Brant and Helms Chapters 5963: Nuclear Medicine

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Brant and HelmsChapters 59-63Nuclear Medicine

• Christopher Sherman

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Outline

• Cerebrovascular System
• Thyroid Imaging and Uptake
• Gastrointestinal Tract
• Genitourinary System
• Inflammation and Infection Imaging
• Conventional Neoplasm Imaging

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Cerebrovascular System

• Radionuclide Brain Imaging
• Planar Brain Imaging
• SPECT Brain Perfusion Imaging

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Planar Brain Imaging

• Only performed for brain death studies.
• Uses radiopharmaceuticals that are perfusion
  agents
• 99mTc-DTPA (diethylenetriaminepenta acetic acid)
• 99mTc-Pertechnetate.
• 99mTc-DTPA and 99mTc-Pertechnetate do not cross
  an intact blood-brain barrier.

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Planar Brain Imaging

• Generally consists of two phases
• Dynamic or angiographic phase (regional brain
  perfusion).
• Delayed static images (distribution of
  radiopharmaceutical in the sagittal sinus and
  cerebral regions).

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Planar Brain Imaging Dynamic Phase Technique

• 15 to 20 mCi (555 to 740 MBq) of 99mTc-DTPA
  or 99mTc-Pertechnetate is intravenously injected.
• Planar imaging is immediately obtained.

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Normal Anterior Radionuclide Angiogram

• Images demonstrate prompt symmetric perfusion
  that in the anterior projection looks like a
  trident.
• The middle and cerebral arteries are seen to the
  right and left and the anterior cerebral arteries
  are seen as a single midline vertical line of
  activity.

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Normal Anterior Radionuclide Angiogram
(99mTc-DTPA)
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Normal Planar Static Brain Scan

• On static images, radioactivity does not normally
  lie within the brain itself because of the
  integrity of the blood-brain barrier.
• Activity is located in the overlying scalp
  tissues, calvarium and subarachnoid space as well
  as within the sagittal and transverse sinuses.

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Normal Planar Static Brain Scan
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Anterior Radionuclide AngiogramBrain Death

• Radionuclide angiogram is a simple, noninvasive
  method of determining the presence or absence of
  intracerebral perfusion and thereby of confirming
  a clinical diagnosis of brain death.
• 99mTc-Pertechnetate and 99mTc-DTPA are the most
  widely used for this purpose.
• 99mTc-HMPAO and 99mTc-ECD also can be used.

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Anterior Radionuclide AngiogramBrain Death

• Need to see distinct activity in the common
  carotid artery to be assure that the radionuclide
  has been delivered especially when using
  99mTc-HMPAO (99mTc-HMPAO is unstable, inject
  within 30 minutes of preparation).

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Anterior Radionuclide AngiogramBrain Death

• In the presence of cerebral death, the injected
  activity typically proceeds through the carotid
  artery to the base of the skull and stops, owing
  to increased intracranial pressure.
• To prevent mistaking scalp perfusion for
  intracerebral blood flow, an elastic band can be
  placed around the head just above the orbits
  (diminished flow to superficial scalp vessels).

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Anterior Radionuclide AngiogramBrain Death
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Brain Death Hot Nose Sign

• When intracranial carotid blood flow ceases in
  the setting of brain death, increased flow
  through the maxillary branch of the external
  carotid artery may produce markedly increased
  perfusion projecting over the nasal area.

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Delayed 99mTc-DTPA ImageBrain Death

• A single anterior or lateral view is obtained
  within 10 to 15 minutes of the completion of the
  angiographic portion of the study to determine
  the presence of sagittal sinus activity.

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Delayed 99mTc-DTPA ImageBrain Death
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Brain Death

• An actual diagnosis of brain death should not be
  made by using nuclear imaging techniques alone.

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Cerebrovascular System

• Radionuclide Brain Imaging
• Planar Brain Imaging
• SPECT Brain Perfusion Imaging

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SPECT Brain Perfusion Imaging

• Uses lipophilic radiopharmaceuticals that cross
  the intact blood-brain barrier and are retained
  by the brain tissue.
• Retention of the radiopharmaceutical is
  proportional to regional blood flow (rCBF).

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SPECT Brain Perfusion Imaging

• 99mTc-HMPAO
• hexmethylpropyleneamine oxime
• Exametazime
• 99mTc-ECD
• ethylene L-cysteinate dimer
• Bicisate

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SPECT Brain Imaging Technique

• Inject 10 to 20 mCi (370 to 740 MBq) of
  99mTc-HMPAO or 99mTc-ECD.
• Limit external external sensory stimuli.
• Obtain SPECT Images 15 to 20 minutes after
  injection.

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SPECT Brain Scan Normal Findings

• Activity is symmetric and greatest in the strip
  of cortex along the convexity of the frontal,
  parietal, temporal and occipital lobes.
• Activity is also high in regions corresponding to
  subcortical gray matter, including the basal
  ganglia and thalmus.
• This is consistent with the four-fold greater
  blood flow in the gray matter than in the white
  matter.

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Normal SPECT Brain Perfusion
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Normal SPECT Brain Perfusion
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SPECT Brain Perfusion Imaging Clinical
Applications

• Suspected brain death.
• Acute stroke.
• Transient ischemic attacks.
• Differentiation of recurrent tumor from radiation
  necrosis.
• Epilepsy.
• Dementias, especially Alzheimers.

