====== Ependymal enhancement ======

Some overlap with periventricular enhancement. Ependymal enhancement often heralds a serious condition
((Guerini H, Helie O, Leveque C, et al. [Diagnosis of
periventricular ependymal enhancement in MRI in
adults]. J Neuroradiol. 2003; 30:46–56)).
 
Main DDx is tumor vs. infectious process.

1. ventriculitis or ependymitis: ependymal enhancement occurs in 64% of cases of pyogenic ventriculitis
((Fukui MB, Williams RL, Mudigonda S. CT and MR
imaging features of pyogenic ventriculitis. AJNR Am
J Neuroradiol. 2001; 22:1510–1516)).

a) infection may occur in the following settings

● following shunt surgery

● after intraventricular surgery

● with indwelling prosthetic devices (e.g. Ommaya reservoir)

● with use of intrathecal chemotherapy

● with meningitis

● with viral ependymitis

● in some cases of CMV encephalitis in immunocompromised patients

● granulomatous involvement: esp. in immunocompromised patients; e.g. tuberculosis, mycobacterium, syphilis

b) infections may be
((Guerini H, Helie O, Leveque C, et al. [Diagnosis of
periventricular ependymal enhancement in MRI in
adults]. J Neuroradiol. 2003; 30:46–56)).

● bacterial (pyogenic) ventriculitis

● tuberculous ventriculitis

● cystic lesions suggest cysticercosis

2. carcinomatous meningitis: typically also produces meningeal enhancement 

3. multiple sclerosis: usually more periventricular (in the white matter)

4. tumors

a) lymphoproliferative disorders

● CNS lymphoma 

● leukemia

b) ependymoma

● with tumor spread

● transient enhancement reported in a child with ependymoma in the absence of tumor spread
((Butler WE, Khan A, Khan SA. Posterior fossa ependymoma with intense but transient disseminated
enhancement but not metastasis. Pediatr
Neurosurg. 2002; 37:27–31))

c) metastasis

d) germ cell tumors

5. tuberous sclerosis: subependymal hamartomas appear as nodules that occasionally enhance. These gradually calcify with age

6. in the presence of appropriate constitutional symptoms: rare causes of linear enhancement

include: neurosarcoidosis, Whipple’s disease, metastatic multiple myeloma (usually nodular)

In immunocompromised patients, the enhancement pattern may help distinguish between the following (which tend to occur in this population
((Guerini H, Helie O, Leveque C, et al. [Diagnosis of
periventricular ependymal enhancement in MRI in
adults]. J Neuroradiol. 2003; 30:46–56))
):

1. thin linear enhancement: suggests virus (CMV or varicella-zoster)


2. nodular enhancement: suggests CNS lymphoma

3. band enhancement: less specific (may occur with virus, lymphoma, or tuberculosis (TB).