Imaging description

The imaging spectrum of neurocysticercosis is broad, which may create challenges in differential diagnosis. Cysticercosis involvement of the central nervous system (CNS) may be divided into parenchymal and extraparenchymal categories [1]. Parenchymal lesions include four stages of evolution of infestation:

1. (1) Vesicular stage – parenchymal cysts and the scolex within them are identified on both CT and MRI. Cysts usually measure <1cm, cyst signal follows that of CSF, and thus the scolex is usually best seen on FLAIR images. No significant enhancement is present at this stage, although minimal cyst wall enhancement and scolex enhancement may be seen on MRI (Fig. 37.1).

2. (2) Colloidal vesicular stage – early degeneration of cysts results in change in signal of cyst fluid. Rupture of cyst and release of antigens results in inflammatory reaction, edema, and ring enhancement seen both on MRI and CT. T2-weighted images may show decreased signal associated with the cyst wall (Fig. 37.2).

3. (3) Granular nodular stage – late degeneration of still active cyst results in decreasing edema. Enhancement becomes more nodular, and cysts get smaller or transform into small nodules, which may start showing calcification (Fig. 37.3).

4. (4) Nodular calcified stage – completion of degeneration results in an inactive lesion with resolution of edema and calcification of nodule, which shows decreased T1 and T2 signal and may be difficult to see on MRI. CT is more sensitive at this stage.