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MRI in thorotrastosis
1Second Department of Medicine, Kurume University School of Medicine, Japan.
Abstract:
Magnetic resonance imaging (MRI) and computed tomography (CT) were performed in four patients with thorotrastosis. On CT scan, Thorotrast (thorium oxide) deposition was shown as high-density areas in the liver and spleen and the abdominal lymph nodes. These deposits were not found on MRIs. Splenic volume was significantly small due to atrophy. The contrast-noise ratio in the spleen on T1-weighted images was significantly lower. Thorotrast deposition does not affect MRI appearance; therefore it may be useful for the early detection of malignant tumors as a complication of thorotrastosis.
Insights
Computed tomography (CT) detects Thorotrast deposition in thorotrastosis patients, while MRI does not. MRI may aid early detection of tumors, a complication of Thorotrast exposure.
Area of Science:
- Radiology
- Medical Imaging
- Nuclear Medicine
Background:
- Thorotrast (thorium dioxide) is a radioactive contrast agent historically used for medical imaging.
- Thorotrast administration can lead to long-term deposition in organs like the liver and spleen, posing a risk for malignancy.
- Evaluating imaging modalities for detecting Thorotrast deposition and its complications is crucial.
Purpose of the Study:
- To compare the effectiveness of CT and MRI in visualizing Thorotrast deposition in patients with thorotrastosis.
- To assess the impact of Thorotrast deposition on spleen morphology and MRI characteristics.
- To determine the potential utility of MRI in the early detection of malignant tumors in thorotrastosis patients.
Main Methods:
- Four patients with a history of Thorotrast exposure underwent both CT and MRI scans.
- Image analysis focused on identifying Thorotrast deposits, evaluating splenic volume and atrophy, and measuring contrast-noise ratio on T1-weighted MRI sequences.
Main Results:
- CT scans clearly showed high-density Thorotrast deposits in the liver, spleen, and abdominal lymph nodes.
- These Thorotrast deposits were not visualized on MRI scans.
- Patients exhibited significantly reduced splenic volume due to atrophy, and a lower contrast-noise ratio in the spleen on T1-weighted MRI.
- Thorotrast deposition did not alter the overall MRI appearance of the organs.
Conclusions:
- CT is effective in identifying Thorotrast deposition, while MRI does not directly visualize these deposits.
- MRI may be a valuable tool for the early detection of malignant tumors, a known complication of thorotrastosis, due to its ability to assess organ changes without being affected by Thorotrast presence.