Neuroimaging in Psychiatry

1. NEUROIMAGING IN
PSYCHIATRY
DR.R.G.ENOCH
MD Psychiatry II Yr
GMKMCH, Salem

2. • Introduction
• History
• Imaging techniques
• Neuroimaging in specific psychiatric disorders
• Important signs
• Conclusion

3. INTRODUCTION
• Psychiatric diseases are mainly diagnosed by their symptoms, with little contribution from
observable signs and none from biological markers so far. This places psychiatry in a unique
position compared to other medical disciplines. The defining symptoms will ultimately have to be
investigated in humans with the diverse techniques of neuroimaging.
• Neuroimaging methodologies allow measurement of the structure, function, and chemistry of
the living human brain.
• Have provided information about the pathophysiology of psychiatric disorders that may be useful
for diagnosing illness and for developing new treatments.

4. HISTORY
• 1918 – the American neurosurgeon Walter dandy introduced the technique of Ventriculography by injection of filtered air directly into one
or both lateral ventricles of the brain.
• 1927 – Egas Moniz introduced cerebral angiography
• 1946 – MR phenomenon explained by Bloch & Purcell [1952 – Nobel prize]
• 1963 – 1st instance of SPECT – Kuhn & Edwards
• 1972 – Computerized tomography [Godfrey Hounsfield, Alan Mcleod Cormack, 1979 – Nobel prize]
• 1983 – Compton Camera for SPECT – Manbir Singh & David Doria
• 1985 – DTI – Le Bihan D & Breton E
• 1987 – MR Angiography – Dumoulin
• 1992 – Functional MRI By Richard R. Ernst

5. Godfrey Hounsfield Richard R. Ernst

6. IMAGING PLANES

7. IMAGING TECHNIQUES
• CT
• MRI
• MRS
• DTI
• fMRI
• PET
• SPECT

8. C T

9. • Takes a series of head X-ray pictures from all
vantage points, 360 degrees around a patient's
head.
• Patient is placed on the CT table in a supine
position and the tube rotates around the patient
in the gantry.
• Head CTs are performed at an angle parallel to
the base of the skull, to prevent unnecessary
irradiation of the orbits
• Slice thickness - between 5 and 10 mm for a
routine Head CT.

10. • The amount of radiation that passes through
each angle is digitized and entered into a
computer.
• The image is a digital image and consists of a
square matrix of elements (pixel), each of
which represents a voxel (volume element)
of the tissue of the patient.
• The attenuation coefficient is measured in
terms of hounsefield units.

11. • Hounsefield units for
Air = -1000
Fat = -60 to -120
Water = 0
compact bone = +1000
• Density
1.Hypodense - CSF ,air, Fat. - BLACK
2.Isodense - Brain tissue - GREY
3.Hyperdense - Bone - WHITE

12. CONTRAST CT
•IV infusion of iodine-containing contrast agents increases the appreciation of tumors and areas of
inflammation.
•The blood-brain barrier, normally prevents the passage of contrast agents. But in the presence of
inflammation or tumors, the blood-brain barrier breaks down and allows accumulation of contrast
agents. These sites appear whiter than the surrounding brain.
•CAUTION – Allergy
•The only component better seen on CT scan is calcification, which may be invisible on MRI.

14. Imaging Plane:
•CT images are acquired only in the axial plane.
Windows:
•Images can be "windowed" to bring out different
structures, which is a post processing step.
•"brain window" for neuroimaging to look at the
parenchyma and ventricular system.
•bone window to evaluate the osseous structures and
paranasal sinuses.

