Diagnostic Imaging of Bilateral Abnormalities of the Basal Ganglia & Thalamus

1. C.N.S.
Bilateral Abnormalities of The Basal
Ganglia & Thalamus

2. Mohamed Zaitoun
Assistant Lecturer-Diagnostic Radiology
Department , Zagazig University Hospitals
Egypt
FINR (Fellowship of Interventional
Neuroradiology)-Switzerland
zaitoun82@gmail.com

5. Knowing as much as
possible about your enemy
precedes successful battle
and learning about the
disease process precedes
successful management

6. Bilateral Abnormalities of The Basal Ganglia &
Thalamus
(i) MR Imaging Anatomy of The Basal Ganglia &
Thalamus
(ii) Blood Supply
(iii) Normal Changes
(iv) Pathological Changes
(v) Radiologic Assessment of Abnormalities of the
Basal Ganglia and Thalamus
(vi) Bright on T1 Basal Ganglia

7. (i) MR Imaging Anatomy of The Basal Ganglia &
Thalamus :
-The deep gray matter nuclei include the basal
ganglia and thalamus , paired structures that are
situated at the base of the forebrain and have
wide connections to the cortex and other parts of
the brain
-Caudate nucleus , putamen , globus pallidus ,
subthalamic nucleus , substantia nigra & ventral
tegmentum

8. -Head of caudate nucleus + putamen = corpus
striatum
-Putamen + globus pallidus = lentiform nucleus
-On axial brain images , the lentiform nucleus
and the head of the caudate nucleus can be
visualized as paired symmetric structures
located between the lateral ventricle and the
insular cortex

9. -The lentiform nucleus which includes the putamen
and the more medially located globus pallidus , is
separated from the caudate head and the
thalamus by the anterior and posterior limbs of
the internal capsule respectively
-At MR imaging , the caudate nucleus and putamen
are isointense relative to the cortical gray matter
with all pulse sequences and do not enhance
after contrast material injection

10. Axial T2-weighted MR
image shows the
normal anatomy of
the deep gray matter
structures
C = caudate nucleus
G = globus pallidus
L = lentiform nucleus
P = putamen
T = thalamus

11. -The globus pallidus is typically slightly hypointense
relative to the putamen , a normal feature that is
attributable to progressive iron deposition as one
ages
-The functions of the basal ganglia are complex ,
these structures are mainly involved in the
production of movement and are a part of the
extrapyramidal motor system but they may also
be involved in memory , emotion and other
cognitive functions

12. -The putamen and globus pallidus are rich in
mitochondria , vascular supply ,
neurotransmitters and chemical content
compared with other areas in the brain and
their high metabolic activity and increased
utilization of glucose and oxygen make them
vulnerable to metabolic abnormalities and
many systemic or generalized disease
processes

13. -Hence , when the basal ganglia are seen to be
affected at MR imaging , the clinical signs and
symptoms can vary from movement disorders
(e.g. chorea, tremors, bradykinesia, dystonia)
to coma, depending on whether there is focal
involvement of the basal ganglia in isolation or
generalized metabolic derangement with
widespread brain necrosis

14. -The thalamus is a midline structure situated
between the cerebral hemispheres and the
midbrain , with paired symmetric portions
located on either side of the third ventricles
-It consists of multiple nuclei that are responsible
for relaying sensory and motor signals to and
from the cerebral cortex and are involved in
regulating consciousness , sleep and alertness ,
hence , lesions affecting the thalamus often
result in disorders of consciousness and
abnormalities of sensation

15. (ii) Blood Supply :
-The basal ganglia derive their blood supply from
the medial and lateral lenticulostriate arteries
which arise from the anterior and middle
cerebral arteries , respectively
-On the other hand , the thalamus derives its
arterial supply from the first and second parts of
the PCA with contributions from the PCOM
-Venous drainage of both the basal ganglia and the
thalamus is into the deep (rather than superficial)
venous system

