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  • 1
    Keywords: Germany ; LUNG ; PERFUSION ; imaging ; VENTILATION ; DIFFERENTIATION ; RESOLUTION ; PATIENT ; IMPACT ; image analysis ; MR ; MRI ; SEQUENCE ; SIGNAL ; MAGNETIC-RESONANCE ; magnetic resonance imaging ; ACQUISITION ; REQUIRES ; SCINTIGRAPHY ; ABNORMALITIES ; acquisitions (GRAPPA) ; ANGIOGRAPHY ; CONTRAST-ENHANCED MRI ; generalized autocalibrating partially parallel ; magnetic resonance imaging (MRI) ; parallel imaging techniques ; PULMONARY PERFUSION
    Abstract: Rationale: Contrast-enhanced magnetic resonance imaging (MRI) of lung perfusion requires a high spatial and temporal resolution. Partially parallel MRI offers an improved spatial and temporal resolution. Objective: To assess the feasibility of partially parallel MRI for the assessment of lung perfusion. Methods: Two healthy volunteers and 14 patients were examined with a contrast-enhanced 3D gradient-echo pulse sequence with partially parallel image acquisitions (TE/TR/alpha: 0.8/1.9 milliseconds/40degrees; voxel size 3.6 X 2.0 X 5.0 mm(3), TA: 1.5 seconds). The image analysis included an analysis of the signal-to-noise ratio in the lungs in areas with normal and impaired perfusion. 3D MR perfusion image data were analyzed for perfusion defects and compared with radionuclide perfusion scans, which were available for 10 of 14 patients. Results: The analysis of the 3D perfusion-weighted data allowed a clear differentiation of perfusion abnormalities: MRI showed normal lung perfusion in 9 of 16 cases, whereas perfusion abnormalities were observed in 7 cases. When compared with the radionuclide perfusion scans, a good intermodality agreement was shown (kappa = 0.74). When compared with normally perfused lung a significantly lower signal to noise ratio was observed in hypoperfused lung (7 versus 17; P = 0.02). Conclusion: Partially parallel MRI might be used for the assessment of lung perfusion. Future studies are required to further evaluate the diagnostic impact of this technique
    Type of Publication: Journal article published
    PubMed ID: 12874514
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  • 2
    Keywords: Germany ; PERFUSION ; imaging ; VISUALIZATION ; TISSUE ; radiation ; kidney ; QUALITY ; renal ; animals ; CONTRAST ; INTERVENTION ; CONTRAST AGENT ; MR ; MAGNETIC-RESONANCE ; arteries ; TRACKING ; CELL CARCINOMA ; INTERVENTIONAL DEVICES ; ANGIOPLASTY ; ARTERY STENT PLACEMENT ; ENDOVASCULAR PROCEDURES ; ENHANCED MR-ANGIOGRAPHY ; FLUOROSCOPY ; magnetic resonance imaging,renal cancer,embolization,interventional radiology ; PIG MODEL
    Abstract: Rationale and Objectives: Magnetic resonance (MR)-guidance of endovascular interventions offers various advantages, including the absence of ionizing radiation, excellent soft tissue contrast, and multiplanar and functional imaging capabilities. The objective of this study was to assess the feasibility of MR-guided renal embolization using active catheter tracking with automatic slice positioning and intraarterial contrast-enhanced MR angiography (MRA).Materials and Methods: MR-guided embolization of 16 kidneys was attempted in 15 pigs using real-time tracking of active 5-Fr. catheters, Embolization was monitored by selective intraarterial projection MRA. Intraarterial three-dimensional (3D) MRA was used for the assessment of embolization results. Additional pathologic correlation was available in 2 animals. The image quality of intraarterial 3D contrast-enhanced-MRA was rated by an independent radiologist who was not involved in the animal experiments.Results: Active catheter tracking with automatic slice positioning allowed reliable catheter guidance and catheterization of the renal artery in all animals. Embolization was successful in all kidneys (11 left, 5 right), as verified by intraarterial 3D contrast-enhanced MRA (ce-MRA) and/or pathology. The image quality of intraarterial 3D ce-MRA was rated excellent in 10 animals, moderate in 4 animals, and poor in 1 animal.Conclusion: Renal embolization using active catheter tracking and intraarterial ce-MRA is feasible. Selective intraarterial ce-MRA allows the assessment of blood supply and organ perfusion before, during, and after therapeutic interventions, thereby complementing MR-guided endovascular interventions
    Type of Publication: Journal article published