15. ABOVE THE LEVEL OF FORAMEN MAGNUM
A. Frontal Lobe
C. Dorsum Sellae
E. Temporal
Lobe
B. Frontal Bone (Superior Surface of Orbital
Part)
D. Basilar Artery
F. Mastoid Air CellsG. Cerebellar Hemisphere

16. AT THE LEVEL OF FOURTH VENTRICLE
A. Frontal Lobe
C. Temporal
Lobe
E. Midbrain
B. Sylvian Fissure (divides frontal, parietal from
temporal)
D. Suprasellar Cistern
F. Fourth VentricleG. Cerebellar Hemisphere

17. ABOVE THE LEVEL OF FOURTH VENTRICLE
A. Falx Cerebri B. Frontal Lobe
C. Anterior Horn of Lateral
Ventricle
E. Quadrigeminal Plate Cistern
D. Third
Ventricle
F. Cerebellum

18. AT THE THIRD VENTRICULAR LEVEL
A. Anterior Horn of the Lateral Ventricle
C. Anterior Limb of the Internal Capsule
E. Posterior Limb of the Internal Capsule
G. Quadrigeminal Plate Cistern
B. Caudate Nucleus (BG)
D. Putamen and Globus Pallidus (BG)
F. Third Ventricle
H. Cerebellar Vermis

19. AT THE LATERAL VENTRICULAR LEVEL
B. Anterior Horn of the Lateral
Ventricle
D. Thalamus
F. Choroid Plexus
A. Genu of the Corpus Callosum
C. Internal Capsule
E. Pineal Gland
G. Straight Sinus

20. ABOVE THE VENTRICULAR LEVEL
B. Frontal Lobe
D. Splenium of the Corpus Callosum
F. Occipital Lobe
A. Falx Cerebri
C. Body of the Lateral
Ventricle
E. Parietal Lobe

21. A. Falx Cerebri
C. Gyrus
B. Sulcus
D. Superior Sagittal Sinus

22. MRI

23. • The principle of MRI is that the nuclei of all atoms are thought to spin about an axis, which is
randomly oriented in space.
• When atoms are placed in a magnetic field, the axes of all odd-numbered nuclei align with the
magnetic field.
• Most abundant odd-numbered nucleus in the brain - hydrogen.
• The axis of a nucleus deviates away from the magnetic field when exposed to a pulse of
radiofrequency electromagnetic radiation oriented at 90 or 180 degrees to the magnetic field.
• When the pulse terminates, the axis of the spinning nucleus realigns itself with the magnetic
field, and during this realignment, it emits its own radiofrequency signal.

26. • MRI scanners collect the emissions of individual realigning nuclei and use computer analysis to
generate a series of two-dimensional images.
• MRI make use of a mathematical operation called a Fourier transform
• By varying the sequence of RF pulses applied & collected, different types of images are created.
• The images can be in the axial, coronal, or sagittal planes.

27. Parameters
• TE (echo time) : time interval in which signals are measured after RF excitation
• TR (repetition time) : the time between two RF excitations is called repetition time
• By varying the TR and TE one can obtain T1WI and T2WI
• In general a short TR (<1000ms) and short TE (<45 ms) scan is T1WI
• Long TR (>2000ms) and long TE (>45ms) scan is T2WI

28. T1WI
• Closely resembles that of CT scan
• Best for visualizing normal neuroanatomy
• Sharp boundaries between grey matter, white matter,
and CSF
• Useful in evaluation of CP angle, cistern& pituitary fossa
• T1 - only sequence that allows contrast enhancement
with gadoliniumdiethylenetriamine pentaacetic acid
(gadolinium-DTPA).
• Gadolinium remains excluded from the brain by the
blood-brain barrier, except in areas where this barrier
breaks down, such as inflammation or tumor - appear
white.

30. T2WI
• T2 pulses last four times as long as T1 pulses, and
the collection times are also extended to
emphasize the signal from hydrogen nuclei
surrounded by water.
• Brain tissue is dark, and CSF is white
• T2 images reveal brain pathology most clearly.
• Less distinct boundaries between white and grey
matter
• Areas within the brain tissue that have
abnormally high water content, such as tumors,
inflammation, or strokes, appear brighter on T2
images

31. INTENSITY
•high signal intensity = white - HYPERINTENSE
•intermediate signal intensity = grey - ISOINTENSE
•low signal intensity = black - HYPOINTENSE

32. FLAIR (Fluid-attenuated inversion recovery)
• FLAIR images are T2-weighted with the CSF signal
suppressed.
• In this method, the T1 image is inverted and added to the
T2 image to double the contrast between gray matter and
white matter.
• Useful for
• imaging cerebral oedema,
• sclerosis of the hippocampus caused by temporal lobe epilepsy and
• for localizing areas of abnormal metabolism in degenerative
neurological disorders.

