CLINICAL RADIOLOGY OF
DR. PIYUSH OJHA
DEPARTMENT OF NEUROLOGY
GOVT MEDICAL COLLEGE, KOTA
• Approximately 10% of all patients with Tuberculosis have CNS
• Greater prevalence in immunocompromised patients and is
seen in ~ 15-20 % of cases of AIDS-related TB.
• Synchronous Extraneural TB may be present in ~50% cases
and may serve as an important clue to the diagnosis of CNS
SPECTRUM OF LESIONS IN CNS TB
• TB meningitis
• Tuberculous granuloma (Tuberculoma)
• Miliary and leptomeningeal granuloma
• Tuberculous abscess
• Tuberculous encephalopathy
• Tuberculous cerebritis
• Vasculitis and infarction
• Cranial neuropathy
• Calvarial tuberculosis, subdural and epidural abscess
• Non-osseous spinal cord tuberculosis
TUBERCULAR MENINGITIS (TBM)
• Most common manifestation of CNS TB in all age groups.
• Result from either haematogenous spread or rupture of
subpial or subependymal focus (Rich focus).
• Enhancing exudate in the basal cisterns is the most common
and also a relatively specific manifestation of leptomeningeal
tuberculosis on CT and MRI images.
• Meningeal enhancement has been found in up to 90% of
cases and is considered to be the most sensitive feature of
• On contrast enhanced CT images, the obliteration of the basal
cisterns by isodense or mildly hyperdense exudates is the
most common finding in TBM.
• The findings are better appreciated on MR imaging than on
CT, especially on postcontrast MR images which show the
enhancing cisternal exudates and leptomeningeal
Contrast-enhanced CT in a patient with TBM demonstrating
marked enhancement in the basal cistern and meninges, with
dilatation of the ventricles
Contrast-enhanced CT scan of a child with TBM demonstrating
acute hydrocephalus and meningeal enhancement.
• Magnetic resonance imaging (MRI) with gadolinium
enhancement is the preferred method of initial
• MRI is the most sensitive test for detecting the extent of
leptomeningeal disease and is superior to CT scan in
detecting parenchymal abnormalities, such as tuberculomas,
abscesses, and infarctions and also readily depicts
• Pre-contrast MRI cannot detect pathological signal from
meningeal inflammation or basal exudates in early stages.
However, in later stages there may be widening of
subarachnoid spaces with associated T1 and T2 shortening of
• Post-contrast T1 images show diffuse meningeal
enhancement around basal cisterns and Sylvian fissures .
• Appearance is nonspecific and has a wide differential
diagnosis that includes meningitis from other infective agents,
inflammatory diseases such as RA, Sarcoidosis and
• Parmar et al. demonstrated that postcontrast fluid
attenuation inversion recovery (FLAIR) images may have a
higher specificity compared to contrast-enhanced T1-
weighted images in detection of leptomeningeal
• Magnetization transfer spin echo imaging following contrast
injection is superior to the conventional postcontrast
imaging in demonstrating meningeal inflammation.
• In later stages, there may be widening of subarachnoid
• Diagnostic triad of tubercular meningitis:-
– Presence of basal exudates
– Infarcts and
• It is considered almost 100% specific but has lower sensitivity,
Axial Contrast-enhanced T1-weighted MRI images shows florid
meningeal enhancement that is most pronounced within the
Axial Postcontrast T1-weighted MR images in a patient demonstrate
enhancing basilar exudates and leptomeningeal enhancement along with a
small tuberculoma in right temporal region and hydrocephaly (more severe in
• Magnetization transfer spin echo (MT-SE) imaging following
contrast injection is superior to conventional post-contrast
imaging in demonstrating meningeal inflammation.
• Quantitative MT ratio is also of value in differentiation of
TB meningitis from other chronic meningitis.
• Significantly lower MT ratio is seen in TB meningitis than
pyogenic and fungal meningitis and significantly higher MT
ratio than viral meningitis.
• Communicating hydrocephalus – Most common complication
of TBM and is caused by blockage of the basal cisterns by
• In some cases, the hydrocephalus may be noncommunicating,
resulting from obstruction due to tuberculoma or rarely
• Ischemic infarcts are also common, seen in 20-40% cases,
mostly within basal ganglia and internal capsule regions,
resulting from vascular compression and occlusion of small
perforating vessels, particularly Lenticulostriate and
Thalamoperforating arteries. (Necrotizing Arteritis).
• Cranial nerve involvement is seen in 17-40% cases, most
commonly affecting II,III,IV and VII th cranial nerves.
• Tuberculous meningitis may also cause dural venous sinus
thrombosis with resultant hemorrhagic infarct.
• Rarely, tuberculosis may present as isolated dural venous
sinus thrombosis without any evidence of meningitis or its
Plain CT Brain showing infarcts involving right basal ganglia and
internal capsule after the appearance of Vasculitis in the
thalamoperforating arteries in a child treated for TBM.
