MR tracking of iron-labeled glass radioembolization microspheres during transcatheter delivery to rabbit VX2 liver tumors: Feasibility study

Twinkle Gupta*, Sumeet Virmani, Tod M. Neidt, Barbara Szolc-Kowalska, Kent T Sato, Robert K. Ryu, Robert J Lewandowski, Vanessa L. Gates, Gayle E Woloschak, Riad Salem, Reed A. Omary, Andrew Christian Larson

*Corresponding author for this work

Research output: Contribution to journalArticle

38 Citations (Scopus)

Abstract

Purpose: To prospectively test the hypothesis that iron labeling of radioembolization microspheres permits their visualization by using magnetic resonance (MR) imaging for in vivo tracking during transcatheter delivery to liver tumors. Materials and Methods: All experiments were approved by the Institutional Animal Care and Use Committee. Phantom studies were performed to quantify microsphere relaxivity and volume susceptibility properties and compare image contrast patterns resulting from aggregate deposition of unlabeled and iron-labeled microspheres. In seven rabbits in which nine VX2 liver tumors were implanted, T2*-weighted gradient-echo (GRE) MR images with negative image contrast (NC), white-marker (WM) GRE images with positive image contrast (PC), and on-reso- nance water-suppression turbo spin-echo (SE) images with PC were obtained before and after catheter-directed administration of microspheres into the hepatic artery. During each injection, serial GRE acquisitions were performed for real-time visualization of microsphere delivery. Contrast-to-noise ratios (CNRs) were measured between regions of microsphere accumulation and regions of normal liver parenchyma that demonstrated no apparent microsphere accumulation. Pre- and postinjec-tion CNR measurements at identical spatial positions were compared by using paired t test (α= .05). Results: Conventional microspheres did not produce detectable image contrast in phantoms. Iron-labeled microspheres produced susceptibility-induced dipole patterns with spatial extent of image contrast increasing with increasing micro- sphere dose. Real-time image series depicted both preferential delivery to tumor tissues and nontargeted delivery to adjacent organs. T2*-weighted GRE, WM GRE, and on-resonance water-suppression turbo SE each permitted in vivo visualization of the microsphere deposition, with postinjection CNR values (mean, 14.29 ± 3.98 [standard deviation], 1.87 ± 0.93, and 19.30 ± 8.72, respectively) significantly greater than corresponding preinjection CNR values (mean, 2.02 ± 4.65, 0.02 ± 0.27, 0.85 ± 2.65, respectively) (P < .05). Conclusion: Microsphere tracking during radioembolization may permit real-time verification of delivery and detection of ex-trahepatic shunting.

Original languageEnglish (US)
Pages (from-to)845-854
Number of pages10
JournalRadiology
Volume249
Issue number3
DOIs
StatePublished - Dec 1 2008

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Feasibility Studies
Microspheres
Glass
Magnetic Resonance Spectroscopy
Iron
Rabbits
Liver
Neoplasms
Noise
Animal Care Committees
Water
Hepatic Artery
Catheters
Magnetic Resonance Imaging
Injections

