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Nuclear Medicine in Cardiology

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Title: The ideal perfusion tracer Author: dr. Hussein Last modified by: PD II Created Date: 10/17/2001 2:20:38 AM Document presentation format: On-screen ... – PowerPoint PPT presentation

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Title: Nuclear Medicine in Cardiology


1
Nuclear Medicine in Cardiology
A. Hussein S. Kartamihardja
Department of Nuclear Medicine Padjadjaran
University Dr. Hasan Sadikin Hospital
2
What does the heart do ?
  • The heart is a powerful muscle consisting of two
    pumps side by side.
  • Its steady beating maintains flow of blood to all
    parts of the body throughout life.

Diagnostic modalities in heart disease
  • ECG/ Treadmill
  • Radiography
  • Echocardiography
  • CT scan
  • MRI
  • Angiography
  • Radionuclide imaging

Department of Nuclear Medicine Padjadjaran
University Dr. Hasan Sadikin Hospital
3
Cardiac Nuclear Medicine
Radiopharmaceutical
Physician
Instrumentation
Department of Nuclear Medicine Padjadjaran
University Dr. Hasan Sadikin Hospital
4
History of nuclear cardiology
  • Blumgard and Weiss (1927)
  • the first use of radioactivity in the
    study of the cardiovascular system
  • Wilson measurement of the circulation times
  • Tl-201 (1971)
  • The development and improvement of SPECT
  • The development and established Tc-labeled agents
  • Alternative stress than physical exercise
  • Gate-spect allows simultaneous assessment both of
    myocardial perfusion, function and assessment of
    myocardial viability
  • Gamma camera coincidence imaging system
  • Myocardial metabolic imaging

Department of Nuclear Medicine Padjadjaran
University Dr. Hasan Sadikin Hospital
5
The ideal perfusion radiopharmaceutical
  • Distribution in the myocardium in linier
    proportional to blood flow.
  • Efficient myocardial extraction from blood on the
    first passage through the heart
  • Stable retention within myocardium during data
    acquisition
  • Rapid elimination allowing repeat studies under
    different conditions
  • Good imaging characteristics (short half life,
    low radiation burden to the patient)
  • Ready availability
  • Competitive pricing
  • No current tracer possesses all of these
    properties.
  • Thallium-201
  • Tc-99m Teboroxim
  • Tc-99m MIBI
  • Tc-99m Tetrofosmin

Department of Nuclear Medicine Padjadjaran
University Dr. Hasan Sadikin Hospital
6
Thallium 201 Basic Properties
  • A metallic element which behaves chemically in a
    similar manner to potassium and is given as
    thallous chloride
  • Photon energy is low, and 88 of its emissions
    are x-ray with photon energy of 60-80keV
  • Gamma photons of 135 and 167 keV (12)
  • Enter myocyte by
  • 60 active transport via Na/K ATPase pump
  • 40 passively along the electrochemical gradient
  • Distribution within the myocardium is
    proportional to blood flow
  • The half life of elimination within the heart is
    approximately 7 hrs

Department of Nuclear Medicine Padjadjaran
University Dr. Hasan Sadikin Hospital
7
Tc-99m MIBI (methoxyisobutylisonitrile)
Tc-99m TETROFOSMIN (Basic Properties)
  • It is lipophilic
  • Distribution within the myocardium is
    proportional to blood flow
  • Diffuses out of the capillary into cardiac
    myocytes and is associated with mitochondria
    within the cell.
  • Cardiac uptake is depend on normal mitochondrial
    function.
  • Liver uptake of tetrofosmin is not as prominent
    as with Tc-99m MIBI
  • No redistribution

Department of Nuclear Medicine Padjadjaran
University Dr. Hasan Sadikin Hospital
8
Correlation between Tl-201 and Tc-99m tetrofosmin
imaging
Department of Nuclear Medicine Padjadjaran
University Dr. Hasan Sadikin Hospital
9
Clinical application of Nuclear Cardiology
  • CAD
  • Acute and post MI
  • Cardiomyopathy
  • Valvular disease and Shunts
  • Cardiotoxicity
  • Aneurysms
  • Transplants
  • Diagnosis prognosis
  • Risk stratification
  • Medical vs. surgical treatment
  • Efficiency of management

Stress-rest Tl-201 and Tc-99m labeled agents has
been widely used in the diagnosis and assessment
of coronary artery disease MPI still an
important position in clinical practiceonly 1/3
of symptom-free men with exercise induced
ST segment depression had coronary angiographic
lesions gt 50 diameter stenosis MPI has been
proposed to improve the accuracy and risk
assessment of exercise testing in patients with
suspected CAD Sensitivity 74 - 96, specificity
65 -97 
Department of Nuclear Medicine Padjadjaran
University Dr. Hasan Sadikin Hospital
10
Principles of myocardial perfusion imaging ?
Imaging at 24 hrs is sometimes performed when the
question of underestimation of myocardial mass in
the redistribution images is clinically important
  • What is coronary artery disease ?
  • A condition where there is progressive damage to
    the vessel wall supplying the coronary arteries.
  • Unbalance between demand and supply O2 to
    myocardium

