Liver Tumors: MR Imaging of Radioactive Holmium Microspheres—Phantom and Rabbit Study

Nijsen, J. Frank W.; Seppenwoolde, Jan‐Henry; Havenith, Thomas; Bos, Clemens; Bakker, Chris J.G.; Schip, Alfred D. van het

doi:10.1148/radiol.2312030594

Cited by 69 publications

(71 citation statements)

References 36 publications

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“…The paramagnetic nature of holmium locally induces a magnetic field inhomogeneity, leading to an enhanced MRI signal decay in gradient echo images (13). The resulting r 2 * relaxivity of the HoAcAc microspheres with a holmium load of 45% (w/w), is 264± 5.7 s −1 mg −1 ml, which is substantially higher than the r 2 * value for the HoPLLA microspheres with a holmium load of 17% (w/w) (92±3.2 s −1 mg −1 ml) (26). This increase of the r 2 * relaxivity represents an enhanced sensitivity of MRI to the HoAcAc microspheres, as compared with HoPLLA microspheres, which can be explained by the increased holmium weight content per sphere.…”

Section: Multimodality Imaging Characteristicsmentioning

confidence: 90%

Microspheres with Ultrahigh Holmium Content for Radioablation of Malignancies

et al. 2009

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Purpose. The aim of this study was to develop microspheres with an ultra high holmium content which can be neutron activated for radioablation of malignancies. These microspheres are proposed to be delivered selectively through either intratumoral injections into solid tumors or administered via an intravascularly placed catheter. Methods. Microspheres were prepared by solvent evaporation, using holmium acetylacetonate (HoAcAc) crystals as the sole ingredient. Microspheres were characterized using light and scanning electron microscopy, coulter counter, titrimetry, infrared and Raman spectroscopy, differential scanning calorimetry, X-ray powder diffraction, magnetic resonance imaging (MRI), and X-ray computed tomography (CT). Results. Microspheres, thus prepared displayed a smooth surface. The holmium content of the HoAcAc microspheres (44% (w/w)) was higher than the holmium content of the starting material, HoAcAc crystals (33% (w/w)). This was attributed to the loss of acetylacetonate from the HoAcAc complex, during rearrangement of acetylacetonate around the holmium ion. The increase of the holmium content allows for the detection of (sub)microgram amounts of microspheres using MRI and CT. Conclusions. HoAcAc microspheres with an ultra-high holmium content were prepared. These microspheres are suitable for radioablation of tumors by intratumoral injections or treatment of liver tumors through transcatheter administration.

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Section: Multimodality Imaging Characteristicsmentioning

confidence: 90%

Microspheres with Ultrahigh Holmium Content for Radioablation of Malignancies

et al. 2009

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“…It is useful to note that the error in R2* (Eq. [3]) decreases for shorter echo spacing ⌬t e , lower relaxation rates R2*, and short echo trains. The number of floating point operations (flops) for pixelwise numerical fitting is of the order O(N e ⅐ M 2 ) for an image size of M ϫ M pixels.…”

Section: Calculation Of the R2* Parameter Mapmentioning

confidence: 96%

“…In all of the above-mentioned applications, a method that combines real-time imaging and R2* mapping would facilitate direct therapy control and optimization, particularly for drug dosage determination. In the current paradigm, mapping is performed after imaging, and nonquantitative T2*-weighted images are used to dynamically monitor the delivery of the agent (2)(3)(4)(5). In some studies T2* quantification was performed once before and once after the delivery.…”

mentioning

confidence: 99%

Simultaneous imaging and R2* mapping using a radial multi‐gradient‐echo (rMGE) sequence

Winkelmann

Schaeffter

Weiß

et al. 2006

Magnetic Resonance Imaging

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Purpose: To demonstrate a rapid MR technique that combines imaging and R2* mapping based on a single radial multi-gradient-echo (rMGE) data set. The technique provides a fast method for online monitoring of the administration of (super-)paramagnetic contrast agents as well as image-guided drug delivery. Materials and Methods:Data are acquired using an rMGE sequence, resulting in interleaved undersampled radial kspaces representing different echo times (TEs). These data sets are reconstructed separately, yielding a series of images with different TEs used for pixelwise R2* mapping. A fast numerical algorithm implemented on a real-time reconstruction platform provides online estimation of the relaxation rate R2*. Simultaneously the images are summed for the computation of a high-resolution image.Results: Convenient high-resolution R2* maps of phantoms and the liver of a healthy volunteer were obtained. In addition to stable intrinsic baseline maps, the proposed technique provides particularly accurate results for the high relaxation rates observed during the presence of (super-)paramagnetic contrast agents. Assuming that the change in R2* is proportional to the concentration of the agent, the technique offers a rough estimate for dynamic dosage. Conclusion:The simultaneous online display of morphological and parametric information permits convenient, quantitative surveillance of contrast-agent administration.

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“…Finally, 166 Ho-microspheres could also be administered under real-time MRI guidance, with direct visualization of the microsphere distribution. Postadministration intrahepatic microsphere distribution was first evaluated with MRI in phantom and animal models by Nijsen and colleagues [52], who showed that Ho-PLLA-MS can be imaged clearly in vivo with MRI. Estimation of the absorbed radiation dose with MRI was performed in 15 patients submitted to whole-liver treatment .…”

Section: Post-treatment Imaging Workupmentioning

confidence: 99%

Multiagent imaging of liver tumors with reference to intra-arterial radioembolization

Maccauro¹,

Lorenzoni²,

Boni

et al. 2013

Clin Transl Imaging

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Intra-arterial radioembolization using microspheres labeled with the high-energy beta-emitter yttrium-90 ( 90 Y) is an innovative therapeutic strategy for primary and secondary hepatic malignancies. An accurate imaging workup plays a pivotal role in correctly selecting patients for treatment, to avoid severe complications and in assessment of the post-administration microsphere distribution. Nuclear medicine imaging modalities are an integral part of a complex multidisciplinary approach. In particular, hepatic perfusion imaging with 99m Tc-macroaggregated albumin particles ( 99m Tc-MAA), which identifies extrahepatic accumulation of radiopharmaceutical and lung shunt, is necessary to correctly select patients who may benefit from the treatment. Furthermore, 99m Tc MAA SPECT-based dose planning may optimize RE efficacy, overcoming the limitations of empirical methods to determine the activity to be administered. Quantitative assessment of the post-administration intrahepatic microsphere distribution with SPECT or PET is important for evaluation of toxicity and efficacy and can be used for the prediction of patient response and for patient-specific therapeutic dose optimization. Finally, [ 18 F]FDG PET/CT imaging is important in the assessment of early response after RE and in predicting patient outcome. This review provides a comprehensive overview of multimodality imaging in the complex management of patients undergoing RE for liver tumors.

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Liver Tumors: MR Imaging of Radioactive Holmium Microspheres—Phantom and Rabbit Study

Abstract: Ho-PLLA-MS used for internal radionuclide therapy can be imaged clearly in vivo with MR imaging.

Cited by 69 publications

References 36 publications

Microspheres with Ultrahigh Holmium Content for Radioablation of Malignancies

Microspheres with Ultrahigh Holmium Content for Radioablation of Malignancies

Simultaneous imaging and R2* mapping using a radial multi‐gradient‐echo (rMGE) sequence

Multiagent imaging of liver tumors with reference to intra-arterial radioembolization

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