SL
Uploaded bySGPGI, lucknow
PPTX, PDF2,957 views

Nuclear cardiology

This document provides an overview of nuclear cardiology techniques used in the assessment of coronary artery disease (CAD). It discusses the history and development of nuclear medicine imaging including planar imaging and SPECT/PET. Key aspects summarized are: 1. SPECT imaging involves injection of radiotracers like thallium-201 or technetium-99m which distribute to the myocardium proportional to blood flow. Gamma photons are detected and reconstructed to provide 3D images of radiotracer distribution. 2. PET imaging uses positron-emitting radiotracers like rubidium-82 or ammonia-13 for perfusion and fluorodeoxyglucose for metabolism. It provides higher resolution functional imaging

Embed presentation

Downloaded 130 times
NUCLEAR MEDICINE IN CAD PRESENTED BY- DR KUNAL KUMAR SINGH DEPT OF CARDIOLOGY, SGPGI LUCKNOW
History Helmann Blumgart Myron Prinzmetal Hal Anger injected radon to measure circulation time in 1927. radiolabelled albumin In 1948 Anger scintallating gamma camera in 1952; beginning of clinical nuclear cardiology
History • Liljestrand-1939-normal blood volume. • 1976-thallium201-two dimensional planar imaging. • 1980s-SPECT using rotating anger camera. • 1990-technetium99m based agents and gated SPECT. • 1990-2003-ECG gated SPECT. • 90% of SPECT in U.S use technetium and 90% are gated SPECT.
SPECT Single Photon Emission Computed Tomography
Basic concept • Intravenously injected radiotracer distributes to myocardium proportional to blood flow • Gamma camera captures the photons, converts to digital data and displays it as a scintillation event • Parallel hole collimator-better localisation of source • Photomultiplier tubes-conversion of signals • Final result-multiple tomograms of radiotracer distribution
Radioactive decay Principles Alpha decay Beta decay Gamma decay
SPECT image display • Short axis images-perpendicular to long axis of the heart, displayed from apex to base. • Vertical long axis-parallel to long axis of heart and parallel to long axis of body. • Horizontal long axis-parallel to long axis of heart, perpendicular to VLA slice.
Effect of Coronary Stenosis on Coronary Blood Flow Reserve
Effect of Coronary Stenosis on Coronary Blood Flow Reserve Illustration of coronary blood flow reserve abnormalities
SPECT perfusion tracers • Thallium 201 • Technetium–99m – Sestamibi (Cardiolyte) – Tetrafosmin (Myoview) – Teboroxime • Dual Isotope – Thallium injected for resting images – Tech -99m injected at peak stress
Thallium-201 • Monovalent cation, property similar to potassium. • Half life 73 hours, emits 80keV photons, t½ 73hrs,85% first pass extraction. • Peak myocardial concentration in 5 min, rapid clearance from intravascular compartment. • Redistribution of thallium-begins 10-15 mins after, related to conc. gradient of thallium between myocyte and blood. • Differential washout-clearance is more rapid from normal myocardium • Hyperinsulinemic states reduce blood conc.&slow redistribution.so fasting recommended
Technetium-99m labelled tracers • Half life 6 hrs,140keV photons,60% extraction • Uptake by passive distribution by gradient • Minimal redistribution-require two separate injections-one at peak stress and one at rest • Single day study-first injected dose is low • Two day study-higher doses injected both rest and stress- optimise myocardial count rate-larger body habitus • Tc99m tracers bound by mitochondria.limiyed washout occurs.so imaging can commence later and can be repeated
Stress protocols • Patient should be NPO for 4-6 hrs • When feasible antiischaemic drugs to be withold(b blockers and long acting calcium channel blockers -48 hrs prior,nitrates at east 12 hrs) • Caffeine and theophylline to be avoided (at least 12 hrs before test)
Stress protocols
Imaging Protocols • Thallium protocols-  Stress protocols-injected at peak stress and images taken at peak stress and at 4 hrs,24hrs  Reversal of a thallium defect is a marker of reversible ischemia  Rest protocols- thallium defect reversibility from initial rest images to delayed redistribution images reflect viable myocardium with resting hypoperfusion  Initial defect persists-irreversible defect
Imaging Protocols  Stress/redistribution/reinjection method commonly used  Reinjection if fixed defects seen at 4 hrs  Timing of stress image-early  Rest redistribution image for resting ischemia/viability
Imaging Protocols • Technitium protocol-  Most common-same day low dose rest/high dose stress- disadvantage is reduction in stress defect contrast.  Viability assessment improved by NTG prior to rest study  2 day imaging protocols are performed in patients with large body habitus( where higher doses are required)
Imaging Protocols • Dual isotope protocol-  Anger camera can collect image in different energy windows  Thallium at rest followed by Tc 99m tracer at peak stress  If there is rest perfusion defect,redistribution imaging taken either 4 hrs prior or 24hrs after Tc99m injection
General Principles of Interpretation and Reporting The key elements to be reported • Perfusion defects - presence and location • Reversibility (stress induced ischemia) • Irreversible or fixed (MI) • The extent of perfusion abnormality • Severity • Extent and severity – Independent risk factors – Risk stratification • It is not sufficient to describe a stress perfusion imaging test as simply “abnormal”
SPECT Image Interpretation and Reporting Visual evaluation A, A large, moderately severe, reversible IW defect reflecting a moderately severe flow reserve abnormality B, A milder reversible IW defect reflecting a less severe stenosis or a severe stenosis with well-developed collaterals minimizing the defect severity In both patients, there is also a mild lateral wall reversible defect
Single vascular territory reversible defects A, A reversible IW defect consistent with inducible ischemia in the RCA territory B, A reversible lateral wall defect consistent with inducible ischemia in the LCX territory C, A reversible anterior wall defect consistent with inducible ischemia in the LAD territory
Reversible defects in more than one vascular territory A, Inducible ischemia in LCX and RCA territories B, Inducible ischemia in LCX and LAD territories
Advantages and Disadvantages of Visual Analysis Accuracy of visual analysis • Experience and training of the reader • Quality of the imaging study Advantage • Incorporate information from the raw data (e.g., Breast or an elevated diaphragm attenuating the inferior wall) • Adjust threshold for interpreting an abnormality Disadvantage • Inherently subjective • Intraobserver and interobserver variability
Semiquantitative visual analysis • A standardised segmentation model – Myocardium is divided into 17 segments – On the basis of 3 short-axis slices and a representative long-axis slice to depict the apex • Perfusion is graded within each segment on a scale of 0 to 4 • 0-normal uptake • 1-mildly reduced uptake • 2-moderately reduced uptake • 3-severely reduced uptake and • 4-no uptake
Semiquantitative visual analysis • The segmental scores are assigned • Subjectively by the image interpreter or • Automatically by software programs • Myocardium divided into 17 segments on the basis of 3 short axis and a long axis slice
Standard segmental myocardial display for semiquantitative visual analysis in a 17-segment model Segmental scoring: severe apical fixed defect extending into the inferoapical and anteroapical walls with evidence of reversible defects in the inferior and lateral walls. SSS = 23; SRS = 15; SDS = SSS − SRS = 8 represents the extent of ischemia
Quantitative analysis of SPECT imaging Circumferential profile of relative tracer activity • The most common technique employed • Around the tomogram of interest, such as a short-axis tomogram • Each short-axis tomogram is sampled at every 3-6o for 360o, along a ray extending from the center of the image
Quantitative analysis of SPECT imaging • The maximum pixel (midportion of the myocardium) are recorded for each angle • The data may be plotted to create a profile of the perfusion pattern relative to the most “normal” area of uptake (assigned a value of 100% uptake)
Quantitative analysis of SPECT imaging Quantitative extent of abnormality • Total amount of myocardium that falls below the lower limit of normal Severity of the perfusion abnormality • Depth of the patient's perfusion abnormality relative to the lower limit of normal Lower limit of normal
