Limits...
The magnetic susceptibility effect of gadolinium-based contrast agents on PRFS-based MR thermometry during thermal interventions.

Hijnen NM, Elevelt A, Pikkemaat J, Bos C, Bartels LW, Grüll H - J Ther Ultrasound (2013)

Bottom Line: No additional susceptibility effect was measured upon Gd release from paramagnetic liposomes.In vivo, intravenous Gd-DTPA injection resulted in a perceived temperature change of 2.0°C ± 0.1°C at the center of the hind leg muscle.Compensation for the phase changes induced by the changing Gd presence is difficult as the magnetic field changes are arising nonlocally in the surroundings of the susceptibility change.

View Article: PubMed Central - HTML - PubMed

Affiliation: Biomedical NMR, Department of Biomedical Engineering, Eindhoven University of Technology, High Tech Campus 11.p 261, Eindhoven, 5656 AE, the Netherlands.

ABSTRACT

Background: Proton resonance frequency shift (PRFS) magnetic resonance (MR) thermometry exploits the local magnetic field changes induced by the temperature dependence of the electron screening constant of water protons. Any other local magnetic field changes will therefore translate into incorrect temperature readings and need to be considered accordingly. Here, we investigated the susceptibility changes induced by the inflow and presence of a paramagnetic MR contrast agent and their implications on PRFS thermometry.

Methods: Phantom measurements were performed to demonstrate the effect of sudden gadopentetate dimeglumine (Gd-DTPA) inflow on the phase shift measured using a PRFS thermometry sequence on a clinical 3 T magnetic resonance-guided high-intensity focused ultrasound (MR-HIFU) system. By proton nuclear magnetic resonance spectroscopy, the temperature dependence of the Gd-DTPA susceptibility was measured, as well as the effect of liposomal encapsulation and release on the bulk magnetic susceptibility of Gd-DTPA. In vivo studies were carried out to measure the temperature error induced in a rat hind leg muscle upon intravenous Gd-DTPA injection.

Results: The phantom study showed a significant phase shift inside the phantom of 0.6 ± 0.2 radians (mean ± standard deviation) upon Gd-DTPA injection (1.0 mM, clinically relevant amount). A Gd-DTPA-induced magnetic susceptibility shift of ΔχGd-DTPA = 0.109 ppm/mM was measured in a cylinder parallel to the main magnetic field at 37°C. The temperature dependence of the susceptibility shift showed dΔχGd-DTPA/dT = -0.00038 ± 0.00008 ppm/mM/°C. No additional susceptibility effect was measured upon Gd release from paramagnetic liposomes. In vivo, intravenous Gd-DTPA injection resulted in a perceived temperature change of 2.0°C ± 0.1°C at the center of the hind leg muscle.

Conclusions: The use of a paramagnetic MR contrast agent prior to MR-HIFU treatment may influence the accuracy of the PRFS MR thermometry. Depending on the treatment workflow, Gd-induced temperature errors ranging between -4°C and +3°C can be expected. Longer waiting time between contrast agent injection and treatment, as well as shortening the ablation duration by increasing the sonication power, will minimize the Gd influence. Compensation for the phase changes induced by the changing Gd presence is difficult as the magnetic field changes are arising nonlocally in the surroundings of the susceptibility change.

No MeSH data available.


Related in: MedlinePlus

The effect of Gd injection in vivo. (A) Schematic drawings of the animal orientation in transversal and coronal directions, and a magnitude image of the rat hind leg as obtained with the PRFS thermometry sequence (coronal view). The red scale bar indicates the voxel locations in plot B. (B) The perceived temperature baseline error over time in vivo over a horizontal line profile in the rat muscle. (C) PRFS voxel signal intensity data obtained at x0 indicating the inflow of Gd-DTPA into the rat hind leg muscle.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4265976&req=5

Figure 3: The effect of Gd injection in vivo. (A) Schematic drawings of the animal orientation in transversal and coronal directions, and a magnitude image of the rat hind leg as obtained with the PRFS thermometry sequence (coronal view). The red scale bar indicates the voxel locations in plot B. (B) The perceived temperature baseline error over time in vivo over a horizontal line profile in the rat muscle. (C) PRFS voxel signal intensity data obtained at x0 indicating the inflow of Gd-DTPA into the rat hind leg muscle.

Mentions: Four animals were injected with Gd-DTPA (0.6 mmol/kg bw) to measure the magnetic susceptibility effect of a changing amount of Gd-CA in the tissue on the phase stability of gradient-echo PRFS images. The animal body temperature was tightly regulated and kept constant at 37°C ± 0.2°C, as measured using the rectal temperature probe. In vivo PRFS thermometry without heating in the absence of a Gd-based contrast agent showed no average temperature change over a period of 10 min with a standard deviation of 0.3°C. Intravenous Gd-DTPA injection resulted in a change of the local magnetic field, which translated into an apparent temperature change of -2.0°C ± 0.1°C (mean ± SD) in the middle of the hind leg muscle (x0 in Figure 3A). Depending on the PRFS voxel location, the presence of Gd-DTPA in the tissue resulted in either a positive (central area) or a negative (peripheral area) phase shift and apparent temperature change (Figure 3B). As expected based on the literature [14], the susceptibility-induced shift showed a symmetrical pattern around the Gd-DTPA-perfused tissue (i.e., x-5 = x+5, x-4 = x+4, etcetera).


