Detection of Calcifications in Retinoblastoma Using Gradient-Echo MR Imaging Sequences: Comparative Study between In Vivo MR Imaging and Ex Vivo High-Resolution CT

Examples of additional signal-intensity voids on T2*-weighted MR images without correspondence with ex vivo high-resolution CT. Patient 13 shows a hypointense nodular structure (A) in the anterior part of the eye (arrow) on T2*-weighted imaging without corresponding hyperattenuation on ex vivo high-resolution CT (B). Histopathology demonstrates a hemorrhage (arrow) precisely matching this additional SIV (C). Adjacent to this hemorrhage multiple linear-arranged spots match hyperattenuated spots on CT. In patient 11 (D), a linear band of SIV on T2*WI is shown outside the tumor along the detached retina (white arrow) and in the iris (black arrow). The gray arrowhead indicates the lens, which is dislocated. Histology (E and F) shows necrotic tumor with dilated vessels (venous congestion) (white arrow) and hemorrhagic necrosis of the iris combined with venous congestion (black arrow). The anterior chamber is infiltrated by neoplastic cells and cellular debris. (H&E staining, ×20 magnification.)

Extra signal-intensity void spots in the anterior part of the eye on gradient-echo T2*-weighted images (arrow, A) were observed in patient 21, with excellent correspondence with HRCT (B). However, a band of additional signal-intensity void spots was present in the anterior part of the tumor on the gradient-echo T2*-weighted MR image (arrow, A) without correspondence on ex vivo high-resolution CT. Histopathologic correlation (C) shows multiple foci of calcifications in the anterior part of the tumor (arrow). (H&E staining, ×20 magnification.)