33. • CSF signal is removed on FLAIR which has two advantages:
1.First, periventricular lesions are better differentiated from CSF
2.Second , infectious exudates may replace CSF in the sulci to appear
hyperintense on FLAIR images

34. TISSUE T1-WEIGHTED T2-WEIGHTED FLAIR
CSF Dark Bright Dark
WHITE MATTER Bright Dark Gray Dark Gray
GREY MATTER Dark Gray Light Gray Light Gray

35. DIFFUSION WEIGHTED IMAGING (DWI)
• The diffusivity of water can provide a mechanism of contrast for MRI.
• Signal in each image pixel is altered based on the diffusivity of water.
• Movement of water molecules is significantly restricted in the intracellular space - this results in
an extremely bright signal on DWI.
• Diffusion, rapidly become restricted in ischemic brain tissue. Visualizes area of ischemic stroke in
1st few hours- earliest to detect ischemia.
• DWI can reveal abnormalities in otherwise normal-appearing tissue, as in regions of edema that
surround a cerebral infarct. Regions with edema show greater signal reductions, because water
can diffuse more readily.

36. • Principle application is in the imaging of white matter where the location, orientation, and
anisotropy of the tracts can be measured
• The architecture of the axons in parallel bundles, facilitate the diffusion of the water molecules
preferentially along their main direction. Such preferentially oriented diffusion is called
anisotrophic diffusion.
• The fiber tracts that run in the same direction as the diffusion gradient of water will show a
greater signal reduction than fibers that run perpendicular.
• DTIs are also used to track fibers. Fiber tracking allows detailed analyses of anatomic
connectivity.

38. PROPERTIES MRI CT
Resolution Higher Lesser
Soft tissue contrast Greater detail Lesser
Bony structures Less detailed More clear and
detailed
S/E Nil Radiation
Claustrophobia Present Absent
Duration of
procedure
Longer Quick
Cost Higher Less expensive
With pacemakers and
metal implants
C / I Can be performed
IMAGING PLANE Any Only axial
Arifacts from bone Absent Present

39. Magnetic Resonance Spectroscopy
• Spectroscopy is the determination of the chemical composition of a substance by observing the
spectrum of electromagnetic energy emerging from it.
• Whereas routine MRI detects hydrogen nuclei to determine brain structure, magnetic resonance
spectroscopy (MRS) can detect several odd-numbered nuclei.
• Hence allows the use of the technique to study many metabolic processes.
• The most commonly used nuclei have been 1H, 31P, and 13C.

40. • The readout of an MRS device is usually in the
form of a spectrum - can also be converted into a
pictorial image of the brain.
• The height of the peak indicates the amount of
the molecule present. Using MRS, the more
metabolite that is present, the taller the peak or
greater the area under the peak.
• The multiple peaks for each nucleus reflect that
the same nucleus is exposed to different electron
environments in different molecules. Thus, the
position in the spectrum indicates the identity of
the molecule in which the nuclei are present.

41. ….MRS
• This technique provides data regarding the levels of
N-acetyl aspartate (NAA, a marker of neuronal density and integrity),
choline (Cho, a marker of cellular density and precursor of neurotransmitter acetyl Choline),
creatine (Cr, a marker of cellular energy),
myo-inositol (mI, a marker of membrane turnover and myelination), and
the complex named Glx formed by Glu and glutamine; both of them are involved in the
synthesis of GABA.

