Radionuclide imaging

1. Radionuclide
Imaging & Its
Applications
SUDARSAN AGARWAL
sushiagarwal@gmail.com
PINNAMANENI MEDICAL
COLLEGE, VIJAYAWADA

2. Atom

3. Atom

4. Electromagnetic Spectrum

5. Ionising radiation
• Alpha radiation – 2N+2P
• Beta radiation – electron emitted by a
nucleus
• Positron -similar to electron except that
it has a positive charge. PARTICULATE
• X-Rays
• Gamma rays
EM RADIATION

6. Types of Ionizing Radiation
Alpha Particles
Radiation
Source
Stopped by a sheet of paper
Beta Particles
Stopped by a layer of clothing
or less than an inch of a substance
(e.g. plastic)
Gamma Rays
Stopped by inches to feet of concrete
or less than an inch of lead

7. Gamma rays are not charged particles like
particles.
and
Gamma rays are electromagnetic radiation with high
frequency.
When atoms decay by emitting or particles to form a
new atom, the nuclei of the new atom formed may still
have too much energy to be completely stable.
This excess energy is emitted as gamma rays

9. Accurate Diagnosis is key to
Surgical practice

10. Accurate Diagnosis is key to
Surgical practice
• X rays , CT
• Ultra
Sound, MRI
• SPECT
, PET

11. MRI
fMRI
SPECT
X-Ray
Ultrasound
CT

12. Diagnostic
Procedure
Typical
effective
dose (mSv)
Equivalent no.
of chest
radiographs
Approximately
equivalent period of
natural background
radiation
Chest X ray
0.02
1
3 days
Thyroid(Tc 99m)
1
50
6 months
Bone (Tc 99 m)
4
200
1.8 years
PET
5
250
2.3 years
CT abdomen
10
500
4.5 years

13. Hybrid Imaging

14. Hybrid Imaging
• PET-CT: radionuclide imaging devices
are combined with CT in a single
imaging system
• The resulting images display the
functional data obtained from the
radionuclide distribution (usually in
color) overlaid on the anatomical
information from CT (usually in grey
scale)

17. Radiotherapy
x
Nuclear Medicine

18. Nuclear medicine
• Nuclear medicine is a subspecialty within
the field of radiology that uses very small
amounts of radioactive material to
diagnose or treat disease

19. • We need a short-lived radio nuclide which
has to be combined to a pharmaceutical of
interest and injected iv and this radio
pharmaceutical goes and attaches to the
organ of interest and we can catch the
gamma rays emitted by it with help of
gamma cameras and pictures are
reconstructed in computer
• (in amounts of Pico molar concentrations
thus not having any effect on the process
being studied)

20. SPECT
1. RADIONUCLIDE
2. PHARMACEUTICAL
3. GAMMA CAMERA

21. 1. RADIONUCLIDE
2. PHARMACEUTICAL
3. GAMMA CAMERA

22. Ideal Radionuclide
• Emits gamma radiation at suitable energy
for detection with a gamma camera
(60 - 400 kev, ideal 150 kev)
• Should not emit alpha or beta radiation
• Half life similar to length of test
• Cheap
• Readily available

24. Technetium
• This is the most common
radio nuclide used in
Nuclear Medicine.
• Taking its name from the
Greek work technetos
meaning artificial , it was
the first element to be
produced artificially.

25. Photon Decay
99mTc
Excited
Nucleus
Gamma ray
99Tc
Stable Nucleus

26. 1. RADIONUCLIDE
2. PHARMACEUTICAL
3. GAMMA CAMERA

27. 1. RADIONUCLIDE
2. PHARMACEUTICAL
3. GAMMA CAMERA

28. Ideal radiopharmaceutical
• Cheap and readily available
• Radionuclide easily incorporated without
altering biological behavior
• Radiopharmaceutical easy to prepare
• Localizes only in organ of interest
• t1/2 of elimination from body similar to
duration of test