Tuberculous meningitis complicated with B/L Infarcts
Axial MR images demonstrate acute bilateral ischemic infarcts,
which are hyperintense on the DW image and hypointense on
the ADC image
Coronal Postcontrast T1-weighted MR image demonstrates a
filing defect within dilated left sigmoid sinus (black arrow)
Dural venous sinus
thrombosis as an only
imaging evidence of
TBM in a 45-year-old
male who presented
with headache and
cerebrospinal fluid PCR
MR Venogram reveals non-visualization of Left transverse and
sigmoid sinuses (white arrow).
PARENCHYMAL GRANULOMA (TUBERCULOMA)
• Tuberculomas -Most common parenchymal lesions in CNS TB.
• Lesion may be solitary, multiple, or Miliary.
• May be seen with or without meningitis.
• May be seen anywhere within the brain parenchyma.
• Most commonly occurs within the frontal and parietal lobes.
• Predominance of Infratentorial lesions in children.
• Granulomas usually involve the cortico-medullary junction
and periventricular region as expected from haematogenous
• Histologically, the mature tuberculoma is composed of a
necrotic caseous center surrounded by a capsule that contains
fibroblasts, epithelioid cells, Langhans giant cells, and
• On Non-contrast CT scans, tuberculoma may be isodense,
hyperdense, or of mixed density.
• On contrast-enhanced CT, it may present a pattern of ring-like
enhancement or, less likely, as an area of nodular or irregular
• A central nidus of calcification with surrounding ring-like
enhancement, known as the Target sign, suggests the
• Nonenhanced MR studies show a mixed, predominantly low
signal intensity lesion with a central zone of high signal
intensity and surrounding high signal intensity edema on T2-
weighted or FLAIR images.
• The central high signal intensity zone corresponds to
Caseating necrosis, and the low signal intensity of the capsule
may be related to a layer of collagenous fibrosis with high
protein concentration and low water content.
• Like contrast-enhanced CT, Post-contrast MR images usually
show a pattern of ring-like enhancement
• Non-caseating granuloma: It is usually iso-/hypointense on
T1 and hyper-intense on T2-weighted images. Homogeneous
enhancement is seen with gadolinium.
• Caseating Solid granuloma: usually hypo-intense on T1 and
strikingly hypo-intense on T2-weighted images. This relative
hypo-intensity is attributed to the granulation tissue and
compressed glial tissue in the central core resulting in greater
cellular density than the brain parenchyma.
• Granuloma with central liquefaction:
– appears centrally hypointense on T1, and hyperintense on
T2-weighted images with a peripheral hypointense rim on
– The low signal intensity of the capsule may be related to a
layer of collagenous fibers with high protein concentration
and low water content and a layer of outer inflammatory
– Gd-DTPA-enhanced T1W images show rim enhancement in
– The edema surrounding the granuloma is relatively less
than pyogenic abscess. However, at times it is significant in
the early stage.
• The differential of tuberculomas is essentially is the
differential of ring-enhancing lesions, and includes:
• Other infections
– Cerebral toxoplasmosis
– CNS cryptococcosis
– Bacterial cerebral abscesses
• Cerebral metastases
• CNS lymphoma
Axial non-contrast CT image
shows a calcified lesion in the
left periventricular region, with
Contrast-enhanced axial CT
image shows ring enhancement
around the calcified lesion,
suggestive of Target sign
T2-weighted MRI of a biopsy-proven, Right parietal tuberculoma.
Note the low–signal-intensity rim of the lesion and the
surrounding hyperintense vasogenic edema.
T2-W axial MR image shows
hypointense lesions in the bilateral
gangliothalamic regions (R>L), with
perilesional oedema and associated
Post-contrastT1 W axial image shows
multiple ring-enhancing lesions, along
with abnormal leptomeningeal
Caseating tuberculoma without liquefaction
T2-W axial MR image shows a
centrally hyperintense granuloma
with a peripheral hypointense rim
with associated perilesional
Gadolinium-enhanced T1-W axial
image shows peripheral ring
enhancement of the same lesion.
Caseating tuberculoma with liquefaction
Multiple supra- and infratentorial tuberculomas in a 27-year-old
female with history of Pulmonary tuberculosis.
Tuberculomas are seen as multiple small ring enhancing lesions
without peripheral edema in Axial and Sagittal
postcontrast T1-weighted MR images
• MR spectroscopy(MRS) shows prominent lipid peaks
in Tuberculomas as compared to other lesions such
as metastasis and high-grade gliomas which shows
lipid peaks in addition to other metabolite peaks like
T2-weighted MRI of a patient with a tuberculoma in the
right parietal lobe.