Bull's-eye polar plot • Data from all of the individual short-axis tomograms can be combined • 2D compilation of all of the 3D short-axis perfusion data
Automated quantitative analysis software Selected short- and long- axis tomograms from stress and rest studies are automatically segmented and scored BULL’s EYE PLOTS 3D Extent of ischemic myocardium (white area) measures 23% of the total myocardium
Advantages and Disadvantages of Quantitative Analysis Advantages • Little or no human interaction • Highly reproducible • Accounts for potential artifacts such as breast or diaphragm attenuation • More objectivity and reproduciblility  Interrogate the effect of therapies on serial changes in myocardial perfusion Disadvantages • Artifacts that are not accounted for by the normal data comparison (motion or other suboptimal quality issues may be called abnormal by quantitation) In practice : Final conclusion is arrived by visual analysis incorporating the quantitative data
Additional signs • Lung uptake of thallium • Transient ischemic dilatation of left ventricle
Lung Uptake • In some patients, substantial tracer uptake is apparent throughout the lung fields after stress that is not present at rest – Often have severe multivessel disease – Elevation of PCWP during exercise – Decreases in EF during exercise • Mechanism: – Ischemia-induced elevation in LA and pulmonary pressures slows pulmonary transit of the tracer  more time for extraction or transudation into the interstitial spaces of the lung
TID: transit Ischemic Dilation (Stress induced LV Cavity Dilation) • Severe, extensive CAD (usually with classic ischemic defect)  Left Main  Prox LAD  MVD  Diffuse subendocardial ischemia TID depends on stress type and protocol used Exercise stress ULN (upper limit of normal) is 1.19 for same day protocol and 1.21 for dual isotope imaging. Vasodilator stress testing ULN is 1.19 for same day protocol and 1.36 for dual isotope imaging.
NORMAL VARIATIONS IN SPECT • Dropout of the upper septum • Apical thinning • Lateral wall may appear brighter than septum • Minimised by review of series of normal volunteers
Technical artifacts • Breast attenuation- – Minimised by Tc99m agents,ECG gated SPECT – Presence of preserved wall motion and thickening • Inferior wall attenuation – Diaphragm overlapping inferior wall – Minimised by gated SPECT, prone position • Extracardiac tracer uptake – Repeat imaging, drink cold water to clear tracer from visceral organs
• • end diastole • • • end systole
Technical artifacts • LBBB- – isolated reversible perfusion defects of septum – Heterogeneity of flow b/w LAD & LCx due to delayed septal relaxation – Reduced O2 demand due to late septal contraction, when wall stress is less • HCM- – due to ASH, appearance of lateral perfusion defect
ECG-gated SPECT • Simultaneous assessment of LV function and perfusion • Involves creation of one cardiac cycle for analysis that represents an average of several hundred beats – counts recorded during any individual cardiac cycle is insufficient • Images acquired during a period of 8 to 15 minutes • Frames are redisplayed sequentially in a cine or movie format • Beat-length windowing • High-quality ECG-gated images
Basis for the technique of ECG gating 1 – end diastolic 4 – end systolic Wall thickening and brightening are seen across the course of systole
ECG-gated SPECT image interpretation Visual assessment of regional myocardial function • Normally brightening - normal regional systolic performance • Diminished but apparent brightening – hypokinetic • Slight brightening - severely hypokinetic • No apparent brightening - akinetic
ECG-gated SPECT - Quantitative Analysis • Computer-based methodology with software capable of quantitative analysis • Fully automated and highly reproducible • Automated interrogation of the apparent epicardial and endocardial borders of all of the tomograms in all three orthogonal planes • These multiple 2D contours are then reconstructed to create a surface- rendered 3D display • Can be viewed from any direction by simple maneuvering • Automated calculation of EF and LV volumes
ECG-gated SPECT - Quantitative Analysis The green “mesh” represents the epicardium, and the gray surface represents the endocardium EF is quantitated from the volume change During image interpretation, gated SPECT images are displayed in the cine format as an endless loop movie
• Combined SPECT/CT or PET/CT scanners-complementary anatomical and functional information
PET • Radiotracers labelled with positron emitting isotopes • Perfusion tracers-Rb82 and n13 ammonia • Metabolic tracer-F18 FDG • Beta decay-positron emission • Annihilation-collide with electron-give two gamma rays of 511keV-travel in opp.direction • PET scanner detects opposing photons in coincidence-spatial and temporal resolution • FDG studies performed after 50 to 75 gm glucose loading 1-2 hrs prior to injection -↑glucose metabolism,FDG uptake and improves image quality
Perfusion tracers • Diffusible tracers-O-15-accumulate and wash out. • Non diffusible- Rb 82, N13
PET - Image Analysis Differentiation of normal, stunned, hibernating and necrotic myocardium • Hibernating myocardium – Presence of enhanced FDG uptake in regions of decreased blood flow ("PET mismatch") • Necrotic myocardium – Concordant reduction in both metabolism and flow ("PET match") • Stunning – Regional dysfunction in presence of normal perfusion
Clinical Application of PET Perfusion Imaging • Segments with reductions in both blood flow and FDG uptake – Only a 20% chance of functional improvement following revascularization • Hibernating segments – 80 to 85% chance of functional improvement following revascularization • The PPV and NPV for improvement in wall motion score after revascularization is 96% • Extent of myocardium with enhanced FDG uptake predicts the magnitude of improvement in EF, exercise tolerance and HF symptoms
HIbernating myocardium Scarred in anteroseptal region
Advantages of PET over SPECT • Higher spatial resolution • Improved attenuation and scatter correction • Quantification regional blood flow – SPECT may fail to detect balanced ischemia in multivessel CAD – ↓blood flow reserve by PET –early identification of CAD • Sensitivity and specificity (95%) for detection of CAD – "probably normal" or abnormal studies by SPECT versus PET • Quantification of myocardial blood flow in absolute terms – “balanced” ischemia may not be detected by SPECT
Limitations • Requirement of an on-site cyclotron for [13N]ammonia • High cost of monthly generator replacement for 82Rb • Relatively short half-lives of both 82Rb and [13N]ammonia limit the utility of PET to patients undergoing pharmacologic stress only
PET with 13N-ammonia and 18F-FDG to assess myocardial viability . Regional myocardial 18F-FDG uptake is disproportionately enhanced compared with regional myocardial blood flow; this pattern is termed perfusion–metabolism mismatch and is indicative of hibernating myocardium
Metabolic tracers • C-11 palmitate • I-123 BMIPP-Ischemic memory-fatty acid metabolism suppressed for longer time after an ischemic event
Comparison with non-nuclear techniques • Dobutamine echocardiography is an established technique for viability detection Relative predictive value of the different forms of radionuclide MPI and of dobutamine echocardiography • Meta-analysis : 52 studies; 1367 patients with ischemic LV dysfunction • For each technique, NPV > PPV • NPV: Highest with FDG-PET, reinjection thallium SPECT and dobutamine echocardiography • PPV : Highest with dobutamine echocardiography and lowest with reinjection thallium SPECT Bax JJ et al. Sensitivity, specificity, and predictive accuracies of various noninvasive techniques for detecting hibernating myocardium. Curr Probl Cardiol 2001
Predictive accuracy of imaging tests for myocardial viability
Assessment of myocardial viability by nuclear imaging in CAD Why viability assessment? • CAD is the major cause of HF • Severe LV dysfunction – not an irreversible condition • Hibernation and stunning are potentially reversible • Viable myocardium can be demonstrated in 20-40% of patients with CAD and LV dysfunction, even in the absence of angina Allman KC et al. Myocardial viability testing and impact of revascularization on prognosis in patients with coronary artery disease and left ventricular dysfunction: a meta-analysis. J Am Coll Cardiol 2002
