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Quantifying Liver Heterogeneity via R2*-MRI with Super-Paramagnetic Iron Oxide Nanoparticles (SPION) to Characterize
Danny Lee1,2, Jason Sohn1,2, Alexander Kirichenko1,2
1Radiation Oncology, Allegheny Health Network, Pittsburgh, PA 15012, USA.
Abstract:
The use of super-paramagnetic iron oxide nanoparticles (SPIONs) as an MRI contrast agent (SPION-CA) can safely label hepatic macrophages and be localized within hepatic parenchyma for T2*- and R2*-MRI of the liver. To date, no study has utilized the R2*-MRI with SPIONs for quantifying liver heterogeneity to characterize functional liver parenchyma (FLP) and hepatic tumors. This study investigates whether SPIONs enhance liver heterogeneity for an auto-contouring tool to identify the voxel-wise functional liver parenchyma volume (FLPV). This was the first study to directly evaluate the impact of SPIONs on the FLPV in R2*-MRI for 12 liver cancer patients. By using SPIONs, liver heterogeneity was improved across pre- and post-SPION MRI sessions. On average, 60% of the liver [range 40-78%] was identified as the FLPV in our auto-contouring tool with a pre-determined threshold of the mean R2* of the tumor and liver. This method performed well in 10 out of 12 liver cancer patients; the remaining 2 needed a longer echo time. These results demonstrate that our contouring tool with SPIONs can facilitate the heterogeneous R2* of the liver to automatically characterize FLP. This is a desirable technique for achieving more accurate FLPV contouring during liver radiation treatment planning.
Insights
Super-paramagnetic iron oxide nanoparticles (SPIONs) improve liver MRI heterogeneity, enabling accurate characterization of functional liver parenchyma (FLP) and aiding radiation treatment planning for liver cancer.
Area of Science:
- Medical Imaging
- Nanotechnology
- Hepatology
Background:
- Super-paramagnetic iron oxide nanoparticles (SPIONs) serve as MRI contrast agents, safely labeling hepatic macrophages.
- SPIONs localize within hepatic parenchyma, facilitating T2*- and R2*-MRI of the liver.
- Quantifying liver heterogeneity using R2*-MRI with SPIONs for functional liver parenchyma (FLP) characterization remains unexplored.
Purpose of the Study:
- To investigate SPIONs' ability to enhance liver heterogeneity for an auto-contouring tool.
- To identify voxel-wise functional liver parenchyma volume (FLPV) using SPION-enhanced R2*-MRI.
- To evaluate the impact of SPIONs on FLPV in liver cancer patients.
Main Methods:
- SPIONs were administered to 12 liver cancer patients prior to R2*-MRI.
- An auto-contouring tool was developed to identify FLPV based on R2* values.
- Liver heterogeneity was compared between pre- and post-SPION MRI sessions.
Main Results:
- SPIONs significantly improved liver heterogeneity across MRI sessions.
- The auto-contouring tool identified an average of 60% FLPV (range 40-78%) using a threshold based on mean R2*.
- The method was successful in 10 out of 12 patients, with two requiring adjusted echo times.
Conclusions:
- SPION-enhanced R2*-MRI facilitates automatic characterization of FLP by leveraging increased liver heterogeneity.
- The developed auto-contouring tool shows promise for accurate FLPV determination.
- This technique is valuable for improving liver radiation treatment planning accuracy.