16. -The superior and inferior thalamostriate veins
along with several smaller surface veins drain
into the paired internal cerebral veins
-These join the basal vein of Rosenthal to form the
great vein of Galen at a point inferior to the
splenium of the corpus callosum where the great
vein of Galen joins the inferior sagittal sinus to
form the straight sinus
-The straight sinus then continues backward to the
torcula and joins the superficial dural venous
sinus system

17. (iii) Normal Changes :
1-Age related :
-Incidence of calcification of lentiform nucleus
increases with age (high attenuation CT ,
increased T1 signal MRI)
-Increased iron deposition causes reduced T2
signal on MRI in lentiform nucleus

18. CT obtained
without the use of
CM demonstrates
bilateral
physiologic
calcification
(arrowheads) in
the basal ganglia

19. Axial gradient-
recalled echo
image clearly
depicts physiologic
iron deposition in
the globus pallidus
(arrowheads) as
symmetric
hypointense areas

20. 2-Enlarged Perivascular Spaces :
-The lentiform nucleus may exhibit enlarged
Perivascular spaces (Virchow-Robin) , CSF
signal on all sequences

21. Axial T2 shows
well-defined
rounded foci
(arrows) that are
isointense relative
to CSF , findings
that represent
prominent
Virchow-Robin
(perivascular)
spaces

22. (iv) Pathological Changes :
1-Toxins
2-Acquired Metabolic Disease
3-Inherited Metabolic Disease
4-Vascular
5-Neurodegenerative
6-Infection (common)
7-Tumors
8-Others

23. 1-Toxins :
a) Exogenous Toxins
b) Hepatic Encephalopathy
c) Prolonged Total Parenteral Nutrition
d) Kernicterus

24. a) Exogenous Toxins :
-Carbon monoxide , methanol & cyanide
-See (Toxic & Metabolic Diseases)
b) Hepatic Encephalopathy :
-See (Toxic & Metabolic Diseases)
c) Prolonged Total Parenteral Nutrition :
-Can lead to excess manganese deposition in
basal ganglia , increased signal in T1
d) Kernicterus :
-Increased signal in globus pallidus on T1 & T2

25. 2-Acquired Metabolic Disease :
a) Hypoglycemia
b) Nonketotic Hyperglycemia
c) Osmotic Myelinolysis
d) Hemolytic Uremic Syndrome
e) Hypoparathyroidism (common)
f) Pseudohypoparathyroidism
g) Pseudo-pseudohypoparathyroidism
h) Hyperparathyroidism

26. a) Hypoglycemia :
-See (Toxic & Metabolic Diseases)
b) Nonketotic Hyperglycemia :
-CT typically shows bilateral or, rarely, unilateral
pallidal or caudate hyperattenuation
-At MR imaging , the abnormal areas are
characteristically hyperintense on T1 and of
variable intensity on T2

27. Nonketotic hyperglycemia in a 68 year old woman with uncontrolled diabetes
and choreoathetoid movements , axial T1 reveals bilateral hyperintense
pallidal areas (arrows)

28. c) Osmotic Myelinolysis :
-See (White Matter Diseases)

29. 3-Inherited Metabolic Disease :
a) Wilson’s Disease
b) Mitochondrial Cytopathies (Leigh’s Disease)
c) NBIA
d) Wernicke’s Encephalopathy
e) Krabbe’s Disease

30. a) Wilson’s Disease :
1-Definition
2-Clinical Picture
3-Radiographic Features

31. 1-Definition :
-Caused by the accumulation of copper resulting
from a deficiency of ceruloplasmin , its serum
transport protein
-This disease is also known as hepatolenticular
degeneration , affects the liver , brain and
other tissues

32. 2-Clinical Picture :
a) Dysarthria
b) Dystonia
c) Tremor
d) Choreoathetosis
e) Liver failure
f) Classic Kayser-Fleischer rings at
ophthalmologic examination

33. 3-Radiographic Features :
a) CT :
-Low density basal ganglia
b) MRI :
*T1 :
-Signal hyperintensity at T1-weighted imaging in
patients with Wilson disease is most
commonly found in the bilateral basal ganglia
and ventrolateral thalami

34. Wilson disease in a 49 year old woman , axial T1 shows bilateral regions of
increased signal intensity within the globus pallidus (arrows) and thalamus
(arrowheads)