29. 99mTc
pertechnetate
• Thyroid scintigraphy
• Salivary gland study
• Meckel’s diverticulum
scintigraphy
18 FDG
• Interictal PET
• Cerebral metabolism PET
• Tumor imaging
99mTc MIBI
• Parathyroid scintigraphy

30. 99mTc
polyphosphate
99mTc red
blood cells
99mTc albumin
• Bone scintigraphy
• Cardiac ventriculography
• GI bleed study
• V/Q scan

31. • Esophageal transit and
99mTc sulphur reflux
colloid
• GI bleed study
99mTc
leucocytes
• White cell scintigraphy
99mTc
iminodiacetic • Hepatobiliary study
acid derivatives

32. 99mTc DTPA
99mTc
DMSA
111In
pentetreotide
• Diuresis renography
• Renal tract obstruction
• Static renal scintigraphy
• Renal scarring
• Somatostatin receptor study

33. 1. RADIONUCLIDE
2. PHARMACEUTICAL
3. GAMMA CAMERA

34. 1. RADIONUCLIDE
2. PHARMACEUTICAL
3. GAMMA CAMERA

35. Gamma Camera
A gamma camera consists of three main parts:
Electronic systems
Detector
Collimator

36. Gamma Camera

37. Positron Emission Tomography
• PET is a nuclear medicine imaging technique that
provides high-resolution tomographic images of
the bio-distribution of a radiopharmaceutical in
vivo .
• A PET scan measures important body
functions, such as blood flow, oxygen use &
glucose metabolism
• Radiopharmaceutical consists of positronemitters, usually very short-lived and produced in
cyclotrons.
• 18 F being one of the most optimal positron
emitters for imaging

38. Glucose
FDG

39. FDG
Plasma
Cell
Glucose
Glucose
Glucose-6-P
18F-FDG
18F-FDG
18F-FDG-6-P
Transport
Phosphorylation
Glycolysis
Glycolysis

40. • Half-life (T 1/2 )
is 110 minutes
• Low average
positron energy
of 0.63 MeV
• Average positron
range in tissue of
0.3 mm

42. • Delay a PET scan by 2 -3 weeks after surgical
intervention
• 2 -3 weeks interval after chemotherapy.
• 3 months after radiation therapy,
• 6 to 8 weeks post-radiation therapy-surgery.
• Should not be performed on pregnant and breast
feeding patients.

43. • Malignant cells show an increased rate of
glucose metabolism ,probably due to presence
on cell surfaces of an abnormally large number
of glucose transporters, along with increased
hexokinase-mediated glycolysis and a reduced
level of dephosphorylating by glucose -6phosphate.

44. Uses
Detect primary , secondary cancer and metastasis
Assess the effectiveness Cancer chemo therapy
Cancer recurrence
Mapping of brain and heart function
Evaluate brain abnormalities, such as tumors, memory
disorders and seizures and other central nervous system
disorders
• Determine blood flow to the heart muscle and thus
determine the effects of a heart attack, or myocardial
infarction
•
•
•
•
•

45. Cardiac Imaging
PET scan of a heart
Arrow points to "dead"
myocardial tissue.

46. Cerebral Imaging

47. •
•
•
•
99mTc-HMPAO
: cross to BBB and fix in the brain
proportionally to perfusion
18FDG : glucose metabolism
99mTc-TRODAT : dopamine transporter
111In-DTPA, 99mTc-DTPA : CSF dynamics, V-P
shunt patency study

48. PET image showing
malignant breast mass
(not revealed by
CT, MRI or Mammo)
PET image of same
patient with enlarged
left axillary lymph
nodes

49. The role of PET after chemotherapy
• Many neoplasms have an enhanced glucose
metabolism compared to normal tissue.
• FDG provides functional data on tumor
metabolism, complementary to morphologic
imaging studies.
• Standard tool for decision making in
lymphoma, Hodgkin`s disease, different solid
tumors post chemotherapy.
• Germ cell tumors (GCT) are characterized by a
high FDG uptake.