Assessment of myocardial viability by nuclear imaging in CAD Group A - > 7 viable segments Group B - ≤ 7 viable segments The outcome depends not only on the presence, but also the extent of viability
Risk Stratification in Stable Chest Pain Syndromes The Relation Between the Extent of Perfusion Defect and Cardiac Event Rate (risk of death or mi)
The Incremental Value of Perfusion Imaging The larger the chi-square value, the stronger the relation between the combination of factors on the x-axis and the natural history outcome . Even when anatomic information is available, the physiologic information provided by SPECT MPI adds significantly to risk prediction ability Hachamovitch R , Berman DS, Kiat H et al Exercise Myocardial perfusion in patients without coronary artery disease: . J Am Coll Cardiol 1993;22;665
Identification of Treatment Benefit After Risk Stratification • Stress MPI in >10,000 patients with suspected CAD • The extent of ischemic myocardium predicted reduction in the risk of death with revascularization • Just over 10% of ischemic myocardium • As the percentage of ischemic myocardium increased, the magnitude of benefit of revascularization increased as well (Currently being tested in ISCHEMIA Trial)
Prognostic Value of Normal MPI • Studies  Benign outcome associated with a normal stress MPI study • ACC/AHA/ASNC Radionuclide Imaging Guidelines – Data of 21,000 patients with normal stress SPECT MPI study – The hard event rate is 0.7% / yr (follow-up of 2 yrs - “warranty period”) • Baseline high risk factors (e.g., DM)  slightly higher risk after a normal stress MPI study (consistent with Bayes’ theorem) • Angiographic CAD with a stable symptom complex – Low-risk outcome (~0.9% / yr) with a normal stress MPI – The mechanism: ? Preserved endothelial function despite CAD allowing appropriate flow-mediated vasodilation during stress reducing impact of angiographic stenosis.
Influence of Perfusion Tracer on Detection of CAD • The choice of radiotracer  does not notably affect the discrimination between the presence and absence of CAD • Studies comparing the widely used agents No significant improvement in sensitivity or specificity • Exception: Demonstration of improved specificity in women with 99mTc- sestamibi • 99mTc-based agents (greater photon energy) – Improved performance in obese patients and those with large breasts – Higher quality gated images
Pharmacologic Stress Testing for Detection of CAD • Vasodilator stress (more powerful hyperemic stress response) – No improved sensitivity to detect CAD – Because of the “roll-off” property of the common perfusion tracers (diffusion limitation at high flow levels) • 2003 ACC/AHA/ASNC Radionuclide Imaging Guidelines – Pooled analysis of 2465 catheterized patients in 17 studies – Sensitivity of 89% and specificity of 75% (similar to exercise SPECT MPI) • Dobutamine stress imaging – Diagnostic ability : Similar to other pharmacologic and exercise stress – Recommended only when other agents are contraindicated • Maximal coronary flow reserve is not achieved often • Substantial side effects
Effect of Submaximal Exercise Performance on CAD Detection • In exercise ECG testing, sensitivity falls significantly if >85% of maximum predicted HR for age is not achieved • Perfusion heterogeneity usually develops at a lower degree of supply- demand mismatch than ECG changes – Sensitivity of MPI is maintained at somewhat lower workloads • No difference in sensitivity between the maximal and the submaximal tests • The extent and severity of reversible perfusion defects are diminished at submaximal workloads, which may affect the prognostic value of the test
Detecting and Defining the Extent of CAD • To formulate a management strategy  Extent of disease >> presence or absence of disease • SPECT MPI is limited by the relative nature of the perfusion information • In TVD with balanced ischemia, the least hypoperfused area appears normal  true extent of CAD may be underestimated • Gated SPECT allows improved sensitivity (85% to 91%) Sharir T, Bacher-Stier C, Dhar S, et al: Identification of severe and extensive CAD by postexercise regional wall motion abnormalities in Tc-99m sestamibi gated SPECT. Am J Cardiol 2000
Imaging in Patients with Established CAD • Clinical questions may remain after angiography regarding the “physiologic significance” of stenoses • SPECT MPI can identify the “culprit” ischemic lesion • The results of stress-rest SPECT MPI correlate generally with invasive measures of coronary flow reserve • Successful PCI  Improvement of SPECT evidence of ischemia
Imaging After CABG • Recurrent symptoms post CABG: SPECT MPI accurately detects presence and location graft stenoses • Routine assessment for ischemia in an asymptomatic patient is not recommended (outcome risk is low in the early years after CABG) • 900 asymptomatic patients post CABG – Defects were common with SPECT MPI – Associated with significantly increased relative risk of death or major events Ficaro EP American Society of Nuclear Cardiology: Imaging Guidelines for Nuclear Cardiology Procedures
• In symptomatic post-CABG patients : Helps to guide the need for intervention • In asymptomatic patients – Implications for clinical decision making are less clear – Extent of SPECT abnormality is important – More extensive perfusion abnormality may justify an invasive approach
Suspected ACS in the Emergency Department • Patients with symptoms suggestive of ACS but with nondiagnostic ECG and biomarker • 99mTc-based perfusion agents may be administered in the ED at rest, with images acquired 45 to 60 minutes later • Images reflect myocardial blood flow at the time of injection (minimal redistribution) • NPV for ruling out MI is high • Positive MPI  higher risk of cardiac events during the index hospitalization as well as during follow-up • Assist triage decisions
Suspected ACS in the Emergency Department • Sensitivity to detect ACS in the ED – SPECT sestamibi - 92% – Initial troponin I (drawn at the same time) - 39% • The maximum troponin I during the first 24 hrs had a sensitivity similar to that of rest sestamibi imaging but at a distinctly later time point • Acute MPI has the potential to identify ACS earlier than biomarkers • One RCT of 46 ED patients with ongoing chest pain and a nondiagnostic ECG – MPI-guided strategy incurred lower costs and resulted in shorter lengths of stay Stowers SA et al: An economic analysis of an aggressive diagnostic strategy with SPECT MPI and early exercise stress testing in ED patients who present with chest pain but nondiagnostic ECGs: Results from a randomized trial. Ann Emerg Med 2000
• The Emergency Room Assessment of Sestamibi for Evaluation of chest pain trial (ERASE) – 2475 patients with symptoms suggestive of ACS – Significant 20% relative reduction in unnecessary admissions with incorporation of MPI into the ED evaluation strategy
NSTEMI and UA SPECT perfusion imaging in patients after medical stabilization of unstable angina Summary of predictive values of SPECT imaging in the aftermath of UA from multiple studies High-risk stress-rest SPECT MPI Despite medical stabilisation, requires intervention Normal SPECT MPI
Assessment of Inducible Ischemia after MI • Three major determinants of natural history risk after an acute MI – Residual resting LV function – Extent of ischemic, jeopardized myocardium – Susceptibility to ventricular arrhythmias • Gated SPECT MPI – Has the ability to provide much of this information – Has the potential to be the single most important test in the stable patient after STEMI • A “low-risk” 201Tl image (no reversible defects and no lung uptake) was associated with a low-risk natural history outcome after MI Beller GA:Clinical value of MPI in CAD. J Nucl Cardiol 2003
AUC(Appropriate Use Criteria) • For optimal patient selection • Term Appropriate does not mandate testing but supports that large proportion of patients within a given indication will be candidates for nuclear imaging. • Term Rarely appropriate does not prohibit testing but implies only limited number of patients within given indication will require nuclear imaging.
Hendel RC, Berman DS, Di Carli MF, Heidenreich PA, Henkin RE, Pellikka PA, Pohost GM, Williams KA. ACCF/ASNC/ACR/AHA/ASE/ SCCT/SCMR/SNM 2009 appropriate use criteria for cardiac radionuclide imaging
Thank you

