Diffusion-Weighted Imaging of Malignant Ocular Masses: Initial Results and Directions for Further Study

A 63-year-old man with uveal melanoma, imaged at 1.5T. A, Axial T2-weighted image shows a hypointense mass along the temporal aspect of the globe. B, Axial ADC map obtained with an EPI technique demonstrates the mass but also shows globe warping and signal-intensity voids in the vitreous, with artifact graded as moderate. ADC was 0.92 × 10⁻³ mm²/s. C, Axial ADC map by using the PROPELLER technique shows no evidence of susceptibility artifact. Extensive background noise is present, but there is high contrast between the high-ADC vitreous and low-ADC mass.

A 15 month-old girl with retinoblastoma, imaged at 3T. A, axial T2-weighted image shows a large hypointense mass in the right globe. Plaque-like hypointensity along the temporal aspect of the globe represents infiltrating tumor (short arrows). A subtle fluid level at the posterior globe represents associated retinal detachment (long arrow). B, axial T1-weighted image shows mild hyperintensity characteristic of retinoblatoma. C, axial contrast-enhanced T1-weighted image shows moderate, slightly heterogeneous enhancement. Note the enhancement of the plaque-like area seen in A, without enhancement of the subretinal fluid seen in A. D, axial T2*-weighted gradient refocused echo-image shows numerous punctate foci of signal loss representing calcifications. E, axial DWI image shows homogeneous signal hyperintense to normal gray matter. F, ADC map shows markedly lower values than normal brain in the dominant mass (short arrow), with an ADC value slightly lower than normal brain within the thinner portion of the tumor (long arrow). (Panels A, B and D reproduced with permission from Head and Neck Imaging, 5^th ed., Eds: Som PM, Curtin HD. “Pathology of the Eye and Orbit,” Cunnane ME, Sepahdari AR, Gardiner M, Mafee MF, p. 612. Copyright Elsevier, 2011.).

A 16-year-old boy with highly undifferentiated carcinoma (presumptively a dedifferentiated medulloepithelioma), imaged at 3T. A, Axial T2-weighted image shows a hypointense mass at the posteroinferior globe. B, Axial T1-weighted image shows an isointense mass (black arrow) in the background of hyperintense exudative retinal detachment. The retinal leaves are elevated and apposed (white arrow). C, Axial contrast-enhanced fat-suppressed T1-weighted image show moderate enhancement of the mass (arrow). D, Axial DWI shows sharp contrast between the cellular mass and the subretinal exudate.

A plot of ADC against lesion thickness for 15 cases of retinoblastoma shows a distribution that best fits a quadratic relationship. Lesions thinner than 0.8–1 cm were all below the nominal z-axis resolution of our technique and thus were affected by partial volume averaging.