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SPECT Brain Perfusion Imaging Cerebral
Infarction

• Only 20 of CT scans are positive 8 hours after
  cerebral infarction.
• Acute infarcts are usually identified on
  nonconstrast MRI within 4 to 6 hours.
• 90 of SPECT brain perfusion images show deficits
  8 hours after cerebral infarction.

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SPECT Brain Perfusion Imaging Cerebral
Infarction

• Sensitivity of CT and SPECT imaging are the same
  at 72 hours postinfarction.
• Small infarcts , particularly those in the white
  matter (lacunar infarcts), may not be detected by
  SPECT.
• SPECT and PET imaging cannot distinguish between
  hemorrhagic and ischemic infarction.

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SPECT Brain Perfusion Imaging Cerebral
Infarction

• During the acute phase of stroke (first hours to
  2 to 3 days after vascular insult) a reduction in
  blood flow to the affected brain is identified.
• The area of affected brain is often greater on
  SPECT imaging than that seen with CT imaging,
  suggesting tissue at risk (prenumbra) surrounding
  the infarct.

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Acute and Chronic Infarction
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SPECT Brain Perfusion Imaging Cerebral
Infarction

• During the subacute phase of stroke (1 to 3 weeks
  after onset of symptoms), the brain SPECT
  perfusion pattern is complicated by the
  phenomenon of increased perfusion termed,
  luxury perfusion.

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Infarction with Luxury Perfusion
T1 with Gadolinium
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SPECT Brain Perfusion Imaging Clinical
Applications

• Suspected brain death.
• Acute stroke.
• Transient ischemic attacks.
• Differentiation of recurrent tumor from radiation
  necrosis.
• Epilepsy.
• Dementias, especially Alzheimers.

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SPECT Brain Perfusion Imaging Recurrent Brain
Tumor

• In conjunction with Thallium-201 SPECT brain
  perfusion imaging may be valuable in
  distinguishing between radiation necrosis and
  tumor recurrence.
• 99mTc-HMPAO generally shows a focal deficit in
  the either necrotic tissue or recurrent tumor.
• Thallium-201 is a marker of viability localizing
  to living tumor cells but not nonviable tumor
  cells or necrotic tissue.

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Recurrent Brain Tumor
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SPECT Brain Perfusion Imaging Epilepsy

• Patients with partial (focal) epilepsy
  refractory to therapy may benefit from surgical
  ablation of the seizure focus.
• The most common pathology at the foci is mesial
  temporal scelrosis (gliotic temporal scarring).
• Although most complex partial seizures arise from
  epilectic foci in the temporal lobes, they may
  arise from other cortical areas.

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SPECT Brain Perfusion Imaging Epilepsy

• If seizure foci can be localized to the temporal
  lobes, about 70 of patients undergoing partial
  temporal lobectomy experience amelioration or
  eradication of seizures. .

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SPECT Brain Perfusion Imaging Epilepsy

• SPECT and PET imaging attempts to localize
  seizure foci based on the metabolic and perfusion
  status of the seizure focus.
• Seizure foci may exhibit hyperperfusion and
  hypermetabolism during seizures.
• 99mTc-HMPAO or ECD for perfusion.
• 18FDG for evaluating metabolism.

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Ictal SPECT Brain Imaging 99mTc-HMPAO
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Ictal 18FDG PET Scan
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Interictal 18FDG PET Scan
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SPECT Brain Perfusion Imaging Epilepsy

• In general, ictal studies are more sensitive in
  the detection of temporal lobe seizure foci than
  are interictal studies, with a sensitivity of 85
  to 95 ictally and about 70 interictally.

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SPECT Brain Perfusion Imaging Alheimers Disease

• Most common and highly suggestive finding of
  Alzheimers disease on 99mTc-HMPAO or 99mTc-ECD
  SPECT imaging is symmetric and bilateral
  posterior temporal and parietal perfusion
  defects.
• Positive predictive value of more than 80.
• This imaging appearance however is not
  pathognomonic (vascular dementia, Parkinsons
  disease and various encephalopathies).

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SPECT Brain Perfusion Imaging Alheimers Disease

• The negative predictive value of of a normal
  SPECT perfusion scan is generally high, and other
  causes for dementia should be sought.
• PET studies demonstrate hypometabolism patterns
  similar to those seen with SPECT brain perfusion
  agents.

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SPECT Brain Perfusion Imaging Alheimers
Disease
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SPECT Brain Perfusion Imaging Alheimers Disease
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PET Scan Alheimers Disease
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Outline

• Cerebrovascular System
• Thyroid Imaging and Uptake
• Gastrointestinal Tract
• Genitourinary System
• Conventional Neoplasm Imaging
• Inflammation and Infection Imaging

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Thyroid Imaging and Uptake

• Both 123I and 131I are used for iodine uptake.
• Iodine (123I) and technetium (99mTc) constitute
  the radionuclides used in imaging the thyroid
  gland.
• Only 131I is used for thyroid therapy.