More Related Content

PDF
Nuclear cardiology
byFrank Meissner
 
PPSX
Myocardial perfusion scintigraphy overview
byMostafa Sayed
 
PPTX
PET scan in cardiac imaging
byMilan Silwal
 
PPSX
Principles of nuclear cardiology
byHiralal Pawar
 
PPTX
Nuclear imaging in cardiology
byrahatul quadir
 
PPT
Nuclear Imaging In Cardiology Cme
byMuhammad Ayub
 
PPTX
Myocardial perfusion imaging SPECT basics
byJennifer Gutiérrez
 
PPTX
PET scan in Cardilogy
byRaghu Kishore Galla
 
Nuclear cardiology
byFrank Meissner
 
Myocardial perfusion scintigraphy overview
byMostafa Sayed
 
PET scan in cardiac imaging
byMilan Silwal
 
Principles of nuclear cardiology
byHiralal Pawar
 
Nuclear imaging in cardiology
byrahatul quadir
 
Nuclear Imaging In Cardiology Cme
byMuhammad Ayub
 
Myocardial perfusion imaging SPECT basics
byJennifer Gutiérrez
 
PET scan in Cardilogy
byRaghu Kishore Galla
 

What's hot

PPTX
Coronary anomalies
byhospital
 
PPTX
Coronary CT Angiography
byLPS Institute of Cardiology Kanpur UP India
 
PPTX
Ct angio in cardiology
byAmit Verma
 
PPT
Ct calcium scoring 1
bySahar Gamal
 
PPTX
Cardiac Magnetic Resonance Imaging
byRahman Ud Din
 
PPTX
Cardiac MRI
byPraveen Nagula
 
PPTX
Myocardial viability
byPrithvi Puwar
 
PPTX
Pulmonary venous hypertension stages & skiagraphic changes
byGOVT MEDICAL COLLEGE TRIVANDRUM
 
PPTX
Assessment of myocardial viability
bySwapnil Garde
 
PDF
IVC Filter
byRichin Koshy
 
PDF
MPI , nuclear cardiac
byBudour Alzahrani
 
PPTX
Left ventricular angiogram (1)
byGOVT MEDICAL COLLEGE TRIVANDRUM
 
PPTX
Coronary ct angiography
bySGPGI, lucknow
 
PPT
CT Coronary Angiography (CTCA)
bySCGH ED CME
 
PPTX
Intravenous Ultrasound
byDhileeban Maharajan
 
PPTX
Coronary CT
byDr.Suhas Basavaiah
 
PPTX
Stress echocardiography
bySruthi Meenaxshi
 
PPT
Cardiac MRI
byMilan Silwal
 
PPTX
Fraction flow reserve
byPriyanka Thakur
 
PPTX
Cardiac Resynchronization therapy.pptx
bydesktoppc
 
Coronary anomalies
byhospital
 
Coronary CT Angiography
byLPS Institute of Cardiology Kanpur UP India
 
Ct angio in cardiology
byAmit Verma
 
Ct calcium scoring 1
bySahar Gamal
 
Cardiac Magnetic Resonance Imaging
byRahman Ud Din
 
Cardiac MRI
byPraveen Nagula
 
Myocardial viability
byPrithvi Puwar
 
Pulmonary venous hypertension stages & skiagraphic changes
byGOVT MEDICAL COLLEGE TRIVANDRUM
 
Assessment of myocardial viability
bySwapnil Garde
 
IVC Filter
byRichin Koshy
 
MPI , nuclear cardiac
byBudour Alzahrani
 
Left ventricular angiogram (1)
byGOVT MEDICAL COLLEGE TRIVANDRUM
 
Coronary ct angiography
bySGPGI, lucknow
 
CT Coronary Angiography (CTCA)
bySCGH ED CME
 
Intravenous Ultrasound
byDhileeban Maharajan
 
Coronary CT
byDr.Suhas Basavaiah
 
Stress echocardiography
bySruthi Meenaxshi
 
Cardiac MRI
byMilan Silwal
 
Fraction flow reserve
byPriyanka Thakur
 
Cardiac Resynchronization therapy.pptx
bydesktoppc
 

Similar to Nuclear cardiology

PPTX
Nuclear Radiology.pptx
byssusere208d4
 
PPT
Cardiac scanning
byMahran Alnahmi
 
PPTX
Nuclear medicine for cardiothoracic surgeons
bySrikanthK120
 
PPTX
Imaging in Myocardial Infarction and Thallium Scan
byDr. Vimal Chaudhary
 
PPT
Left ventricular function evaluation
byMostafa Sayed
 
PDF
מאמר1
byRoylerner
 
PDF
מאמר1
byRoylerner
 
PDF
Nuclear cardiology dated info
byFrank Meissner
 
PPTX
ARTIFACTS IN myocardial perfusion scan.pptx
byDrAnoshaAslamkamal
 
PPT
Role of nuclear medicine
byLokender Yadav
 
PPTX
Non-Invasive physiological assessment of coronary circulatory function
byPRAVEEN GUPTA
 
PPTX
MPS mucopolysaccharidoses IN MEDICAL.pptx
byMUHAMMADUSMANYOUSUF1
 
PPTX
Seminar presentation 7
bySumaiyaShams
 
PPTX
Assessment of myocardial viability
byAshish Golwara
 
PPTX
Non Invasive testing of myocardial ischemia AA.pptx
byhospital
 
PPTX
Nuclear Cardiology Imaging about Myocardial Perfusion Scintigraphy
byYurikoAndre
 
PPT
Nuclear imaging bck
byRambabu Satipedakala
 
PPTX
Overview Myocardial Viability by Imaging.pptx
bydimassetiaji11
 
PPTX
RADIO ISOTOPES PROTOCOLS myocardial perfusionfinal.pptx
byjustsami2000
 
PPT
cardiovascular_imaging.ppt
bydeardiarymystery1
 
Nuclear Radiology.pptx
byssusere208d4
 
Cardiac scanning
byMahran Alnahmi
 
Nuclear medicine for cardiothoracic surgeons
bySrikanthK120
 
Imaging in Myocardial Infarction and Thallium Scan
byDr. Vimal Chaudhary
 
Left ventricular function evaluation
byMostafa Sayed
 
מאמר1
byRoylerner
 
מאמר1
byRoylerner
 
Nuclear cardiology dated info
byFrank Meissner
 
ARTIFACTS IN myocardial perfusion scan.pptx
byDrAnoshaAslamkamal
 
Role of nuclear medicine
byLokender Yadav
 
Non-Invasive physiological assessment of coronary circulatory function
byPRAVEEN GUPTA
 
