Download Nuclear cardiology methods in routine clinical practice

Nuclear cardiology methods in
routine clinical practice
Materials for medical students
Lang O., Kamínek M.
Dept Nucl Med, School of Medicine,
Praha, Olomouc
Nuclear cardiology
 Set of non-invasive mostly imaging
diagnostic methods of the cardiovascular
system
 Huge expansion during last 30 years, in
Czech rep. during last 10 years
 Examination of venous system of lower
extremities and lung perfusion are included
Seminar includes
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Imaging in nuclear cardiology (NC)
NC methods
Myocardial perfusion
Myocardial viability
Heart function
Examination of pulmonary embolism
New trends
Ways of imaging in NC
 Detectors of ionizing radiation – gamma cameras
 Source of radiation inside the patient body radiopharmaceutical, tracer
 Ways of distribution - perfusion, metabolic
process, receptors, etc.
 Source of information - ionizing photon (gamma)
 Digital images - processing, archiving, transfer
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planar, tomographic
• SPECT (transversal), PET (coincidence)
Data collection by
gamma cameras
PET camera
Way of tomography - SA slices
Other tomographic slices
Parts of left ventricle myocardium
Legenda:
1 - apex
2 - anterior wall
VLA
SA
3 - lateral wall
4 - inferior wall
5 – septum
HLA
Pollar map
Heart examination
 Myocardium imaging
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perfusion during stress and rest (80%)
viability
necrosis, innervation, ischemia
 Mechanical function assessment
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steady-state ventriculography (multigated - MUGA)
Angiocardiography (first-pass)
non-imaging systems
Myocardial perfusion
rate of NC examinations
number/1000 inhabitants./year
12
10
8
6
4
2
0
CR 1999
EU 1994
EU 1998
USA 1994
Why stress?
Pathophysiology of CAD
Hemodynamic effect of coronary stenoses
Collaterals
Ischemic cascade
Rest myocardial perfusion in CAD
 Physiological compensatory arteriolar
dilatation in the region supplied by
narrowed artery
 Blood flow remains the same as in the
region supplied by normal artery
 Radiopharmaceutical distribution remains
homogenous
Stress myocardial perfusion in CAD
 Arteriolar dilatation in the bed of normal artery
for blood flow increase
 Blood flow through the normal artery increases
 Arteriolae in the bed of narrowed artery are
already dilated - no further dilatation can
occure, so blood flow remains as in the resting
state
 Non-homogenous perfusion
(radiopharmaceutical distribution) as a result
Ischemic cascade
Type of stress
 Mechanical dynamic stress
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ergometer (bicycle), tread-mill
 Pharmacological stress
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vasodilators - adenosine, dipyridamole
positively inotropic drugs - dobutamine,
arbutamine
atropine
 Combined of all mentioned above
Ergometer
 Goal is to achieve at least 85% of maximal heart
rate (220-age) or double-product more than 25000
 Increase by 50 (25) W after every 3 (2) minutes
 Rate of pedalling 40 to 60 per minute
 Radiopharmaceutical injection at peak stress
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distribution proportional to blood flow at the time of
injection
 Maintain this stress for at least 1 to 2 minutes
 Withdraw betablockers (BB), patient fasting
Dipyridamole stress
 Acts indirectly via the adenosin (block its
removal)
 Dilates coronary resistant arteries - it makes
possible to assess coronary flow reserve
 Maximal effect is achieved 3 to 4 minutes after
stopping the 4 minutes infusion
 Its effect can be stopped with theophyllines
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withdraw them before the test
 Usually used in patients using BB, unable to
exercise, with LBBB
Contraindications to perform
dipyridamole stress
 Patients with chronic obstructive pulmonary
disease treated by theophyllines
(dobutamine can be used)
 Patients should avoid tee, cofee, cola before
the test to prevent false negative results
(insuficient or no vasodilation)
Dipyridamole stress
Side effects of dipyridamole
 They occures in approximately 30% of
patients
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headache
neck tension
warm feeling
dizziness
nausea, hypotension
chest pain (very seldom)
Performance of dipy stress
 Dipyridamole applied by intravenous infusion
 Usual dosage is 0.56 (0.75; 0.84) mg/kg
 Dose is diluted with saline to 50 ml
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to prevent local side effects (arm pain)
 Duration of infusion is 4 minutes
 If the patient is unable of any physical stress,
tracer is injected 3-5 min. after stopping
infusion
Combined stress
 Dipyridamole is infused according to previous
rules to sitting or lying patient
 3 to 6 min. bicycle stress follows
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better image quality
lower frequency of side effects
can be performed even in patients with hypotension
 1 to 2 min. before stopping bicycle stress
radiopharmaceutical is injected
Test arrangement
 Right arm - tourniquet of tonometer
 Left arm - infusion through the cannula
 Saline is connected after stopping
dipyridamole for venous link for the case of
any complication
 Patient is sitting on the ergometer, ECG
electrodes according to Mason and Likar
Dobutamine stress
 If dipyridamole is contraindicated
 Dobutamine intravenously in the dose of 5 to 10
g/kg/min., increase every 3 min. up to dose of 40
g/kg/min.