42. NUCLEI USED IN MRS & THEIR USES IN PSYCHIATRY
NUCLEUS CLINICAL USES
1H MRI
19F Measurement of p02, glucose metabolism, and
pH
7Li Pharmacokinetics
23Na MRI
31P Measurement of pH and the concentrations of
ATP and GTP
14N Measurement of glutamate, urea, ammonia
13C Analysis of metabolite turnover rate,
Pharmacokinetics
17O Measurement of metabolic rate
2H Measurement of perfusion

43. Functional MRI
• A new sequence is the T2 or blood oxygen level-dependent (BOLD) sequence, which detects levels
of oxygenated hemoglobin in the blood.
• Neuronal activity - local increase in blood flow, which in turn increases the local oxygenated
hemoglobin concentration.
• This change can be detected essentially in real time with the T2 sequence, which thus detects the
functionally active brain regions. This process is the basis for the technique of fMRI.

46. • fMRI is useful to localize neuronal activity to a particular lobe or subcortical nucleus or even to a
single gyrus.
• fMRI detect tissue perfusion not the neuronal metabolism.
• First, a routine T 1 MRI image is obtained; then the T2 images are superimposed to allow more
precise localization.
Advantages
• Possible to study both cerebral anatomy & Functional Neurophysiology using a single technique
• No radioactive isotopes used, a great advantage over PET and SPECT.
• Used in criminal psychiatry or federal investigations as a lie detector
…fMRI

47. Limitations
1.The volume of brain in which blood flow increases exceeds the volume of activated neurons by
about 1 to 2 cm and limits the resolution of the technique. Sensitivity & resolution can be improved
by using iron oxide particles.
2.Two tasks that activates neurons 5 mm apart will yield overlapping signals on fMRI & thus are
indistinguishable by this technique.
3.Procedure takes 20 Minutes to 3 hours, during which the subject’s head must remain in exactly
the same position.
…fMRI

48. SPECT
• Manufactured radioactive isotopes are used to study regional differences in cerebral blood flow
within the brain.
• radioactive isotopes emit single gamma ray.
• the pattern of photon emission is recorded according to the level of perfusion in different regions
of the brain.
• As with fMRI, it provides information on the cerebral blood flow, which is highly correlated with
the rate of glucose metabolism, but does not measure neuronal metabolism directly.
• SPECT uses compounds labelled with single photon-emitting isotopes:
1. iodine- 123,
2. technetium-99m, and
3. xenon- 133.

49. 1. Xenon- 133 is a noble gas that is inhaled directly and quickly enters the blood and is distributed
to areas of the brain as a function of regional blood flow – but can measure blood flow only on
the surface of the brain, which is an important limitation.
2. Assessment of blood flow over the whole brain with SPECT requires the injectable tracers,
technetium-99m-D,L-hexamethylpropyleneamineoxime (HMPAO) or iodoamphetamine. These
isotopes are attached to molecules that are highly lipophilic and rapidly cross the blood-brain
barrier and enter cells. Thus, over time, the tracers are concentrated in areas of relatively
higher blood flow.
3. Iodine- 123-labeled ligands can be used to study muscarinic, dopaminergic, and serotonergic
receptors
…SPECT

50. PET
• The isotopes used in PET decay by emitting positrons
• The positrons bind with and annihilate electrons, thereby
giving off photons that travel in 180-degree opposite
directions.
• the resolution of the PET image is higher - 3 mm, which is
the distance positrons move before colliding with an
electron.
• Relatively few PET scanners are available because they
require an onsite cyclotron to make the isotopes.
• The most commonly used isotopes in PET are
• fluorine- 18 (18F),
• nitrogen- 13 , and
• oxygen- 15.

51. • These isotopes are usually linked to another molecule, except in the case of oxygen- 15. The
most commonly reported ligand has been [18F]fluorodeoxyglucose (FDG), an analogue of
glucose that the brain cannot metabolize.
• Use of glucose is a highly sensitive indicator of the rate of brain metabolism.
• The brain regions with the highest metabolic rate and the highest blood flow take up the most
FDG but cannot metabolize and excrete the usual metabolic products. The concentration of
FDG builds up in these neurons and is detected by the PET camera.
1. Water- 15 and nitrogen - 13 are used to measure blood flow, and
2. 15O can be used to determine the metabolic rate.
3. 18F-labeled 3 ,4-dihydroxyphenylalanine (DOPA), the fluorinated precursor to dopamine,
has been used to localize dopaminergic neurons.
• PET has been used increasingly to study normal brain development and function as well as to
study neuropsychiatric disorders.