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Thyroid Uptake Iodine-131

• Decays by beta emission and has a half-life of
  8.04 days.
• High radiation dose to the thyroid.
• The principle gamma emission of 364 keV is
  considerably higher than the ideal for imaging
  with gamma cameras.
• Low price.
• Readily available.

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Thyroid Imaging and Uptake Iodine-123

• Decays by electron capture with a photon energy
  of 159 keV.
• Half life of 13 hours.
• Lower radiation dose to the thyroid.
• High cost because it is produce by cyclotron.
• Iodine of choice for thyroid imaging.

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Thyroid Imaging Technetium-99m

• Technetium-99m pertechnetate is trapped by the
  thyroid in the same manner as iodides but is not
  organified.
• 6 hour half-life.
• Principle gamma energy of 140 keV.
• Readily available.
• Only 1 to 5 of administered activity is trapped
  by the thyroid, so image background is high.

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Iodine Uptake Test

• Thyroid uptake is based on the principle that the
  administered radiopharmaceutical is concentrated
  by the thyroid gland in a manner that reflects
  the glands handling of stable dietary iodine and
  therefore the functional status of the gland.

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Iodine Uptake Test

• The diagnosis of hyperthyroidism or
  hypothyroidism is not made by using radioactive
  iodine.
• Serum measurements of thyroid hormone or
  thyroid-stimulating hormone (TSH) are used to
  diagnose hyperthyroidism or hypothyroidism.

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Iodine Uptake Test Technique

• Uptake is conventionally expressed in as the
  percentage of the administered activity in the
  thyroid gland at a given time after
  administration.

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Iodine Uptake Test Technique

• 5 ?Ci (0.2 MBq) of 131I-sodium or 10 to 20 ?Ci
  (0.4 to 0.7 MBq) of 123I-sodium administered in
  capsule or liquid form.
• An identical amount of activity, standard, is
  placed in a neck phantom and compared with that
  in the patients thyroid using a single-crystal
  counting probe with a flat-field collimater.

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Iodine Uptake TestNormal Results

• 4-hour 6 to 18
• 24 hour 10 to 30

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Iodine Uptake Test Results

• 4-hour 6 to 18
• 24 hour 10 to 30
• Glands demonstrating a poor avidity for iodide
  are considered to be hypofunctioning.
• Glands demonstrating increased avidity for iodide
  are considered to be hyperfunctioning.

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Elevated Radioiodine Uptake

• Primary hyperthyroidism (Graves disease or toxic
  nodular goiter) and secondary hyperthyroidism
  (increased production of TSH by the pituitary)
  commonly produce elevated iodine uptakes.
• Toxic nodular goiters (Plummers disease) may
  yield uptake values in the high, normal or mildly
  elevated range.

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Reduced Radioiodine Uptake

• Primary or secondary hypothyroidism may produce
  decreased radioiodine uptake however because of
  the prevalence of iodine in the American diet it
  has become increasingly difficult to use reduced
  radioiodine uptake as in indicator of
  hypothyroidism.

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Thyroid Imaging and Uptake

• Both 123I and 131I are used for iodine uptake.
• Iodine (123I) and technetium (99mTc) constitute
  the radionuclides used in imaging the thyroid
  gland.
• Only 131I is used for thyroid therapy.

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Thyroid Gland Imaging Indications

• To relate the general structure of the gland to
  function, particularly in differentiating Graves
  disease from toxic multinodular goiter.
• To determine function in a specific area (ie to
  see if a palpable nodule is functional).
• To locate ectopic tissue.
• To assist in the evaluation of congenital
  hypothyroidism or organification defects.
• To determine if a cervical or mediastinal mass is
  thyroid tissue.

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Thyroid Imaging Technique

• Image the thyroid gland 20 minutes after the
  intravenous administration of 5 to 10 mCi (185 to
  370 MBq) of 99mTc-Pertechnetate using a
  scintillation camera with a pinhole collimater.
• Imaging with 123I is performed 16 to 24 hours
  after the oral administration of 200 to 600 ?Ci
  (7.4 to 22.2 MBq) to a fasting patient.

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Normal Iodine-123 Thyroid Scan
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99mTc-Pertechnetate Thyroid Scan Lingual Thyroid
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123I or 131I imaging of the ChestSubsternal
thyroid
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99mTc-Pertechnetate Thyroid ScanCongenital
Organification Defect
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Thyroid Nodules

• Fine-needle aspiration biopsy has largely
  supplanted radionuclide imaging as the initial
  investigative procedure for palpable thyroid
  nodules.
• Thyroid imaging can be useful in patients with
  indeterminate cytology results or with suppressed
  TSH levels.

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Thyroid Nodules

• Nodules are classified at imaging with respect to
  the relative amount of activity present.
• Cold nodules demonstrate absence of activity.
• Hot nodules demonstrate focally increased
  activity.

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Cold Nodules

• Nonspecific finding.
• Most cold nodules are benign.
• The small percentage of cold nodules that prove
  to be cancerous are sufficient to warrant further
  investigation of all cold nodules.
• The reported percentage of cold nodules harboring
  thyroid cancer varies depending on the study but
  is generally thought to be about 20.
• Likelihood of cancer increases if the patient is
  young.

