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Conference Paper: Comparison of gadolinium loaded and empty carbon nanotubes as high performance MRI contrast agent

TitleComparison of gadolinium loaded and empty carbon nanotubes as high performance MRI contrast agent
Authors
KeywordsMedical sciences
Radiology and nuclear medicine
Issue Date2009
PublisherSpringer New York LLC.
Citation
The 2009 World Molecular Imaging Congress, Montreal, Canada, 23-26 September 2009. How to Cite?
AbstractIntroduction: Gadolinium loaded ultra-short single walled carbon nanotubes (US-tubes) has been proposed as an effective high r2 relaxivity contrast agent for use in MR molecular imaging. However, the true active ingredients for inheriting its high performance r2 characteristics, is remain unknown. In this study, we compare the R2 and R2* relaxation rate of the US-tubes with/without Gadolinium ions encapsulation. Methods: Two types of US-tubes MRI phantoms were prepared: (i) Gadonanotubes with 41 μM Gd and (ii) empty US-tubes. Each type of nanotubes was dispersed in pluronic solution with carbon concentration of 275 mg/L and transferred to a 1 cc syringe for MRI imaging. MRI imaging was performed in a 3T MRI scanner using a 35 mm volume coil with 2D spin echo (TR=1500 ms, TE=20–80 ms with 10 ms increment) and 2D gradient echo (alpha=90, TR=1500 ms, TE=20–80 ms with 5 ms increment) sequences to evaluate the R2 and R2* respectively. A 1 mm thick single slice was obtained at each TE cutting in the middle of the 3.5 cm long filled syringe placed parallel to the main magnetic field. T2 and T2* were determined by linear fitting of the measured image intensities at each TE at each phantom into log(S) = log(S0)-TE/T2 and log(S) = log(S0)-TE/T2*. Results and Discussions: Table 1 shows the estimated R2 and R2* relaxation rates of the phantoms. R2 represents the coefficient of determinations of the linear fitting. Both Gadonanotubes and empty US-tubes show high R2 and R2* relaxation rates with the R2* being 6–11% stronger than R2. The slight increase in R2* may attribute to bulk magnetic susceptibility effects due to the presence of metal ions inside the US-tubes. Nethertheless,the R2* observed is small when compared with that of other superparamagnetic contrast agents which usually show a few times increase in R2*. This may be due to the low concentration (in μM) and lose density packing of the metal ions inside the tubes. For empty US-tubes, it is observed that its relaxivities are as good as Gadolinium loaded US-tubes. Additional Gd3+ loading does not significantly increase the relaxivities of the US-tubes. Therefore, it is reasonable to consider using empty US-tubes as a high performance MRI contrast agent as well as drug/gene delivery carrier, with the delivery items being encapsulating inside its hollow interior space.
DescriptionMolecular Imaging and Biology, 2009, v. 12, suppl. 1, p. S41-S42
Abstract no. J080
Persistent Identifierhttp://hdl.handle.net/10722/126198
ISSN
2015 Impact Factor: 2.569
2015 SCImago Journal Rankings: 1.041

 

DC FieldValueLanguage
dc.contributor.authorTang, AMYen_HK
dc.contributor.authorWong, Ken_HK
dc.contributor.authorAnanta, JSen_HK
dc.contributor.authorLam, EYMen_HK
dc.contributor.authorWilson, LJen_HK
dc.contributor.authorWong, Sen_HK
dc.date.accessioned2010-10-31T12:15:07Z-
dc.date.available2010-10-31T12:15:07Z-
dc.date.issued2009en_HK
dc.identifier.citationThe 2009 World Molecular Imaging Congress, Montreal, Canada, 23-26 September 2009.en_HK
dc.identifier.issn1536-1632-
dc.identifier.urihttp://hdl.handle.net/10722/126198-
dc.descriptionMolecular Imaging and Biology, 2009, v. 12, suppl. 1, p. S41-S42-
dc.descriptionAbstract no. J080-
dc.description.abstractIntroduction: Gadolinium loaded ultra-short single walled carbon nanotubes (US-tubes) has been proposed as an effective high r2 relaxivity contrast agent for use in MR molecular imaging. However, the true active ingredients for inheriting its high performance r2 characteristics, is remain unknown. In this study, we compare the R2 and R2* relaxation rate of the US-tubes with/without Gadolinium ions encapsulation. Methods: Two types of US-tubes MRI phantoms were prepared: (i) Gadonanotubes with 41 μM Gd and (ii) empty US-tubes. Each type of nanotubes was dispersed in pluronic solution with carbon concentration of 275 mg/L and transferred to a 1 cc syringe for MRI imaging. MRI imaging was performed in a 3T MRI scanner using a 35 mm volume coil with 2D spin echo (TR=1500 ms, TE=20–80 ms with 10 ms increment) and 2D gradient echo (alpha=90, TR=1500 ms, TE=20–80 ms with 5 ms increment) sequences to evaluate the R2 and R2* respectively. A 1 mm thick single slice was obtained at each TE cutting in the middle of the 3.5 cm long filled syringe placed parallel to the main magnetic field. T2 and T2* were determined by linear fitting of the measured image intensities at each TE at each phantom into log(S) = log(S0)-TE/T2 and log(S) = log(S0)-TE/T2*. Results and Discussions: Table 1 shows the estimated R2 and R2* relaxation rates of the phantoms. R2 represents the coefficient of determinations of the linear fitting. Both Gadonanotubes and empty US-tubes show high R2 and R2* relaxation rates with the R2* being 6–11% stronger than R2. The slight increase in R2* may attribute to bulk magnetic susceptibility effects due to the presence of metal ions inside the US-tubes. Nethertheless,the R2* observed is small when compared with that of other superparamagnetic contrast agents which usually show a few times increase in R2*. This may be due to the low concentration (in μM) and lose density packing of the metal ions inside the tubes. For empty US-tubes, it is observed that its relaxivities are as good as Gadolinium loaded US-tubes. Additional Gd3+ loading does not significantly increase the relaxivities of the US-tubes. Therefore, it is reasonable to consider using empty US-tubes as a high performance MRI contrast agent as well as drug/gene delivery carrier, with the delivery items being encapsulating inside its hollow interior space.-
dc.languageengen_HK
dc.publisherSpringer New York LLC.-
dc.relation.ispartofWorld Molecular Imaging Congress-
dc.rightsThe original publication is available at www.springerlink.com-
dc.subjectMedical sciences-
dc.subjectRadiology and nuclear medicine-
dc.titleComparison of gadolinium loaded and empty carbon nanotubes as high performance MRI contrast agenten_HK
dc.typeConference_Paperen_HK
dc.identifier.openurlhttp://library.hku.hk:4550/resserv?sid=HKU:IR&issn=1536-1632&volume=12, suppl. 1&spage=S41&epage=S42&date=2009&atitle=Comparison+of+gadolinium+loaded+and+empty+carbon+nanotubes+as+high+performance+MRI+contrast+agent-
dc.identifier.emailLam, EYM: elam@eee.hku.hken_HK
dc.identifier.doi10.1007/s11307-009-0251-y-
dc.identifier.hkuros171690en_HK
dc.identifier.volume12-
dc.identifier.issuesuppl. 1-
dc.identifier.spageS41-
dc.identifier.epageS42-

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