with acute symptomatic and chronic expanding Stanford type B aortic dissections. Methods: Between 1997 and 2004, of 125 patients with acute and chronic aortic type B dissections, 88 were treated conservatively. Thirty-seven patients ( 29 male, mean age 58 years, range 30-82 years) underwent endovascular repair (30%) using 44 stent grafts of 3 different designs: Excluder ( W. L. Gore & Associates, Inc, Flagstaff, Ariz), Talent ( Medtronic Vascular, Santa Rosa, Calif), and Endofit (Endomed, Inc, Phoenix, Ariz). Indications for treatment were acute symptomatic type B dissection in 15 patients, chronic expanding aortic dissection greater than 55 mm in 14, rupture in 3, and simultaneous type A repair in 5 patients. Twenty-two operations were performed on an emergency basis. Patient characteristics, procedural variables, outcome, and complications were prospectively recorded. All patients underwent follow-up by computed tomography before discharge, at 6 and 12 months, and annually thereafter ( mean follow-up: 24 months). Results: Correct deployment was achieved in 97% of cases. There were no instances of primary conversion, paraplegia, or stroke. Complete false lumen thrombosis was observed in 11 patients (44%). Perioperative complication rate was 22%. Thirty-day mortality rate in acute and chronic dissections was 19% and 0%, respectively. Freedom from aortic reintervention was 81%, 73%, and 68%, freedom from late rupture was 97%, 90%, and 80%, and overall success rate was 76%, 65%, and 57% at 1, 2, and 5 years, respectively. Results for patients with chronic dissections are significantly ( P =.038) better than results in those with acute dissections. Conclusions: Despite the minimally invasive approach, the complication and mortality rates for endovascular therapy of aortic dissections are still high. Frank reporting of these sequelae is if great importance to clarify the recent limitations of the method
    Type of Publication: Journal article published
    PubMed ID: 16872963
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    Keywords: OPTIMIZATION ; SIMULATIONS ; ASSOCIATION ; DESIGN ; ENERGY ; SELECTION ; FEASIBILITY ; FLUENCE ; MODULATED RADIATION-THERAPY ; MAGNETIC-FIELDS ; IMPT
    Abstract: The most recent experimental results obtained with laser-plasma accelerators are applied to radiotherapy simulations. The narrow electron beam, produced during the interaction of the laser with the gas jet, has a high charge (0.5 nC) and is quasimonoenergetic (170 +/- 20 MeV). The dose deposition is calculated in a water phantom placed at different distances from the diverging electron source. We show that, using magnetic fields to refocus the electron beam inside the water phantom, the transverse penumbra is improved. This electron beam is well suited for delivering a high dose peaked on the propagation axis, a sharp and narrow tranverse penumbra combined with a deep penetration. (c) 2006 American Association of Physicists in Medicine
    Type of Publication: Journal article published
    PubMed ID: 16485422
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    Keywords: radiotherapy ; Germany ; LUNG ; ALGORITHM ; CT ; IMAGES ; imaging ; SYSTEM ; TIME ; PATIENT ; treatment ; SIGNAL ; NUMBER ; REGION ; Jun ; COMPUTED-TOMOGRAPHY ; MOTION ; RECONSTRUCTION ; FEASIBILITY ; ORGAN MOTION ; RE ; INCREASE ; DIAPHRAGM ; PHASE ; SIZE ; RESPIRATORY MOTION ; cone beam CT ; respiratory gating
    Abstract: A new online imaging approach, linac-integrated cone beam CT (CBCT), has been developed over the past few years. It has the advantage that a patient can be examined in their treatment position directly before or during a radiotherapy treatment. Unfortunately, respiratory organ motion, one of the largest intrafractional organ motions, often leads to artefacts in the reconstructed 3D images. One way to take this into account is to register the breathing phase during image acquisition for a phase-correlated image reconstruction. Therefore, the main focus of this work is to present a system which has the potential to investigate the correlation between internal (movement of the diaphragm) and external (data of a respiratory gating system) information about breathing phase and amplitude using an inline CBCT scanner. This also includes a feasibility study about using the acquired information for a respiratory-correlated 4D CBCT reconstruction. First, a moving lung phantom was used to develop and to specify the required methods which are based on an image