35. *T2 :
-T2 hyperintensity is also seen typically
involving:
1-Basal ganglia :
-Putamen
-Globus pallidus
-Caudate nucleus
2-Thalamus : ventrolateral aspect

36. T2 shows bilaterally symmetric areas of abnormal T2 prolongation in the
ventrolateral thalamus (arrowheads) , putamina (white arrows) and
caudate nuclei (black arrows)

37. -Signal hyperintensity in the midbrain combined
with sparing of the superior colliculus , red
nucleus and portions of the substantia nigra ,
this combination of findings produces the
(face of the giant panda) appearance on axial
T2

39. CP = Cerebral
Peduncles
SN = Substantia
Nigra
R = Red nucleus
VTA = Ventral
Tegmental Area
PCA = Posterior
Cerebral Artery
MB = Mammillary
Body

41. Face of the giant
panda
it is produced as a
result of high signal
intensity in the
tegmentum with
preserved normal
signal intensity in the
red nuclei (eyes of the
panda) and substantia
nigra (ears of the
panda) and
hypointensity of the
superior colliculi (chin
of the panda

42. b) Mitochondrial Cytopathies (Leigh’s Disease) :
-See (White Matter Diseases)

43. c) Neurodegeneration with Brain Iron
Accumulation (NBIA) :
1-Defintion
2-Radiographic Features

44. 1-Defintion :
-Named also ( pantothenate kinase–associated
neurodegeneration )
-NBIA is a heterogeneous group of disorders
characterized by brain degeneration and
excessive iron deposition in the basal ganglia

45. 2-Radiographic Features :
-MRI :
*T1 :
-The bilateral globus pallidus may sometimes
appear hyperintense
*T2 :
-Low signal in central globus pallidus on T2 due to
iron deposition with surrounding high signal ( eye
of the tiger )

47. Pantothenate kinase–associated neurodegeneration in a 1 year old boy , (a) T1
shows mild bilateral symmetric hyperintensity of the globus pallidus (arrows) ,
(b) T2 shows bilateral areas of high signal intensity in the center of the globus
pallidus interna , surrounded by low signal intensity producing the “eye of the
tiger” sign (arrowheads)

48. Coronal T2 shows bilateral hyperintense pallidal areas on background areas
of T2 shortening (eye-of-the-tiger sign) (arrows)

49. d) Wernicke Encephalopathy :
-See (White Matter Diseases)
e) Krabbe’s (Globoid) Leukodystrophy :
-See (White Matter Diseases)

50. 4-Vascular :
a) Lacunar Infarcts
b) Arterial Occlusion
c) Deep Cerebral Venous Thrombosis
d) Hypoxic Ischemic Encephalopathy

51. a) Lacunar Infarcts (small deep) :
-CT:
Well defined low attenuation lesions
-MRI :
-High T2 signal

52. b) Arterial Occlusion :
-Bilateral acute synchronous arterial infarctions
of the thalamus are not uncommon and are
usually the result of occlusion of the rostral
basilar artery
-These acute infarcts characteristically
demonstrate hyperintensity on T2 and
restricted diffusion on diffusion-weighted

53. (a) DWI shows bilateral hyperintense areas in the paramedian thalamus (arrows) , (b)
TOF shows occlusion of the rostral portion of the basilar artery (arrow) , (c) & (d) :
NECT obtained 3 days later show bilateral subacute infarcts of the thalamus
(arrows in c) and an infarct in the right cerebellar hemisphere (arrow in d)

54. c) Deep Cerebral Venous Thrombosis :
-Venous hypertension and cerebral edema caused
by deep CVT typically result in T2 prolongation in
the thalamus usually involving the internal
capsule , basal ganglia and deep white matter as
well
-Hemorrhagic conversion is common resulting in
decreased signal with all pulse sequences but
especially with gradient recalled echo sequences

55. -Simultaneous bilateral involvement of the
thalamus and basal ganglia in the appropriate
clinical setting should prompt a search for
subtle signs of venous thrombosis such as loss
of flow void and hyperintense thrombus in the
straight sinus , vein of Galen and internal
cerebral veins on conventional MR images