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99mTc-Pertechnetate Thyroid Scan Nonfunctioning
Thyroid Adenoma
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Hot Nodules

• Most nodules that demonstrate increased
  radionuclide activity are benign, although
  thyroid carcinoma has been describe in a small
  percentage (lt1).
• Hot nodules almost always represent
  hyperfunctioning ademonas half of these
  hyperfunctioning adenomas are autonomous (not
  suppressible with exogenous thyroid hormone).
• Autonoumous hyperfunctioning nodule may produce
  enough thyroid hormone to inhibit pituitary
  secretion of TSH.

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99mTc-Pertechnetate Thyroid Scan
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Discordant Thyroid Nodule

• A small number of cases of hot nodules on
  99mTc-Pertechnetate imaging have subsequently
  proved to be cold or discordant on iodine
  imaging.
• A small number of these discordant lesions have
  been shown to be thyroid carcinoma.
• Discordant images are believed to be produced by
  either lack of organification of iodine or the
  rapid turnover of organified iodine.

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Discordant Thyroid Nodule

• Keep in mind that 99mTc-Pertechnetate imaging
  occurs 20 minutes after injection while
  radioiodine imaging is normally performed 24
  hours after ingestion of the radiopharmaceutical.
• It has been recommended that patient with hot
  nodules on pertechnetate scan be re-imaged using
  an iodine agent to determine whether a lesion
  represents a discordant nodule (further
  workup/biopsy) or a true hyperfunctioning adenoma.

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Discordant Thyroid Nodule
Mixed papillary follicular carcinoma
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99mTc-Pertechnetate Thyroid Scan
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Diffuse Toxic Goiter (Graves Disease)

• Thought to be of autoimmune origin.
• Presents with thyromegaly.
• On 99mTc-Pertechnetate scan, the thyroid has
  uniform increased activity and the salivary
  glands are difficult to identify.
• Because salivary glands are not normally seen on
  123I scan, it is often difficult to differentiate
  Gravess disease from a normal scan.
• 24-hour iodine uptake is high, in the range of
  40 to 70.

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99mTc-Pertechnetate Thyroid Scan
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Diffuse Goiter in Patient with Graves
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Acute and Subacute Thyroiditis

• Acute (bacterial) and subacute (viral or
  autoimmune) thyroiditis are uncommon diseases and
  have such typical clinical feature that they are
  usually diagnosed on physical and clinical
  grounds alone.
• Subacute thyroiditis usually presents as a
  painful swollen gland with elevated circulating
  thyroid hormone levels but markedly decreased
  radioiodine uptake.

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99mTc-Pertechnetate Thyroid Scan
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Chronic Thyroiditis

• Chronic thyroiditis (Hashimotos thyroiditis) is
  the most common form of inflammatory disease of
  the thyroid.
• Thought to be autoimmune in origin.
• More common in females.
• Thyromegaly is usually the presenting symptom.
• Depending on the stage and severity, symptoms of
  mild hyper- or hypo-thyroidism may be present.

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Chronic Thyroiditis

• Scan appearance varies from diffusely uniform
  increased activity in the gland early in the
  disease (which may resemble Graves disease) to a
  coarsely patchy distribution of activity within
  the gland later in the disease (which may mimic
  multinodular goiter).

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123I Thyroid Scan Chronic Thyroiditis
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Multinodular Goiter

• Typically presents as an enlarged gland with
  multiple cold, warm and hot areas.
• Nodule generally constitute a spectrum of thyroid
  adenomas ranging from hyperfunctioning to cytic
  or degenerative lesions.
• Most commonly seen in middle aged women.
• In adults, the cold lesions identified in
  multinodular goiter are significantly less likely
  to represent carcinoma than a solitary cold
  nodule.

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99mTc-Pertechnetate Thyroid ScanMultinodular
Goiter
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Thyroid Carcinoma

• 90 of all thyroid cancers are well-differentiated
  .
• 80 to 90 are papillary thyroid cancers.
• 10 to 20 are follicular thyroid cancers.
• Metastatic disease from well-differentiated
  thyroid cancers have the ability to concentrate
  iodine thus making them amenable to metastasis
  localization and adjunctive radioiodine therapy.
• Overall prognosis of patients with
  well-differentiated types of thyroid cancer is
  good (95 5-year survival).

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Thyroid Carcinoma

• Papillary thyroid carcinoma frequently
  metastasizes to the cervical lymph nodes.
• Follicular thyroid carcinoma frequently
  metastasizes hematogenously to the lungs and
  bones (65 to 85 concentrate radioiodine).

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Whole-body 131I Scan Follicular Thyroid Cancer
Metastatic Disease
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Thyroid Carcinoma

• 5 of thyroid carcinoma is anaplastic or poorly
  differentiated.
• Occur primarily in older patients.
• Poor prognosis.
• Medullary carcinoma of the thyroid constitutes 5
  of malignant thyroid lesions.
• Hurthle cell carcinoma is a variant of follicular
  cell carcinoma, is generally more aggressive and
  metastasizes early.
• Metastasis from above types of tumors do not
  concentrate iodine well.

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Thyroid Carcinoma

• Non-radioiodine-avid thyroid carcinomas can be
  successfully imaged using either 99mTc-sestamibi
  or fluorine-18 deoxyglucose (18FDG) positron
  emission tomography.

