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J Xiong, M Krause, KK Kwong, ES Gragoudas, LH Y Young; MRI of Blood Volume With MS 325 in Experimental Choroidal Melanoma . Invest. Ophthalmol. Vis. Sci. 2002;43(13):1138.
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Purpose: Functional magnetic resonance imaging (MRI) is a non-invasive technique offering high tissue resolution and accurate measurement of physiologic parameters in vivo. This technique was applied to determine blood volume in untreated and hyperthermia-treated choroidal melanoma. MS 325 was used as new intravascular albumin-bound gadolinium-based contrast agent. Methods: Experimental pigmented choroidal melanomas were established in albino rabbits. MRI was performed in 7 untreated eyes and 7 eyes treated by a Neodymium:Yttrium-Lanthanum-Fluoride-(Nd:YLF-)laser at 1047 nm. 3D-spoiled gradient echo pulse sequences were used to acquire T1 weighted axial images. At first, a set of images was collected without contrast agent. MS 325 was then injected intravenously and images were obtained within 12 min after the injection. Signal intensities were measured within tumor, ciliary body, choroid, and iris, and relative signal intensities were determined for these tissues in relation to vitreous. Results: In untreated tumors, the relative signal intensity was higher after injection of MS 325 (5.61 + 0.70) than without MS 325 (2.90 + 0.33; p = 0.018). In contrast, the relative signal intensity of treated tumors did not differ significantly before and after MS 325 (6.19 + 1.59 and 6.13 + 1.64). All other studied tissues of untreated and treated eyes showed a significant increase of relative signal intensities in the presence of MS 325. Conclusions: In experimental choroidal melanomas, functional MRI with MS 325 provides non-invasive measurement of the blood volume. The technique detects vascular occlusion in hyperthermia-treated choroidal melanoma. Further studies are needed to investigate the feasibility of this technique for the evaluation of tumor viability following treatments.
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