50. • Advantages
• Disadvantages
• Safety and Risk

51. Advantages
• Assesses body function and in monitoring
flow rate
• Can measure body composition using
dilution analysis.
• Whole body scanning
• Response to radiotherapy and
chemotherapy

52. Disadvantages
• Generally poor resolution compared with
other imaging modalities
• Radiation risks due to administered
radionuclide
• Can be invasive, usually requiring an
injection into the blood stream.
• Disposal of radio activity waste.
• Relatively high costs associated with radio
tracer production and administration.

53. Safety and risk
• Nuclear medicine is not safe for the use of
human beings, so therefore should not be
used on healthy people.
• Also the procedure is not recommended
for pregnant women because unborn
babies have a greater sensitivity to
radiation than children or adults.

54. Safety and risk
• Radioactive substances are emitted in to
the body so the safest way is to use a radio
nuclide which has a short half life, so it
can decay to a safe level in the fastest
possible time.

55. Safety and risk
• Most of the
administered
radioactive isotopes is
excreted as urine via the
kidney and bladder but
same is excreted as
perspiration and saliva.
This means that the
patient has radio active
substances on their skin
and should take extra
care when around other
people.

56. Safety and risk
• Safety precautions to be
taken when near a
patient has been injected
with radioactive
substance. Wear a
pathology gown and
disposable gloves also
minimise the time spend
with the patient and
maximise the distance
from the patient.

58. GIT

59. Hepato biliary Imaging
• Evaluates hepatocellular function and patency of
the biliary system
• Performed with a variety of compounds that
share the common iminodiacetate moiety
• Although it is an excellent test to decide whether
the common bile and cystic ducts are
patent, biliary scintigraphy does not identify gall
stones or give any anatomic information

60. Red: A lipophilic
component
Blue : A polar
component

61. IDA Derivatives
• HIDA - Little used today
• DISIDA (Disofenin) -85% extracted by the
hepatocytes
• BRIDA (Mebrofenin) -98% extracted by
the hepatocytes

62. Pathways of IDA derivatives
• The lipophilic component : binding to
hepatocyte receptors for bilirubin
• Transported through the same pathways
as bilirubin, except for conjugation

63. Normal Study
• Immediate demonstration of Hepatic Parenchyma
• Normal Liver (5 mins),
• Intrahepatic Bile ducts (10-15 mins),
• CBD, GB & Duodenum (15-30 mins),
• Small Intestine (>30 mins)

64. Filling Phase

65. Emptying phase

67. Indications
• Functional assessment of the hepatobiliary
system
• Integrity of the hepatobiliary tree
– Evaluation of suspected acute Cholecystitis
– Evaluation of suspected chronic biliary tract
disorders
– Evaluation of common bile duct obstruction
– Detection of bile extravasation
– Evaluation of congenital abnormalities

68. Contraindications
• Hypersensitivity to
– IDA derivative
– Local anesthetics of the amide type
• Cardiac arrhythmias
• Pregnancy

69. Acute Cholecystitis
• Investigation of choice is Ultrasound
• Most effective investigation is Radionuclide biliary
scanning
Diagnostic test
Sensitivity
Specificity
Ultra sound
85%
95%
Tc HIDA scan
95%
95%
• No filling of Gall bladder after 4 hours of injection
indicates obstruction
• A normal HIDA scan excludes it. 100% negative
predictive value.

70. Biliary
Atresia
Excluded by
demonstrating
transit of
radiotracer
into the bowel

71. Bile Leaks
• Most appropriate non-invasive imaging
technique for evaluation of bile leaks
• Sensitivity: 87%,
• Specificity: 100%

72. Liver & Spleen
• Radionuclide imaging of liver and spleen depends
on the function common to both i.e, phagocytosis.
• The most commonly used agent is 99m Tc Sulphur
colloid.
• In normal scan there is homogenous distribution
of 99m Tc Sulphur colloid through out the organ

73. SMALL INFARCTING SPLEEN
99mTc COLLOID STUDY AFTER
SPLEENECTOMY
SHOWING VIABLE AND
FUNCTONING SPLENIC TISSUE
IN THE OMENTUM

74. LIVLIVER
SECONDARIES
ER
SECONDARIES

75. Tc SULPHUR
COLLOID –
KUPFER CELLS
Tc HIDA
HEPATOCYTES

76. Meckel’s Scan
• The Meckel ’s scan is performed by giving
Tc Pertechnetate , which is taken up by the
ectopic gastric mucosa in the diverticulum
and localized with scintigraphy
• The diagnosis of Meckel’s diverticulum is
difficult.
• Plain abdominal radiographs, CT, US are
rarely helpful.