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99mTc-Sestamibi scan
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18FDG PETscan Thyroid Cancer
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Thyroid Carcinoma

• Whole-body evaluation for metastatic thyroid
  disease (well-differentiated) is first performed
  within 1 to 2 months after total or subtotal
  thyroidectomy.
• Thyroid hormone is withheld during this period to
  all for endogenous TSH stimulation of any
  remaining normal tissue in the thyroid bed and
  any functioning metastatic lesions.

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Thyroid Carcinoma

• 3 to 5 mCi (111 to 185 MBq) of 131I is
  administered orally and sequential whole-body
  images are obtained over the next 48 hours.
• Knowledge of the whole-body distribution of
  radioiodine before and after ablation is
  essential.
• 131I activity is commonly seen in the salivary
  glands, stomach, bowel and bladder.
• Mild diffuse activity in the liver is also normal
  and caused by clearance of the bound iodine by
  the liver.

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Whole-body 131I Scan Pre- and Post-Ablation or
Total Thyroidectomy
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Thyroid Carcinoma

• Metastatic lesions are only infrequently
  visualized with 123I or 131I whole-body imaging
  when there is functioning thyroid tissue in the
  neck.
• Ablation of residual tissue allows for sufficient
  TSH stimulation of distant metastatic sites, thus
  allowing for their detection on follow-up
  imaging.
• Once all the residual thyroid tissue in the neck
  has been ablated, follow-up imaging with 123I or
  131I may be performed at 6-month to 1-year
  intervals.

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Whole-body 131I Scan Residual Thyroid Tissue
and Star Artifact
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Metastatic Thyroid Cancer
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Outline

• Cerebrovascular System
• Thyroid Imaging and Uptake
• Gastrointestinal Tract
• Genitourinary System
• Conventional Neoplasm Imaging
• Inflammation and Infection Imaging

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Gastrointestinal Tract

• Liver-Spleen Imaging.
• Hepatic Blood Pool Imaging.
• Gastrointestinal Bleeding Studies.
• Hepatobiliary Imaging.

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Liver-Spleen Imaging Indications

• Confirmation or evaluation of suspected
  hepatocellular diseases, hepatomegaly or
  splenomegaly.
• Confirmation of specific space-occupying lesions
  such as focal nodular hyperplasia.

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Liver-Spleen Imaging Radiopharmaceuticals

• Radionuclide imaging of the liver and spleen
  capitalizes on a function common to both of these
  organs phagocytosis.
• 99mTc-sulfur colloid.
• Average particle size of 0.3 to 1.0 ?m.
• Reticuloendothelial system (Kupffer cells) .
• 80 to 90 of injected particles are sequestered
  by the liver.
• 5 to 10 localize in the spleen.

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Liver-Spleen Imaging Technique

• Both planar and SPECT imaging techniques are
  used.
• 4 to 6 mCi (148 to 222 MBq) of 99mTc-sulfur
  colloid.
• Image 5 to 10 minutes after injection to allow
  for adequate accumulation in the liver.
• Anterior, posterior and oblique views are often
  obtained.
• A marker is often placed at right inferior costal
  margin for localization.

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Normal sulfur colloid liver-spleen scan
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Liver-Spleen Imaging

• Any localized space-occupying process in the
  liver may present as a focal area of decreased
  activity.
• Lesions as small as 8 mm may be identified.
• Lesions 2 to 2.5 cm are routinely imaged.
• Defects in the hepatic parenchyma are
  nonspecific.
• Solitary intrahepatic defects may be produced by
  various lesions.

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Liver-Spleen Imaging

• In any patient with several liver defects,
  metastatic disease must be a primary
  consideration.

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Metastatic Colon Carcinoma
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Liver-Spleen Imaging Colloid Shift

• Increased radiocolloid concentration by the
  spleen and bone marrow compared with the liver is
  called colloid shift.
• Found in patients with diseases that cause
  derangement of hepatic function and/or portal
  hypertension.
• Hepatic cirrhosis is the most common abnormality
  presenting in this fashion.

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Cirrhosis with Ascites
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Hepatitis
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Liver-Spleen Imaging Primary Liver Neoplasms

• Hepatoma.
• Focal nodular hyperplasia.
• Hepatic cell adenoma.

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Liver-Spleen Imaging Primary Liver Neoplasms

• Hepatoma.
• Focal defect on sulfur colloid imaging
• Multifocal forms exist.
• Frequently occur in association with preexisting
  hepatic disease, most notably alcoholic
  cirrhosis.
• Hepatomas are also generally gallium-67 avid.
• Focal nodular hyperplasia.
• Hepatic cell adenoma.

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Hepatoma in a Patient with Cirrhosis
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Liver-Spleen Imaging Primary Liver Neoplasms

• Hepatoma.
• Focal nodular hyperplasia.
• Asymptomatic mass.
• Contain Kupffer cells (normally concentrate and
  occasionally hyperconcentrate radiocolloid).
• In most cases they appear indistinguishable from
  normal hepatic parenchyma on sulfur collid scan.
• Hepatic cell adenoma.

