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    Keywords: measurement ; CANCER ; proliferation ; Germany ; LUNG ; THERAPY ; ALGORITHM ; ALGORITHMS ; ANATOMICAL MODEL ; AUTOMATIC DETECTION ; BAYESIAN-ANALYSIS ; cancer screening ; chest ; CLASSIFICATION ; COMMON ; computed tomography (CT),image processing ; computers,diagnostic aid ; computers,neural networks ; CT ; DENSITY ; DIAGNOSIS ; EMPHYSEMA ; FOLLOW-UP ; follow-up studies ; GENERATION ; GROUND-GLASS OPACITIES ; HIGH-RESOLUTION CT ; IMAGES ; imaging ; INFORMATION ; lung cancer ; LUNG-CANCER ; MASK ; MULTIPLE NEURAL-NETWORKS ; NETWORK ; NETWORKS ; neural networks ; QUANTIFICATION ; screening ; segmentation ; SOLITARY PULMONARY NODULES ; SPIRAL CT ; SUPPORT ; SYSTEM ; SYSTEMS ; thorax ; TOMOGRAPHY IMAGES ; TOOL ; TOTAL LUNG CAPACITY ; VENTILATION ; VISUALIZATION ; VOLUME
    Abstract: The proliferation of digital data sets and the increasing amount of images, e.g. through the use of multislice spiral CT or multiple follow-up examinations in the context of new therapies, are ideal prerequisites for computer-aided diagnosis (CAD) in chest radiology. Multiple studies have described the applications and advantages of computer assistance in performing different diagnostic tasks. More powerful computers will enable the introduction of these systems into the clinical routine and could provide an enormous increase in morphological and functional information. The commercial introduction of tools for detection and visualization of pulmonary nodules has already begun. This is one of the most widely-reported applications in view of the ongoing studies on lung cancer screening. The next generation of tools will improve the diagnosis of emphysema through detection, quantification and classification. Many more uses are being developed, for instance the detection and classification of infiltrates, volume measurements or functional pulmonary imaging (e.g. dynamic ventilation CT or (3)Helium-MRI). Grossly simplified, most systems use a three level structure consisting of segmentation/feature extraction, classification of extracted features and an output unit. The output can be mere visualization through color-coding, volume measurements or calculated probabilities. The output supports the radiologist in establishing his findings and preparing differential and final diagnoses as well as providing quantitative data for follow-up studies. Different techniques are used for segmentation of lung areas as the basis for a variety of applications. Some commonly-used techniques for this and other tasks are density masks and threshold-based algorithms. Data processing is predominantly carried out with Bayesian classifiers or neural networks. This article describes the current status of research and provides insight into the common schemes and capabilities of the systems. It focuses particularly on common topics such as segmentation, volume measurement, detection of pulmonary nodules, quantification of emphysema and analysis of ground glass opacities
    Type of Publication: Journal article published
    PubMed ID: 14610697
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  • 3
    Keywords: Germany ; LUNG ; PERFUSION ; DIAGNOSIS ; imaging ; INFORMATION ; VOLUME ; DISEASE ; TIME ; PATIENT ; BLOOD-FLOW ; primary ; HIGH-RESOLUTION MEASUREMENT ; MRI ; TRACER BOLUS PASSAGES ; SEQUENCE ; LUNG PERFUSION
    Abstract: Purpose: To assess the use of time-resolved parallel 3D MRI for a quantitative analysis of pulmonary perfusion in patients with cardiopulmonary disease. Materials and Methods: Eight patients with pulmonary embolism or pulmonary hypertension were examined with a time-resolved 3D gradient echo pulse sequence with parallel imaging techniques (FLASH 3D, TE/TR: 0.81 1.9 ms; flip angle: 40degrees; GRAPPA). A quantitative perfusion analysis based on indicator dilution theory was performed using a dedicated software. Results: Patients with pulmonary embolism or chronic thromboembolic pulmonary hypertension revealed characteristic wedge-shaped perfusion defects at perfusion MRI. They were characterized by a decreased pulmonary blood flow (PBF) and pulmonary blood volume (PBV) and increased mean transit time (MTT). Patients with primary pulmonary hypertension or Eisenmenger syndrome showed a more homogeneous perfusion pattern. The mean MTT of all patients was 3.3 +/- 4.7 s. The mean PBF and PBV showed a broader interindividual variation (PBF: 104-322ml/100ml/min; PBV: 8-21ml/100 ml). Conclusion: Time-resolved parallel 3D MRI allows at least a semi-quantitative assessment of lung perfusion. Future studies will have to assess the clinical value of this quantitative information for the diagnosis and management of cardiopulmonary disease