 Monitore ECG, HR and BP, if 85% of maximal HR
is not achieved, add Atropine
 Radiopharmaceutical is injected 1 to 2 min. before
stopping stress
 Contraindications: ventricular tachycardia, severe
hypertension, hypertrophic cardiomyopathy
Myocardial perfusion protocols
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One-day (Tl, Tc, FDG) - two-days (Tc, FDG, Tl)
Stress - rest or rest - stress (Tc, Tl-Tc)
Stress - (redistribution) - reinjection (Tl)
Stress - metabolism (Tc - FDG)
Stress - rest - metabolism (Tc, FDG)
Rest - redistribution - (late redistribution) (Tl)
Rest - metabolism (Tc - FDG)
Radiopharmaceuticals for
perfusion
Tl-201 chlorid or Tc-99m MIBI for
SPECT, N-13H3 or H2O-15 for
PET
Distribution in the myocardium
rely on cells perfusion
Tl-201 has redistribution
Tc-99m MIBI does not have
redistribution
Data processing
 Quantitative analysis of myocadial perfusion
distribution
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CEqual™ - uses pollar maps for standardization and
comparison with „normals“
 Gated (synchronized) tomography (QGSPECT)
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divides cardiac cycle into 8 periods
makes possible to evaluate mechanical function of
the heart (ejection fraction - EF)
Quantification of perfusion
QGSPECT
Basic patterns of myocardial
perfusion imaging (MPI)
 Normal finding
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homogenous perfusion during stress as well as rest
 Sign of ischemia
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perfusion defect during stress which disappears on
rest (reversible defect)
 Sign of scar
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perfusion defect on stress and rest (fixed defect)
 Sign of ischemia and scar
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combination of both mentioned above
Main clinical indication of MPI
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Detection of ischemic heart disease
Hemodynamic effect of coronary stenoses
Prognosis of patients with konwn CAD
Evaluation of revascularization effect and
detection of restenosis
Risk stratification of patients after MI
Myocardial viability
Acute coronary syndromes
Cardiac risk in non-cardiac surgery
Detection of CAD
66y old pt, atypical chest pain, ECHO difuse wall motion
abnormality, Ao+mi reg, sci isch. of inferior wall, EF 40%
Detection of CAD
basic parameters
 Planar Tl-201 scintigraphy - qualitative
evaluatioin
 Group of 4.678 pts - sens. 82%, spec. 88%
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pts without MI - sens. 85%
pts after MI - sens. 99%
one-vessel disease - sens. 79%
two-vessel disease - sens. 88%
three vessel disease - sens. 92%
Detection of CAD
basic parameters
 Referral bias
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only patients with positive scintigraphy are referred to
coronarography
patients with normal scintigraphy are not catheterized
higher sensitivity but decline of specificity
 Normalcy rate (used instead of specificity)
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negative scintigraphy in patients with very low pretest
probabilty of CAD based on history, symptoms, stress
ECG
Detection of CAD
basic parameters
 SPECT Tl-201 scintigraphy
 Group of 1.527 pts - sens. 90%, spec. 70%
(more false positives due to artefacts),
normalcy rate 89%
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pts without MI - sens. 85%
pts after MI - sens. 99%
one-vessel disease - sens. 83%
two-vessel disease - sens. 93%
three-vessel disease - sens. 95%
Detection of CAD
basic parameters
 SPECT Tl-201 scintigraphy
 Group of 704 pts
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stenosis of 50 to 70% - sens. 63%
stenosis of 75 to 100% - sens. 88%
 Dipyridamole stress (1.272 pts)
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sens. 87%
spec. 81%
Detection of CAD
basic parameters
 SPECT Tl-201 scintigraphy
 Asymptomatic pts
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5.000 coronarograms
normal scintigraphy exclude CAD
positive scintigrapy has positive predictive
value (PPV) of 50% - does not confirm CAD
Detection of CAD
basic parameters
 SPECT Tl-201 scintigraphy
 Individual arteries (1.200 pts)
 SPECT is better than planar scintigraphy
(better localisation)
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LAD - sens. 80%, spec. 83%
LCx - sens. 72%, spec. 84%
RCA - sens. 83%, spec. 84%
Detection of CAD
basic parameters
 SPECT Tc-99m MIBI scintigraphy
 Sensitivity 87%
 Specificity 73% (less artefacts using
GSPECT)
 Normalcy rate 92%
 Optimal indication for detection of CAD
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pretest probability 0.15 to 0.50 + pos. stress ECG
pretest probability 0.50 to 0.85
Detection of CAD
basic parameters
 Difference was not confirmed
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Tl-201 vs Tc-99m MIBI
MIBI vs Myoview
physical vs pharmacological stress
men vs women
 Improvement of accuracy was confirmed
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SPECT vs planar scintigraphy