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Focal Nodular Hyperplasia
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Liver-Spleen Imaging Primary Liver Neoplasms

• Hepatoma.
• Focal nodular hyperplasia.
• Hepatic cell adenoma.
• Usually encounter in young women who have used
  birth control pills.
• Ususally asymtomatic but can hemorrhage.
• Kupffer cell are not a prominent feature of these
  lesions.
• Present a focal defects on colloid imaging.

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Gastrointestinal Tract

• Liver-Spleen Imaging.
• Hepatic Blood Pool Imaging.
• Gastrointestinal Bleeding Studies.
• Hepatobiliary Imaging.

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Hepatic Blood Pool Imaging

• Confirmation that an asymptomatic lesion seen on
  either ultrasound or contrast enhanced CT
  examination is a cavernous hemangioma.
• Cavernous hemangioma is highly likely when a
  defect seen with 99mTc-sulfur colloid imaging
  shows increased activity after administration of
  a 99mTc-labeled blood pool agent, such as
  99mTc-red blood cells.
• Use of SPECT imaging increases the sensitivity.

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99mTc-Red Blood Cell Scan Hepatic Hemangioma
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Gastrointestinal Tract

• Liver-Spleen Imaging.
• Hepatic Blood Pool Imaging.
• Gastrointestinal Bleeding Studies.
• Hepatobiliary Imaging.

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Gastrointestinal Bleeding Studies

• Both 99mTc- red blood cells and 99mTc sulfur
  colloid can effectively be used to localize
  gastrointestinal bleeding.
• Red blood cells are almost always used and have
  greater specificity.
• Because of significant background activity in the
  upper abdomen and the diagnostic efficacy of EGD,
  nuclear medicine imaging are most advantageous in
  evaluating lower GI bleeding.

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Gastrointestinal Bleeding Studies

• Common causes of lower GI bleeding in adults are
• Diverticular disease.
• Angiodysplasia.
• Neoplasms.
• Inflammatory bowel disease.
• Bleeding rates on the order of 0.2 mL/minute are
  reliable detected with radionuclide techniques.

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99mTc-Red Blood Cells Proximal Small Bowel
Bleeding
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99mTc-Red Blood Cells Lower Gastrointestinal
Bleeding
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Gastrointestinal Tract

• Liver-Spleen Imaging.
• Hepatic Blood Pool Imaging.
• Gastrointestinal Bleeding Studies.
• Hepatobiliary Imaging.

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Hepatobiliary Imaging

• Accurate and convenient imaging in acute and
  chronic biliary states.
• Common indications
• Acute (calculous or acalculous) cholecystitis.
• Biliary patency.
• Identification of biliary leaks.
• Differentiation of biliary atresia from neonatal
  hepatitis in neonates.

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Hepatobiliary Imaging Radiopharmaceuticals

• Analogs of 99mTc-iminodiacetic acid (IDA).
• Most widely used is diisopropyl IDA (DISIDA
  disofenin or Hepatolite).
• Rapidly removed from the the circulation by
  active transport into the hepatocytes and
  secreted into the bile canaliculi, then the
  biliary radicals, bile duct, gallbladder and
  small intestine.
• IDA analogs are excreted without being
  conjugated.

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Hepatobiliary Imaging Technique

• In patients with acute disease, a minimum of 2
  hours of fasting is suggested.
• 3 to 10 mCi (111 to 370 MBq) of 99mTc-labeled IDA
  in injected intravenously.
• Anterior planar images are obtained at 5-minute
  intervals for the 1st half-hour of the study.
• Similar images are then obtained at 10 minute
  intervals.

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Hepatobiliary Imaging Interpretation

• Normally the gallbladder is visualized in the
  first half-hour of the study, as are the common
  bile duct and duodenum.
• Visualization of the gallbladder confirms that
  the cystic duct is patent.
• If the above structures are not identified at 1
  hour, delayed images should be obtained for up to
  4 hours.

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Normal 99mTc-DISIA Hepatobiliary Scan
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Acute Cholecystitis

• More than 95 of patients with acute
  cholecystitis have cystic duct obstruction.
• In the proper clinical setting, the diagnosis of
  acute cholecystitis (calculus or acalculus) in a
  fasting patient may be reliably made in the
  presence of normal hepatic uptake and excretion
  of the radiopharmaceutical through the common
  duct, but without visualization of the
  gallbladder over a period of 4 hours after
  injection.

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Technetium-99m Hepatobiliary ScanAcute
Cholecystitis
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Rim Sign of Acute Cholecystitis
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Rim Sign of Acute Cholecystitis

• Also called the pericholecystic hepatic activity
  sign.
• Seen in about 20 of patients whose gallbladders
  are not visualized on hepatobiliary scans.
• May be the result of inflammation causing
  regional hepatic hyperemia.
• 40 of patients with a rim sign have either a
  perforated or a gangrenous gallbladder.

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Rim Sign of Acute Cholecystitis
149
Cystic Duct Sign

• Small nubbin of activity in the cystic duct
  proximal to the site of obstruction.

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Cystic Duct Sign
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Use of Pharmacologic Intervention

• Morphine causes constriction of the sphincter of
  Oddi (increased smooth muscle tone) with
  subsequent rise in intraductal pressure in the
  common duct by 60, producing increased flow of
  the radiopharmaceutical into the gallbladder.
• Typical dosage is 0.04 mg/kg diluted in 10 mL of
  saline.
• Nonvisualization of the gallbladder 30 minutes
  after morphine has the same implication as lack
  of visualization on 4-hour images.