77. Meckel’s in Children
• Single most accurate diagnostic test for
Meckel’s is scintigraphy with Tc
Pertechnetate
• Its preferentially taken up by the mucus
secreting cells of gastric mucosa and
ectopic gastric tissue in the diverticulum

78. Meckel’s in Adults
• As ectopic gastric mucosa is reduced, agents like
pentagastrin, glucagon and cimetidine are used
• Pentagastrin indirectly increases the metabolism
of mucus producing cells
• Glucagon inhibits peristaltic dilution and washout
of intraluminal radionuclide
• Cimetidine decreases the peptic secretion and
therefore retards the release of pertechnetate from
the diverticular lumen, thus resulting in higher
radionuclide concentrations in wall of
diverticulum

79. NORMAL
STUDY

80. WITHOUT
H2
BLOCKADE
SO TRACER
IS SEEN
IN THE
INTESTINAL
LUMEN DUE
TO GASTRIC
SECRETION
OF
THE TRACER.

81. MECKEL”S DIVERTICULUM IN THE RIGHT SIDE OF THE PELVIS

82. Achalasia
Normal Study
Achalasia

83. GI Bleed
• Tc labeled RBC is the most sensitive but least
accurate method for localization of GI
bleeding
• With this technique, the patient’s own RBC s
are labeled and reinjected.
• The labeled blood is extravasated into the GI
tract lumen, creating a focus that can be
detected scintigraphically.
• Multiple images are collected over 24 hours

84. GI Bleed
• The tagged RBC scan can detect bleeding
as slow as 0.1 ml/ min
• Unfortunately, spatial resolution is
lacking, and blood may move retrograde
in the colon or distally in the small bowel.
• If RBC scan is negative, angiography is
unlikely to be revealing. Thus its used as
a guide to the utility of angiography

85. INDICATIONS
1. RECURRENT BLEEDING
2. ENDOSCOPY IS INCONCLUSIVE
3. COMORBIDITIES
99mTc COLLOID
99mTc RBC

86. Renal System

87. The main tracers used in evaluation of the kidney:
• DMSA : Di Mercapto Succinic Acid
• DTPA : Di-ethylene Tri-amine Penta-Acetic acid
• MAG3 : Mercapto Acetyl triGlycine

88. 99mTc-DMSA :
is cleared by both filtration
and secretion, but the clearance is
relatively complex and it does bind to
parenchymal tissues.
• It is useful as a renal cortical imaging agent.
•
99mTc-DMSA

89. 99mTc-DTPA:
is primarily a glomerular
filtration agent.
• It is also useful for evaluation of
obstruction and renal function.
• It is less useful in patients with renal
failure.
•
99mTc-DTPA

90. 99m
Tc-MAG3:
Tc-MAG3 is cleared by tubular
secretion, and no glomerular filtration
occurs.
• The tracer is well suited for evaluation of
renal function and diuretic scintigraphy
• Also, it is an excellent tracer to evaluate
renal plasma flow.
•
99m

91. Procedure
• After a bolus injection of the
tracer, images are obtained that can be
used to estimate relative renal function.
• When the tracer reaches the collecting
system, a diuretic is given and half-life
is calculated based on the slope of the
curve in response to the diuretic.

92. Renal Cortical Scintigraphy
• Done with 99mTcDMSA
• Acute infection can
produce abnormalities
in the scan; and if the
test is being
performed to evaluate
for cortical scarring, it
should be done at
least 3 months after an
acute infection

93. Image of the kidneys
obtained 3 hours after
administration of
99mTc-DMSA shows
that the left kidney is
decreased in size, and
contains several focal
cortical defects, most
notably at both poles.