reconstruction using only projections belonging to a certain moving phase. For that purpose, the corresponding phase has to be detected for each projection. In the case of the phantom, an electrical signal allows one to track the movement in real time. The number of projections available for the image reconstruction depends on the breathing phase and the size of the position range from which projections should be used for the reconstruction. The narrower this range is, the better the inner structures can be located, but also the noise of the images increases due to the limited number of projections. This correlation has also been analysed. In a second step, the methods were clinically applied using data sets of patients with lung tumours. In this case, the breathing phase was detected by an external gating system (AZ-733V, Anzai Medical Co.) based on a pressure sensor attached to the patient's abdominal region with a fixation belt. The comparison of the reconstructed 4D CBCT images and the corresponding 4D CT images used for the treatment planning provides the required information for the calculation of possible setup errors
    Type of Publication: Journal article published
    PubMed ID: 16723776
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    Keywords: radiotherapy ; Germany ; THERAPY ; imaging ; PATIENT ; IMPACT ; treatment ; ASSOCIATION ; PROSTATE-CANCER ; COMPUTED-TOMOGRAPHY ; MOTION ; TRACKING ; RECONSTRUCTION ; IMAGE GUIDANCE ; cone beam CT ; adaptive radiotherapy ; GUIDED RADIATION-THERAPY ; IGRT
    Abstract: One of the most prominent imaging techniques in image-guided radiotherapy (IGRT) is the acquisition of cone beam computed tomographies (CBCTs) at the linac with the patient in treatment position. CBCTs provide accurate 3-dimensional (3D) knowledge about the patient's anatomy for every treatment fraction and are therefore well suited for all adaptive corrections of errors related to interfractional uncertainties of the treatment process. In this paper, we first describe the technical development and implementation of this new imaging technique at our linac, i.e., the hardware components and their operating parameters are discussed in detail for a standard image acquisition of CBCTs. Then, an extension of this approach for the acquisition of complete images for extended field of views-the "shifted detector" technique-is presented followed by a first investigation of how CBCTs can be reliably used for adaptive dose calculations. Finally, a first clinical application, the process of automatic patient positioning based on CBCT images, is discussed. From our investigations, we conclude that the technical development of linac-integrated CBCTs bears an enormous potential for the correction of interfractional treatment errors. However, image quality and reconstruction speed of the images leave room for improvement. The development of clinical strategies for the optimal application of this new image modality in a clinical environment is one the major tasks for the future. (c) 2006 American Association of Medical Dosimetrists
    Type of Publication: Journal article published
    PubMed ID: 16551530
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    Keywords: Germany ; MODEL ; CT ; segmentation ; ACCURACY ; RESOLUTION ; kidney ; pig ; MR ; MRI ; NUMBER ; arteries ; HEAD ; COMPUTED-TOMOGRAPHY ; MAGNETIC-RESONANCE ANGIOGRAPHY ; MR-ANGIOGRAPHY ; DIGITAL SUBTRACTION ANGIOGRAPHY ; ANGIOGRAPHY ; MR angiography ; LEVEL ; PHASE ; SIZE ; branching ; SPECIMENS ; CATHETER ; high-field MRI ; WILMS-TUMOR
    Abstract: Background: MRI at 3.0 T enables high-spatial resolution for renal MR angiography. Objective: Evaluation of an arterial tree model in animal kidney specimens with comparison of digital subtraction angiography (DSA) and high-field MRI to find out the maximum spatial resolution of intrarenal vessels. It was considered that objective quantitation of angiogram quality could be achieved. Materials and methods: A total of 27 pig kidney specimens were examined by MR angiography (flash 3D) using a 3.0-T scanner (TRIO; Siemens, Erlangen, Germany) with an eight-channel head coil and a voxel size of 0.9x0.9x1.1 mm in the early arterial phase after implantation of a 4F catheter in the renal artery. DSA (Integris, Philips, Best, The Netherlands) was performed immediately after the MRI. With the help of semiautomated segmentation, all vessels were marked for comparison of the vessel trees. The Wilcoxon rank test was used for statistical evaluation of vessel numbers and branching depths. Results: Objective comparison between DSA and MR angiography was achieved. High-field MR angiography had the ability to depict vessels up to the seventh branching on average. Significant differences in vessel delineation and counts were found from the fifth level of intrarenal branching onwards with DSA showing an advantage. Conclusion: High-field MRI has great potential in the detection of intrarenal arteries and is comparable to DSA in visualization of the central intrarenal vessel tree
