Figure 1: The avid enhancement in the basilar cisterns (top row left) is typical for granulomatous infections such as TB but may also mimic leptomeningeal metastases. The subcortical enhancing tuberculoma (top row right) with surrounding FLAIR-hyperintense edema (bottom row left) demonstrates no restricted diffusion (bottom row right) and would also be more suspicious for metastasis if not for the typical concomitant basilar distribution of infection.
- Caused by Mycobacterium tuberculosis
- 10% of patients with tuberculosis have CNS involvement
- Hematogenous spread from primary lung involvement is most common, though direct extension can occur as well
- Most commonly secondary to hematogenous spread from a pulmonary source
- Highly variable, ranging from meningitis to coma
- Tuberculoma: seizures, increased ICP, papilledema
- Occurs at all ages but is more common earlier in life
- Morbidity and mortality
- Morbidity – mental retardation, paralysis, seizures, rigidity, speech or visual deficits
- Mortality ~ 25%, more common in AIDS patients
- Basilar meningitis is the most common presentation
- Masslike, typically supratentorial and parenchymal, may be large
- Tuberculous abscess
- Large (often >3cm), solitary and frequently multiloculated
- Ischemia and infarction may also result from vasculitis
- Tuberculous meningitis:
- Isodense to hyperdense exudate effacing the CSF spaces
- T1WI and T2WI
- Exudate isointense to hyperintense
- Increased intensity in affected CSF spaces
- Helpful for detecting infarct as a complication
- Basilar predominant meningeal enhancement
- Round or lobulated mass with surrounding edema
- Rare calcifications
- Solid or ring enhancing
- Hypointense to parenchyma
- May have hyperintense rim
- Noncaseating: hyperintense
- Caseating: hypointense
- May show central restriction
- Noncaseating: nodular, homogeneous enhancement
- Caseating: peripheral rim enhancement with variable signal centrally
- TB Abscess:
- Solitary, multiloculated ring-enhancing
- Hyperintense lesion with hypointense rim and vasogenic edema
- Multiloculated ring enhancement
- Imaging Recommendations
- Standard protocol MR (including DWI) with intravenous contrast
- Can be very difficult to distinguish from other infectious processes or metastatic disease when in the form of an abscess or Tuberculoma. However, the homogeneous low central T2 signal intensity of a caseating tuburculoma is very uncommon in other entities. When there is involvement of the basilar cisterns, TB should be at the top of your differential with coccidioidomycosis, racemose neurocysticercosis and other granulomatous processes.
For more information, please see the corresponding chapter in Radiopaedia.
Contributor: Sean Dodson, MD
Ahluwalia V, et al. MRI Spectrum of CNS Tuberculosis. JIACM. 2013; 14(1):83-90.
Kim TK, et al. Intracranial Tuberculoma: Comparison of MR with Pathologic Findings. AJNR. 1995; 16:1903-08.
Rabelo NN, et al. Differential Diagnosis between Neoplastic and Non-Neoplastic Brain Lesions in Radiology. Arq Bras Neurocir. 2016. Doi: 10.1055/s-0035-1570362.
Smith AB, et al. Central Nervous System Infections Associated with Human Immunodeficiency Virus Infection; Radiologic-Pathologic Correlation. Radiographics. 2008; 28(7):2033-58.
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