94. Diuretic Scintigraphy:
• Diuretic scintigraphy is performed with
DTPA or MAG3.
• MAG3 is more useful in patients with
renal insufficiency, but DTPA is more
economical.
• Diuretic scinitigraphy offers a
quantitative assessment of obstruction
and does not require an invasive
procedure, intravenous iodinated
contrast medium, or anesthesia.

95. Dynamic function images over 40 minutes demonstrate
good uptake of tracer by both kidneys & prompt
visualization of the collecting systems. A slight relative
delay in clearance from the right kidney is noted.

96. Horse Shoe Kidney

97. Ectopic Kidney

99. Radioactive Iodine Uptake test
• Is less widely used because of more precise
biochemical measurements of T3 T4 TSH
• This test in the past involved oral administration of
Iodine 123
• A normal result is 15-30% uptake of the radionuclide
after about 24 hours.
• Use of Iodine 123 is preferable over Iodine 131(8 days)
because of a shorter half life(12 hours) and lesser
radiation exposure

100. Thyroid - scintigraphy
99m PERTECHNETATE
Trapped but not organified
Competes with iodide for uptake
Cheap and readily available
IODINE (123I or 131 I)
Trapped and organified
Better for retrosternal goitres
Expensive, cyclotron generated

101. NORMAL
THYROID
UPTAKE
HOT NODULE
COLD NODULE

102. • 20% of cold nodules are Malignant
• 5% of hot nodules are Malignant
• Thus routine isotope scanning is no longer
used to distinguish Benign from
Malignant

103. Mechanism of Action
Radioiodine nuclide release energy  beta & gamma
• I 131 ablates principally due to the short range
beta radiation. It destroys cells at the end of their
path
• The accompanying high energy penetrating
Gamma ray radiation mostly escapes the patient
producing unwanted radiation fields

104. Indications for Thyroid
Scintigraphy
1. Thyroid nodules
2. Thyrotoxicosis
3. Goiter
4. Ectopic thyroid
5. Thyroid cancer
6. Retrosternal mass
7. Work up of neonates with low T4 and/or high TSH
8. Occult thyroid malignancy
9. Metastasis
10.Swellings in thyroid region

105. Contraindications
Absolute
1. Pregnancy
2. Breastfeeding
Relative
1. Bone marrow depression
2. Pulmonary function restriction.
3. Salivary gland function restriction.
4. Presence of neurological symptoms.

106. Short-term complications
•
•
•
•
•
•
•
Radiation thyroiditis(transient)
Sialadenitis
Gastritis 30%
Bone marrow depression
Xerostomia
Nausea/vomiting
Hypospermia

107. Long-term complications
•
•
•
•
•
•
Radiation pulmonary fibrosis
Permanent bone marrow depression
Chronic hypospermia or azoospermia
Early onset of menopause
Chronic dry eye
Hypoparathyroidism (rare and transient)

108. Ectopic Thyroid

109. Radio Iodine Ablation
Graves
Thyroid cancer

110. Radio Iodine Ablation
Graves
Thyroid cancer

111. Graves disease
• RAI has been used since 1940 (more than 50 years) for
treating thyroid disease
• High rate of success with permanent cures affected
and few undesirable effects for hyperthyroid &
thyroid cancer
• The majority of patient receive anti thyroid drug but
the success rate is limited
• Anti thyroid therapy failed, prime candidate for
radioiodine therapy

112. Tc 99m Pertechnetate
Thyroid scintigram
• Symmetrically
enlarged gland
• Homogenous tracer
distribution uniform
uptake without
nodularity(occasion
ally cold nodule
seen)
• Prominent
pyramidal lobe

114. SOLITARY COLD
NODULES

115. Treatment
• 3 option :
– medical therapy  antithyroid drugs
– radioactive iodine
– surgery  thyroidectomy, partial or complete
surgical
• None is the best treatment
• USA  radioactive is the first choice (69%)
115