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging

Cite this

Gupta, Twinkle ; Virmani, Sumeet ; Neidt, Tod M. ; Szolc-Kowalska, Barbara ; Sato, Kent T ; Ryu, Robert K. ; Lewandowski, Robert J ; Gates, Vanessa L. ; Woloschak, Gayle E ; Salem, Riad ; Omary, Reed A. ; Larson, Andrew Christian. / MR tracking of iron-labeled glass radioembolization microspheres during transcatheter delivery to rabbit VX2 liver tumors : Feasibility study. In: Radiology. 2008 ; Vol. 249, No. 3. pp. 845-854.
@article{0d3df5baa69f4b24b5a088ceaeb78db9,
title = "MR tracking of iron-labeled glass radioembolization microspheres during transcatheter delivery to rabbit VX2 liver tumors: Feasibility study",
abstract = "Purpose: To prospectively test the hypothesis that iron labeling of radioembolization microspheres permits their visualization by using magnetic resonance (MR) imaging for in vivo tracking during transcatheter delivery to liver tumors. Materials and Methods: All experiments were approved by the Institutional Animal Care and Use Committee. Phantom studies were performed to quantify microsphere relaxivity and volume susceptibility properties and compare image contrast patterns resulting from aggregate deposition of unlabeled and iron-labeled microspheres. In seven rabbits in which nine VX2 liver tumors were implanted, T2*-weighted gradient-echo (GRE) MR images with negative image contrast (NC), white-marker (WM) GRE images with positive image contrast (PC), and on-reso- nance water-suppression turbo spin-echo (SE) images with PC were obtained before and after catheter-directed administration of microspheres into the hepatic artery. During each injection, serial GRE acquisitions were performed for real-time visualization of microsphere delivery. Contrast-to-noise ratios (CNRs) were measured between regions of microsphere accumulation and regions of normal liver parenchyma that demonstrated no apparent microsphere accumulation. Pre- and postinjec-tion CNR measurements at identical spatial positions were compared by using paired t test (α= .05). Results: Conventional microspheres did not produce detectable image contrast in phantoms. Iron-labeled microspheres produced susceptibility-induced dipole patterns with spatial extent of image contrast increasing with increasing micro- sphere dose. Real-time image series depicted both preferential delivery to tumor tissues and nontargeted delivery to adjacent organs. T2*-weighted GRE, WM GRE, and on-resonance water-suppression turbo SE each permitted in vivo visualization of the microsphere deposition, with postinjection CNR values (mean, 14.29 ± 3.98 [standard deviation], 1.87 ± 0.93, and 19.30 ± 8.72, respectively) significantly greater than corresponding preinjection CNR values (mean, 2.02 ± 4.65, 0.02 ± 0.27, 0.85 ± 2.65, respectively) (P < .05). Conclusion: Microsphere tracking during radioembolization may permit real-time verification of delivery and detection of ex-trahepatic shunting.",
author = "Twinkle Gupta and Sumeet Virmani and Neidt, {Tod M.} and Barbara Szolc-Kowalska and Sato, {Kent T} and Ryu, {Robert K.} and Lewandowski, {Robert J} and Gates, {Vanessa L.} and Woloschak, {Gayle E} and Riad Salem and Omary, {Reed A.} and Larson, {Andrew Christian}",
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MR tracking of iron-labeled glass radioembolization microspheres during transcatheter delivery to rabbit VX2 liver tumors : Feasibility study. / Gupta, Twinkle; Virmani, Sumeet; Neidt, Tod M.; Szolc-Kowalska, Barbara; Sato, Kent T; Ryu, Robert K.; Lewandowski, Robert J; Gates, Vanessa L.; Woloschak, Gayle E; Salem, Riad; Omary, Reed A.; Larson, Andrew Christian.

In: Radiology, Vol. 249, No. 3, 01.12.2008, p. 845-854.

Research output: Contribution to journalArticle

TY - JOUR

T1 - MR tracking of iron-labeled glass radioembolization microspheres during transcatheter delivery to rabbit VX2 liver tumors

T2 - Feasibility study

AU - Gupta, Twinkle

AU - Virmani, Sumeet

AU - Neidt, Tod M.

AU - Szolc-Kowalska, Barbara

AU - Sato, Kent T

AU - Ryu, Robert K.

AU - Lewandowski, Robert J

AU - Gates, Vanessa L.

AU - Woloschak, Gayle E

AU - Salem, Riad

AU - Omary, Reed A.