53. PET SPECT
Emits positron Emits gamma radiation
Higher spatial resolution 3-5 mm Lower 7-10 mm
Costly Economical
Limited half life Longer half life of isotopes
Not easily available Easily available

55. NEUROIMAGING IN SPECIFIC
PSYCHIATRIC DISORDERS

56. SCHIZOPHRENIA
CT/MRI
•Consistent lateral and third ventricular enlargement - most replicated finding in schizophrenia
•Reduced volumes of cortical gray matter - during the earliest stages of the disease.
•Frontal lobe abnormalities in prefrontal gray matter and orbitofrontal regions.
•Parietal lobe abnormalities, particularly of the inferior parietal lobule
•Reduced symmetry in several brain areas in schizophrenia, including the temporal, frontal, and
occipital lobes. This reduced symmetry originate during fetal life and to be indicative of a disruption
in brain lateralization during neurodevelopment.

58. • The second most replicated finding, is medial
temporal lobe involvement
• decrease in the size of the region, including
the amygdala, the hippocampus, and the
parahippocampal gyrus and superior
temporal gyrus (STG).
• Hippocampus is not only smaller in size but
also functionally abnormal (disturbed
glutamate transmission in functional scans)
• Positive symptoms - decreased volume of
superior temporal gyrus
• Negative symptoms - enlarged lateral
ventricle & decreased volume of medial
temporal lobe structures
• All these structural abnormalities may be
static or progressive.
SCHIZOPHRENIA

59. MRS
•NAA levels were lower in hippocampus and frontal lobes
DTI
•DTI to investigate white matter pathology particularly in frontotemporal tracts. the frontotemporal
connections investigated in schizophrenia are
• uncinate fasciculus (UF),
• cingulum bundle (CB),
• the arcuate fasciculus (AF)
• inferior longitudinal fasciculus (ILF)
•A number of studies have shown reduced anisotropy in patients
compared with controls
SCHIZOPHRENIA

60. fMRI/PET
•Hypofrontality
•With memory and executive tasks – abnormal activations in temporal lobe,
prefrontal cortices, and limbic structures
•On emotional stimulus – consistent diminished activation in limbic and
paralimbic regions, especially the amygdala.
•Functional scans have also revealed lower levels of phosphomonoester &
inorganic phosphate and higher levels of phophodiester.
SCHIZOPHRENIA

61. MOOD DISORDERS
CT/MRI
•Most consistent abnormality in depression – increased frequency of abnormal hyperintensities in
subcortical regions, such as periventricular regions, the basal ganglia, and the thalamus.
•Also present in bipolar I disorder, these hyperintensities appear to reflect the deleterious
Neurodegenerative effects of recurrent affective episodes.
•Ventricular enlargement, cortical atrophy, and sulcal widening also have been
•Reduced hippocampal or caudate nucleus volumes, or both
•Diffuse and focal areas of atrophy have been associated with increased illness severity, and
bipolarity.

62. DEPRESSION

63. DEPRESSION
fMRI
•Normal sadness is associated with an increase in
blood flow and neuronal activity in the thalamus
and medial PFC
•More specific activation is seen in the left
amygdala, hippocampal formation, and
parahippocampal gyrus

64. • Inactivation of left prefrontal cortex in depressed
• During inhibition task - greater activation in frontal and anterior temporal areas in MDD

65. PET
•The most widely replicated PET finding in depression is decreased anterior brain metabolism, which is
generally more pronounced on the left side.
•Relative increase in nondominant hemispheric activity.
DEPRESSION

66. • Shifts from depression into hypomania – causes a reversal of hypofrontality, such that greater left
hemisphere reductions are seen in depression compared with greater right hemisphere reductions in mania.
• Other studies - reductions of cerebral blood flow or metabolism, or both, in the dopaminergically innervated
tracts of the mesocortical and mesolimbic systems in depression.
• Antidepressants partially normalize these changes.
• Increased glucose metabolism has also been observed in several limbic regions, particularly among severe
recurrent depression and a family history of mood disorder.
• Increased glucose metabolism is correlated with intrusive ruminations.