    Type of Publication: Journal article published
    PubMed ID: 14872369
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  • 4
    Keywords: measurement ; Germany ; LUNG ; THERAPY ; EMPHYSEMA ; IMAGES ; QUANTIFICATION ; TOOL ; VENTILATION ; RESOLUTION ; TIME ; PATIENT ; TRANSPLANTATION ; FLOW ; MRI ; SIGNAL ; magnetic resonance ; REGION ; REGIONS ; PARAMETERS ; SERIES ; MOTION ; HYPERPOLARIZED HE-3 ; PULMONARY VENTILATION ; LUNG VENTILATION ; hyperpolarized ; MAPS ; PULMONARY ; SOFTWARE TOOL ; 2D ; CLINICAL-SIGNIFICANCE ; pulmonary function ; PULMONARY-FUNCTION ; He-3 ; HE-3 GAS ; hyperpolarized gas ; LUNG MOTION CORRECTION
    Abstract: Purpose: He-3-MRI is able to visualize the regional distribution of lung ventilation with a temporal and spatial resolution so far unmatched by any other technique. The aim of the study was the development of a new software tool for quantification of dynamic ventilation parameters in absolute physical units. Materials and Methods: During continuous breathing, a bolus of hyperpolarized He-3 (300 ml) was applied at inspiration and a series of 168 coronal projection images simultaneously acquired using a 2D FLASH-sequence. Postprocessing software was developed to analyze the He-3 distribution in the lung. After correction for lung motion, several ventilation parameters (rise time, delay time, He-3 amount and He-3 peak flow) were calculated. Due to normalization of signal intensities, these parameters are presented in absolute physical units. The data sets were analyzed on a ROI basis as well as on a pixel-by-pixel basis. Results: Using the developed software, the measurements were analyzed in 6 lung-healthy volunteers, in one patient after lung transplantation, and in one patient with lung emphysema. The volunteers' parameter maps of the pixel-based analysis showed an almost homogeneous distribution of the ventilation parameters within the lung. In the parameter maps of both patients, regions with poor ventilation were observed. Conclusion: The developed software permits an objective and quantitative analysis of regional lung ventilation in absolute physical units. The clinical significance of the parameters, however, has to be determined in larger clinical studies. The software may become valuable in grading and following pulmonary function as well as in monitoring any therapy
    Type of Publication: Journal article published
    PubMed ID: 15383970
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  • 5
    Keywords: measurement ; evaluation ; Germany ; LUNG ; PERFUSION ; imaging ; QUANTIFICATION ; VENTILATION ; TIME ; BLOOD-FLOW ; MR ; MRI ; SEQUENCE ; SIGNAL ; ACQUISITION ; DIFFERENCE ; REGION ; arteries ; REGIONS ; EMBOLISM ; ANGIOGRAPHY ; PULMONARY PERFUSION ; LUNG PERFUSION ; PULMONARY ; HEALTHY-VOLUNTEERS ; CINE-MRI ; perfusion,lung,phase-contrast,MRI,parallel imaging
    Abstract: Purpose: Evaluation of lung perfusion by contrast-enhanced 3D MRI using partial parallel imaging techniques. Materials and Methods: Eight healthy volunteers were examined using a contrast-enhanced dynamic FLASH 3D sequence with partial parallel imaging technique at 1.5 T MRI with a TA of 1.5 sec. The whole lung was covered by 36 coronal slices. A ventral, middle and dorsal, slice of each lung was manually segmented and signal-to-time curves were computed. For absolute quantification of blood flow through the right and left pulmonary artery, phase-contrast flow measurements were performed. Results: No significant difference was found between the signal intensity in the right (8.9 +/- 2.6) and left (8.0 +/- 3.5) lung, corresponding to a left-to-right signal intensity ratio of 0.9. A significantly higher signal intensity was found in the dorsal regions of the lungs (p = 0.01) compared to the ventral regions. The time to peak of the signal intensity was significantly shorter in the dorsal (15.3 sec) and middle (15.7 sec) regions of the lungs (p = 0.03 and p = 0.04, respectively) than in the ventral regions (16.3 sec). The ratio between blood flow through the left (2.2 L/min) and right (2.7 L/min) lung was 0.84. Conclusion: Partial parallel image acquisition can assess the perfusion of the lungs at high temporal resolution. The perfusion is slightly higher on the right than on the left. The signal increases faster and has a higher peak in the dorsal lung regions
    Type of Publication: Journal article published
    PubMed ID: 15026945
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  • 6