AU - Larson, Andrew Christian

PY - 2008/12/1

Y1 - 2008/12/1

N2 - Purpose: To prospectively test the hypothesis that iron labeling of radioembolization microspheres permits their visualization by using magnetic resonance (MR) imaging for in vivo tracking during transcatheter delivery to liver tumors. Materials and Methods: All experiments were approved by the Institutional Animal Care and Use Committee. Phantom studies were performed to quantify microsphere relaxivity and volume susceptibility properties and compare image contrast patterns resulting from aggregate deposition of unlabeled and iron-labeled microspheres. In seven rabbits in which nine VX2 liver tumors were implanted, T2*-weighted gradient-echo (GRE) MR images with negative image contrast (NC), white-marker (WM) GRE images with positive image contrast (PC), and on-reso- nance water-suppression turbo spin-echo (SE) images with PC were obtained before and after catheter-directed administration of microspheres into the hepatic artery. During each injection, serial GRE acquisitions were performed for real-time visualization of microsphere delivery. Contrast-to-noise ratios (CNRs) were measured between regions of microsphere accumulation and regions of normal liver parenchyma that demonstrated no apparent microsphere accumulation. Pre- and postinjec-tion CNR measurements at identical spatial positions were compared by using paired t test (α= .05). Results: Conventional microspheres did not produce detectable image contrast in phantoms. Iron-labeled microspheres produced susceptibility-induced dipole patterns with spatial extent of image contrast increasing with increasing micro- sphere dose. Real-time image series depicted both preferential delivery to tumor tissues and nontargeted delivery to adjacent organs. T2*-weighted GRE, WM GRE, and on-resonance water-suppression turbo SE each permitted in vivo visualization of the microsphere deposition, with postinjection CNR values (mean, 14.29 ± 3.98 [standard deviation], 1.87 ± 0.93, and 19.30 ± 8.72, respectively) significantly greater than corresponding preinjection CNR values (mean, 2.02 ± 4.65, 0.02 ± 0.27, 0.85 ± 2.65, respectively) (P < .05). Conclusion: Microsphere tracking during radioembolization may permit real-time verification of delivery and detection of ex-trahepatic shunting.

AB - Purpose: To prospectively test the hypothesis that iron labeling of radioembolization microspheres permits their visualization by using magnetic resonance (MR) imaging for in vivo tracking during transcatheter delivery to liver tumors. Materials and Methods: All experiments were approved by the Institutional Animal Care and Use Committee. Phantom studies were performed to quantify microsphere relaxivity and volume susceptibility properties and compare image contrast patterns resulting from aggregate deposition of unlabeled and iron-labeled microspheres. In seven rabbits in which nine VX2 liver tumors were implanted, T2*-weighted gradient-echo (GRE) MR images with negative image contrast (NC), white-marker (WM) GRE images with positive image contrast (PC), and on-reso- nance water-suppression turbo spin-echo (SE) images with PC were obtained before and after catheter-directed administration of microspheres into the hepatic artery. During each injection, serial GRE acquisitions were performed for real-time visualization of microsphere delivery. Contrast-to-noise ratios (CNRs) were measured between regions of microsphere accumulation and regions of normal liver parenchyma that demonstrated no apparent microsphere accumulation. Pre- and postinjec-tion CNR measurements at identical spatial positions were compared by using paired t test (α= .05). Results: Conventional microspheres did not produce detectable image contrast in phantoms. Iron-labeled microspheres produced susceptibility-induced dipole patterns with spatial extent of image contrast increasing with increasing micro- sphere dose. Real-time image series depicted both preferential delivery to tumor tissues and nontargeted delivery to adjacent organs. T2*-weighted GRE, WM GRE, and on-resonance water-suppression turbo SE each permitted in vivo visualization of the microsphere deposition, with postinjection CNR values (mean, 14.29 ± 3.98 [standard deviation], 1.87 ± 0.93, and 19.30 ± 8.72, respectively) significantly greater than corresponding preinjection CNR values (mean, 2.02 ± 4.65, 0.02 ± 0.27, 0.85 ± 2.65, respectively) (P < .05). Conclusion: Microsphere tracking during radioembolization may permit real-time verification of delivery and detection of ex-trahepatic shunting.

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