Department of Nuclear Medicine Padjadjaran
University Dr. Hasan Sadikin Hospital
11
Cardiac stress test
  • Physical exercises
  • Exercise has to be adequate to produced the
    heterogenity in blood flow to achieve high
    detection sensitivity
  • Treadmil
  • Ergocycle
  • Pharmacological
  • Pharmacological stress test become important,
    since many patients are unable to exercise
  • Pharmacological stress agents largely remove the
    need for patient cooperation and motivation, and
    enable a confident assessment of cardiac function
    in virtually all cases
  • Dipyridamole
  • Dobutamine
  • Adenosine

Department of Nuclear Medicine Padjadjaran
University Dr. Hasan Sadikin Hospital
12
Dipyridamole
  • Coronary artery dilator
  • The effects of dipyridamole include a mild
    decrease in systolic BP, slight increase HR.
  • The side effects include flushing, abdominal
    pain, nausea, vomiting, transient AV block and
    bronchospasm
  • Infusion dose of 0.56 mg/kg over four minutes
    (0.14 ml/kg/min)

Department of Nuclear Medicine Padjadjaran
University Dr. Hasan Sadikin Hospital
13
Dobutamine
  • The ß-agonists increase myocardial oxygen demand
    through a combined inotropic and chronotropic
    action
  • It dilates the distal coronary vessels, which
    leads to an increase in coronary flow
  • Dose up to 40 ug/kg/min (commence at 10 ug/kg/min
    and proceed in 10 ug/kg/min step every 3 min)
  • Non-cardiac symptoms cause by dobutamine include
    tingling, flushing, nausea, headache, shaking and
    lightheadedness

Department of Nuclear Medicine Padjadjaran
University Dr. Hasan Sadikin Hospital
14
Adenosine
  • Is a naturally occurring purine which mediates
    the cellular action of dipyridamole
  • No significant difference between the coronary
    hyperemic response to adenosine and dipyridamol
  • Has very short half life of between 2 10
    seconds
  • Maximal coronary vasodilatation is achieved in
    85 of patients with intravenous dose of
    140ugr/kg/min
  • Side effect are similar to those with dipyridamol

Department of Nuclear Medicine Padjadjaran
University Dr. Hasan Sadikin Hospital
15
Spect imaging
  • In SPECT imaging, the heart is viewed in 3 planes
  • The horizontal long axis, which is parallel to
    the long axis of the heart from base to apex. It
    begins at the inferior aspect of the heart and
    progresses superiorly
  • The vertical long axis, which is perpendicular to
    the horizontal long axis. It begins at the
    lateral aspect of left ventricle and proceeds
    medially through the septum
  • The short axis of the heart which is
    perpendicular to both of the long axes. It begins
    at the base of the heart and progress through the
    mid plane to the apex

Department of Nuclear Medicine Padjadjaran
University Dr. Hasan Sadikin Hospital
16
Image interpretation
  • I. Defects
  • Location
  • Extent
  • Severity
  • Reversible or fixed
  • Quantitative or semi quantitative analysis
  • II. Other information
  • Transient ischemic dilation
  • Lung uptake

Department of Nuclear Medicine Padjadjaran
University Dr. Hasan Sadikin Hospital
17
Normal perfusion scan
  • There is a wide variety of normal appearances
    arising from variation in size and position of
    the heart, body size and quality of tomographic
    acquisition
  • Knowledge of these variation and confidence in
    their identification is vital to prevent the
    reporting of defects as normal variant
  • An important issue to bear in mind if difficulty
    arise in distinguishing normal variants from true
    defects

Department of Nuclear Medicine Padjadjaran
University Dr. Hasan Sadikin Hospital
18
Department of Nuclear Medicine Padjadjaran
University Dr. Hasan Sadikin Hospital
19
G 2121-00
PRE-PTCA
POST-PTCA
Differences between stress and rest/redistribution
imaging indicates reversibility (ischemia)
Department of Nuclear Medicine Padjadjaran
University Dr. Hasan Sadikin Hospital
20
M724499
PATIENT NO M724499 SEX MALE AGE 53
YRS CLINICAL INDICATION TWO ACUTE CORONARY
EPISODES
ANGIOGRAM A STENOSIS AT THE PROXIMAL AND
MIDDLE THIRDS OF THE LAD ARTERY
Department of Nuclear Medicine Padjadjaran
University Dr. Hasan Sadikin Hospital
21
REST MPI SPECT
GATED BLOOD POOL
NO S 0585/01  SEX MALE AGE
60 YRS ECG NON Q-WAVE MYOCARDIAL INFARCTION
S 0585/01
Department of Nuclear Medicine Padjadjaran
University Dr. Hasan Sadikin Hospital
22
Comparison between SPECT and Treadmill exercise
test
Variable SPECT Treadmill
Availability
Cost
Familiarity
Accuracy
Localization
Extent of disease
Viable myocardium
Left ventricular function
Risk assessment
Department of Nuclear Medicine Padjadjaran
University Dr. Hasan Sadikin Hospital
23
Risk Stratification
Outcome following non-fatal MI Low risk
group 50 - 66 of the patients Can be managed
with medical treatment High risk group 34 - 50
of the patients Prone to future complications
with 3 months death, re-infarction, CHF and
unstable angina
  • Separation of high and low risk groups
  • Clinical evaluation
  • Rest and stress ECG
  • Rest and stress RNA
  • Rest and stress MPI
  • Rest and stress echo
  • Angiography
  • Recommended by ACC AHA
  • Task Force
  • Nuclear cardiology separates high risk patient
    who need invasive and expensive procedures and
    low risk patient who do not.
  • Acts as a Gate - Keeper for referral to
    angiography.