    Keywords: brain ; SPECTRA ; IRRADIATION ; radiotherapy ; tumor ; Germany ; THERAPY ; DIAGNOSIS ; FOLLOW-UP ; imaging ; DIFFERENTIATION ; TISSUE ; TUMORS ; radiation ; PATIENT ; MR ; SIGNAL ; MR spectroscopy ; SPECTROSCOPY ; stereotactic ; LESIONS ; PROGRESSION ; TUMOR PROGRESSION ; RECURRENCE ; PROGNOSTIC-FACTORS ; positron emission tomography ; POSITRON-EMISSION-TOMOGRAPHY ; tomography ; SPECT ; PET ; AMINO-ACIDS ; LOW-GRADE ASTROCYTOMAS ; TRACER ; GLIOMAS ; 2D ; ONCOLOGY ; brain tumor ; BRAIN-TUMORS ; GLIOMA ; FDG PET ; F-18 FLUORODEOXYGLUCOSE ; single photon emission tomography
    Abstract: Purpose: To evaluate the clinical value of 1H MR spectroscopy (1 H MRSI) for follow-up of irradiated glioma compared to posi-. tron emission tomography (PET) with [18F]-2-fluoro-deoxy-D-glucose (FDG-PET) and single photon emission tomography with [1231]-a-methyl-L-tyrosine (IMT-SPECT). Materials and Methods: Twenty-four patients with irradiated gliomas were examined using 1H MRSI (2D spectroscopic imaging; PRESS; TE=135 msec; 1.5T Magnetom Vision, Siemens; Voxel size 9 x 9 x 15 mm(3)). MR spectra (n = 233) were evaluated in areas suspicious of tumor (n = 86) as well as in healthy appearing brain tissue (n = 147). Relative signal intensity ratios of choline (Cho), creatine (Cr) and N-acetyl-aspartate (NAA) were calculated. PET. scans (n = 19) were performed with 200 - 250 MBq FDG, IMT-SPECT examinations (n = 14) with 200 - 250 mBq IMT. Based on clinical and MRI/CT, follow-up lesions were classified as either neoplastic [PIT] or non-neoplastic [nPT]. Results: True positive results for the diagnosis of PT/nPT were 88/89% (1H MRSI), 73/100 % (PET) and 100/75 % (SPECT). Cho/Cr showed highly significant changes for PT. Determinating a correlation between Cho, Cr, NAA and IMT-SPECT as well as FDG-PET was not possible because of different location of maximum tracer uptake and acquired 2D I H MRSI. Conclusion: IMT-SPECT seems to be superior to detect tumor progression in irradiated gliomas. 1 H MRSI was more suitable than FDG-PET to differentiate between recurrence and radiation-induced changes. FDG-PET plays a role as sensitive method for detecting high-grade tumors. PET and SPECT allowed the examination of the entire tumor including surrounding brain tissue with higher spatial resolution than the acquired 2D 1H MRSI. A main limitation of our study was that only 2D 1 H MRSI was used, with only parts of the tumor evaluated. The use of 3D MR spectroscopic imaging may further increase the diagnostic accuracy
    Type of Publication: Journal article published
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  • 7
    Keywords: brain ; Germany ; MODEL ; MODELS ; PERFUSION ; imaging ; SYSTEM ; CONTRAST ; MAGNETIC-RESONANCE ; magnetic resonance imaging ; NERVOUS-SYSTEM ; CEREBRAL-BLOOD-FLOW ; CENTRAL-NERVOUS-SYSTEM ; CONTRAST-ENHANCED MRI ; functional MRI ; ENHANCEMENT ; INVERSION ; ARTERIAL ; contrast-enhanced ; functional imaging ; ARTERIAL WATER ; ASL ; BALLOON MODEL ; BOLD-fMRI ; BRAIN PERFUSION ; dynamic contrast enhanced-MRI ; dynamic susceptibility contrast-MRI ; FMRI ; HIGH-SPATIAL-RESOLUTION ; OXYGEN-CONSUMPTION ; QUIPSS II
    Abstract: This review presents the basic principles of functional imaging of the central nervous system utilizing magnetic resonance imaging. The focus is set on visualization of different functional aspects of the brain and related pathologies. Additionally, clinical cases are presented to illustrate the applications of functional imaging techniques in the clinical setting. The relevant physics and physiology of contrast-enhanced and non-contrast-enhanced methods are discussed. The two main functional MR techniques requiring contrast-enhancement are dynamic T1 - and T2(*)-MRI to image perfusion. Based on different pharmacokinetic models of contrast enhancement diagnostic applications for neurology and radio-oncology are discussed. The functional non-contrast enhanced imaging techniques are based on "blood oxygenation level dependent (BOLD)-fMRI and arterial spin labeling (ASL) technique. They have gained clinical impact particularly in the fields of psychiatry and neurosurgery
    Type of Publication: Journal article published
    PubMed ID: 15871087
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  • 8
    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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  • 9
    Keywords: OPTIMIZATION ; BLOOD ; Germany ; DIAGNOSIS ; imaging ; ACCURACY ; TIME ; PATIENT ; CONTRAST ; CONTRAST AGENT ; SEQUENCE ; ACQUISITION ; PARAMETERS ; CURVES ; MAGNETIC-RESONANCE ANGIOGRAPHY ; magnetic resonance angiography ; GD-DTPA ; BOLUS ; AGENT ; TRANSIT-TIME ; normalization ; intensity ; PHASE ; POWER ; contrast-enhanced ; PULMONARY-ARTERIES ; TEMPORAL RESOLUTION ; geometry of contrast bolus ; RENAL-ARTERIES ; thoracic vessels ; VASCULAR SYSTEM
