Serial CT and MR Imaging of Carmustine Wafers

CT scan obtained less than 24 hours after surgery shows four clearly defined wafers. One wafer has an unusual appearance, half-increased attenuation and half-decreased attenuation (arrow)

CT study.

A, Less than 24 hours after surgery, two well-defined wafers are seen.

B, Follow-up study at 2 months shows faint wafer remnants (arrows).

←MR study.

A–C, T1-weighted (A), T2-weighted (B), and contrast-enhanced T1-weighted (C) images less than 24 hours after surgery show three well-defined, decreased-signal wafers (arrows, A). There is no enhancement; subtle increased T1 signal is visible in the operative bed.

D–F, T1-weighted (D), T2-weighted (E), and contrast-enhanced T1-weighted (F) images 1 week after surgery show resolving postoperative changes with decreased edema, mass effect, and intracranial gas. The wafers are still easily seen but are somewhat less distinct.

G–I, T1-weighted (G), T2-weighted (H), and contrast-enhanced T1-weighted (I) images 2 months after surgery. The wafers have increased signal on T1-weighted image (arrows, G) and less prominent decreased signal on T2-weighted image. There is enhancement of the operative bed and in the parenchyma.

J–L, T1-weighted (J), T2-weighted (K), and contrast-enhanced T1-weighted (L) images 5 months after surgery show increased T2 signal abnormality in the brain. Incomplete wafer remnants are seen on T2-weighted image only (arrows, K). After contrast administration, marked increased enhancement is seen in operative bed and parenchyma (L).