    Type of Publication: Journal article published
    PubMed ID: 16896692
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    Keywords: Germany ; LUNG ; CT ; SIGNAL ; COMPUTED-TOMOGRAPHY ; RECONSTRUCTION ; FEASIBILITY ; HELICAL CT ; DEVICES ; DIAPHRAGM ; SCANS ; respiratory gating ; laser sensor ; CCD camera ; free-breathing ; prospective gating
    Abstract: Purpose: The aim was to investigate the feasibility and image quality of prospective respiratory gating for 3-D computed tomography (CT) of the lung. Material and Methods: Eight anesthetized pigs underwent prospectively gated multidetector computed tomography using 2 devices: a charge-coupled device (CCD) camera and a laser sensor. The output signal of both gating devices was connected to the scanner instead of ECG unit. Inspiratory and expiratory images were obtained during "free-breathing" and analyzed in MPR mode for sharpness of bronchi, diaphragm and lung using a 4-point-score (1, excellent to 4, severe artifacts). Results: The CCD camera worked in all animals. Using the laser sensor, only 50% of expiratory scans could be acquired. All acquired images showed excellent sharpness (CCD camera vs. laser sensor) for trachea (1.1 +/- 0.3 vs. 1.3 +/- 0.5), bronchi (1.4 +/- 0.7 vs. 1.8 +/- 0.6), lung fissures (1.0 vs. 1.1 0.3), and lung parenchyma (1.0 +/- 0.2 vs. 1.4 +/- 0.6), and minor to major artifacts for diaphragm (1.5 +/- 0.8 vs. 2.0 +/- 1.0, P 〈 0.05) and pericardial lung structures (1.9 +/- 0.7 vs. 2.3 +/- 0.5). Conclusion: High image quality for inspiratory and expiratory scans was achieved by free-breathing 3-D CT of the lung using noncontact prospective respiratory gating
    Type of Publication: Journal article published
    PubMed ID: 16625110
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    Keywords: Germany ; LUNG ; CT ; EMPHYSEMA ; HIGH-RESOLUTION CT ; QUANTIFICATION ; VOLUME ; PATIENT ; IMPACT ; REDUCTION ; SIMULATION ; PARAMETERS ; COMPUTED-TOMOGRAPHY ; OBSTRUCTIVE PULMONARY-DISEASE ; THIN-SECTION CT ; HELICAL CT ; RE ; multidetector CT ; LUNG-VOLUME ; low dose ; MULTISLICE CT ; 3-dimensional quantitative volumetric analysis ; ALPHA-1-ANTITRYPSIN DEFICIENCY ; dose simulation ; LUNG DENSITY-MEASUREMENTS ; MACROSCOPIC MORPHOMETRY ; multidetector computed tomography ; VOLUME REDUCTION
    Abstract: Purpose: Quantitative evaluation of the lung parenchyma might be impaired or unreliable by use of reduced-dose CT protocols. Aim of the study was to define the threshold where reduced dose has significant impact on quantitative emphysema parameters. Materials and Methods: Thirty patients with severe centrilobular emphysema underwent multidetector computed tomography (120 kV, 150 mAs). Original CT raw data were simulated using 10 mAs settings (10-100 SlMmAs). Quantitative analysis provided lung volume, emphysema volume, emphysema index, mean lung density, and 4 emphysema volume classes. Simulated low-dose results were compared with original acquisition. Results: Emphysema index showed no clinical relevant variation down to 30 SlMmAs. The large emphysema volume class was significantly different below 50 SlMmAs. The intermediate and small classes showed an overproportional variation below 50 SlMmAs. Conclusions: Dose reduction down to 30 SlMmAs is possible for clinical routine. Settings below 50 SlMmAs significantly alter the indetailed 3-dimensional emphysema quantification
    Type of Publication: Journal article published
    PubMed ID: 16778622
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    Keywords: CANCER ; Germany ; LUNG ; THERAPY ; chest ; CT ; IMAGES ; imaging ; SYSTEM ; computed tomography ; NUCLEAR-MEDICINE ; TIME ; QUALITY ; MEMBRANE ; COMPUTED-TOMOGRAPHY ; SERIES ; MOTION ; ARTIFACTS ; nuclear medicine ; dynamic MRI ; HELICAL CT ; radiology ; ONCOLOGY ; RE ; EX-VIVO ; DIAPHRAGM ; methods ; PHASE ; NUCLEAR ; IMAGE QUALITY ; respiration ; lungs ; RESPIRATORY MOTION ; phantom ; tumor motion ; MEDICINE ; NOV ; comparison ; DETECTOR CT ; PORCINE LUNGS ; ex-vivo study ; GUIDED RADIOTHERAPY ; retrospective gating