GSPECT, quantification, prone projection
Pts prognosis
Prognosis of pts with known CAD
basic parameters
 Good prognosis - normal scintigraphy
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2.825 pts without MI
• annual increment of death 0.24%
• annual increment of MI 0.53%
 Signs of poor prognosis
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more perfusion defects in more arterial territories
increased uptake in lungs and transient LV dilatation
reversible defects, large and severe defects
Pts after revascularization
detection of culprit lesion
56 y old pt, typical AP, positive stress ECG
SCG arteries stenoses, way of treatmen:
1. CABG RIA, RMS I, III a IV
2. PTCA RMS III a IV
Pts after revascularization
assessment of the result
moderate ischemia of the lateral wall, after PTCA LCx: perfusion and
wall motion improvement, EF from 56% to 63%, stress ECG positive in
both
Pts after revascularization
prognosis
chi - square = 26.76
p = 0.00000023
RR = 3.15
40
30
20
25
40
8
10
0
no
9
positive
negative
MPI
yes
Cardiac
events
Pts after revascularization
summary
 Early after the procedure
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negative scintigraphy - good prognosis
positive scintigraphy - no predictive value
 Ability of long-term prognosis
 Restenosis detection
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in symptomatic patients
in asymptomatic patients with positive stress ECG
Pts after MI
 Definition of infarct size
 Assessment of salvaged myocardium thanks
to different ways of therapy
 Evaluation of myocardial viability in
location of wall motion abnormality
 Risk stratification using stress perfusion
scintigraphy
Pts after MI
scintigrapnic findings
 Group of 55 pts
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pos 38 (69%), borderline 3 (5%), neg 14 (26%)
 Group after QMI (32 pts)
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pos 23 (72%), borderline 2 (6%), neg 7 (22%)
 Group after nQMI (23 pts)
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pos 15 (65%), borderline 1 (4%), neg 7 (31%)
 Group with positive enzymes kinetics (35 pts)
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pos 25 (71%), borderline 3 (9%), neg 7 (20%)
Pts after MI with positive scinti
types of impairment
 Group of 41 pts
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scar 6 (15%), scar + ischemia 9 (22%), isch 26 (63%)
 Group after QMI (25 pts)
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scar 5 (20%), scar + ischemia 7 (28%), isch 13 (52%)
 Group after nQMI (16 pts)
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scar 1 (6%), scar + ischemia 2 (13%), isch 13 (81%)
 Group with positive enzymes kinetics (25 pts)
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scar 4 (16%), scar + ischemia 8 (32%), isch 13 (52%)
74y old pt, nQIM 9/98, left - scinti before PTCA 2.11.98, then PTCA
LAD and OM with stents, right - scinti after PTCA 17.12.98
Pts after MI
summary
 High risk pts (shock, failure, persistent AP,
previous MI) - coronarography
 Without failure with EF < 40% - scintigraphy
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viability and residual ischemia
 Moderate risk - stress scintigraphy
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conservative vs invasive therapy
 Low risk - stress ECG
Myocardial viability
clinical significance
 Important before revascularization
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prediction of cardiac function improvement (>
25% of myocardium should be viable)
 Patients with cardiac failure
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decline of mortality but increase of cardiac
failure due to CAD nowadays
high prevalence of viable myocardium among
pts in waiting list for heart transplantation
Myocardial viability
characteristics
 Defined by perfusion, metabolism and function
 Stunned myocardium
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wall motion abnormality but normal perfusion and
preserved metabolism
 Hibernating myocardium
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wall motion and perfusion abnormality but
preserved metabolism
 Scar
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abnormality of all characteristics
Myocardial viability
PET examination (mismatch = hibernation)
Myocardial viability
principle of the assessment
 Preserved function of ATP-ase
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late accumulation of Tl-201
 Preserved glucose metabolism
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accumulation of F-18 FDG
 Preserved mitochondrial function
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accumulation of Tc-99m MIBI
 Preserved answer to dobutamine
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dobutamine echocardiography
50y old woman, QMI of anterior wall treated by rescue
PTCA LAD with stent implant. 6/99, ECHO anterior wall
motion abnorm., stress scinti 7/99 apico-antero-septal scar,
examination by Tl-201 9/99, F-18 FDG 10/99