67. SPECT
•Baseline cerebral blood flow is lower in frontal cortex and sub-cortical nuclei bilaterally.
•Medication response – normalization of cerebral blood flow deficit.
DEPRESSION

68. OCD
CT/MRI
•Bilaterally smaller caudate in OCD pts.
•Significantly more cerebral grey matter & less white matter volume than normal controls.
•Decreased volume of left orbital frontal cortex.
•Abnormality in length of corpus callosum.
•Abnormality in pituitary volume may also be noted.
•Larger anterior cingulate volumes - increased ocd symptom severity

69. OCD
• Increased grey matter in lenticular nuclei
• Decreased grey matter in anterior
cingulate gyri

70. OCD - MRS
•Reduction in NAA levels in various regions of brain involved in CSTC circuitry including corpus
striatum, thalamus, basal ganglia, and anterior cingulate cortex.
•Similarly, studies also suggest higher levels of Glx in caudate nucleus and anterior cingulate cortex
(hyperglutaminergic state)

71. OCD
DTI
•Drug naive OCD patients showed significant increase in fractional anisotropy (FA) in the Corpus
callosum, Internal capsule, white matter in the area to the right caudate.

72. PET - OCD
•Increased metabolism in the the orbitofrontal
cortex, caudate nucleus, anterior cingulate cortex,
thalamus, and parietal cortex.
•Cortico-striatal-thalamic-cortical (CSTC) circuitry
plays a important role in mediating the compulsive
and impulsive features of OCDs - Increased activity
in these circuits both at rest, and on exposure to
feared stimuli.
•Pharmacological and behavioral treatments
reportedly reverse these abnormalities.

73. ANXIETY DISORDERS
• Volumetric MRI studies of panic disorder – smaller OFC, putamen, and temporal lobe volume,
and lower gray matter density in parahippocampal cortex
• Intrinsically exaggerated amygdala hyperresponsivity and abnormal structure or function in the
mPFC and hippocampus.
• Both PET and fMRI studies have identified altered resting-state regional cerebral blood flow
(rCBF). Specifically, patients show altered function in parahippocampal gyrus, hippocampus,
superior temporal gyrus.

74. MRS studies demonstrated that in
comparison with healthy controls,
participants with panic disorder showed
a significantly greater rise in brain lactate
in response to the same level of
hyperventilation.
PANIC DISORDER - MRS

75. • The first reported structural abnormality in PTSD was a reduced left hippocampal volume in Vietnam
veterans with PTSD.
• Numerous studies subsequently reported left, right, or bilateral hippocampal volume reduction in PTSD.
Volume reductions were associated with severity of combat exposure.
• Evidence for smaller left amygdala volumes in adults with PTSD
• Several studies have pointed to abnormal structural characteristics in the anterior cingulate cortex (ACC)
PTSD

76. • fMRI studies have found increased activity in
amygdala, a brain region associated with fear.

77. DEMENTIA

78. ALZHEIMER'S DISEASE
CT
•Cerebral atrophy (typical dilatation of
lateral ventricles & widening of cortical
sulci) particularly in posterior temporal
& parietal regions

79. • Change in global (whole brain and
ventricles) and regional (entorhinal
cortex, hippocampus, corpus callosum)
volumes
• MRI evidence of medial temporal lobe
(MTL) atrophy appears to be most
closely associated with the disorder.
• MTL atrophy is often observed even in
the early stages of mild cognitive
impairment (MCI), making it potentially
useful as a prognostic tool.
ALZHEIMER’S - MRI

80. fMRI
•During the encoding of new memories, decreased fMRI activation in the hippocampus and related
structures within the medial temporal lobe
MRS
•There is decreased levels of NAA and increased levels of myo-inositol compared to those of age-
matched comparison subjects.
ALZHEIMER
• related to the loss of neurons and an
increase in gliosis.
• Few studies suggest glutamate and
glutamine can be found in subjects with
MCI impairment and AD - reflect a
combination of ongoing metabolic
dysfunction and increased gliosis.