    Abstract: Purpose: Little is known about the dispersion of a defined contrast bolus during its passage through the heart and pulmonary vasculature. The Purpose of this study was to analyze factors influencing a defined contrast bolus for ce-MRA of thoracic vessels. Materials and Methods: For analysis of bolus geometry, an ECG-gated saturation-recovery Turbo-Flash sequence with a TI of 20 msec was used. it was acquired axially at the level of the pulmonary trunc, so that with one data acquisition a curve analysis was possible in the ascending and descending aorta, and in the pulmonary trunc. Twenty-nine patients received 3 ml of Gd-DTPA diluted with saline to a total of 20 ml. Contrast injection was done using a MR compatible power injector with injection rates varying between 1, 2 and 4 ml/sec. Each injection was followed by a saline flush of 20ml with the same injection rate and mode. Cardiac function was assessed by cine imaging, and phase contrast measurements. After normalization to baseline signal intensity (SI), bolus curves were fitted using a gamma-variate fit and peak signal intensity (peak SI), time-to-peak (TP), upslope, mean transit time (MTT) and dispersion of the contrast bolus were calculated. Furthermore, T, and [Gd] in the experimental setting were calculated as follows: T-1 =T-1o/ In [SI/Sl(0)], and [Gd](exp) [1/T-1 - 1/T-1o]/ R-1. They were then extrapolated [Gd] to clinical conditions by [Gd](clin) = [Gd](exp) (.) 10/1.5, and minimal blood T-1 by T-1clin = 1 / [1/T-1o + R-1 [Gd](clin)]. Results: With increasing injection rate, there was a significant decrease (p < 0.001) of MTT in all target vessels. However, this decrease was not linear: a 4-fold increase in injection rate lead to a 2-fold decrease in MTT e. g. in the ascending aorta. MTT was significantly shorter in the pulmonary trunc compared with that in the ascending and descending aorta (p < 0.001), regardless of injection rate (p < 0.001). Vice versa, dispersion of the contrast bolus was significantly lower in the pulmonary trunc, and increased with higher injection rates. There was no clinically relevant difference in minimal blood T, between the different target vessels, for clinical conditions extrapolated values ranged between 20 und 79 msec. Heart function parameters only had a minor influence of bolus curve parameters. Conclusion: Analysis of bolus geometry enables determination of transit times of a defined contrast bolus through a defined target vessel in the thoracic cavity. Bolus geometry is mainly determined by injection parameters, cardiac function is of minor importance. Dispersion of contrast bolus and M17 increase from the pulmonary trunc to the ascending aorta. The knowledge of these facts may help optimizing of injection parameters and the total amount of contrast agent for contrast-enhanced MRA of thoracic vessels
    Type of Publication: Journal article published
    PubMed ID: 15871079
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  • 10
    Keywords: Germany ; MODEL ; CT ; NETWORKS ; SYSTEM ; PATIENT ; TRANSPORT ; NUMBER ; SINGLE ; teleradiology ; economy ; telemedicine,CT
    Abstract: Purpose: To evaluate, discuss and compare economic aspects of teleradiological applications in CT examinations in a small hospital. Scenario (1): CT examination by an extern institution including transport of a patient. Szenario (2): External consultation of an internal CT examination (teleradiology according to ROV). Scenario (3): Complete in-house radiology department. To evaluate economic aspects of teleradiology service providers. Materials and Methods: Costs have been separated into fixed and variable costs in a model. Total costs of 500 CT examinations per year have been calculated for the three scenarios. A break-even analysis has been performed to determine the necessary/minimal number of CTs per year for economical advantages. The number of CT consultations for teleradiology service providers to make profit has been calculated. Results: Scenario (1): This is the most cost-effective scenario for 500 CTs per year, but most time-consuming. Beyond 548 CTs per year using a single slice CT and 965 CTs per year using a multislice CT the teleradiology scenario [scenario (2)] is most cost-effective. Beyond 1065 CTs per year an in-house radiology department [scenario (3)] is economically reasonable. On the basis of 30 Euros per CT consultation a teleradiology service providing system will be profitable starting from 322 CT consultations per year. Conclusion: Teleradiology applications are economically reasonable in a wide range in small hospitals. CT teleradiology services can also be provided on a cost-effective basis at a reachable number of consultations
    Type of Publication: Journal article published
    PubMed ID: 15973605
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