MPS mucopolysaccharidoses IN MEDICAL.pptx
byMUHAMMADUSMANYOUSUF1
 
Seminar presentation 7
bySumaiyaShams
 
Assessment of myocardial viability
byAshish Golwara
 
Non Invasive testing of myocardial ischemia AA.pptx
byhospital
 
Nuclear Cardiology Imaging about Myocardial Perfusion Scintigraphy
byYurikoAndre
 
Nuclear imaging bck
byRambabu Satipedakala
 
Overview Myocardial Viability by Imaging.pptx
bydimassetiaji11
 
RADIO ISOTOPES PROTOCOLS myocardial perfusionfinal.pptx
byjustsami2000
 
cardiovascular_imaging.ppt
bydeardiarymystery1
 

Recently uploaded

PPT
Frameworks for Identifying Systemic Sclerosis and Its Complications: From Pat...
byPVI, PeerView Institute for Medical Education
 
PPTX
Evidence based oral medicine in dentistry .pptx
bymrugajoshi101
 
PPTX
Sweet Dreams - an ILC Partners webinar on sleep
byILC- UK
 
PDF
2026 Autism and Neurodiversity Conferences and Events - Table 1.pdf
by101autism
 
PPTX
Human Communication slp-1 lecture 5.pptx
byDr Zonera Khalid PT
 
PPTX
OSPE in Pharmacology | Complete Guide for II MBBS Students 2026
byShivankan Kakkar
 
PDF
PEDIATRIC CATARACT & IT'S MANAGEMENT BY SAMIKSHA RAI
bySamikshaRai22
 
PDF
How Nepali Politics Collapsed the Health System l A Critical Analysis
byPublic Health Concern Nepal
 
PPTX
Histology of Musculoskeletal Tissues.pptx
byDaniel Komolafe
 
PDF
MCQ of 10th NHPC Masters of Optometry.pdf
byBipin Koirala
 
PDF
Best Ayurvedic Sexologist in Madhepura, Bihar Dr. Sunil Dubey
byDubey Clinic
 
PPTX
Ultrasound Basics Physics for Interventional Pain Physicians
bySushpaDas
 
PPTX
JANUARY 2026 ONCOLOGY CARTOONS BY DR KANHU CHARAN PATRO
byKanhu Charan
 
PDF
Cognitive Shadows : Analyzing Modern Traversals of Trauma-Based Mind Control ...
byGAURAV. H .TANDON
 
PDF
Airway Obstruction Management Techniques and strategies
byemaanarif2004
 
PPTX
Special Senses (RIT): Vision, Hearing & Taste Explained with Clinical Correlates
byBALAJI SOMA
 
PPTX
INTRODUCTION TO DENTAL X-RAY, HISTORY, PROPERTIES AND USES OF X-RAY
byDr. Sakshat Lamichhane
 
PPTX
Human Digestive System (RIT): Physiology, Digestion & Absorption Explained
byBALAJI SOMA
 
PPTX
Climate Change and Biological Systems_20260113_062004_0000.pptx
bykeyksbykeyks
 
PPTX
2025 BASIC first aid for lay persons.pptx
bymdiescobillo
 
Frameworks for Identifying Systemic Sclerosis and Its Complications: From Pat...
byPVI, PeerView Institute for Medical Education
 
Evidence based oral medicine in dentistry .pptx
bymrugajoshi101
 
Sweet Dreams - an ILC Partners webinar on sleep
byILC- UK
 
2026 Autism and Neurodiversity Conferences and Events - Table 1.pdf
by101autism
 
Human Communication slp-1 lecture 5.pptx
byDr Zonera Khalid PT
 
OSPE in Pharmacology | Complete Guide for II MBBS Students 2026
byShivankan Kakkar
 
PEDIATRIC CATARACT & IT'S MANAGEMENT BY SAMIKSHA RAI
bySamikshaRai22
 
How Nepali Politics Collapsed the Health System l A Critical Analysis
byPublic Health Concern Nepal
 
Histology of Musculoskeletal Tissues.pptx
byDaniel Komolafe
 
MCQ of 10th NHPC Masters of Optometry.pdf
byBipin Koirala
 
Best Ayurvedic Sexologist in Madhepura, Bihar Dr. Sunil Dubey
byDubey Clinic
 
Ultrasound Basics Physics for Interventional Pain Physicians
bySushpaDas
 
JANUARY 2026 ONCOLOGY CARTOONS BY DR KANHU CHARAN PATRO
byKanhu Charan
 
Cognitive Shadows : Analyzing Modern Traversals of Trauma-Based Mind Control ...
byGAURAV. H .TANDON
 
Airway Obstruction Management Techniques and strategies
byemaanarif2004
 
Special Senses (RIT): Vision, Hearing & Taste Explained with Clinical Correlates
byBALAJI SOMA
 
INTRODUCTION TO DENTAL X-RAY, HISTORY, PROPERTIES AND USES OF X-RAY
byDr. Sakshat Lamichhane
 
Human Digestive System (RIT): Physiology, Digestion & Absorption Explained
byBALAJI SOMA
 