56. (a) T2 shows bilateral hyperintense areas in the thalamus (arrowheads) and caudate heads (arrows) , (b) Phase-
contrast MRV shows absence of normal flow in the internal cerebral veins, vein of Galen and straight sinus
(arrows) with preservation of the superior sagittal and transverse sinuses , (c) Phase-contrast MR venogram
obtained in a different patient depicts the internal cerebral veins (black arrows) , basal vein of Rosenthal (curved
arrow) and vein of Galen (straight white arrows) which drains into the straight sinus (arrowheads) ISS = inferior
sagittal sinus , SS = sigmoid sinus , SSS = superior sagittal sinus , TS = transverse sinus

57. d) Hypoxic Ischemic Encephalopathy :
-See (Toxic & Metabolic Diseases)

58. 5-Neurodegenerative :
a) Parkinson’s Disease
b) Huntington’s Disease
c) Fahr Disease
d) Creutzfeldt-Jakob Disease

59. a) Parkinson’s Disease :
-See (White Matter Diseases)

60. b) Huntington’s Disease :
-Autosomal dominant inherited disease manifested
by choreiform movements and dementia
-Radiographic Features :
*Caudate nucleus atrophy
*Boxcar appearance of frontal horns
-Caudate head atrophy resulting in enlargement of
the frontal horns

61. -This can be quantified by an number of
measurements :
1-Frontal horn width to intercaudate distance
ratio (FH/CC) :
-The normal mean FH/CC ratio range is 2.2 to
2.6
As the caudate heads reduce in volume the CC
distance will approach the FH distance and the
ratio will approach 1

64. 2-Intercaudate distance to inner table width
ratio (CC/IT) :
-The normal mean FH/CC ratio range is 2.2 to
2.6
As the caudate heads reduce in volume the CC
distance will approach the FH distance and the
ratio will approach 1

66. c) Fahr Disease :
1-Definition
2-Radiographic Features
3-Differential Diagnosis

67. 1-Definition :
-known as bilateral striopallidodentate calcinosis
-Characterized by the bilaterally symmetric
deposition of calcium in the basal ganglia ,
thalamus , dentate nuclei, and centrum
semiovale in the absence of
hypoparathyroidism

68. 2-Radiographic Features :
a) CT :
-Calcification is extensive and has a fairly typical
distribution
-Basal ganglia and thalami :
*Symmetric involvement of caudate , lentiform
nucleus , thalamus and dentate nuclei
*Globus pallidus affected first
-Subcortical white matter

72. b) MRI :
*T1 :
-Contrary to expectation , the calcified areas are
of high signal , attributed to the surface area
of calcium crystals
*T2 :
-Calcified areas demonstrate low to iso-intense
signal

73. (a) Hyperintense signal in T1 , (b) Heterogenous with
FLAIR , (c) Strongly hypointense on T2

74. 3-Differential Diagnosis :
*Hypoparathyroidism or
pseudohypoparathyroidism (end-organ
resistance to parathyroid hormone) which can be
confirmed with measurements of serum calcium ,
phosphorus and parathyroid hormone levels
*Pseudopseudohypoparathyroidism in which there
is no abnormality of calcium metabolism in
asymptomatic patients is another possible
diagnosis in patients with widespread cerebral
calcification

75. d) Creutzfeldt-Jakob Disease :
-See (CNS Infections)

76. 6-Infection (common) :
Cerebral Toxoplasmosis :
See (CNS Infections)

77. 7-Tumors :
a) CNS Lymphoma
b) Primary Bilateral Thalamic Glioma

78. a) CNS Lymphoma :
See (CNS Tumors)

79. Primary CNS lymphoma (confirmed histologically) in a 55-year-old man
with headache , altered mental status and AIDS , (a) T2 depicts
bilateral ill-defined isointense to hypointense areas involving the basal
ganglia and thalamus with extensive perifocal edema , (b) T1+C , the
lesions (arrowheads) demonstrate avid enhancement

