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MR imaging of malignant uveal melanoma: role of pulse sequence and contrast agent
F Mihara1, K L Gupta, S Murayama
1Department of Diagnostic Radiology, University of Maryland Medical System, Baltimore 21201.
Abstract:
To determine the most sensitive pulse sequence and to clarify the role of each pulse sequence in the MR diagnosis of uveal malignant melanoma, noncontrast T1- and T2-weighted, and postcontrast T1-weighted, spin-echo images were compared blindly and independently by two experienced observers. Thirty uveal malignant melanomas, preselected by ophthalmoscopy and sonography for size greater than 2 mm, were examined with a 1.5-T superconducting MR unit with an orbital surface coil. Fifteen tumor studies were done after the patient was injected with gadopentetate dimeglumine. Postcontrast T1-weighted images were the most sensitive in detecting melanomas, demonstrating tumors 2 mm in height accurately on axial planes and 1.6 mm in height on combined orthogonal planes. The contrast-to-noise ratio between melanoma and vitreous fluid was greatest on postcontrast T1-weighted images (average, 72.1), followed by noncontrast T1-weighted images (average, 32.9), and then by T2-weighted images (average, -21.2). Postcontrast T1-weighted images also proved useful in differentiating melanomas from subretinal fluid collections when combined with noncontrast images. We conclude that postcontrast T1-weighted images are most helpful in detecting small uveal melanomas and in differentiating melanomas from subretinal fluid collections.
Insights
Postcontrast T1-weighted magnetic resonance imaging (MRI) is the most sensitive method for detecting small uveal melanomas. This technique also aids in distinguishing melanomas from subretinal fluid, improving diagnostic accuracy.
Area of Science:
- Ophthalmology
- Radiology
- Medical Imaging
Background:
- Uveal malignant melanoma is a significant intraocular malignancy.
- Accurate diagnosis and characterization are crucial for effective treatment planning.
- Magnetic Resonance Imaging (MRI) offers detailed visualization of ocular structures.
Purpose of the Study:
- To identify the most sensitive MRI pulse sequence for diagnosing uveal malignant melanoma.
- To elucidate the diagnostic role of various MRI pulse sequences.
- To compare the efficacy of noncontrast T1-weighted, T2-weighted, and postcontrast T1-weighted images.
Main Methods:
- Comparison of noncontrast T1-weighted, T2-weighted, and postcontrast T1-weighted spin-echo MRI sequences.
- Blind, independent assessment by two experienced observers.
- Study involved 30 preselected uveal melanomas (size > 2 mm) using a 1.5-T MRI with an orbital surface coil.
- Fifteen studies included gadopentetate dimeglumine administration.
Main Results:
- Postcontrast T1-weighted images demonstrated the highest sensitivity in melanoma detection.
- Accurate detection of tumors as small as 2 mm axially and 1.6 mm in combined orthogonal planes.
- Greatest contrast-to-noise ratio between melanoma and vitreous fluid observed with postcontrast T1-weighted images (average, 72.1).
- Postcontrast T1-weighted images, combined with noncontrast images, aided in differentiating melanomas from subretinal fluid.
Conclusions:
- Postcontrast T1-weighted MRI sequences are most effective for detecting small uveal melanomas.
- This imaging technique is valuable for differentiating uveal melanomas from subretinal fluid collections.
- Optimizing MRI protocols enhances diagnostic capabilities for ocular tumors.