Climate Change and Biological Systems_20260113_062004_0000.pptx
bykeyksbykeyks
 
2025 BASIC first aid for lay persons.pptx
bymdiescobillo
 

Nuclear cardiology

  • 1.
    NUCLEAR MEDICINE INCAD PRESENTED BY- DR KUNAL KUMAR SINGH DEPT OF CARDIOLOGY, SGPGI LUCKNOW
  • 2.
    History Helmann Blumgart MyronPrinzmetal Hal Anger injected radon to measure circulation time in 1927. radiolabelled albumin In 1948 Anger scintallating gamma camera in 1952; beginning of clinical nuclear cardiology
  • 3.
    History • Liljestrand-1939-normal bloodvolume. • 1976-thallium201-two dimensional planar imaging. • 1980s-SPECT using rotating anger camera. • 1990-technetium99m based agents and gated SPECT. • 1990-2003-ECG gated SPECT. • 90% of SPECT in U.S use technetium and 90% are gated SPECT.
  • 4.
    SPECT Single Photon EmissionComputed Tomography
  • 5.
    Basic concept • Intravenouslyinjected radiotracer distributes to myocardium proportional to blood flow • Gamma camera captures the photons, converts to digital data and displays it as a scintillation event • Parallel hole collimator-better localisation of source • Photomultiplier tubes-conversion of signals • Final result-multiple tomograms of radiotracer distribution
  • 6.
  • 9.
    SPECT image display •Short axis images-perpendicular to long axis of the heart, displayed from apex to base. • Vertical long axis-parallel to long axis of heart and parallel to long axis of body. • Horizontal long axis-parallel to long axis of heart, perpendicular to VLA slice.
  • 11.
    Effect of CoronaryStenosis on Coronary Blood Flow Reserve
  • 12.
    Effect of CoronaryStenosis on Coronary Blood Flow Reserve Illustration of coronary blood flow reserve abnormalities
  • 13.
    SPECT perfusion tracers •Thallium 201 • Technetium–99m – Sestamibi (Cardiolyte) – Tetrafosmin (Myoview) – Teboroxime • Dual Isotope – Thallium injected for resting images – Tech -99m injected at peak stress
  • 15.
    Thallium-201 • Monovalent cation,property similar to potassium. • Half life 73 hours, emits 80keV photons, t½ 73hrs,85% first pass extraction. • Peak myocardial concentration in 5 min, rapid clearance from intravascular compartment. • Redistribution of thallium-begins 10-15 mins after, related to conc. gradient of thallium between myocyte and blood. • Differential washout-clearance is more rapid from normal myocardium • Hyperinsulinemic states reduce blood conc.&slow redistribution.so fasting recommended
  • 17.
    Technetium-99m labelled tracers •Half life 6 hrs,140keV photons,60% extraction • Uptake by passive distribution by gradient • Minimal redistribution-require two separate injections-one at peak stress and one at rest • Single day study-first injected dose is low • Two day study-higher doses injected both rest and stress- optimise myocardial count rate-larger body habitus • Tc99m tracers bound by mitochondria.limiyed washout occurs.so imaging can commence later and can be repeated
  • 18.
    Stress protocols • Patientshould be NPO for 4-6 hrs • When feasible antiischaemic drugs to be withold(b blockers and long acting calcium channel blockers -48 hrs prior,nitrates at east 12 hrs) • Caffeine and theophylline to be avoided (at least 12 hrs before test)
  • 19.
  • 23.
    Imaging Protocols • Thalliumprotocols-  Stress protocols-injected at peak stress and images taken at peak stress and at 4 hrs,24hrs  Reversal of a thallium defect is a marker of reversible ischemia  Rest protocols- thallium defect reversibility from initial rest images to delayed redistribution images reflect viable myocardium with resting hypoperfusion  Initial defect persists-irreversible defect
  • 24.
    Imaging Protocols  Stress/redistribution/reinjectionmethod commonly used  Reinjection if fixed defects seen at 4 hrs  Timing of stress image-early  Rest redistribution image for resting ischemia/viability
  • 25.
    Imaging Protocols • Technitiumprotocol-  Most common-same day low dose rest/high dose stress- disadvantage is reduction in stress defect contrast.  Viability assessment improved by NTG prior to rest study  2 day imaging protocols are performed in patients with large body habitus( where higher doses are required)
  • 26.
    Imaging Protocols • Dualisotope protocol-  Anger camera can collect image in different energy windows  Thallium at rest followed by Tc 99m tracer at peak stress  If there is rest perfusion defect,redistribution imaging taken either 4 hrs prior or 24hrs after Tc99m injection
  • 29.
    General Principles ofInterpretation and Reporting The key elements to be reported • Perfusion defects - presence and location • Reversibility (stress induced ischemia) • Irreversible or fixed (MI) • The extent of perfusion abnormality • Severity • Extent and severity – Independent risk factors – Risk stratification • It is not sufficient to describe a stress perfusion imaging test as simply “abnormal”
  • 30.
    SPECT Image Interpretationand Reporting Visual evaluation A, A large, moderately severe, reversible IW defect reflecting a moderately severe flow reserve abnormality B, A milder reversible IW defect reflecting a less severe stenosis or a severe stenosis with well-developed collaterals minimizing the defect severity In both patients, there is also a mild lateral wall reversible defect
  • 31.
    Single vascular territoryreversible defects A, A reversible IW defect consistent with inducible ischemia in the RCA territory B, A reversible lateral wall defect consistent with inducible ischemia in the LCX territory C, A reversible anterior wall defect consistent with inducible ischemia in the LAD territory
  • 32.
    Reversible defects inmore than one vascular territory A, Inducible ischemia in LCX and RCA territories B, Inducible ischemia in LCX and LAD territories
  • 33.
    Advantages and Disadvantagesof Visual Analysis Accuracy of visual analysis • Experience and training of the reader • Quality of the imaging study Advantage • Incorporate information from the raw data (e.g., Breast or an elevated diaphragm attenuating the inferior wall) • Adjust threshold for interpreting an abnormality Disadvantage • Inherently subjective • Intraobserver and interobserver variability
  • 34.
    Semiquantitative visual analysis •A standardised segmentation model – Myocardium is divided into 17 segments – On the basis of 3 short-axis slices and a representative long-axis slice to depict the apex • Perfusion is graded within each segment on a scale of 0 to 4 • 0-normal uptake • 1-mildly reduced uptake • 2-moderately reduced uptake • 3-severely reduced uptake and • 4-no uptake
  • 35.
    Semiquantitative visual analysis •The segmental scores are assigned • Subjectively by the image interpreter or • Automatically by software programs • Myocardium divided into 17 segments on the basis of 3 short axis and a long axis slice
  • 36.
    Standard segmental myocardialdisplay for semiquantitative visual analysis in a 17-segment model Segmental scoring: severe apical fixed defect extending into the inferoapical and anteroapical walls with evidence of reversible defects in the inferior and lateral walls. SSS = 23; SRS = 15; SDS = SSS − SRS = 8 represents the extent of ischemia
  • 38.
    Quantitative analysis ofSPECT imaging Circumferential profile of relative tracer activity • The most common technique employed • Around the tomogram of interest, such as a short-axis tomogram • Each short-axis tomogram is sampled at every 3-6o for 360o, along a ray extending from the center of the image
  • 39.
    Quantitative analysis ofSPECT imaging • The maximum pixel (midportion of the myocardium) are recorded for each angle • The data may be plotted to create a profile of the perfusion pattern relative to the most “normal” area of uptake (assigned a value of 100% uptake)
  • 40.
    Quantitative analysis ofSPECT imaging Quantitative extent of abnormality • Total amount of myocardium that falls below the lower limit of normal Severity of the perfusion abnormality • Depth of the patient's perfusion abnormality relative to the lower limit of normal Lower limit of normal
  • 41.
    Bull's-eye polar plot •Data from all of the individual short-axis tomograms can be combined • 2D compilation of all of the 3D short-axis perfusion data
  • 42.
    Automated quantitative analysissoftware Selected short- and long- axis tomograms from stress and rest studies are automatically segmented and scored BULL’s EYE PLOTS 3D Extent of ischemic myocardium (white area) measures 23% of the total myocardium
