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  • 1
    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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  • 2
    Keywords: brain ; AGENTS ; BLOOD ; Germany ; PERFUSION ; imaging ; QUANTIFICATION ; VOLUME ; EFFICIENCY ; TUMORS ; RESOLUTION ; BLOOD-FLOW ; MR ; SUSCEPTIBILITY ; magnetic resonance imaging ; REGIONS ; CONTRAST AGENTS ; gadobenate dimeglumine ; CONTRAST-ENHANCED MRI ; contrast media ; STROKE ; LOSSES ; CBF ; CBV
    Abstract: Rationale and Objective: The objective of this study was to compare 0.1 and 0.2 mmol/kg body weight (bw) doses gadobenate dimeglumine (Gd-BOPTA; MultiHance) and gadobutrol (Gd-BT-DO3A; Gadovist) for cerebral perfusion magnetic resonance (MR) imaging at 1.5 T. Methods: Twelve healthy male volunteers enrolled into a randomized intraindividual comparative study underwent 4 perfusion MR imaging examinations with 0.1 and 0.2 mmol/kg bw doses of each contrast agent. The imaging parameters, slice positioning, and contrast agent application were highly standardized. Quantitative determinations based on signal intensity/time (SI/T) curves at regions of interest (ROI) on the gray and white matter were made of the regional cerebral blood volume and flow (rCBV and rCBF, respectively), the percentage signal drop, and the full width half maximum (FWHM) of the SI/T curve. Qualitative evaluation of the quality of the rCBV and rCBF maps was assessed by an independent offsite blinded reader. Results: A single dose of both agents was sufficient to achieve high-quality, diagnostically valid perfusion maps at 1.5 T, and no significant benefit for one agent over the other was noted for quantitative or qualitative determinations. The susceptibility effect, described by percentage of signal loss (gadobutrol: 29.4% vs gadobenate dimeglumine: 28.3%) and the FWHM (gadobutrol: 6.4 seconds vs gadobenate dimeglumine: 7.0 seconds) were similar for 0.1 mmol/kg bw doses of the 2 agents. Double doses of the 2 agents produced better overall image quality but no clinical benefit over the single-dose examinations. Conclusion: Both the 1 molar MR contrast agent gadobutrol and the weak protein-interacting agent gadobenate dimeglumine permit the acquisition of high-quality perfusion maps at doses of 0.1 mmol/kg bw. The susceptibility effect is comparable for both agents and stronger than for conventional MR contrast agents
    Type of Publication: Journal article published
    PubMed ID: 16481908
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  • 3
    Keywords: brain ; tumor ; AGENTS ; BLOOD ; Germany ; PERFUSION ; IMAGES ; imaging ; DISEASE ; DISEASES ; PROTEIN ; PROTEINS ; TIME ; SERA ; QUALITY ; CONTRAST ; SUFFICIENT ; CONTRAST AGENT ; FLOW ; HIGH-RESOLUTION MEASUREMENT ; INJECTION ; MR ; MRI ; TRACER BOLUS PASSAGES ; SIGNAL ; ALZHEIMERS-DISEASE ; PERFORMANCE ; ACQUISITION ; DECREASE ; NUMBER ; LOW-GRADE ASTROCYTOMAS ; CONTRAST AGENTS ; GADOBENATE-DIMEGLUMINE ; gadobenate dimeglumine ; VESSELS ; AFFINITY ; BOLUS ; STROKE ; MAPS ; AGENT ; albumin ; SERUM ; serum albumin ; DISORDERS ; review ; BRAIN-TUMORS ; GLIOMA ; perfusion study ; Alzheimer's disease ; BLOOD-VESSELS ; CEREBRAL BLOOD-VOLUME ; ISCHEMIC-STROKE ; TRANSIT-TIME ; tumor imaging
    Abstract: Today there are several indications for cerebral perfusion MRI. The major indications routinely used in increasing numbers of imaging centers include cerebrovascular disease, tumor imaging and recently psychiatric disorders. Perfusion MRI is based on the injection of a gadolinium chelate and the rapid acquisition of images as the bolus of contrast agent passes through the blood vessels in the brain. The contrast agent causes a signal change; this signal change over time can be analysed to measure cerebral hemodynamics. The quality of brain perfusion studies is very dependent on the contrast agent used: a robust and strong signal decrease with a compact bolus is needed. MultiHance (gadobenate dimeglumine, Gd-BOPTA) is the first of a new class of paramagnetic MR contrast agents with a weak affinity for serum proteins. Due to the interaction of Gd-BOPTA with serum albumin, MultiHance presents with significantly higher T1- and T2-relaxivities enabling a sharper bolus profile. This article reviews the indications of perfusion MRI and the performance of MultiHance in MR perfusion of different diseases. Previous studies using perfusion MRI for a variety of purposes required the use of double dose of contrast agent to achieve a sufficiently large signal drop to enable the acquisition of a clear input function and the calculation of perfusion rCBV and rCBF maps of adequate quality. Recent studies with Multi-Hance suggest that only a single dose of this agent is needed to cause a signal drop of about 30% which is sufficient to allow the calculation of high quality rCBV and rCBF maps
    Type of Publication: Journal article published
    PubMed ID: 15645153
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  • 4
    Abstract: Due to poor correlation of slice thickness and orientation, verification of radiological methods with histology is difficult. Thus, a procedure for three-dimensional reconstruction, reslicing and parameterization of histological data was developed, enabling a proper correlation with radiological data. Two different subcutaneous tumors were examined by MR microangiography and DCE-MRI, the latter being post-processed using a pharmacokinetic two-compartment model. Subsequently, tumors were serially sectioned and vessels stained with immunofluorescence markers. A ray-tracing algorithm performed three-dimensional visualization of the histological data, allowing virtually reslicing to thicker sections analogous to MRI slice geometry. Thick slices were processed as parameter maps color coding the marker density in the depth of the slice. Histological 3D reconstructions displayed the diffuse angioarchitecture of malignant tumors. Resliced histological images enabled specification of high enhancing areas seen on MR microangiography as large single vessels or vessel assemblies. In orthogonally reconstructed histological slices, single vessels were delineated. ROI analysis showed significant correlation between histological parameter maps of vessel density and MR parameter maps (r=0.83, P=0.05). The 3D approach to histology improves correlation of histological and radiological data due to proper matching of slice geometry. This method can be used with any histological stain, thus enabling a multivariable correlation of non-invasive data and histology.
