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MRI-based biodistribution assessment of holmium-166 poly(L-lactic acid) microspheres after radioembolisation
Gerrit H van de Maat1, Peter R Seevinck, Mattijs Elschot
1Image Sciences Institute, University Medical Center Utrecht, Q S.459, PO Box 85500, 3508 GA Utrecht, The Netherlands. g.h.vandemaat@umcutrecht.nl
Objectives:
To demonstrate the feasibility of MRI-based assessment of the intrahepatic Ho-PLLA-MS biodistribution after radioembolisation in order to estimate the absorbed radiation dose.
Methods:
Fifteen patients were treated with holmium-166 ((166)Ho) poly(L-lactic acid)-loaded microspheres (Ho-PLLA-MS, mean 484 mg; range 408-593 mg) in a phase I study. Multi-echo gradient-echo MR images were acquired from which R (2) maps were constructed. The amount of Ho-PLLA-MS in the liver was determined by using the relaxivity r (2) of the Ho-PLLA-MS and compared with the administered amount. Quantitative single photon emission computed tomography (SPECT) was used for comparison with MRI regarding the whole liver absorbed radiation dose.
Results:
R (2) maps visualised the deposition of Ho-PLLA-MS with great detail. The mean total amount of Ho-PLLA-MS detected in the liver based on MRI was 431 mg (range 236-666 mg) or 89 ± 19 % of the delivered amount (correlation coefficient r = 0.7; P < 0.01). A good correlation was found between the whole liver mean absorbed radiation dose as assessed by MRI and SPECT (correlation coefficient r = 0.927; P < 0.001).
Conclusion:
MRI-based dosimetry for holmium-166 radioembolisation is feasible. Biodistribution is visualised with great detail and quantitative measurements are possible.
Insights
MRI accurately assessed holmium-166 poly(L-lactic acid)-loaded microspheres (Ho-PLLA-MS) biodistribution after radioembolisation. This MRI-based dosimetry allows for detailed visualization and quantitative measurement of radiation dose.
Area of Science:
- Radiology
- Nuclear Medicine
- Medical Physics
Background:
- Radioembolisation using holmium-166 poly(L-lactic acid)-loaded microspheres (Ho-PLLA-MS) is a treatment for liver cancer.
- Accurate dosimetry is crucial for effective treatment and minimizing side effects.
- Current methods for assessing biodistribution and radiation dose may have limitations.
Purpose of the Study:
- To evaluate the feasibility of using Magnetic Resonance Imaging (MRI) to assess the intrahepatic biodistribution of Ho-PLLA-MS.
- To determine if MRI can be used to estimate the absorbed radiation dose after radioembolisation.
- To compare MRI-based dosimetry with Single Photon Emission Computed Tomography (SPECT).
Main Methods:
- Fifteen patients undergoing radioembolisation with Ho-PLLA-MS were included in a phase I study.
- Multi-echo gradient-echo MRI sequences were acquired to generate R2 maps.
- The amount of Ho-PLLA-MS was quantified using MRI-derived relaxivity (r2) and compared to SPECT for radiation dose assessment.
Main Results:
- R2 maps effectively visualized Ho-PLLA-MS deposition in the liver with high detail.
- MRI detected 89% (±19%) of the administered Ho-PLLA-MS, showing good correlation (r=0.7) with administered amounts.
- A strong correlation (r=0.927) was observed between MRI and SPECT for whole-liver absorbed radiation dose estimation.
Conclusions:
- MRI-based dosimetry is a feasible method for holmium-166 radioembolisation.
- MRI provides detailed visualization of Ho-PLLA-MS biodistribution.
- Quantitative MRI measurements enable accurate estimation of absorbed radiation dose.
