The Role of Fat-Suppression Technique and Gadopentetate Dimeglumine in Magnetic Resonance Imaging Evaluation of Intraocular Tumors and Simulating Lesions

Is CT Still Useful in the Study Protocol of Retinoblastoma?

“…Imaging studies are used for diagnostic purposes only in very selected instances, as in cases in which ophthalmoscopy is impossible, such as with the presence of opaque ocular refractive media and massive retinal detachment or for differentiating lesions simulating retinoblastoma. 11,[14][15][16][17][18][19][20][21][22][23] The purpose of this study was to assess the utility of the association of ophthalmologic evaluation and MR imaging in the detection of intralesional calcifications in retinoblastoma, to evaluate whether CT is still mandatory in the protocol study of retinoblastoma and simulating lesions.…”

MR Imaging Findings of the Uveal Schwannoma

“…Therefore, mushroom shape favors uveal melanoma, and oval shape favors uveal schwannoma. However, some uveal melanomas may appear as an oval mass, [19][20][21] which may be similar to uveal schwannomas. In this circumstance, the shape of the tumor cannot distinguish uveal schwannoma from oval uveal melanoma.…”

“…Therefore, the difference in signal intensity of the tumor with respect to the brain may be the feature to differentiate uveal schwannoma from uveal melanoma. De Potter et al 20 reported that, in a small fraction of patients (Ͻ5%) with uveal melanoma, the tumor appeared hypointense on SE T1WI and isointense on SE T2WI with respect to the vitreous body on the basis of a study of 43 patients. However, it is still impossible to differentiate uveal schwannoma from uveal amelanotic melanoma on the basis of the signal intensity of the tumor on MR imaging.…”

“…By contrast, uveal melanomas are less likely to occur in the peripheral choroid or ciliary body. 19,20 In addition, extraocular growth detected by MR imaging is identified in 10%-15% of all cases of uveal melanoma, 19,20 whereas extraocular growth of a uveal schwannoma should not be seen. These findings may be helpful in the differentiation of uveal schwannoma from uveal melanoma.…”

“…19 Melanoma has short T1 and T2 values, a finding that has been attributed to paramagnetic proton relaxation by stable radicals in the melanin. [19][20][21] Amelanotic melanoma does not show the shortened T1 values. However, most uveal schwannomas were misdiagnosed as malignant melanoma in the previously published literature.…”