Abstract
Purpose: :
High-resolution magnetic resonance imaging relies solely on uniform field strength to give true anatomical proportions. The present study was conducted to demonstrate new options for analysis and interpretation of intraocular lesions using this technology.
Methods: :
High-resolution MR ocular images were acquired on an ultra high-field MR unit (7.1 Tesla, ClinScan, Bruker BioScan, Germany) using a 2-channel coil with 4 coil elements and T2- weighted Turbo Spin Echo sequences ex vivo in ten human enucleated eyes with different intraocular lesions. Ultrasonography and ultrasound biomicroscopy was also performed in each case. Histological preparations provided a final diagnosis.
Results: :
For imaging a field of view of 40x40 mm with a matrix size of 512x512 pixels and a slice thickness of 700 µm yielded in-plane resolution of 80x80 µm. The examinations were performed in enucleated eyes with choroidal melanoma, iris melanoma with scleral perforation, intraocular metastasis of esophageal cancer, melanoma of ciliary body, subretinal bleeding in an eye with perforated keratitis and transmitted uveitis, hemorrhagic choroidal ablation and premature retinopathy with phthisis and ossification processes of bulbar structures. MR imaging allowed differentiation between solid and cystic tumorous structures. In case of hemorrhage, fluid-fluid levels could be identified. Melanin and calcifications caused significant hypointensity. Microstructure of the lesion was confirmed by histological evaluation.
Conclusions: :
This study demonstrates the potential of high-field MRI for visualizing and differential diagnosis of intraocular lesions. At present, particularly for humans, access to this technology is still limited due to the small tube diameter. Nevertheless the development of ultra-high resolution MRI will permit visualization of tumor spread and evaluation of non classified intraocular structures in the near future.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • differentiation • tumors