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S. McCaffery, I.K. Dafarti, E. Aghaian, T.L. Phillips, W. Dillon, J.M. O'Brien; Tumor Volume Assessment of Choroidal Melanoma by High–Resolution Reformattable 3D MRI Improves Proton Beam Radiotherapy Planning . Invest. Ophthalmol. Vis. Sci. 2006;47(13):2257.
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© ARVO (1962-2015); The Authors (2016-present)
To assess the efficacy of 3D high–resolution reformattable MRI in the calculation of choroidal melanoma tumor volume for proton beam radiotherapy planning.
High–resolution reformattable 3D fast spin echo (FSE) MRI was obtained in 80 consecutive patients with choroidal melanoma. MRI tumor measurements were determined by a neuroradiologist in conjuction with the ocular oncologist and the radiation oncologist. Tumors were divided into four categories by size as classified by maximal apical thickness and basal diameter. Tumor volume was then calculated from the T2–weighted FSE sequence data and subsequently compared to volume obtained from traditional methods. Complementary conventional techniques utilized intraoperative transpupillary transillumination coupled with indirect ophthalmoscopy and transcleral illumination for tantalum marker clip delineation of tumor margins, as well as A– and B–scan ultrasonography with ultrasound biomicropsy for tumors involving the ciliary body. Tumor volume was calculated by radiation oncology using the standard EYEPLAN software and comparision of proposed beam margins was made using tumor delineation data obtained from conventional and investigational methods.
3D MRI assessment of tumor volume was comparable to conventional methods when the maximal apical thickness exceeded 3mm. In certain clinical scenarios, MRI volumetric assessment was superior to traditional approaches and led to a modification of the treatment field. This was particularly true for extra large tumors, for peripapillary tumors overhanging the optic nerve, and for tumors surrounded by reactive pigmentation or hemorrhage. MRI assessment of tumor contour allowed for the administration of highly–specific and customized proton beam radiotherapy.
Reformattable high–resolution 3D MRI improves the assessment of choroidal melanoma tumor volume and facilitates customization of proton beam radiotherapy to maximize therapeutic effect and to minimize treatment of uninvolved tissue.
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