  • 43.
    Advantages and Disadvantagesof Quantitative Analysis Advantages • Little or no human interaction • Highly reproducible • Accounts for potential artifacts such as breast or diaphragm attenuation • More objectivity and reproduciblility  Interrogate the effect of therapies on serial changes in myocardial perfusion Disadvantages • Artifacts that are not accounted for by the normal data comparison (motion or other suboptimal quality issues may be called abnormal by quantitation) In practice : Final conclusion is arrived by visual analysis incorporating the quantitative data
  • 45.
    Additional signs • Lunguptake of thallium • Transient ischemic dilatation of left ventricle
  • 46.
    Lung Uptake • Insome patients, substantial tracer uptake is apparent throughout the lung fields after stress that is not present at rest – Often have severe multivessel disease – Elevation of PCWP during exercise – Decreases in EF during exercise • Mechanism: – Ischemia-induced elevation in LA and pulmonary pressures slows pulmonary transit of the tracer  more time for extraction or transudation into the interstitial spaces of the lung
  • 47.
    TID: transit IschemicDilation (Stress induced LV Cavity Dilation) • Severe, extensive CAD (usually with classic ischemic defect)  Left Main  Prox LAD  MVD  Diffuse subendocardial ischemia TID depends on stress type and protocol used Exercise stress ULN (upper limit of normal) is 1.19 for same day protocol and 1.21 for dual isotope imaging. Vasodilator stress testing ULN is 1.19 for same day protocol and 1.36 for dual isotope imaging.
  • 48.
    NORMAL VARIATIONS INSPECT • Dropout of the upper septum • Apical thinning • Lateral wall may appear brighter than septum • Minimised by review of series of normal volunteers
  • 50.
    Technical artifacts • Breastattenuation- – Minimised by Tc99m agents,ECG gated SPECT – Presence of preserved wall motion and thickening • Inferior wall attenuation – Diaphragm overlapping inferior wall – Minimised by gated SPECT, prone position • Extracardiac tracer uptake – Repeat imaging, drink cold water to clear tracer from visceral organs
  • 51.
  • 52.
    Technical artifacts • LBBB- –isolated reversible perfusion defects of septum – Heterogeneity of flow b/w LAD & LCx due to delayed septal relaxation – Reduced O2 demand due to late septal contraction, when wall stress is less • HCM- – due to ASH, appearance of lateral perfusion defect
  • 53.
    ECG-gated SPECT • Simultaneousassessment of LV function and perfusion • Involves creation of one cardiac cycle for analysis that represents an average of several hundred beats – counts recorded during any individual cardiac cycle is insufficient • Images acquired during a period of 8 to 15 minutes • Frames are redisplayed sequentially in a cine or movie format • Beat-length windowing • High-quality ECG-gated images
  • 54.
    Basis for thetechnique of ECG gating 1 – end diastolic 4 – end systolic Wall thickening and brightening are seen across the course of systole
  • 55.
    ECG-gated SPECT imageinterpretation Visual assessment of regional myocardial function • Normally brightening - normal regional systolic performance • Diminished but apparent brightening – hypokinetic • Slight brightening - severely hypokinetic • No apparent brightening - akinetic
  • 56.
    ECG-gated SPECT -Quantitative Analysis • Computer-based methodology with software capable of quantitative analysis • Fully automated and highly reproducible • Automated interrogation of the apparent epicardial and endocardial borders of all of the tomograms in all three orthogonal planes • These multiple 2D contours are then reconstructed to create a surface- rendered 3D display • Can be viewed from any direction by simple maneuvering • Automated calculation of EF and LV volumes
  • 57.
    ECG-gated SPECT -Quantitative Analysis The green “mesh” represents the epicardium, and the gray surface represents the endocardium EF is quantitated from the volume change During image interpretation, gated SPECT images are displayed in the cine format as an endless loop movie
  • 58.
    • Combined SPECT/CTor PET/CT scanners-complementary anatomical and functional information
  • 59.
    PET • Radiotracers labelledwith positron emitting isotopes • Perfusion tracers-Rb82 and n13 ammonia • Metabolic tracer-F18 FDG • Beta decay-positron emission • Annihilation-collide with electron-give two gamma rays of 511keV-travel in opp.direction • PET scanner detects opposing photons in coincidence-spatial and temporal resolution • FDG studies performed after 50 to 75 gm glucose loading 1-2 hrs prior to injection -↑glucose metabolism,FDG uptake and improves image quality
  • 61.
    Perfusion tracers • Diffusibletracers-O-15-accumulate and wash out. • Non diffusible- Rb 82, N13
  • 62.
    PET - ImageAnalysis Differentiation of normal, stunned, hibernating and necrotic myocardium • Hibernating myocardium – Presence of enhanced FDG uptake in regions of decreased blood flow ("PET mismatch") • Necrotic myocardium – Concordant reduction in both metabolism and flow ("PET match") • Stunning – Regional dysfunction in presence of normal perfusion
  • 63.
    Clinical Application ofPET Perfusion Imaging • Segments with reductions in both blood flow and FDG uptake – Only a 20% chance of functional improvement following revascularization • Hibernating segments – 80 to 85% chance of functional improvement following revascularization • The PPV and NPV for improvement in wall motion score after revascularization is 96% • Extent of myocardium with enhanced FDG uptake predicts the magnitude of improvement in EF, exercise tolerance and HF symptoms
  • 64.
  • 65.
    Advantages of PETover SPECT • Higher spatial resolution • Improved attenuation and scatter correction • Quantification regional blood flow – SPECT may fail to detect balanced ischemia in multivessel CAD – ↓blood flow reserve by PET –early identification of CAD • Sensitivity and specificity (95%) for detection of CAD – "probably normal" or abnormal studies by SPECT versus PET • Quantification of myocardial blood flow in absolute terms – “balanced” ischemia may not be detected by SPECT
  • 66.
    Limitations • Requirement ofan on-site cyclotron for [13N]ammonia • High cost of monthly generator replacement for 82Rb • Relatively short half-lives of both 82Rb and [13N]ammonia limit the utility of PET to patients undergoing pharmacologic stress only
  • 67.
    PET with 13N-ammoniaand 18F-FDG to assess myocardial viability . Regional myocardial 18F-FDG uptake is disproportionately enhanced compared with regional myocardial blood flow; this pattern is termed perfusion–metabolism mismatch and is indicative of hibernating myocardium
  • 68.
    Metabolic tracers • C-11palmitate • I-123 BMIPP-Ischemic memory-fatty acid metabolism suppressed for longer time after an ischemic event
  • 71.
    Comparison with non-nucleartechniques • Dobutamine echocardiography is an established technique for viability detection Relative predictive value of the different forms of radionuclide MPI and of dobutamine echocardiography • Meta-analysis : 52 studies; 1367 patients with ischemic LV dysfunction • For each technique, NPV > PPV • NPV: Highest with FDG-PET, reinjection thallium SPECT and dobutamine echocardiography • PPV : Highest with dobutamine echocardiography and lowest with reinjection thallium SPECT Bax JJ et al. Sensitivity, specificity, and predictive accuracies of various noninvasive techniques for detecting hibernating myocardium. Curr Probl Cardiol 2001
  • 72.
    Predictive accuracy ofimaging tests for myocardial viability
  • 73.
    Assessment of myocardialviability by nuclear imaging in CAD Why viability assessment? • CAD is the major cause of HF • Severe LV dysfunction – not an irreversible condition • Hibernation and stunning are potentially reversible • Viable myocardium can be demonstrated in 20-40% of patients with CAD and LV dysfunction, even in the absence of angina Allman KC et al. Myocardial viability testing and impact of revascularization on prognosis in patients with coronary artery disease and left ventricular dysfunction: a meta-analysis. J Am Coll Cardiol 2002
  • 74.
    Assessment of myocardialviability by nuclear imaging in CAD Group A - > 7 viable segments Group B - ≤ 7 viable segments The outcome depends not only on the presence, but also the extent of viability
