Ferumoxtran-10, a superparamagnetic iron oxide as a magnetic resonance enhancement agent for imaging lymph nodes: a phase 2 dose study.
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BACKGROUND AND PURPOSE: Dextran-coated ultrasmall superparamagnetic iron oxide ferumoxtran-10 (Combidex) is used in reticuloendothelial MR imaging. Our purpose was to determine the optimal dose and imaging time for lymph node evaluation. MATERIALS: Twenty-four healthy volunteers underwent neck MR imaging before and 6, 12, 24, and 36 hours after receiving 1.1, 1.7, 2.6, or 3.4 mg Fe/kg ferumoxtran-10. Vital signs, serum and urine levels, and adverse events were monitored. Qualitative nodal architecture, size, and signal-intensity changes were assessed on T1-, T2-, and T2*-weighted (fast field-echo 25 degrees or 80 degrees flip angle [FFE-25 or FFE-80]) images. Region-of-interest intensities were measured quantitatively. RESULTS: Consistently strong enhancement in normal nodes was found with 24- and 36-hour T2- and T2*-weighted imaging after 2.6 and 3.4 mg Fe/kg doses. No serious adverse events occurred. With 2.6 mg Fe/kg, unblinded (vs blinded) specificities at 24 and 36 hours, respectively, were 100% and 100% (vs 88% and 88%) with T2-weighted, 96% and 96% (vs 73% and 85%) with FFE-25, and 100% and 92% (vs 85% and 88%) with FFE-80 sequences. With 3.4 mg Fe/kg, unblinded (vs blinded) specificities at 24 and 36 hours, respectively, were 89% and 79% (vs 75% and 75%) with T2-weighted, 84% and 79% (vs 95% and 100%) with FFE-25, and 95% and 79% (vs 95% and 80%) with FFE-80 sequences. CONCLUSION: Ferumoxtran-10 nodal imaging appears to be effective and safe. Signal intensity and specificity for normal nodes were best 24 or 36 hours after 2.6 and 3.4 mg Fe/kg doses. Nodal conspicuity was best with T2- and T2*-weighted sequences. (+info)
Optimal pulse sequence for ferumoxides-enhanced MR imaging used in the detection of hepatocellular carcinoma: a comparative study using seven pulse sequences.
(10/625)
OBJECTIVE: To identify the optimal pulse sequence for ferumoxides-enhanced magnetic resonance (MR) imaging in the detection of hepatocelluar carcinomas (HCCs). MATERIALS AND METHODS: Sixteen patients with 25 HCCs underwent MR imaging following intravenous infusion of ferumoxides. All MR studies were performed on a 1.5-T MR system, using a phased-array coil. Ferumoxides (Feridex IV) at a dose of 15 micromol/Kg was slowly infused intravenously, and axial images of seven sequences were obtained 30 minutes after the end of infusion. The MR protocol included fast spin-echo (FSE) with two echo times (TR3333-8571/TE18 and 90-117), singleshot FSE (SSFSE) with two echo times (TRinfinity/TE39 and 98), T2*-weighted gradient- recalled acquisition in the steady state (GRASS) (TR216/TE20), T2*-weighted fast multiplanar GRASS (FMPGR) (TR130/TE8.4-9.5), and T2*-weighted fast multiplanar spoiled GRASS (FMPSPGR) (TR130/TE8.4-9.5). Contrast-to-noise ratios (CNRs) of HCCs determined during the imaging sequences formed the basis of quantitative analysis, and images were qualitatively assessed in terms of lesion conspicuity and image artifacts. The diagnostic accuracy of all sequences was assessed using receiver operating characteristic (ROC) analysis. RESULTS: Quantitative analysis revealed that the CNRs of T2*-weighted FMPGR and T2*-weighted FMPSPGR were significantly higher than those of the other sequences, while qualitative analysis showed that image artifacts were prominent at T2*-weighted GRASS imaging. Lesion conspicuity was statistically significantly less clear at SSFSE imaging. In term of lesion detection, T2*-weighted FMPGR, T2*- weighted FMPSPGR, and proton density FSE imaging were statistically superior to the others. CONCLUSION: T2*-weighted FMPGR, T2*- weighted FMPSPGR, and proton density FSE appear to be the optimal pulse sequences for ferumoxidesenhanced MR imaging in the detection of HCCs. (+info)
Iron particle labeling of haematopoietic progenitor cells: an in vitro study.