201Tl
rest
redistribution
VLA
99mTc
MIBI rest
18F
FDG
rest
VLA
50y old woman, QMI antero-septal 1995, after PTCA LAD
1997, recurrent AP, stress scinti 11/98 antero-septal scar, Tl201 1/99, F-18 FDG 2/99, ECHO unable to evaluate
99mTc
MIBI
rest
201Tl
redistribution
VLA
99mTc
MIBI rest
18F
FDG
rest
VLA
72y old woman, MI 4/00, PTCA LAD 5/00, exam. 7/00, viab. 8/00,
PTCA LAD 9/00, follow up exam. 10/00 – perfusion improv. about 7%
of myocardium of LV, EF as well as wall motion the same
Myocardial viability
accuracy of different methods
Acute coronary syndromes
 Imaging of jeopardized myocardium
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injection on admission, imaging after stabilization
PPV of perfusion defect 90%
NPV of no defect 100%
 Infarction size measurement
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examination before leaving (correlates with histology)
 Viability
 Risk stratification
Acute coronary syndromes
 Examination
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rest SPECT perfusion with Tc-99m MIBI
 Indication
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non-diagnostic ECG
 Limitation
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availability
 Benefit
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cost
Cardiac risk assessment in noncoronary surgery
 Separates group of pts with higher risk
 Group of 2020 pts
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perfusion defect - perioperative events in 20%
of pts
no perfusion defect - perioperative events in 2%
of pts
Radionuclide ventriculography
(MUGA)
 Information about regional and global
ventricular function
 Excellent reproducibility of the results
 Indications
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cardiotoxicity of cytostatics
alternative in pts non-evaluable with ECHO
Radionuclide
angiocardiography
 First-pass
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evaluation of right ventricle function
quantification of central circulation shunts
 Non-imaging devices
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can monitore EF on CCU
can be used for ambulatory EF monitoring
Non-imaging devices
Post-stress ventriculography
Imaging of myocardial
sympathetic receptor density
I-123 MIBG
 Tracer accumulates in postganglionic
praesynaptic vesicules
 Non-invasive assessment of myocardial
sympathetic tone
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prognosis of pts with cardiac failure
 Rational treatment of cardiac failure with
beta-blockers
New trends
 New tracers for myocardial perfusion
imaging
 Imaging of myocardial ischemia
 Imaging of myocardial necrosis
 Imaging of cells apoptosis
 Imaging of endothellin receptors
 Imaging of gene expression
Conclusion
 Nuclear cardiology tests can display noninvasively myocardial perfusion distribution
during different pathophysiological conditions
above all
 They contribute to myocardial viability
assessment in acute and chronic forms of CAD
 Cooperation of cardiologists with nuclear
medicine physicians is essential for proper use
of this methods in favour of our patients
Radionuclide venography and
lung scintigraphy
 Main clinical indication is suspicion of
pulmonary embolism
 Main clinical significance is negative finding
- can exclude embolism
 Widely available is perfusion scintigraphy
 Correlation with chest radiograph is essential
 Ventilation scintigraphy is useful in embolism
of less than 50% of pulmonary circulation
Lung perfusion scintigraphy
 Tc-99m MAA as a tracer
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capillary microembolism
display pulmonary blood flow distribution
It does not increase pulmonary pressure
Injection in supine position
Planar or SPECT imaging
Procedure takes approximately 30 min.
Interpretation is visual - PIOPED criteria
Lung perfusion scintigraphy
patient imaging
Lung perfusion scintigraphy
planar images - normal
Lung perfusion scintigraphy
planar and SPECT slices - embolism
Lung perfusion and ventilation
pulmonary embolism
anterior view, left - perfusion, right - ventilation
Lung perfusion and ventilation
pulmonary embolism
ANT
POST
RPO
LPO
perfusion
ventilation
Radionuclide venography
 Displays patency/abrupt cutoff of lower limbs
deep venous system
 Displays abnormal collateralization
 Displays irregular or asymmetric filling
 Does not display thrombus
 Injection of Tc-99m MAA into dorsal pedal
veins - lung perfusion scintigraphy follows
 Procedure takes approx. 40 to 60 minutes
Radionuclide venography
injection and imaging
Radionuclide venography
left without, right with tourniquets
Radionuclide venography
pathological findings
New trends
 Thrombi imaging
 Labeled thrombocytes
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not readily available
 Receptors imaging
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Acutect - not registered in the Czech rep.
• peptide binding to receptors of activated
thrombocytes labelled with Tc-99m
 Result available in the order of 4 to 6 hours