81. DTI
•Significant frontal, temporal, and parietal white
matter diffusion tensor changes in MCI and
Alzheimer's disease that correlate with cognitive
functioning.
PET/ SPECT
•Reduced blood flow and metabolism in parietal,
posterior temporal, and posterior cingulate cortices,
with variable reductions in other cortical regions.
ALZHEIMER

82. • Recent development of PET imaging is with the Aβ-binding agent Pittsburgh Compound B (PIB-PET).
• In contrast to PET or SPECT, the PIB-PET has the potential to demonstrate qualitative differences between
Alzheimer's disease and cognitively intact elderly individuals.
• PIB-PET may also detect the presence of Aβ deposition in mild cognitive impairment – can be used to
detect preclinical Alzheimer's disease.
ALZHEIMER
PIB-PET
AD
MCI
FTD

83. FRONTOTEMPORAL DEMENTIA
•MRI - circumscribed frontal and/or temporal atrophy
•Severe sharply localised atrophy – “knife-blade atrophy”

84. 1.Behavioral variant
– Bifrontal atrophy
2.Semantic
– inferior temporal
atrophy
3. PNFA – Perisylvian atrophy

85. • PET or SPECT in FTD selective frontal and/or anterior temporal reduction in blood flow or metabolism.
• Alzheimer's disease - reductions in blood flow and metabolism in posterior temporal and parietal regions.

86. DEMENTIA WITH LEWY BODIES
• Greater hypoperfusion with FDG-PET in occipital regions than Alzheimer's disease.

87. • Imaging the presynaptic dopaminergic
terminals using 123I-FP-CIT SPECT ( 123I-N-3-
fluoropropyl-2beta-carbomethoxy-3beta-4-
iodophenyl tropane ) [ DATSCAN ] - reveals a
marked loss of presynaptic dopaminergic
terminals in the corpus striata in DLB,
whereas there is no change in these
terminals in normal individuals and in
patients with Alzheimer's disease
123I-FP-CIT SPECT

88. CT/ MRI
•Increased total brain volume < 4 years of age in ASD
whose neonatal head circumferences were normal
•At 5 years - 15 to 20 percent of children developed
macrocephaly.
•Size of the amygdala increase in the first few years
of life, followed by a decrease in size over time.
•The size of the striatum has also been found in
several studies to be enlarged
•Positive correlation of striatal size with frequency of
repetitive behaviors.
AUTISM SPECTRUM DISORDER

89. AUTISM - fMRI
fMRI studies have provided evidence - they focus more on
the mouth region of the face rather than on the eye region
rather than scanning entire face, they focus more on
individual features of the face.
In response to socially relevant stimuli, they have greater
amygdala hyperarousal.
In terms of "theory of mind," that is, the ability to attribute
emotional states of others, right temporal lobe become
activated in controls but not in autism. This difference is due
to dysfunction of the mirror neuron system (MNS).

90.  During face processing tasks - Atypical
pattern of frontal lobe activation
 During memory and language-based tasks -
decreased activation in the left frontal
regions – so they utilized more visual
strategies during language processing.
AUTISM - fMRI

91. ADHD
MRI
•Shows no consistent findings.
•Increased cortical grey & white matter volumes from 5 yrs of age with peak at 12-15 yrs of age.
•Decrease in the volume of posterior inferior cerebellar vermis may be noted.(region involved in
attention processing)

92. ADHD - PET
•PET scans have also shown that female adolescents with ADHD have globally lower glucose metabolism
than both control female and male adolescents.
White, Red, Orange = higher glucose metabolism
Blue, Green, Purple = lower glucose metabolism

93. • Pet scan has also shown lower CBF and metabolic rates in the frontal lobes of children with ADHD.
• Less striatal activation during cognition inhibition tasks.
ADHD - PET

94. IMPORTANT SIGNS

95. HUMMING BIRD SIGN / PENGUIN SIGN
• Seen in Progressive Supranuclear palsy (PSP)
• significant midbrain atrophy with sparing of pons known as “hummingbird” sign.