    Abstract: Purpose: To analyse the image quality of retrospectively gated helical CT using controlled respiratory motion of porcine lung explants. Materials and methods: Five porcine lungs were examined inside a chest phantom. A silicone membrane was rhythmically inflated and deflated to simulate diaphragmatic respiration. Dynamic images (regular respiration at 8/min) and static scans (w/o respiration) at 0/25/50/75 and 100% of maximum inspiration were acquired with a 40-row detector CT scanner (rotation time 1 s, pitch 0.1). Image quality on multi-planar reformations was evaluated by two observers. Partial projection artifacts, step ladder-artifacts and noise were compared for upper, middle and lower parts of the lung and different respiratory phases (scores 0-3 for absent, minimal, moderate and diagnostically relevant artifacts). Results: Partial projection effects were limited to dynamic scans (mean score 1.33). Stepladder artifacts predominated in dynamic series compared to static series (mean score 0.55 versus 0.1; p 〈 0.001). Image noise was not related to lung motion (mean scores 0.68-0.81). All artifacts predominated close to the diaphragm compared to the upper and middle parts of the lung (p 〈 0.001 to p = 0.02, respectively). Partial projection and stepladder artifacts were less in end-inspiration and end-expiration than within the respiration (p 〈 0.001 and p = 0.17, respectively). Diagnostically relevant artifacts were noted 9 times (9/9 close to diaphragm, 7/9 partial-projection). Conclusions: Even in ideal realistic conditions, helical 4D-CT produced tolerable artifacts which could be overcome by radiologists. (c) 2007 Elsevier Ireland Ltd. All rights reserved
    Type of Publication: Journal article published
    PubMed ID: 17923161
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    Keywords: tumor ; evaluation ; Germany ; CT ; DENSITY ; imaging ; SYSTEM ; SAMPLE ; SAMPLES ; TISSUE ; HEART ; RESOLUTION ; MICE ; NUCLEAR-MEDICINE ; RAT ; animals ; RATS ; CONTRAST ; CONTRAST AGENT ; EXPERIENCE ; NUMBER ; MUSCLE ; STABILITY ; MORPHOLOGY ; COMPUTED-TOMOGRAPHY ; KINETICS ; nuclear medicine ; AGENT ; radiology ; SINGLE ; RE ; TECHNICAL ASPECTS ; methods ; PRINCIPLES ; NUCLEAR ; technology assessment ; correlation ; EVALUATE ; animal ; phantom ; physics ; Rabbits ; BONE ARCHITECTURE ; micro-CT ; INITIAL-EXPERIENCE ; animal investigations
    Abstract: Purpose: Investigation of the hardware and image characteristics of a novel micro-CT system and evaluation of its potential to image animals and tissue samples. Materials and Methods: The scanner was characterized by phantom studies regarding image homogeneity, CT number stability, soft-tissue contrast, spatial resolution and X-ray dose. The phantoms used were specially designed to evaluate the imaging of mice and rats. Scans of hearts with coronary stents were performed and the tissue morphology and vascularization of tumor-bearing rodents were studied with dynamic contrast-enhanced (DCE) CT. Results: The CT numbers of the acrylic phantoms were reproducible with a 4 HU deviation. The inter-pixel deviation was low but depended on the scan mode. The correlation coefficient between CT number and iodine concentration (06000 HU) was 0.99. Single wires, lumen and endo-luminal plaques of heart stents were distinguishable. The density-time courses were reliably recorded and made it possible to distinguish the tumor and muscle tissue in DCE micro-CT scans Conclusion: The novel micro-CT scanner is suitable for studying tissue densities and contrast agent kinetics
    Type of Publication: Journal article published
    PubMed ID: 17592806
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    Keywords: CANCER ; INVASION ; tumor ; carcinoma ; evaluation ; Germany ; CT ; DIAGNOSIS ; FOLLOW-UP ; SPIRAL CT ; TOOL ; DISEASE ; TUMORS ; computed tomography ; RESOLUTION ; PATIENT ; primary ; NO ; METASTASIS ; adenocarcinoma ; COMPUTED-TOMOGRAPHY ; sensitivity ; specificity ; VESSELS ; QUESTIONNAIRE ; pancreatic carcinoma ; HELICAL CT ; HYDRO-CT ; methods ; ROW CT ; CURVED PLANAR REFORMATIONS ; invasion score ; MULTISLICE SPIRAL CT ; resectability ; VASCULAR INVASION