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We present a method for labeling bone marrow haematopoietic progenitor cells with iron particles. Labeling was assessed by magnetic resonance imaging and electron microscopy. Labeling with iron particles could allow the following by imaging techniques of haematopoietic cells in physiologic and pathologic conditions such as the engraftment of haematopoietic progenitor cells or the migration of myelomonocytic cells in inflammatory diseases. (+info)
T1-weighted magnetic resonance imaging sequence appropriate for the evaluation of the longitudinal relaxation effect of superparamagnetic iron oxide: a phantom study.
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The goal of this study was to determine a T1-weighted magnetic resonance (MR) imaging sequence appropriate for evaluating the longitudinal relaxation effect of superparamagnetic iron oxide (ferumoxides) in a phantom study. An agarose phantom that included various concentrations of ferumoxides (0 - 0.5 mmol/l in 0.05 mmol/l increments) was examined for six types of T1-weighted imaging sequences using a 1.5-T MR unit. Three-dimensional (3D) fast spoiled gradient-echo (SPGR) imaging with a short echo time showed a strong linear correlation between the concentration of ferumoxides and the enhancement ratio. Two-dimensional (2D) fast SPGR imaging showed a high signal-to-noise ratio of the phantom even at low ferumoxides concentrations. These results suggest that 3D fast SPGR imaging is an appropriate technique for the evaluation of the longitudinal relaxation effect of ferumoxides, and that 2D fast SPGR imaging can be useful for evaluating the longitudinal relaxation effect at lower ferumoxides concentrations. (+info)
Detection of small hypervascular hepatocellular carcinomas in cirrhotic patients: comparison of superparamagnetic iron oxide-enhanced MR imaging with dual-phase spiral CT.
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OBJECTIVE: To compare the performance of superparamagnetic iron oxide (SPIO)-enhanced magnetic resonance (MR) maging at 1.5T and dual-phase spiral computed tomography (CT) for the depiction of small hypervascular hepatocellular carcinomas (HCCs). MATERIALS AND METHODS: Forty-three patients with 70 small nodular HCCs (5-20 mm; mean, 13.7 mm) were examined. Diagnosis was based on the results of surgical biopsy in 22 patients and by the combined assessment of MR imaging, lipiodol CT, alpha feto-protein levels, and angiographic findings in 21. MR imaging consisted of respiratory-triggered turbo spin-echo T2-weighted imaging, T1-weighted fast low-angle shot, and T2* -weighted fast imaging with steady-state precession imaging before and after SPIO enhancement. CT imaging was performed with 5-mm collimation and 1:1.4 pitch, and began 30 and 65 secs after the injection of 150 mL of contrast medium at a rate of 3 mL/sec. Two blinded observers reviewed all images independently on a segment-by-segment basis. Diagnostic accuracy was evaluated using receiver operating characteristics(ROC) analysis. RESULTS: The mean areas (Az) under the ROC curves were 0.85 for SPIOenhanced MR imaging and 0.79 for dual-phase spiral CT (p <.05). The mean sensitivity of SPIO-enhanced MR imaging was significantly higher than that of CT (p <.05), i.e. 70.6% for MR imaging and 58.1% for CT. MR imaging had higher false-positive rates than dual-phase spiral CT, but the difference was not statistically significant (3.7% vs 3.3%) (p >.05). CONCLUSION: SPIO-enhanced MR imaging is more sensitive than dual-phase spiral CT for the depiction of small hypervascular hepatocellular carcinomas. (+info)
Characterization of focal liver lesions with superparamagnetic iron oxide-enhanced MR imaging: value of distributional phase T1-weighted imaging.
