Related Experiment Video
Updated: Aug 12, 2026
Magnetic-, Acoustic-, and Optical-Triple-Responsive Microbubbles for Magnetic Hyperthermia and Pothotothermal Combination Cancer Therapy
Published on: May 22, 2020
MRI of blood volume with superparamagnetic iron in choroidal melanoma treated with thermotherapy
Matthias H J Krause1, Kenneth K Kwong, Evangelos S Gragoudas
1Massachusetts General Hospital-Nuclear Magnetic Resonance (MGH-NMR) Center, Harvard Medical School, Charlestown, MA, USA.
Abstract:
Functional magnetic resonance imaging (MRI) with a new intravascular contrast agent, monocrystalline iron oxide nanoparticles (MION), was applied to assess the effect of transpupillary thermotherapy in a rabbit model of choroidal melanoma. 3D-spoiled gradient recalled sequences were used for quantitative assessment of blood volume. The MRI-parameters were 5/22/35 degrees (time of repetition (TR)/echo delay (TE)/flip angle (FA)) for T(1)- and 50/61/10 degrees for T(2)-weighted sequences. Images were collected before and at different times after MION injection. In all untreated tissues studied, MION reduced the T(2)-weighted signal intensity within 0.5 h and at 24 h (all p <== 0.012), whereas no significant changes were detected in treated tumors. T(1)-weighted images also revealed differences of MION-related signal changes between treated tumors and other tissues, yet at lower sensitivity and specificity than T(2). The change of T(2)-weighted MRI signal caused by intravascular MION allows early distinction of laser-treated experimental melanomas from untreated tissues. Further study is necessary to determine whether MRI can localize areas of tumor regrowth within tumors treated incompletely.
Insights
Functional magnetic resonance imaging (MRI) using monocrystalline iron oxide nanoparticles (MION) effectively distinguishes treated choroidal melanomas from untreated tissues in rabbits. This technique aids in early detection of treatment effects in experimental models.
Area of Science:
- Biomedical Imaging
- Oncology
- Nanotechnology
Background:
- Choroidal melanoma is a significant ocular malignancy.
- Assessing treatment efficacy in choroidal melanoma requires sensitive imaging techniques.
- Intravascular contrast agents offer potential for enhanced MRI contrast.
Purpose of the Study:
- To evaluate the use of functional MRI with monocrystalline iron oxide nanoparticles (MION) for assessing transpupillary thermotherapy in a rabbit choroidal melanoma model.
- To determine if MION-enhanced MRI can differentiate between treated and untreated tumors.
- To assess the sensitivity and specificity of T(1)- and T(2)-weighted MRI sequences.
Main Methods:
- Functional MRI was performed on a rabbit choroidal melanoma model before and after MION injection.
- 3D-spoiled gradient recalled sequences were used for quantitative blood volume assessment.
- T(1)- and T(2)-weighted MRI sequences were acquired using specific parameters (TR/TE/FA).
Main Results:
- MION significantly reduced T(2)-weighted signal intensity in untreated tissues (p <== 0.012) within 0.5 h and at 24 h post-injection.
- No significant signal changes were observed in MION-injected treated tumors.
- T(2)-weighted MRI demonstrated higher sensitivity and specificity than T(1)-weighted MRI in distinguishing treated from untreated tissues.
Conclusions:
- T(2)-weighted MRI with intravascular MION allows for early distinction between laser-treated experimental choroidal melanomas and untreated tissues.
- Further research is needed to explore MRI's capability in detecting tumor regrowth after incomplete treatment.
More Related Videos
13:41Magnetic Resonance-Guided High Intensity Focused Ultrasound Generated Hyperthermia: A Feasible Treatment Method in a Murine Rhabdomyosarcoma Model
Published on: January 13, 2023
10:25A Dorsal Skinfold Window Chamber Tumor Mouse Model for Combined Intravital Microscopy and Magnetic Resonance Imaging in Translational Cancer Research
Published on: April 12, 2024