MRS of a patient with an Intracerebral tuberculoma
demonstrating an elevated lactate peak (LA) with diminished N-
acetyl aspartate (NAA) and choline (CH) peaks typical of an
inflammatory mass in the brain.
• Disseminated / Miliary tuberculoma:
– a subtle clinical event demonstrated in patients with
miliary pulmonary tuberculosis who have no clinical brain
– May also occur in patients with TB meningitis.
– Since the dissemination is hematogenous, the lesions are
usually located at the corticomedullary junctions.
– The lesions are tiny (2-3 mm in diameter) scattered small
granulomas that may be invisible on noncontrast
– These lesions occasionally can be seen as small
hypodensities on CT scan.
– Post-contrast shows numerous round areas of intense
– Leptomeningeal granulomas show similar appearance;
however, they are seen located in the sulcal spaces and
• In visible lesions, MRI shows small lesions that are
hypointense on T2-weighted sequences.
• Postcontrast T1-weighted MR images show numerous, round,
small, homogeneous, enhancing (usually ring enhancement)
• Invisible lesions that may or may not enhance after
intravenous injection of gadolinium can be clearly visible on
magnetization transfer spin echo T1-weighted imaging with or
Contrast-enhanced CT scan shows multiple bilateral ring-
enhancing lesions (Tuberculomas) in the frontal and parietal
Axial Contrast-enhanced T1-weighted MR image demonstrates
multiple enhancing Caseating and Non-Caseating tuberculomas,
predominantly within the left frontal and parietal lobes
Miliary CNS tuberculosis
Axial Contrast-enhanced T1-weighted MR image shows multiple
small high-signal-intensity foci within both cerebral hemispheres
T1-weighted gadolinium-enhanced MRI in a patient with multiple
enhancing tuberculomas in both cerebellar hemispheres.
Miliary CNS tuberculosis
Miliary brain tuberculosis in a 20-year-old female with 3-month
history of cough, weight loss, newly added generalized
headache, dizziness, nausea, and vomiting.
No obvious abnormality in the T1- and T2-weighted images.
Miliary BRAIN tuberculosis
Axial Postcontrast T1-weighted MR image shows numerous bilateral
tiny enhancing nodules scattered throughout the brain parenchyma.
• Sometimes, healed tuberculomas appear as calcified foci on
• Similarly, calcification in the basal cisterns has been
demonstrated a few years after meningeal tuberculosis.
Axial noncontrast CT image shows two calcified lesions in right
frontal lobe without edema or mass effect
• Occur in less than 10% of patients with CNS TB.
• Characterized by a central area of liquefaction with pus.
• More common in the elderly and immunocompromised.
• May be solitary or multiple and are frequently multiloculated.
• Tuberculous abscess is different from tuberculomas which
contain central caseation and liquefaction mimicking pus.
• On imaging, a TB abscess may be indistinguishable from a
Caseating tuberculoma or a pyogenic abscess.
• However, TB abscess has thinner and smoother enhancing
walls, is larger (> 3 cm in diameter), and it has peripheral
oedema and mass effect.
• The Tuberculous abscess is hypodense with peripheral edema
and mass effect on CT.
• On T2-weighted MR images, central necrotic area has
increased signal intensity.
• Postcontrast images demonstrate ring enhancement that is
usually thin and uniform, although it may be irregular and
thick, especially in immunocompromised patients
• Differentiation of TB abscess from pyogenic abscess can be
done with MRS and Magnetization transfer (MT) imaging.
• On MR spectroscopy, TB abscess does not demonstrate amino
acids peak at 0.9 ppm as compared to pyogenic abscess
which shows amino acids peak at 0.9 ppm.
• MT ratio in a TB abscess is lower than that found in a pyogenic
Multilobulated enhancement of the lesion is seen in the
Postcontrast CT images.
22-year-old female with
hemiparesis, left facial
paresis, and sixth and
seventh cranial nerves
Axial T1-weighted image shows a predominantly isosignal lesion
in the left hemisphere of cerebellum with extension to CPA and
prepontine cistern accompanied by marked peripheral edema
and mass effect
tumor in a 22-year-old
female with Miliary
right hemiparesis, left facial
paresis, and sixth and
seventh cranial nerves
Multilobulated enhancement of the lesion is seen in the
Postcontrast T1-weighted images
T1-weighted gadolinium-enhanced MRI in a child with a
tuberculous abscess in the left parietal region.
Note the enhancing thick-walled abscess.
Axial Pre- and postcontrast T1-weighted MR images in a 38-year-old male
with cognitive and speech disorders show two hypointense lesions in both
frontal lobes with peripheral edema having thick ring-like enhancement
Axial postcontrast T1-weighted MR images in a 22-year-old female with
pulmonary miliary tuberculosis and 3-month history of headache, nausea,
vomiting, and recent seizure demonstrate bifrontal irregularly enhancing
lesions with mild peripheral edema.
