Effect of Concentration of SH U 555A Labeled Human Melanoma Cells on MR Spin Echo and Gradient Echo Signal Decay at 0.2, 1.5, and 3T

Pintaske, J.; Bantleon, Rüdiger; Kehlbach, Rainer; Claussen, Claus D.; Wiskirchen, Jakub; Schick, Fritz

doi:10.1007/s10334-006-0029-z

Cited by 10 publications

(10 citation statements)

References 25 publications

(32 reference statements)

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“…Although signal loss reaches a plateau as TE increases, the area of the signal void continues to expand, which is consistent with the work of Pintaske et al [29,30]. The blooming effect at longer T E is somewhat advantageous, because it increases the area of signal change, making it more conspicuous.…”

Section: Discussionsupporting

confidence: 90%

Fast low-angle positive contrast steady-state free precession imaging of USPIO-labeled macrophages: theory and in vitro experiment

Mascheri

Dharmakumar

Zhang

et al. 2009

Magnetic Resonance Imaging

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The feasibility of imaging macrophages labeled with ultrasmall superparamagnetic iron-oxide nanoparticles (USPIO) with fast low-angle positive contrast steady-state free precession (FLAPS) was investigated through theory and in vitro experiment. Human macrophage cells were labeled with USPIO and imaged at 1.5T. The metric "Visibility", which combines magnitude and spatial extent of positive contrast, was used to evaluate the images. Negative contrast steady-state free precession (SSFP) and gradient-echo (GRE) imaging were also evaluated. Positive contrast was observed for relatively high concentrations of labeled cells for flip angles less than α = 25°. Theoretical and experimental results indicate that positive Visibility was maximized at α = 10° and 15°. Low flip angle SSFP also provided negative contrast comparable to standard SSFP and GRE imaging. Results suggest that USPIO-labeled macrophages are capable of producing the conditions necessary for positive contrast with FLAPS at clinical field strength (1.5T) and resolution (0.8 × 0.8 × 3 mm 3 ).

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Section: Discussionsupporting

confidence: 90%

Fast low-angle positive contrast steady-state free precession imaging of USPIO-labeled macrophages: theory and in vitro experiment

Mascheri

Dharmakumar

Zhang

et al. 2009

Magnetic Resonance Imaging

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“…Of course, the transfected SK-Br-3 oncocytes by SPIO also showed increased iron content and decreased MR imaging signal, but because SPIO into the cells mainly relied on passive transfer (of the role of swallowing drink). 15,21,26 The cellular iron content in the transfected SK-Br-3 oncocytes by SPIO was less than that in transfected SK-Br-3 oncocytes by antisense probes after transfection within 36 h, so it resulted in lower contrast. This is because, from speculation of the theory, the way that antisense probe entered the oncocytes was not only passive transfer, but also active transfer.…”

Section: Discussionmentioning

confidence: 98%

“…Whereas the multisection gradientecho sequence in MR scanning has higher sensitivity to SPIO, 8,16,21,26 we used this sequence in MR scanning, the results show that the antisense probe can enter SK-Br-3 oncocytes efficiency, increase cellular iron content and reduce the signal intension after MR imaging. Of course, the transfected SK-Br-3 oncocytes by SPIO also showed increased iron content and decreased MR imaging signal, but because SPIO into the cells mainly relied on passive transfer (of the role of swallowing drink).…”

Section: Discussionmentioning

confidence: 99%

Preparation and Quality Test of Superparamagnetic Iron Oxide Labeled Antisense Oligodeoxynucleotide Probe: A Preliminary Study