    PubMed ID: 14734926
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  • 3
    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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  • 4
    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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  • 5
    Keywords: brain ; SPECTRA ; CANCER ; CANCER CELLS ; CELLS ; GROWTH ; IRRADIATION ; radiotherapy ; tumor ; carcinoma ; CELL ; Germany ; human ; MICROVESSEL DENSITY ; MODEL ; PERFUSION ; PROSTATE ; THERAPY ; tumor growth ; imaging ; METABOLISM ; TUMORS ; SURGERY ; radiation ; RAT ; RATS ; CONTRAST ; MRI ; MAGNETIC-RESONANCE ; PROTON ; RESONANCE SPECTROSCOPY ; SPECTROSCOPY ; magnetic resonance imaging ; ACID ; PROSTATE-CANCER ; CANCER-CELLS ; EXCHANGE ; PARAMETERS ; tomography ; CARCINOMAS ; TCR ; prostate carcinoma ; VASCULARIZATION ; MAPS ; prostate cancer,dynamic MRI,proton MR spectroscopy,radiotherapy
    Abstract: Rationale and Objectives: To establish an experimental setting for monitoring perfusion and metabolism in orthotopic prostate cancer at 1.5 T using dynamic contrast-enhanced magnetic resonance imaging (DCE MRI) and H-1-MR spectroscopy (MRS).Methods: Dunning rat prostate cancer cells were injected into the prostate by open surgery. Twelve tumor-bearing rats (5 of these irradiated) and 6 healthy controls were followed up using gadolinium-diethylenetriaminepentaacetic acid -enhanced dynamic MRI and H-1-MRS. Amplitude and the exchange rate constant k(ep) were calculated (2-compartment model). From H-1-MR spectra, ratios of choline (Cho) and creatine (tCr) were calculated. All tumors were examined histologically.Results: On DCE MRI parameter maps, tumors showed increased vascularization. k(ep) and microve.ssel density were correlated (r = 0.97). Tumors showed elevated Cho/tCr and an unexpected lipid fraction (2.0-2.2 parts per million). Irradiation slowed tumor growth significantly. Changes of perfusion and metabolism could be detected in all tumors during follow up.Conclusion: DCE MRI and H-1-MRS has potential to characterize orthotopic Dunning prostate cancer in rats, which is a promising model similar to human prostate carcinomas
    Type of Publication: Journal article published
    PubMed ID: 14701987
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  • 6
    Keywords: evaluation ; Germany ; LUNG ; MODEL ; CT ; EMPHYSEMA ; imaging ; TOOL ; DISEASE ; MRI ; CYCLE ; SEQUENCE ; INVIVO ; MAGNETIC-RESONANCE ; magnetic resonance imaging ; PARAMETERS ; MOTION ; PULMONARY ; TRUEFISP ; HEALTHY-VOLUNTEERS ; EXPIRATION ; HUMAN DIAPHRAGM SHAPE ; INSPIRATORY PUMP ; lung dynamic,magnetic resonance imaging,respiration,model,spirometry ; LUNG-VOLUMES ; WALL MECHANICS
    Abstract: Rationale and Objectives: To investigate diaphragm and chest wall motion during the whole breathing cycle using magnetic resonance imaging (MRI) and a volumetric model in correlation with spirometry.Materials and Methods: Breathing cycles of 15 healthy volunteers were examined using a trueFISP sequence (5 slices in 3 planes, 3 images per second). Time-distance curves were calculated and correlated to spirometry. A model for vital capacity (VC), continuous time-dependent vital capacity (tVC), and investigating the influence of horizontal and vertical parameters on tVC was introduced.Results: Time-distance curves of the breathing cycle using MRI correlated highly significant with spirometry (P 〈 0.0001). VC calculated by the model was similar to VC measured in spirometry (5.00 L vs. 5.15 L). tVC correlated highly significantly with spirometry (P 〈 0.0001). Vertical parameters had a more profound influence on tVC change than horizontal parameters.Conclusions: Dynamic MRI is a simple noninvasive method to evaluate local chest wall motion and respiratory mechanics. It widens the repertoire of tools for lung examination with a high temporal resolution
    Type of Publication: Journal article published
    PubMed ID: 15021323
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  • 7
    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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  • 8
    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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  • 9