Department of Nuclear Medicine Padjadjaran
University Dr. Hasan Sadikin Hospital
24
Myocardial perfusion scan findings associated
with increased risk for cardiac events after
acute myocardial infarction
  • Perfusion defects induced by exercise or
    pharmacological
  • Reversible perfusion defects in multiple coronary
    vascular territories
  • Large perfusion defect size
  • Improved reperfusion after Tl-201 reinjection
  • Increased lung uptake
  • Left ventricular cavity dilatation
  • Left ventricular dysfunction on gated myocardial
    perfusion scan
  • Abnormal right ventricular uptake

Department of Nuclear Medicine Padjadjaran
University Dr. Hasan Sadikin Hospital
25
Myocardial Viability / Hibernation
  • Persistently impaired myocardial and left
    ventricular function at rest, due to reduced
    coronary blood flow. (Rahimtola)
  • The functional abnormality can be partially or
    completely restored to normal by reducing
    myocardial oxygen demand and/or increasing
    coronary blood flow
  • Myocardial dysfunction is expected to be
    irreversible in regions with myocardial scar, but
    can be improved in region with ischemic but
    viable or hibernating myocardium.
  • The determination of myocardium viability in
    patients with CAD and the LV dysfunction has
    become a frequent issue since interventional
    cardiology is growing rapidly.
  • The differentiation of scar from hibernating
    myocardium is important.
  • Up to now, radionuclide myocardial imaging holds
    the most important promise in this field.
  • Metabolic measurement by PET may be the most
    sensitive non-invasive approach for the
    evaluation of myocardial viability.

Department of Nuclear Medicine Padjadjaran
University Dr. Hasan Sadikin Hospital
26
Myocardial Viability
Why separate viable from scar tissue ?
  • Surgical treatment for viable myocardium results
    in 11.5 event rate compared to 50 after medical
    treatment
  • Surgical treatment for poor viability and scar
    have survival rate of 79 compared to 97 with
    viable tissue
  • LVD due to viable tissue have worse
    prognostic than scars with annual survival of 50
    compared with 92 (PET data)

Department of Nuclear Medicine Padjadjaran
University Dr. Hasan Sadikin Hospital
27
Techniques for assessing myocardial viability
  • Regional wall motion evaluation
  • Ventriculography (gated spect)
  • Echocardiography (dobutamine)
  • Radionuclide angiography
  • Magnetic resonance imaging
  • Perfusion and cell membrane integrity
  • Tl-201protocols
  • Tc-99m sestamibi
  • Tc-99m tetrofosmin
  • Nitrate-augmented perfusion imaging
  • Assessment of metabolism
  • Well established for predicting functional
    recovery after revisualization
  • F-18 FDG
  • I-123 fatty acids (IPPA, BMIPP)

Department of Nuclear Medicine Padjadjaran
University Dr. Hasan Sadikin Hospital
28
Cost Effectiveness of Nuclear Cardiology
  • Historical Background
  • Nuclear Cardiology as a better stress test
  • Detection of CAD as a benchmark for success
  • Gold standard coronary angiography
  • Misconceptions
  • Expensive stress test
  • Sensitivity lt 100
  • False positive
  • Imperfect correlation with angiography
  • The changing paradigm
  • Angiography provides information on anatomy
  • Nuclear cardiology provides information on
    function/physiology
  • Physiology is as important as anatomy, and
    perhaps more important
  • Functional testing with nuclear imaging provide
    comparable prognostic information at lower cost
    than angiography, non-invasive
  • Information provided by nuclear cardiology can
    reduce cost and optimize treatment

Department of Nuclear Medicine Padjadjaran
University Dr. Hasan Sadikin Hospital
29
Summary
  • MPI has been widely used and an important
    position in the diagnosis and assessment of CAD
    Sensitivity 74 - 96, specificity 65 -97

Nuclear cardiology separates persistent defect
with LV dysfunction but viable myocardium from
scar tissue
  • Nuclear cardiology separates high risk patient
    who need invasive and expensive procedures from
    low risk patient who do not.
  • Acts as a Gate - Keeper for referral to
    angiography.

Cost of management strategies using MPI are
cheaper and equally effective when compared with
strategies without MPI with same outcome.
Department of Nuclear Medicine Padjadjaran
University Dr. Hasan Sadikin Hospital
30
Thank you !
Department of Nuclear Medicine Padjadjaran
University Dr. Hasan Sadikin Hospital
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