Wen

Ouyang

et al. 2009

Ann Biomed Eng

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Molecular imaging of tumor antisense gene techniques have been applied to the study of magnetic resonance (MR) gene imaging associated with malignant tumors. In this study, we designed, synthesized, and tested a novel molecular probe, in which the antisense oligodeoxynucleotide (ASODN) was labeled with superparamagnetic iron oxide (SPIO), and its efficiency was examined by in vitro MR imaging after SK-Br-3 mammary carcinoma cell lines (oncocytes) transfection. The SPIO-labeled ASODN probe was prepared through SPIO conjugated to ASODN using a chemical cross linking method. Its morphology and size were detected by atomic force microscope, size distribution were detected by laser granulometer, the conjugating rate and biological activity were determined by high performance liquid chromatography, and the stability was determined by polyacrylamide gel electrophoresis. After that, the probes were transfected into the SK-Br-3 oncocytes, cellular iron uptake was analyzed qualitatively at light and electron microscopy and was quantified at atomic absorption spectrometry, and the signal change of the transfected cells was observed and measured using MR imaging. The morphology of the SPIO-labeled ASODN probe was mostly spherical with well-distributed scattering, and the diameters were between 25 and 40 nm (95%) by atomic force microscope and laser granulometer, the conjugating rate of the probe was 99%. Moreover, this probe kept its activity under physiological conditions and could conjugate with antisense oligodeoxynucleotide. In addition, light microscopy revealed an intracellular uptake of iron oxides in the cytosol and electron microscopic studies revealed a lysosomal deposition of iron oxides in the transfected SK-Br-3 oncocytes by antisense probes, some of them gathered stacks, and the iron content of the group of transfected SK-Br-3 oncocytes by antisense probe is significantly higher (18.37 +/- 0.42 pg) than other contrast groups, the MR imaging showed that transfected SK-Br-3 oncocytes by antisense probe had the lowest signal of all. The SPIO-labeled ASODN probe shows unique features including well-distributed spherical morphology, high conjugating rate and loading efficiency, and the signal intensity of SPIO-labeled ASODN-transfected SK-Br-3 oncocytes is reduced in MR imaging. These results indicate that the SPIO-labeled ASODN probe is potentially useful as a MR targeting contrast enhancing agent to specifically diagnose tumors which had over-expression of the c-erbB2 oncogene at an early stage.

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“…In a magnitude image of a gradient‐echo sequence, the shifted frequencies and the resulting phase offsets are visible as signal voids, where the degree of extinction is dependant on the distance and the concentration of the nanoparticles ( 7, 24). Here, the signal voids cannot be distinguished from native low signal tissue, which makes the magnitude image an inappropriate tool for the uncorrupted detection of SPIO particles.…”

Section: Methodsmentioning

confidence: 99%

Utilizing echo‐shifts in k‐space for generation of positive contrast in areas with marked susceptibility alterations

Eibofner¹,

Steidle²,

Kehlbach³

et al. 2011

Magnetic Resonance in Med

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A technique for generation of positive contrast near susceptibility alterations utilizing echo-shifts in k-space is introduced, based on altered Larmor-frequencies and resulting phase-shifts accumulating during the echo-time at the site of local magnetic field gradients. 3D gradient-echo raw-data is acquired and weighted with an inverse Hanning filter. The filter partly suppresses central raw-data points, while maintaining outer areas. Reconstruction of the filtered raw-data results in images where pixels with apparent magnetic field gradients are highlighted against homogeneous pixels. Further processing steps are introduced to remove remaining intensities in the homogeneous parts of the filtered image. Feasibility is shown by an agar phantom containing magnetically labeled cells, with concentrations of 25, 50, 100, and 250 cells/μL, and by images of the human head. The technique allows detection of echo-shifted pixels with automatic suppression of magnetically homogeneous parts while keeping post-processing time short. Fewer than four labeled cells per pixel were clearly displayed with positive contrast. Application to the human head shows bright veins and complete suppression of homogeneous regions. The presented technique has high potential for specific detection of low concentrations of labeled cells or susceptibility altered regions in vivo with positive contrast, whereas areas with low spin density are not highlighted.

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Effect of Concentration of SH U 555A Labeled Human Melanoma Cells on MR Spin Echo and Gradient Echo Signal Decay at 0.2, 1.5, and 3T

Cited by 10 publications

References 25 publications

Fast low-angle positive contrast steady-state free precession imaging of USPIO-labeled macrophages: theory and in vitro experiment

Fast low-angle positive contrast steady-state free precession imaging of USPIO-labeled macrophages: theory and in vitro experiment

Preparation and Quality Test of Superparamagnetic Iron Oxide Labeled Antisense Oligodeoxynucleotide Probe: A Preliminary Study

Utilizing echo‐shifts in k‐space for generation of positive contrast in areas with marked susceptibility alterations

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