96. MICKEY MOUSE/MORNING GLORY SIGN
• Classically seen in PSP
• selective atrophy of the midbrain tegmentum with relative preservation of tectum and cerebral peduncles
resembling the head of a Mickey Mouse
• lateral margin of midbrain tegmentum - abnormal concavity - resembles morning glory.

97. EYE OF TIGER APPEARANCE
• Seen in Hallervorden-Spatz disease/ NBIA.
• Hyperintense area in Globus Pallidus surrounded by hypointense area
• Central high signal – due to gliosis and neuronal loss
• Surrounding Low signal – due to excessive iron accumulation

98. HOT-CROSS-BUN SIGN
• Seen in Multiple System Atrophy
• Crucifrom hyperintensities in Pons
• selective degeneration of pontocerebellar tracts

99. FACE OF GIANT PANDA
• Seen in Wilson’s disease.
• High signal intensity in the Midbrain tegmentum sparing the red nucleus (forms eyes)
• Preservation of signal intensity of the lateral portion of the pars reticulata of the substantia nigra makes up the ears.
• Hypointensity of the superior colliculus makes up the chin/mouth
• Similar changes when seen in Pons – Face of Miniature Panda / panda Cub Sign
• Together called as – Double Panda Sign.

100. Double Panda Sign.

101. ELEPHANT SIGN
• Seen in Alzheimer disease
• represents atrophy of medial aspect of the temporal lobes and hippocampi

102. HOCKEY STICK SIGN
• Characteristic of variant CJD
• Bilateral FLAIR hyperintensities involving the pulvinar thalamic nuclei.

103. DAWSON FINGERS
• Multiple sclerosis
• Sagittal FLAIR MR shows multiple ovoid hyperintensities (arrows) contacting the corpus callosum
and radiating perpendicularly from the lateral ventricles.

104. Extradural vs subdural hematoma: lemon vs banana

105. NEUROCYSTICERCOSIS
TUBERCULOMA

106. Fahrs syndrome

107. TUBEROUS
SCLEROSIS
TUBERS
SUBEPENDYMAL
NODULES

108. Summary
• A CT scan takes a series of head X-ray pictures around a patient's head.
• MRI scanners use strong magnetic fields, and RF waves to alter the H2 atom and generate images of the organs in
the body.
• DTI uses the diffusion of water molecules to generate contrast in MR images
• fMRI measures brain activity by detecting blood oxygen level–dependent (BOLD) changes
• MR Spectroscopy is the determination of the chemical composition of a substance by observing the spectrum of
electromagnetic energy emerging from it.
• SPECT uses radioactive isotopes that emit single gamma ray to study cerebral blood flow within the brain.
• PET uses isotopes that decay by emitting positrons which emit a pair of photons

109. CONCLUSION
• Functional and structural neuroimaging are key techniques of modern brain research and play a
major role in the quest for biological markers of mental disorders.
• They have already contributed greatly to the pathophysiology of mental disorders, their clinical
applications in diagnosis or treatment monitoring are under reseaech.
• Neuroimaging could also monitor and compare the brain effects of different psychiatric and
psychological treatments, and eventually aid in the development of new interventions in future.

110. REFERENCES
1. Kaplan and Sadocks Comprehensive textbook of Psychiatry – 9, 10th Edition
2. Kaplan and Sadocks Synopsis of Psychiatry – 11th Edition
3. Postgraduate Textbook of Psychiatry – Neeraj Ahuja, 3rd Edition
4. Neuroradiology Signs - Mai-Lan Ho
5. Journals