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Morphine Augmentation
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Normal Gallbladder Response to Cholecystokinin
(CCK)
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Abnormal Gallbladder Response to Cholecystokinin
(CCK)
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Hepatobiliary Imaging

• Accurate and convenient imaging in acute and
  chronic biliary states.
• Common indications
• Acute (calculous or acalculous) cholecystitis.
• Biliary patency.
• Identification of biliary leaks.
• Differentiation of biliary atresia from neonatal
  hepatitis in neonates.

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Technetium-99m Hepatobiliary ScanBiliary Leak
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Hepatobiliary Imaging

• Accurate and convenient imaging in acute and
  chronic biliary states.
• Common indications
• Acute (calculous or acalculous) cholecystitis.
• Biliary patency.
• Identification of biliary leaks.
• Differentiation of biliary atresia from neonatal
  hepatitis in neonates.

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Biliary Atresia and Neonatal Hepatitis

• Imaging with 99mTc-IDA analogs has been used to
  exclude a diagnosis of biliary atresia by
  demonstrating patent extrahepatic biliary systems
  in jaundiced neonates.
• In the absence of visualization of the biliary
  tree, atresia may not be successfully
  differentiated from severe hepatocellular disease
  produced by neonatal hepatitis.
• Phenobarbital stimulated excretion of
  radiopharmaceutical.

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Technetium-99m Hepatobiliary ScanNeonatal
Hepatitis
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Technetium-99m Hepatobiliary ScanBiliary Atresia
162
Gastrointestinal Tract

• Liver-Spleen Imaging.
• Hepatic Blood Pool Imaging.
• Gastrointestinal Bleeding Studies.
• Hepatobiliary Imaging.

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Outline

• Cerebrovascular System
• Thyroid Imaging and Uptake
• Gastrointestinal Tract
• Genitourinary System
• Conventional Neoplasm Imaging
• Inflammation and Infection Imaging

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Genitourinary Imaging

• With the widespread use of computed tomography
  and ultrasound, the evaluation of renal anatomy
  by nuclear techniques has diminished.
• The role of nuclear renal scanning has become
  confined to functional analysis.

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Radionuclide Renal Evaluation

• Anatomic imaging (visual assessment of renal
  cortex).
• Renal functional imaging visual assessment of
  renal blood flow, uptake and excretion.
• Renogram time-activity curve that provides a
  graphic representation of the uptake and
  excretion of a radiopharmaceutical by the
  kidneys.

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Anatomic (Cortical) Imaging

• Usually performed for evaluation of
• Space-occupying lesions.
• Functioning pseudotumors such as cortical columns
  of Bertin.
• Edema or scarring associated with acute or
  chronic pyelonephritis, especially in children.
• 99mTC-DSMA (dimercaptosuccinic acid) and SPECT
  are generally used.

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99mTc-DMSA Cortical Imaging of the Kidneys
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99mTc-DMSA Pyelonephritis
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Radionuclide Renal Evaluation

• Anatomic imaging (visual assessment of renal
  cortex).
• Renal functional imaging visual assessment of
  renal blood flow, uptake and excretion.
• Renogram time-activity curve that provides a
  graphic representation of the uptake and
  excretion of a radiopharmaceutical by the
  kidneys.

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Renal Physiology

• The excretory function of the kidneys consists of
  two primary mechanisms
• Passive filtration through the glomerulus.
• Active secretion by the tubules.

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Genitourinary Imaging Radiopharmaceuticals

• Those excreted by tubular secretions.
• 99mTc-MAG3.
• Those excreted by glomerular function.
• 99mTc-DTPA.
• Those bound in the renal tubules for a
  sufficiently long time to permit cortical
  anatomic imaging.
• 99mTc-dimercaptosuccinic acid (DMSA).

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Functional Renal Imaging

• Alternative to intravenous urography providing
  anatomic, functional and collecting system
  patency information.
• Has two phases
• Renal perfusion (renal blood flow)
• Renal function

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Functional Renal Imaging Technique

• Intravenous injection of 10 to 20 mCi (370 to 740
  MBq) of 99mTc-DTPA (glomerular) or 99mTc-MAG3
  (tubular).
• Imaging renal perfusion is usually begun as the
  bolus is visualized in the proximal abdominal
  aorta with subsequent serial images made every 1
  to 5 seconds.

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99mTc-DTPA Normal renal blood flow
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Functional Imaging Technique

• At the end of the renal perfusion sequence,
  imaging for renal function begins.
• Dynamic or sequential static, 3 to 5 minute
  images are obtained over 20 to 30 minutes.

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99mTc-MAG3 Normal Renogram
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Functional Renal Imaging Technique

• Time-activity curves (renograms) are created from
  regions of interest placed over the renal
  parenchyma on the sequential static images.
• Renograms are graphic representations of the
  uptake and excretion of a radiopharmaceutical.
• The classic renogram curve is obtained using
  agents that are eliminated by tubular secretion.
  (e.g. ,99mTc-MAG3).