    Keywords: brain ; measurement ; radiotherapy ; tumor ; BLOOD ; Germany ; PERFUSION ; THERAPY ; FOLLOW-UP ; follow-up studies ; imaging ; QUANTIFICATION ; VOLUME ; TISSUE ; NUCLEAR-MEDICINE ; radiation ; PATIENT ; BLOOD-FLOW ; blood flow ; FLOW ; MRI ; SEQUENCE ; treatment ; stereotactic ; radiosurgery ; STEREOTACTIC RADIOSURGERY ; DECREASE ; metastases ; CEREBRAL-BLOOD-FLOW ; PREDICTION ; NORMAL TISSUE ; nuclear medicine ; brain metastases ; GLIOMAS ; LOBE EPILEPSY ; QUIPSS-II ; radiology ; RE ; THERAPIES ; IMAGING TECHNIQUES ; TUMOR VOLUME ; ARTERIAL ; neoplasm metastasis ; relative regional cerebral blood flow ; VOLUME MAPS
    Abstract: Rationale and Objectives: To assess if preradiation and early follow-up measurements of relative regional cerebral blood flow (rrCBF) can predict treatment outcome in patients with cerebral metastases and to evaluate rrCBF changes in tumor and normal tissue after stereotactic radiosurgery using arterial spin-labeling (ASL) and first-pass dynamic susceptibility-weighted contrast-enhanced (DSC) perfusion MRI. Methods: In 25 patients with a total of 28 brain metastases, DSC MRI and ASL perfusion MRI using the Q2TIPS sequence were performed with a 1.5-T unit. Measurements were performed prior to and at 6 weeks. 12 weeks, and 24 weeks after stereotactic radiosurgery. Follow-up examinations were completely available in 25 patients for Q2TIPS and 17 patients with 18 metastases for DSC MRI. The rrCBF of the metastases and the normal brain tissue was determined by a region-of-interest analysis. rrCBF values were correlated with the treatment outcome that was classified according to tumor volume changes at 6 months. Results: The alteration of the rrCBF at the 6-week follow-up was highly predictive for treatment outcome. A decrease of the rrCBF value predicted tumor response correctly in all metastases for Q2TIPS and in 13 of 16 metastases for DSC MRI. The pretherapeutic rrCBF was not able to predict treatment outcome. The rrCBF values in normal brain tissue affected by radiation doses less than 0.5 Gy remained unchanged after therapy. Conclusion: These preliminary results suggest that ASL and DSC MRI techniques determining rrCBF changes in brain metastases after stereotactic radiosurgery allow the prediction of treatment outcome
    Type of Publication: Journal article published
    PubMed ID: 15087722
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  • 10
    Keywords: BLOOD ; Germany ; LUNG ; PERFUSION ; imaging ; QUANTIFICATION ; VOLUME ; TIME ; BLOOD-FLOW ; blood flow ; FLOW ; HIGH-RESOLUTION MEASUREMENT ; MRI ; TRACER BOLUS PASSAGES ; MAGNETIC-RESONANCE ; magnetic resonance imaging ; AGE ; PARAMETERS ; SCINTIGRAPHY ; CONTRAST-ENHANCED MRI ; magnetic resonance imaging (MRI) ; QUANTITATIVE-ANALYSIS ; HEALTHY ; LUNG PERFUSION ; TRANSIT-TIME ; HEALTHY-VOLUNTEERS ; ARTERIAL ; INFLATION ; contrast-enhanced
    Abstract: Rationale and Objectives: The effect of breathholding on pulmonary perfusion remains largely unknown. The aim of this study was to assess the effect of inspiratory and expiratory breathhold on pulmonary perfusion using quantitative pulmonary perfusion magnetic resonance imaging (MRI). Methods and Results: Nine healthy volunteers (median age, 28 years; range, 20-45 years) were examined with contrast-enhanced time-resolved 3-dimensional pulmonary perfusion MRI (FLASH 313, TR/TE: 1.9/0.8 ms; flip angle: 40degrees; GRAPPA) during end-inspiratory and expiratory breathholds. The perfusion parameters pulmonary blood flow (PBF), pulmonary blood volume (PBV), and mean transit time (MTT) were calculated using the indicator dilution theory. As a reference method, end-inspiratory and expiratory phase-contrast (PC) MRI of the pulmonary arterial blood flow (PABF) was performed. Results: There was a statistically significant increase of the PBF (Delta = 182 mL/100mL/min), PBV (Delta = 12 mL/100 mL), and PABF (Delta = 0.5 L/min) between inspiratory and expiratory breathhold measurements (P 〈 0.0001). Also, the MTT was significantly shorter (Delta = -0.5 sec) at expiratory breathhold (P = 0.03). Inspiratory PBF and PBV showed a moderate correlation (r = 0.72 and 0.61, P less than or equal to0.008) with inspiratory PABF. Conclusion: Pulmonary perfusion during breathhold depends on the inspiratory level. Higher perfusion is observed at expiratory breathhold
    Type of Publication: Journal article published
    PubMed ID: 15654250
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