    Abstract: Objective: It was the aim of this study to evaluate a new infiltration score to determine the resectability of pancreatic carcinomas in preoperative planning. Materials and Methods: Eighty patients with suspected pancreatic tumor were examined prospectively using 16-row spiral CT. The scans were evaluated for the presence of pancreatic carcinoma, peripancreatic tumor extension and vascular invasion using a standardized questionnaire. Invasion of the surgically relevant vessels was evaluated using a new invasion score. The operative and histological findings and the clinical follow-up served as the gold standard. Results: Forty patients had a pancreatic carcinoma, 5 had metastasis of a different primary tumor, and in 35 patients, there was no malignant pancreatic disease. The sensitivity for tumor detection was 100%, with a specificity of 88% for differentiating between malignant and benign pancreatic tumors. Invasion of the surrounding vessels was evaluated correctly using the invasion score, with a sensitivity of 89% and a specificity of 99%. In evaluation of resectability, a sensitivity of 94% and a specificity of 89% were achieved. Conclusion: Using 16-row spiral CT, the invasion score is a valid tool for correctly assessing invasion in relevant vessels in cases of pancreatic carcinoma and for determining resectability. Copyright (C) 2008 S. Karger AG, Basel and IAP
    Type of Publication: Journal article published
    PubMed ID: 18434758
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    Keywords: BLOOD ; Germany ; LUNG ; MODEL ; chest ; CT ; IMAGES ; SUPPORT ; VENTILATION ; computed tomography ; BLOOD-FLOW ; pig ; FLOW ; NO ; CARE ; DIFFERENCE ; PARAMETERS ; tomography ; RECRUITMENT ; PRESSURE ; CEREBRAL-BLOOD-FLOW ; COMPUTED-TOMOGRAPHY ; SERIES ; INCREASE ; LIFE ; DYNAMIC CT ; methods ; PORCINE MODEL ; CIRCULATION ; MEDICINE ; dynamic ; DERECRUITMENT ; ARDS ; ASSISTED VENTILATION ; Basic life support (BLS) ; BYSTANDER CARDIOPULMONARY-RESUSCITATION ; CARDIAC-ARREST ; Cardiopulmonary resuscitation (CPR) ; Chest compression ; CPR ; Haemodynamics ; LUNG COLLAPSE ; Return of spontaneous circulation ; TO-MOUTH VENTILATION
    Abstract: Aim: The importance of ventilatory support during cardiac arrest and basic life support is controversial. This experimental study used dynamic computed tomography (CT) to assess the effects of chest compressions only during cardiopulmonary resuscitation (CCO-CPR) on alveolar recruitment and haemodynamic parameters in porcine model of ventricular fibrillation. Materials and methods: Twelve anaesthetized pigs (26 +/- 1 kg) were randomly assigned to one of the following groups: (1) intermittent positive pressure ventilation (IPPV) both during basic life support and advanced cardiac life support, or (2) CCO during basic life support and IPPV during advanced cardiac life support. Measurements were acquired at baseline prior to cardiac arrest, during basic life support, during advanced life support, and after return of spontaneous circulation (ROSC), as follows: dynamic CT series, arterial and central venous pressures, blood gases, and regional organ blood flow. The ventilated and atelectatic lung area was quantified from dynamic CT images. Differences between groups were analyzed using the Kruskal-Wallis test, and a p 〈 0.05 was considered statistically significant. Results: IPPV was associated with cyclic alveolar recruitment and de-recruitment. Compared with controls, the CCO-CPR group had a significantly larger mean fractional area of atelectasis (p = 0.009), and significantly tower PaO2 (p = 0.002) and mean arterial pressure (p = 0.023). The increase in mean atelectatic lung area observed during basic life support in the CCO-CPR groupremained clinically relevant throughout the subsequent advanced cardiac life support period and following ROSC, and was associated with prolonged impaired haemodynamics. No inter-group differences in myocardial and cerebral blood flow were observed. Conclusion: A lack of ventilation during basic life support is associated with excessive atelectasis, arterial hypoxaemia and compromised CPR haemodynamics. Moreover, these detrimental effects remain evident even after restoration of IPPV. (C) 2008 Elsevier Ireland Ltd. ALL rights reserved
    Type of Publication: Journal article published
    PubMed ID: 18556110
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    Keywords: IRRADIATION ; radiotherapy ; Germany ; LUNG ; THERAPY ; ALGORITHM ; CT ; imaging ; INFORMATION ; SYSTEM ; SYSTEMS ; EXPOSURE ; TISSUE ; computed tomography ; validation ; NUCLEAR-MEDICINE ; TIME ; PATIENT ; COMPLEX ; MARKER ; SIGNAL ; PERFORMANCE ; MARKERS ; REGION ; REGISTRATION ; LOCALIZATION ; COMPUTED-TOMOGRAPHY ; MOTION ; nuclear medicine ; GATED RADIOTHERAPY ; IMRT ; ORDER ; radiology ; RE ; THERAPIES ; breathing cycle ; methods ; NUCLEAR ; technique ; MUTUAL INFORMATION ; RESPIRATORY MOTION ; phantom ; ENGLAND ; PREDICT ; MAXIMIZATION ; tumor motion ; MEDICINE ; X-RAY ; particle therapy ; LIMITS ; POSITION ; CONE-BEAM CT ; LUNG-TUMORS