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Typical Regions of Interest for Computer Analysis
179
Typical Renogram Curve
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Renography

• The normal-computer generated renogram curve
  using a tubular radiopharmaceutical consists of
  three phases
• Renal perfusion or vascular transit phase (30 to
  60 seconds).
• Cortical or tubular concentration phase (1 to 5
  minutes).
• Clearance or excretion phase.

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Typical Renogram Curve
182
Renography

• The renogram curves for each kidney should be
  relatively symmetric.
• The shapes of the curves should be inspected for
  alterations from the normal configuration.

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Renography

• Data commonly derived from 99mTc-MAG3 renograms
  include
• Time to peak activity Normal is 3 to 5 minutes.
• Relative renal uptake ratios at 2 to 3 minutes
  Activity of each kidney should be equal, ideally
  50. A value of 40 or less is considered
  abnormal.
• Half-time excretion Time for half of the peak
  activity to be cleared. Normal is 8 to 12
  minutes.

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99mTc-MAG3 Acute Pyelonephritis
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99mTc-MAG3 Acute Pyelonephritis
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Posterior Flow Images after 99mTc-MAG3Acute
Tubular Necrosis
187
Typical Renogram Curve
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Posterior Flow Images after 99mTc-MAG3Acute
Tubular Necrosis
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Posterior Flow Images after 99mTc-MAG3Acute
Tubular Necrosis
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Diuretic Renography

• In patients with nonobstructive hydronephrosis
  and/or hydroureter due to vesicoureter reflux,
  previous obstruction or functional uretopelvic
  disorders, the dilated intrarenal collecting
  system may fill but not reach pressures
  sufficient to open the ureteropelvic junction.
• This give the impression of a fixed anatomic
  abnormality rather than a functional abnormality.

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Diuretic Renography

• By increasing urine flow using a diuretic
  (Lasix), a functional obstruction may be overcome
  by increasing pressure in the renal pelvis and
  thus allowing urine to flow from the collecting
  system into the ureter and bladder.
• Differentiation of a fixed anatomic from a
  functional abnormality.

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Characterisitic Time-activity Curves in a
Diuretic Renogram
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Non-obstructed Patulous Collecting System
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Non-obstructed Patulous Collecting System
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Abnormal Diuretic Renogram with Obstruction
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Abnormal Diuretic Renogram with Obstruction
197
High Grade Obstruction of the Right Kidney
Collecting System
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Captopril Renography

• Renovascular (renal artery stenosis) hypertension
  constitutes about 1 to 4 of all cases of
  hypertension.
• Most common cause of renal artery stenosis is
  atherosclerosis, predominantly in the elderly
• The second most common cause is fibromuscular
  dysplasia, occurring primarily in women younger
  than 35 years.

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Renal Artery Stenosis

• Significant renal artery stenosis (60 to 75)
  decreases afferent arteriolar blood pressure
  which stimulates renin secretion by the
  juxtaglomerular apparatus.
• Renin secretion ultimately results in the
  formation of Angiotensin II which vasoconstricts
  efferent arterioles.
• Effferent arteriolar constriction restores
  glomerular filtration pressure and rate (GFR).

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Captopril Renography

• When an ACE inhibitor is given to a patient with
  renal artery stenosis, there is a decrease in GFR
  that is scintigraphically detectable.
• Captopril renography is highly specific for renal
  artery stenosis.
• A positive test indicates that the patients
  hypertension is renin dependent, most commonly
  produced by renal artery stenosis, and that it is
  likely to be improved by renal revascularization.
  

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Renal Artery Stenosis

• Patients should be selected carefully and limited
  to those with a moderate to high probability of
  renovascular hypertension.

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Renal Artery Stenosis

• Selection criteria includes
• Initial presentation of hypertension older than
  60 years or younger than 20 years.
• Severe or accelerated hypertension resistant to
  medication therapy.
• Hypertension previously well controlled but now
  difficult to manage medically.
• Hypertension in patients with other evidence of
  vascular disease.
• Unexplained renal dysfunction in patients with
  recent onset of hypertension.
• Unexplained hypertension in patients with
  abdominal bruits.

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Captopril Renography

• Using the glomerular agent 99mTc-DTPA, the
  principle finding is decreased uptake and
  excretion caused by the captopril induced drop in
  glomerular filtration.
• Using the primarily tubular agent 99mTc-MAG3, the
  captopril induced drop in GFR results in
  increased cortical retention.

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Pre- and Post-Captopril 99mTc-MAG3
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Pre-CaptoprilRenal Blood Flow and Renogram
99mTc-MAG3
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Post-CaptoprilRenal Blood Flow and Renogram
99mTc-MAG3
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Outline

• Cerebrovascular System
• Thyroid Imaging and Uptake
• Gastrointestinal Tract
• Genitourinary System
• Inflammation and Infection Imaging
• Conventional Neoplasm Imaging

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POST

• Extra CNS Slides

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POST

• Extra Thyroid and Parathyroid Slides

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POST

• Extra GI Slides

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Attenuation Secondary to Breast Tissue
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Accessory Spleen
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Splenic Abscess
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Splenic Infarcts
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Lymphoma of the Spleen
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Long-standing common bile duct obstruction
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Meckels Scan
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Gastric Emptying
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Abnormal Diuretic Renogram with Obstruction