    Type of Publication: Journal article published
    PubMed ID: 15747142
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  • 5
    Keywords: imaging ; PERFUSION ; NUCLEAR-MEDICINE ; MR ; radiology ; nuclear medicine ; MR imaging
    Type of Publication: Meeting abstract published
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  • 6
    Keywords: ANGIOGENESIS ; CELL LUNG-CANCER ; DOPPLER ; Germany ; IN-VIVO ; PERFUSION ; imaging ; QUANTIFICATION ; BLOOD-FLOW ; animals ; tumour ; CONTRAST ; NUDE-MICE ; US ; VASCULARIZATION ; COLOR DOPPLER ; intermittent sonography,ultrasound contrast agent,quantification,blood how,perfusion,tumour angiogen ; MYOCARDIAL PERFUSION ; ULTRASOUND-INDUCED DESTRUCTION
    Type of Publication: Journal article published
    PubMed ID: 12946512
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  • 7
    Keywords: CELLS ; GROWTH ; proliferation ; Germany ; IN-VIVO ; TOXICITY ; VITRO ; imaging ; EFFICIENCY ; LINES ; TIME ; INDUCTION ; RAT ; MRI ; CELL-LINES ; fibroblasts ; MAGNETIC-RESONANCE ; molecular imaging ; magnetic resonance imaging ; BONE-MARROW ; PARTICLES ; LINE ; LOCALIZATION ; STEM-CELLS ; PROGENITOR CELLS ; cell lines ; RE ; HUMAN-FIBROBLASTS ; HUMAN FIBROBLASTS ; IRON ; progenitor ; TAT PEPTIDE ; HISTOLOGY ; NANOPARTICLES ; cell tracking ; FERUMOXIDES ; IN-VIVO TRACKING ; iron oxide particle ; MR CONTRAST AGENTS
    Abstract: Rationale: Superparamagnetic iron-oxide particles are used frequently for cellular magnetic resonance imaging and in vivo cell tracking. The purpose of this study was to compare the labeling characteristics and efficiency as well as toxicity of superparamagnetic iron oxide (SPIO) and ultrasmall superparamagnetic ironoxide (USPIO) for 3 cell lines. Methods: Using human fibroblasts, immortalized rat progenitor cells and HEP-G2-hepatoma cells, dose- and time-dependence of SPIO and USPIO uptake were evaluated. The amount of intracellular (U)SPIO was monitored over 2 weeks after incubation by T-2-magnetic resonance relaxometry, ICP-mass-spectrometry and histology. Transmission-electronmicroscopy was used to specify the intracellular localization of the endocytosed iron particles. Cell death-rate and proliferation-index were assessed as indicators of cell-toxicity. Result: For all cell lines, SPIO showed better uptake than USPIO, which was highest in HEP-G2 cells (110 +/- 2 pg Fe/cell). Cellular iron concentrations in progenitor cells and fibroblasts were 13 +/- 1 pg Fe/cell and 7.2 +/- 0.3pg Fe/cell, respectively. For all cell lines T-2-relaxation times in cell pellets were below detection threshold (〈 3 milliseconds) after 5 hours of incubation with SPIO (3.0 mu mol Fe/mL growth medium) and continued to be near the detection for the next 6 days. For both particle types and all cell lines cellular iron oxide contents decreased after recultivation and surprisingly were found lower than in unlabeled control cells after 15 days. Viability and proliferation of (U)SPIO-labeled and unlabeled cells were not significantly different. Conclusions: The hematopoetic progenitor, mesenchymal fibroblast and epithelial HEP-G2 cell lines accumulated SPIO more efficiently than USPIO indicating SPIO to be better suited for cell labeling. However, the results indicate that there may be an induction of forced cellular iron elimination after incubation with (U)SPIO
    Type of Publication: Journal article published
    PubMed ID: 16024988
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