    Abstract: Respiratory motion limits the potential of modern high-precision radiotherapy techniques such as IMRT and particle therapy. Due to the uncertainty of tumour localization, the ability of achieving dose conformation often cannot be exploited sufficiently, especially in the case of lung tumours. Various methods have been proposed to track the position of tumours using external signals, e. g. with the help of a respiratory belt or by observing external markers. Retrospectively gated time-resolved x-ray computed tomography (4D CT) studies prior to therapy can be used to register the external signals with the tumour motion. However, during treatment the actual motion of internal structures may be different. Direct control of tissue motion by online imaging during treatment promises more precise information. On the other hand, it is more complex, since a larger amount of data must be processed in order to determine the motion. Three major questions arise from this issue. Firstly, can the motion that has occurred be precisely determined in the images? Secondly, how large must, respectively how small can, the observed region be chosen to get a reliable signal? Finally, is it possible to predict the proximate tumour location within sufficiently short acquisition times to make this information available for gating irradiation? Based on multiple studies on a porcine lung phantom, we have tried to examine these questions carefully. We found a basic characteristic of the breathing cycle in images using the image similarity method normalized mutual information. Moreover, we examined the performance of the calculations and proposed an image-based gating technique. In this paper, we present the results and validation performed with a real patient data set. This allows for the conclusion that it is possible to build up a gating system based on image data, solely, or ( at least in avoidance of an exceeding exposure dose) to verify gates proposed by the various external systems
    Type of Publication: Journal article published
    PubMed ID: 18495978
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    Keywords: CANCER ; tumor ; carcinoma ; CELL ; Germany ; CT ; imaging ; DISEASE ; DIFFERENTIATION ; TISSUE ; computed tomography ; SURGERY ; PATIENT ; primary ; MRI ; MAGNETIC-RESONANCE ; magnetic resonance imaging ; NO ; DIFFERENCE ; NUMBER ; METASTASIS ; metastases ; REGION ; REGIONS ; DISSEMINATED TUMOR-CELLS ; adenocarcinoma ; COMPUTED-TOMOGRAPHY ; CELL CARCINOMA ; renal cell carcinoma ; pancreas ; ENHANCEMENT ; methods ; multidetector CT ; RENAL-CELL
    Abstract: Aims: To investigate the characteristics of metastasis to the pancreas using computed tomography (CT) and magnetic resonance imaging (MRI). Methods: Twenty-two patients with metastases to the pancreas were examined preoperatively by MRI (7/22) and/or multidetector CT (15/22). Pre- and post-contrast images were acquired and morphology, size, and contrast enhancement of the tumor analyzed. Subsequently, all patients underwent surgery, and the histopathologic findings were compared with the imaging results. Results: In 22 patients, a total of 29 metastases were found on CT and MRI. These metastases originated from renal cell carcinomas (RCC; 22/29), colorectal carcinoma (3/29), and other malignancies (4/29). The metastases differed not in size or location, but in their contrast enhancement characteristics. RCC metastases had either intense homogeneous enhancement (in small lesions) or rim enhancement (in large lesions). Outer regions of colorectal metastases showed no difference from normal pancreatic tissue, whereas the inner area showed hypo-enhancement due to central necrosis. Conclusion: Imaging features of metastases from RCC point to their primary origin. While they can be distinguished from primary adenocarcinoma of the pancreas, differentiation from endocrine carcinoma might be difficult. Differentiation of colorectal carcinoma remains to be investigated on larger numbers of cases. Copyright (C) 2008 S. Karger AG, Basel and IAP
    Type of Publication: Journal article published
    PubMed ID: 18434757
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