80. b) Primary Bilateral Thalamic Glioma :
-Low grade Astrocytoma
-PBTG is a rare but characteristic neoplasm that
demonstrates bilateral involvement of the
thalamus in children and young adults
-CT and MR imaging typically reveal a mass that
symmetrically enlarges both sides of the
thalamus

81. -MRI :
*T1 :
Isointense
*T2 :
Hyperintense
*T1+C :
No enhancement

82. (a) FLAIR shows bilaterally symmetric , well-defined hyperintense areas
and enlargement of the thalamus (arrows) , (b) T1+C , the thalamus
(arrows) demonstrates diffuse hypointensity

83. 8-Others :
a) Neurofibromatosis Type 1
b) Neuro Behcet Disease
c) Flavivirus Encephalitis

84. a) Neurofibromatosis Type 1 :
-High signal intensity lesions seen in the basal
ganglia on T1 & T2 , predominantly involve the
globus pallidus and internal capsules
bilaterally and symmetrically
-See Congenital Disease

85. (a) T2 shows bilateral pallidal areas of hyperintensity (arrows)
that have no mass effect , (b) On T1 , the foci (arrows) appear
hyperintense

86. Type 1 neurofibromatosis in a 20 year old man , axial T1 shows
bilateral symmetric regions of signal hyperintensity in the
globus pallidus (arrowheads)

87. b) Neuro-Behcet Disease :
-Behçet disease is a multisystemic , recurrent
inflammatory disorder of unknown cause ,
autoimmune , infectious and genetic causes
have all been postulated as responsible for
the classic clinical triad of uveitis , oral ulcers
and genital ulcers

88. -Focal or multifocal lesions are common in Neuro-
Behçet disease in the brainstem , basal ganglia
(bilateral involvement in one-third of cases) and
thalamus and, less commonly the white matter of
the cerebral hemispheres and cervicothoracic
spinal cord
-These lesions are hyperintense on T2 are
hypointense on T1 , enhance after contrast
material administration and are typically
associated with vasogenic edema

89. Neuro-Behçet disease in a 49 year-old man with headache and personality
Disorders , axial T2 reveals poorly defined areas of T2 prolongation in both
caudate nuclei and the right lentiform nucleus

90. c) Flavivirus Encephalitis :
-Known as Japanese encephalitis
-The most characteristic MR imaging finding of
Japanese encephalitis is T2 hyperintensity
typically with bilateral involvement of the
posteromedial thalamus
-Intrarlesional hemorrhages and restricted
diffusion have also been described

91. Seropositive Japanese B encephalitis in a 14 year old boy with fever and
malaise , T2 (a) and diffusion weighted (b) reveal asymmetric ill-defined
hyperintense areas in the thalamus (arrows in a) and the left frontal and
parieto-occipital cortex (arrowheads in a)

92. (v) Radiologic Assessment of Abnormalities of
the Basal Ganglia and Thalamus :
-Bilaterally symmetric diffuse abnormalities
involving the lentiform and caudate nuclei in
their entirety typically suggest systemic or
metabolic causes , whereas asymmetric , focal
or discrete lesions affecting only part of the
basal ganglia tend to indicate involvement by
infections or neoplasms

93. -The thalamus is usually involved together with
the basal ganglia
-Bilateral thalamic involvement with no
abnormality of the basal ganglia is less
common and more often due to focal ( arterial
occlusion , flavivirus infection , PBTG ) rather
than generalized abnormalities

94. (vi) Bright on T1 Basal Ganglia :
a) Deposition of Paramagnetic Substances
b) Calcification
c) Hamartomas
d) Indeterminate

95. a) Deposition of Paramagnetic Substances :
1-Hemorrhage
2-Hemorrhagic Infarction
3-Wilson’s Disease
4-Long Term Parenteral Nutrition ( manganese
deposition )
b) Calcification :
-Usually hypointense or isointense on spin echo
sequences , may be hyperintense depending on
crystalline structure

96. c) Hamartomas :
-Neurofibromatosis type 1 , may be high signal
on T1 as well as T2 , globus pallidus , internal
capsule , brainstem & cerebellum , no
perilesional edema or enhancement
d) Indeterminate :
-Chronic liver disease with portocaval shunt