Fig. 18.1
Carmustine Gliadel wafers. Axial (a) and coronal (b) CT images obtained on the first postoperative day show the linear hyperattenuating wafers (arrows) lining the right parietal surgical cavity. Axial T2-weighted (c), FLAIR (d), T1-weighted (e), and post-contrast axial T1-weighted (f) MR images obtained at 2 postoperative days show linear low-signal-intensity wafers (arrows) along the margins of the resection cavity. Axial T2-weighted (g) and T1-weighted (h) MR images obtained approximately 2 months later show partial resorption of the wafers
Fig. 18.2
Recurrent tumor. Axial (a) and sagittal (b) post-contrast T1-weighted MR images show an enhancing focus adjacent to the surgical cavity (arrow) with corresponding elevated perfusion on the CBV map (c). Follow-up post-contrast T1-weighted MRI (d) shows interval of the enhancing mass (arrow), compatible with tumor progression in the same patient treated with the carmustine wafers shown in Fig. 18.1
The use of carmustine wafers yields a small, but statistically significant, improvement in survival in patients with newly diagnosed high-grade glial neoplasms. However, the presence of carmustine wafers is associated with a relatively higher incidence of cerebrospinal fluid leaks (5 % vs. 0.8 % in a placebo-treated group) and intracranial hypertension (9.1 % vs. 1.7 % in the placebo group).
18.4 Differential Diagnosis
The main differential consideration for hyperattenuation in the region of the surgical cavity on CT includes hemorrhage, mineralization, and other implanted materials, such as the Ommaya reservoir and Gliasite (Figs. 18.3, 18.4, 18.5, and 18.6). The thin, linear configuration of the wafers is the key to their proper identification.