116. Percentage relapse of
hyperthyroidism

117. Cure rate
• 59.1 % (6th month)
• 72.7 % (12th month)
• 92.0% (24th month)

118. • Return to normal T4  Take 2-6 months
• During interval  May need to continue
antithyroid drugs
• Monitored  Hypothyroidism and recurrent
hyperthyroidism
• There is no optimal dose for RAI ~
controversial
• Goals for RAI treatment vary from inducing
hypothyroidism to restoring euthyroidism

119. Before radioiodine therapy :
• Stop Antithyroid drugs 3-4 wks before
• Shall not have iodine containing
injection/tablets for 4 months
• Patient have to fast overnight & an hour
afterwards

120. Take home message (Graves)
• Iodine-131 therapy has been available for over
50 years
• There is no standard treatment for Graves’
hyperthyroidism (medical, surgical and
radioactive iodine)
• RAI is Proven to be save, effective and
economical form of treatment for thyroid
diseases
• Appropriate patient selection & explanation the
expected outcomes are essential

121. Radio Iodine Ablation
Graves
Thyroid cancer

122. Radio Iodine Ablation
Graves
Thyroid cancer

123. Thyroid cancer
• Incidence of thyroid cancer is increasing
--Mortality rate of 2-5%
--Recurrence rate post-lobectomy 5% - 20%
• No doubt that surgery is the primary treatment
Total thyroidectomy is the choice
• Surgery alone has remained inadequate to
ensure complete cure

124. RAI Decreased recurrence and death rates in the
following ways:
1.Destroyed remaining normal thyroid tissue
2.Destroys occult microscopic cancer
3.The use of higher doses of I-131 treatment
permits post-ablative total body scanning

125. RESIDUAL CA
THYROID TISSUE
METASTASIS IN
CERVICAL &
MEDIASTINAL LN

126. • Follicular thyroid cancer demonstrate a capability of taking
up iodine, although less than that of normal thyroid cells.
• 50% of papillary carcinomas are also able to take up iodine
and the presence of follicular elements on histology is an
indicator of iodine uptake capabilities.
• Medullary, anaplastic carcinomas and lymphomas of the
thyroid do not take up I-131, which therefore has no role in
therapy following ablation of remnant thyroid tissue.
• Medullary thyroid cancer could be treated with I-131 MIBG
(metaiodobenzylguanidine)

127. Optimal dose
•
•
•
•
Ablation dose : 30 – 200 mCi
Metastatic lesions : 150 – 300 mCi
Conservative approach 150 mCi
Repeated treatments were given but
not exceeding a cumulative dose of
1000 mCi

128. Elimination
• I 131 leaves through
saliva, sweat, blood, urine, faeces
• Majority of administered RAI has been
extracted after 48 hours

129. Near / total thyroidectomy
4-6 week post-surgery
Thyroid / whole body scan
Preventive
ablation
Negative
Positive
Hormone
substitution/suppression
Radio ablation
80-100 mCi
• Tg
• Whole body scan
Positive
Radioiodine therapy
100-150 mCi
5 months
1 month hormone off
Negative
Survival rate :
• 91% (322 patients) up to 15 yrs
• 90-100% up to 7 yrs with or without local or regional
metastases

130. Key to success in thyroid Cancer
•
•
•
•
Early detection
Adequate thyroidectomy
Post operative radioiodine therapy
Meticulous follow-up surveillance

131. Take home message( Ca Thyroid)
• Radioactive Iodine recommended as an
adjunctive therapy (ablation / preventive) for
thyroid cancer after thyroidectomy for the
complete management of well-differentiated
thyroid cancer
• External beam radiotherapy for Anaplastic ca
• Radiation exposure after a latent period of 30
years can cause Papillary cancer
• RIA is best for Follicular cancer

132. Future Trends
• Monoclonal antibodies or
their fragments are
potentially ideal vehicles to
carry radioisotopes to
specific sites within the body
• But radiolabel has to be
inserted without affecting
the binding site

133. Thank you…