The magnetic susceptibility effect of gadolinium-based contrast agents on PRFS-based MR thermometry during thermal interventions.

Hijnen NM, Elevelt A, Pikkemaat J, Bos C, Bartels LW, Grüll H - J Ther Ultrasound (2013)

The effect of Gd injection in vivo. (A) Schematic drawings of the animal orientation in transversal and coronal directions, and a magnitude image of the rat hind leg as obtained with the PRFS thermometry sequence (coronal view). The red scale bar indicates the voxel locations in plot B. (B) The perceived temperature baseline error over time in vivo over a horizontal line profile in the rat muscle. (C) PRFS voxel signal intensity data obtained at x0 indicating the inflow of Gd-DTPA into the rat hind leg muscle.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4265976&req=5

Figure 3: The effect of Gd injection in vivo. (A) Schematic drawings of the animal orientation in transversal and coronal directions, and a magnitude image of the rat hind leg as obtained with the PRFS thermometry sequence (coronal view). The red scale bar indicates the voxel locations in plot B. (B) The perceived temperature baseline error over time in vivo over a horizontal line profile in the rat muscle. (C) PRFS voxel signal intensity data obtained at x0 indicating the inflow of Gd-DTPA into the rat hind leg muscle.
Mentions: Four animals were injected with Gd-DTPA (0.6 mmol/kg bw) to measure the magnetic susceptibility effect of a changing amount of Gd-CA in the tissue on the phase stability of gradient-echo PRFS images. The animal body temperature was tightly regulated and kept constant at 37°C ± 0.2°C, as measured using the rectal temperature probe. In vivo PRFS thermometry without heating in the absence of a Gd-based contrast agent showed no average temperature change over a period of 10 min with a standard deviation of 0.3°C. Intravenous Gd-DTPA injection resulted in a change of the local magnetic field, which translated into an apparent temperature change of -2.0°C ± 0.1°C (mean ± SD) in the middle of the hind leg muscle (x0 in Figure 3A). Depending on the PRFS voxel location, the presence of Gd-DTPA in the tissue resulted in either a positive (central area) or a negative (peripheral area) phase shift and apparent temperature change (Figure 3B). As expected based on the literature [14], the susceptibility-induced shift showed a symmetrical pattern around the Gd-DTPA-perfused tissue (i.e., x-5 = x+5, x-4 = x+4, etcetera).

Bottom Line: No additional susceptibility effect was measured upon Gd release from paramagnetic liposomes.In vivo, intravenous Gd-DTPA injection resulted in a perceived temperature change of 2.0°C ± 0.1°C at the center of the hind leg muscle.Compensation for the phase changes induced by the changing Gd presence is difficult as the magnetic field changes are arising nonlocally in the surroundings of the susceptibility change.

View Article: PubMed Central - HTML - PubMed

Affiliation: Biomedical NMR, Department of Biomedical Engineering, Eindhoven University of Technology, High Tech Campus 11.p 261, Eindhoven, 5656 AE, the Netherlands.

ABSTRACT

Background: Proton resonance frequency shift (PRFS) magnetic resonance (MR) thermometry exploits the local magnetic field changes induced by the temperature dependence of the electron screening constant of water protons. Any other local magnetic field changes will therefore translate into incorrect temperature readings and need to be considered accordingly. Here, we investigated the susceptibility changes induced by the inflow and presence of a paramagnetic MR contrast agent and their implications on PRFS thermometry.

Methods: Phantom measurements were performed to demonstrate the effect of sudden gadopentetate dimeglumine (Gd-DTPA) inflow on the phase shift measured using a PRFS thermometry sequence on a clinical 3 T magnetic resonance-guided high-intensity focused ultrasound (MR-HIFU) system. By proton nuclear magnetic resonance spectroscopy, the temperature dependence of the Gd-DTPA susceptibility was measured, as well as the effect of liposomal encapsulation and release on the bulk magnetic susceptibility of Gd-DTPA. In vivo studies were carried out to measure the temperature error induced in a rat hind leg muscle upon intravenous Gd-DTPA injection.

Results: The phantom study showed a significant phase shift inside the phantom of 0.6 ± 0.2 radians (mean ± standard deviation) upon Gd-DTPA injection (1.0 mM, clinically relevant amount). A Gd-DTPA-induced magnetic susceptibility shift of ΔχGd-DTPA = 0.109 ppm/mM was measured in a cylinder parallel to the main magnetic field at 37°C. The temperature dependence of the susceptibility shift showed dΔχGd-DTPA/dT = -0.00038 ± 0.00008 ppm/mM/°C. No additional susceptibility effect was measured upon Gd release from paramagnetic liposomes. In vivo, intravenous Gd-DTPA injection resulted in a perceived temperature change of 2.0°C ± 0.1°C at the center of the hind leg muscle.

Conclusions: The use of a paramagnetic MR contrast agent prior to MR-HIFU treatment may influence the accuracy of the PRFS MR thermometry. Depending on the treatment workflow, Gd-induced temperature errors ranging between -4°C and +3°C can be expected. Longer waiting time between contrast agent injection and treatment, as well as shortening the ablation duration by increasing the sonication power, will minimize the Gd influence. Compensation for the phase changes induced by the changing Gd presence is difficult as the magnetic field changes are arising nonlocally in the surroundings of the susceptibility change.

No MeSH data available.


Related in: MedlinePlus