  • 75.
    Risk Stratification inStable Chest Pain Syndromes The Relation Between the Extent of Perfusion Defect and Cardiac Event Rate (risk of death or mi)
  • 76.
    The Incremental Valueof Perfusion Imaging The larger the chi-square value, the stronger the relation between the combination of factors on the x-axis and the natural history outcome . Even when anatomic information is available, the physiologic information provided by SPECT MPI adds significantly to risk prediction ability Hachamovitch R , Berman DS, Kiat H et al Exercise Myocardial perfusion in patients without coronary artery disease: . J Am Coll Cardiol 1993;22;665
  • 77.
    Identification of TreatmentBenefit After Risk Stratification • Stress MPI in >10,000 patients with suspected CAD • The extent of ischemic myocardium predicted reduction in the risk of death with revascularization • Just over 10% of ischemic myocardium • As the percentage of ischemic myocardium increased, the magnitude of benefit of revascularization increased as well (Currently being tested in ISCHEMIA Trial)
  • 78.
    Prognostic Value ofNormal MPI • Studies  Benign outcome associated with a normal stress MPI study • ACC/AHA/ASNC Radionuclide Imaging Guidelines – Data of 21,000 patients with normal stress SPECT MPI study – The hard event rate is 0.7% / yr (follow-up of 2 yrs - “warranty period”) • Baseline high risk factors (e.g., DM)  slightly higher risk after a normal stress MPI study (consistent with Bayes’ theorem) • Angiographic CAD with a stable symptom complex – Low-risk outcome (~0.9% / yr) with a normal stress MPI – The mechanism: ? Preserved endothelial function despite CAD allowing appropriate flow-mediated vasodilation during stress reducing impact of angiographic stenosis.
  • 79.
    Influence of PerfusionTracer on Detection of CAD • The choice of radiotracer  does not notably affect the discrimination between the presence and absence of CAD • Studies comparing the widely used agents No significant improvement in sensitivity or specificity • Exception: Demonstration of improved specificity in women with 99mTc- sestamibi • 99mTc-based agents (greater photon energy) – Improved performance in obese patients and those with large breasts – Higher quality gated images
  • 80.
    Pharmacologic Stress Testingfor Detection of CAD • Vasodilator stress (more powerful hyperemic stress response) – No improved sensitivity to detect CAD – Because of the “roll-off” property of the common perfusion tracers (diffusion limitation at high flow levels) • 2003 ACC/AHA/ASNC Radionuclide Imaging Guidelines – Pooled analysis of 2465 catheterized patients in 17 studies – Sensitivity of 89% and specificity of 75% (similar to exercise SPECT MPI) • Dobutamine stress imaging – Diagnostic ability : Similar to other pharmacologic and exercise stress – Recommended only when other agents are contraindicated • Maximal coronary flow reserve is not achieved often • Substantial side effects
  • 81.
    Effect of SubmaximalExercise Performance on CAD Detection • In exercise ECG testing, sensitivity falls significantly if >85% of maximum predicted HR for age is not achieved • Perfusion heterogeneity usually develops at a lower degree of supply- demand mismatch than ECG changes – Sensitivity of MPI is maintained at somewhat lower workloads • No difference in sensitivity between the maximal and the submaximal tests • The extent and severity of reversible perfusion defects are diminished at submaximal workloads, which may affect the prognostic value of the test
  • 82.
    Detecting and Definingthe Extent of CAD • To formulate a management strategy  Extent of disease >> presence or absence of disease • SPECT MPI is limited by the relative nature of the perfusion information • In TVD with balanced ischemia, the least hypoperfused area appears normal  true extent of CAD may be underestimated • Gated SPECT allows improved sensitivity (85% to 91%) Sharir T, Bacher-Stier C, Dhar S, et al: Identification of severe and extensive CAD by postexercise regional wall motion abnormalities in Tc-99m sestamibi gated SPECT. Am J Cardiol 2000
  • 83.
    Imaging in Patientswith Established CAD • Clinical questions may remain after angiography regarding the “physiologic significance” of stenoses • SPECT MPI can identify the “culprit” ischemic lesion • The results of stress-rest SPECT MPI correlate generally with invasive measures of coronary flow reserve • Successful PCI  Improvement of SPECT evidence of ischemia
  • 84.
    Imaging After CABG •Recurrent symptoms post CABG: SPECT MPI accurately detects presence and location graft stenoses • Routine assessment for ischemia in an asymptomatic patient is not recommended (outcome risk is low in the early years after CABG) • 900 asymptomatic patients post CABG – Defects were common with SPECT MPI – Associated with significantly increased relative risk of death or major events Ficaro EP American Society of Nuclear Cardiology: Imaging Guidelines for Nuclear Cardiology Procedures
  • 85.
    • In symptomaticpost-CABG patients : Helps to guide the need for intervention • In asymptomatic patients – Implications for clinical decision making are less clear – Extent of SPECT abnormality is important – More extensive perfusion abnormality may justify an invasive approach
  • 86.
    Suspected ACS inthe Emergency Department • Patients with symptoms suggestive of ACS but with nondiagnostic ECG and biomarker • 99mTc-based perfusion agents may be administered in the ED at rest, with images acquired 45 to 60 minutes later • Images reflect myocardial blood flow at the time of injection (minimal redistribution) • NPV for ruling out MI is high • Positive MPI  higher risk of cardiac events during the index hospitalization as well as during follow-up • Assist triage decisions
  • 87.
    Suspected ACS inthe Emergency Department • Sensitivity to detect ACS in the ED – SPECT sestamibi - 92% – Initial troponin I (drawn at the same time) - 39% • The maximum troponin I during the first 24 hrs had a sensitivity similar to that of rest sestamibi imaging but at a distinctly later time point • Acute MPI has the potential to identify ACS earlier than biomarkers • One RCT of 46 ED patients with ongoing chest pain and a nondiagnostic ECG – MPI-guided strategy incurred lower costs and resulted in shorter lengths of stay Stowers SA et al: An economic analysis of an aggressive diagnostic strategy with SPECT MPI and early exercise stress testing in ED patients who present with chest pain but nondiagnostic ECGs: Results from a randomized trial. Ann Emerg Med 2000
  • 88.
    • The EmergencyRoom Assessment of Sestamibi for Evaluation of chest pain trial (ERASE) – 2475 patients with symptoms suggestive of ACS – Significant 20% relative reduction in unnecessary admissions with incorporation of MPI into the ED evaluation strategy
  • 89.
    NSTEMI and UA SPECTperfusion imaging in patients after medical stabilization of unstable angina Summary of predictive values of SPECT imaging in the aftermath of UA from multiple studies High-risk stress-rest SPECT MPI Despite medical stabilisation, requires intervention Normal SPECT MPI
  • 90.
    Assessment of InducibleIschemia after MI • Three major determinants of natural history risk after an acute MI – Residual resting LV function – Extent of ischemic, jeopardized myocardium – Susceptibility to ventricular arrhythmias • Gated SPECT MPI – Has the ability to provide much of this information – Has the potential to be the single most important test in the stable patient after STEMI • A “low-risk” 201Tl image (no reversible defects and no lung uptake) was associated with a low-risk natural history outcome after MI Beller GA:Clinical value of MPI in CAD. J Nucl Cardiol 2003
  • 91.
    AUC(Appropriate Use Criteria) •For optimal patient selection • Term Appropriate does not mandate testing but supports that large proportion of patients within a given indication will be candidates for nuclear imaging. • Term Rarely appropriate does not prohibit testing but implies only limited number of patients within given indication will require nuclear imaging.
  • 95.
    Hendel RC, BermanDS, Di Carli MF, Heidenreich PA, Henkin RE, Pellikka PA, Pohost GM, Williams KA. ACCF/ASNC/ACR/AHA/ASE/ SCCT/SCMR/SNM 2009 appropriate use criteria for cardiac radionuclide imaging
  • 96.