• A syndrome exclusively present in infants and children,
described by Udani and Dastur in Indian children with
• Characteristic features of this entity are the development of a
diffuse cerebral disorder in the form of convulsions, stupor,
and coma, without signs of meningeal irritation or focal
• Pathologically, there is diffuse oedema of cerebral white
matter with loss of neurons in the grey matter.
• Neuroimaging shows severe unilateral or bilateral cerebral
• On T2-weighted images, hyperintensity is seen in white
matter suggesting myelin loss.
• These patients also show diffuse alteration of MT ratio in
white matter which reverts back to normal after clinical
Axial T2-W MR images show diffused white matter oedema with
gyral swelling with associated Hydrocephalus.
The patient had a history of ATT therapy for cerebral tuberculosis
about six months prior to this presentation.
• TB cerebritis is rare but has specific clinical,
radiological, and pathological manifestations.
• The involved areas show extensive inflammatory
exudates, Langerhans’ giant cells, reactive parenchymal
changes, and diffuse Caseating and noncaseating
microgranulomas in the cortex.
• CT imaging shows intense focal gyral enhancement
• On MR imaging, focal cerebritis appears hypointense
on T1, hyperintense on T2 and small areas of patchy
enhancement on post-contrast scan.
Post-contrast axial CT image showing intense focal gyral
enhancement in the region of the left sylvian fissure, with
surrounding cerebral oedema, suggestive of Focal cerebritis
VASCULITIS & INFARCTION
• Intracranial Vasculitis is a common finding in patients dying
from TB meningitis and a major factor contributing towards
residual neurological deficits.
• Vasculitis is initiated by direct invasion of vessel wall by
mycobacterium or may result from secondary extension of
• Infarction resulting from vascultits is more common in infants
and children and is most frequently seen at basal ganglia,
cerebral cortex, Pons, and cerebellum.
• The MCA territories are commonly affected and the infarcts
are frequently bilateral.
• MR imaging shows areas of hyperintensities on T2-weighted
• Diffusion weighted images are the gold standard in acute
• Commonly seen in association with TBM.
• Partly due to vascular compromise resulting in
ischemia of nerve or may be due to entrapment of
nerves by the exudates.
• Large tuberculomas may also compress the nerves,
resulting in compression neuropathy.
• Commonly affected are II, III, IV,and VII cranial nerves.
• On MR imaging, the affected nerves appear thickened
and may show hyper-intensity on T2-weighted images.
• On contrast, the proximal portion of the nerve root is
commonly affected and may show enhancement.
• Calvarial involvement in tuberculosis is rare.
• Before the advent of effective chemotherapy, calvarial
tuberculosis was estimated to represent 0.2 - 1.3% of all cases
of skeletal tuberculosis.
• About 50% of the cases reported in the literature were in
patients younger than 10 years, and 70-90% were younger
than 20 years.
• The disease is rarely seen in infants.
• It is believed that calvarial tuberculosis occurs by
haematogenous seeding of bacilli into the diploic space.
• Tuberculosis may present as a subgaleal swelling (Pott’s puffy
tumour) with a discharging sinus when the outer table is
• Involvement of the inner table is associated with formation
of underlying extradural granulation tissue.
• MRI, in most cases, leads to a conclusive diagnosis.
• Proton density and T2-weighted images show a high-signal
intensity soft-tissue mass within the defect in bone.
• This may project into the subgaleal and/or epidural spaces
and show peripheral capsular enhancement on the
• MR imaging is sensitive in demonstrating changes in the
meninges and the ventricular walls and in detecting
parenchymal foci of involvement.
DURAL & SUBDURAL PATHOLOGY
• Tuberculous pus formation occurs between the duramater
and the leptomeninges and may appear loculated.
• It appears iso- to hypo-intense on T1W images and
hyperintense on T2W.
• The dural granulomas appear isointense on T1W images and
hypo- to isointense on T2W.
• Rim enhancement can be seen on post-contrast images.
• Lesions generally appear to be iso-intense on T1W images,
and have mixed intensity on T2W images.
• In post-contrast images, uniform enhancement can be seen if
the TB inflammatory process is phlegmonous in nature
whereas peripheral enhancement is seen if true epidural
abscess formation or caseation has developed .
• Epidural Tuberculous abscess may occur as primary lesions or
may be seen in association with an underlying tuberculous
Tuberculous abscess with epidural and subdural empyema and
Coronal and sagittal postcontrast T1-Wt MRI images demonstrate epidural
and subdural collections over the bifrontal cerebral convexities with
intraparenchymal and calvarial extension. Peripheral edema, irregular marked
enhancement of the lesion as well as dural enhancement are evident.
The bony destructive lytic lesions are seen in the bone window CT image
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