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OBJECTIVE: To determine the potential value of distributional-phase T1-weighted ferumoxides-enhanced magnetic resonance (MR) imaging for tissue characterization of focal liver lesions. MATERIALS AND METHODS: Ferumoxides-enhanced MR imaging was performed using a 1.5-T system in 46 patients referred for evaluation of known or suspected hepatic malignancies. Seventy-three focal liver lesions (30 hepatocellular carcinomas (HCC), 12 metastases, 15 cysts, 13 hemangiomas, and three cholangiocarcinomas) were evaluated. MR imaging included T1-weighted double-echo gradient-echo (TR/TE: 150/4.2 and 2.1 msec), T2*-weighted gradient-echo (TR/TE: 180/12 msec), and T2-weighted turbo spin-echo MR imaging at 1.5 T before and after intravenous administration of ferumoxides (15 mmol/kg body weight). Postcontrast T1-weighted imaging was performed within eight minutes of infusion of the contrast medium (distributional phase). Both qualitative and quantitative analysis was performed. RESULTS: During the distributional phase after infusion of ferumoxides, unique enhancement patterns of focal liver lesions were observed for hemangiomas, metastases, and hepatocellular carcinomas. On T1-weighted GRE images obtained during the distributional phase, hemangiomas showed a typical positive enhancement pattern of increased signal; metastases showed ring enhancement; and hepatocellar carcinomas showed slight enhancement. Quantitatively, the signal-to-noise ratio of hemangiomas was much higher than that of other tumors (p <.05) and was similar to that of intrahepatic vessels. This finding permitted more effective differentiation between hemangiomas and other malignant tumors. CONCLUSION: T1-weighted double-echo FLASH images obtained soon after the infusion of ferumoxides, show characteristic enhancement patterns and improved the differentiation of focal liver lesions. (+info)
Accumulation of ultrasmall superparamagnetic particles of iron oxide in human atherosclerotic plaques can be detected by in vivo magnetic resonance imaging.
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BACKGROUND: One of the features of high-risk atherosclerotic plaques is a preponderance of macrophages. Experimental studies with hyperlipidemic rabbits have shown that ultrasmall superparamagnetic particles of iron oxide (USPIOs) accumulate in plaques with a high macrophage content and that this induces magnetic resonance (MR) signal changes. The purpose of our study was to investigate whether USPIO-enhanced MRI can also be used for in vivo detection of macrophages in human plaques. METHODS AND RESULTS: MRI was performed on 11 symptomatic patients scheduled for carotid endarterectomy before and 24 (n=11) and 72 (n=5) hours after administration of USPIOs (Sinerem) at a dose of 2.6 mg Fe/kg. Histological and electron microscopical analyses of the plaques showed USPIOs primarily in macrophages within the plaques in 10 of 11 patients. Histological analysis showed USPIOs in 27 of 36 (75%) of the ruptured and rupture-prone lesions and 1 of 14 (7%) of the stable lesions. Of the patients with USPIO uptake, signal changes in the post-USPIO MRI were observed by 2 observers in the vessel wall in 67 of 123 (54%) and 19 of 55 (35%) quadrants of the T2*-weighted MR images acquired after 24 and 72 hours, respectively. For those quadrants with changes, there was a significant signal decrease of 24% (95% CI, 33% to 15%) in regions of interest in the images acquired after 24 hours, whereas no significant signal change was found after 72 hours. CONCLUSIONS: Accumulation of USPIOs in macrophages in predominantly ruptured and rupture-prone human atherosclerotic lesions caused signal decreases in the in vivo MR images. (+info)
Magnetic resonance imaging of targeted catheter-based implantation of myogenic precursor cells into infarcted left ventricular myocardium.
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OBJECTIVES: This study was designed to test the hypothesis that myocardial implantation of myogenic precursor cells (MPC) loaded with iron oxide can be reliably detected in vivo by cardiac magnetic resonance imaging (MRI). BACKGROUND: In vivo imaging of targeted catheter-based implantation of MPC into infarcted left ventricular (LV) myocardium is unavailable. METHODS: The study was conducted in seven farm pigs (four with anterior myocardial infarction), in which autologous MPC were injected through a percutaneous catheter allowing for LV electromechanical mapping and guided micro-injections into normal and infarcted myocardium. Cardiac MRI was used to detect implanted MPC previously loaded with iron oxide nanoparticles. RESULTS: Magnetic resonance imaging data were compared with LV electromechanical mapping and cross-registered pathology. All 9 injections into normal and 12 injections into locally damaged myocardium were detected on T2-weighted spin echo and inversion-recovery true-fisp MRI (low signal areas) with good anatomical concordance with sites of implantation on electromechanical maps. All sites of injection were confirmed on pathology that showed in all infarct animals iron-loaded MPC at the center and periphery of the infarct as expected from MRI. CONCLUSIONS: Targeted catheter-based implantation of iron-loaded MPC into locally infarcted LV myocardium is accurate and can be reliably demonstrated in vivo by cardiac MRI. The ability to identify noninvasively intramyocardial cell implantation may be determinant for future experimental studies designed to analyze subsequent effects of such therapy on detailed segmental LV function. (+info)