Principles of nuclear cardiology
Download
1 / 87

Principles of nuclear cardiology - PowerPoint PPT Presentation


  • 152 Views
  • Uploaded on

Principles of nuclear cardiology. History. Hermann blumgart-1927-injected radon to measure circulation time Liljestrand-1939-normal blood volume Myron prinzmetal-1948- radiolabelled albumin Hal anger-1952-gamma camera-beginning of clinical nuclear cardiology

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about ' Principles of nuclear cardiology' - toril


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

History
History

  • Hermann blumgart-1927-injected radon to measure circulation time

  • Liljestrand-1939-normal blood volume

  • Myron prinzmetal-1948- radiolabelled albumin

  • Hal anger-1952-gamma camera-beginning of clinical nuclear cardiology

  • 1976-thallium201-two dimensional planar imaging



Spect single photon emission computed tomography
SPECT single photon emission computed tomography


Basic concept
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


Spect image display
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



Spect perfusion tracers
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
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 min.after ,related to conc.gradient of thallium between myocyte and blood



  • Thallium protocols- myocardium

    • Stress protocols-injected at peak stress and images taken at peak stress and at 4 hrs,24hrs

    • Reversal of a thallium defect 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



Technetium 99m labelled tracers
Technetium-99m labelled tracers myocardium

  • 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



  • 2 day image protocol better for image quality occurs.so imaging can commence later and can be repeated

  • 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


Dual isotope protocol
Dual isotope protocol occurs.so imaging can commence later and can be repeated

  • 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


Radionuclide properties
Radionuclide Properties occurs.so imaging can commence later and can be repeated


Stress protocols
Stress protocols occurs.so imaging can commence later and can be repeated



Interpretation and reporting
Interpretation and reporting after infusion

  • Myocardium devided into 17 segments on the basis of 3 short axis and a long axis slice

  • Perfusion graded from 0(normal perfusion) to 4(no uptake)

  • SSS-summed stress score-stress perfusion abnormality

  • SRS –summed rest score-extent of infarction

  • SDS-summed difference score-stress induced ischemia


Visual analysis of perfusion spect
Visual Analysis of Perfusion SPECT after infusion

  • 0-normal uptake,

  • 1-mildly reduced uptake,

  • 2-moderately reduced uptake,

  • 3-severely reduced uptake, and

  • 4-no uptake



Ant three dimensional short axis perfusion data

Stress

Apex

Inf

Rest

Septum  Lateral

Stress

Apex

Rest

Lat

Inferior  Anterior

Sep

Ant

Stress

Lat

Sep

Rest

Inf

Apex  Base

Normal


Ant three dimensional short axis perfusion data

Apex

Stress

Inf

Rest

Septum  Lateral

Stress

Apex

Rest

Lat

Inferior  Anterior

Sep

Ant

Stress

Lat

Sep

Inf

Rest

Apex  Base

Reversible Ischeamia, defect appears

at stress and disappears during rest


Ant three dimensional short axis perfusion data

Apex

Stress

Inf

Rest

Septum  Lateral

Stress

Apex

Rest

Lat

Inferior  Anterior

Sep

Ant

Stress

Lat

Sep

Inf

Rest

Apex  Base

Fixed Scar, defect is seen in both stress and rest


Interpretation of the findings spect
Interpretation of the three dimensional short axis perfusion dataFindings-SPECT

Stress Rest Interpretation

  • No defects No defects Normal

  • Defect No defect Ischemia

  • Defect Defect Scar/ hibernating

  • Defect location (anterior, posterior, lateral, or septalwall), size (small, medium, or big), severity (mild, moderate,absent), degree of reversibility at rest (completely reversible, partially reversible, irreversible)

  • Regional wall motion, EDV, ESV, EF

(Stress-induced

ischemia)


Additional signs
Additional signs three dimensional short axis perfusion data

  • Lung uptake of thallium

  • Transient ischemic dilatation of left ventricle


Thallium 201 lung uptake
Thallium-201 Lung Uptake three dimensional short axis perfusion data

  • ↑ lung uptake of thallium following stress -marker of severe CAD,elevation of PCWP,↓EF

  • ↑PCWP-slow pulmonary transit-more extraction

  • Minimal splanchnic uptake,early image after stress-lung uptake more apparent in thallium

  • More liver uptake,delayed imaging-lung uptake missed with Tc99m


Tid transit ischemic dilation stress induced lv cavity dilation
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


Variations
Variations Dilation)

  • Dropout of the upper septum

  • Apical thinning

  • Lateral wall may appear brighter than septum

  • Minimised by review of series of normal volunteers


Technical artifacts
Technical artifacts Dilation)

  • 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


  • LBBB- Dilation)

    • 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



Gated spect
Gated SPECT anatomical and functional information

  • Simultaneous assessment of LV function and perfusion

  • Each R-R interval is devided into prespecified number of frames

  • Frame one represent end diastole,middle frames end systole

  • An average of several hundred beats of a particular cycle length acquired over 8-15 min.



Radionuclide ventriculography
Radionuclide ventriculography systole

  • MUGA scanning-multiple gated acquisition

    • Tc 99m labelled r.b.c or albumin

    • Image constructed over an average cardiac cycle by e.c.g gating,16-32 frames /cycle

    • Image acquired in antr.,LAO, left lateral projections

    • Size of chambers,RWMA,LV function

    • Time activity curve-LV volumes



PET through rt.chambers-lungs-lt.chambers

  • 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


Perfusion tracers
Perfusion tracers through rt.chambers-lungs-lt.chambers

  • Diffusible tracers-O-15-accumulate and wash out.

  • Non diffusible-Rb82,N13ammonia

  • Rb82-generator produced,t½76s.


Advantage of pet
Advantage of PET through rt.chambers-lungs-lt.chambers

  • Higher spatial resolution

  • Improved attenuation correction

  • Quantification regional blood flow

    • SPECT may fail to detect balanced ischemia in multivessel CAD

    • ↓blood flow reserve by PET –early identification of CAD

  • Higher sensitivity and specificity(95%)for detection of CAD


Limitations
Limitations through rt.chambers-lungs-lt.chambers

  • High cost

  • Requirement of cyclotron

  • Short half life-pharmacological stress only


Metabolic tracers
Metabolic tracers through rt.chambers-lungs-lt.chambers

  • C-11 palmitate

  • I-123 BMIPP-Ischemic memory-fatty acid metabolism suppressed for longer time after an ischemic event

  • F18 FDG-imaging myocardial glucose utilisation with PET

    • Phosphorylated and trapped in myocardium

    • Uptake may be increased in hibernating but viable myocardium




Viability pet study
Viability PET Study PET mismatch pattern indicative of viable myocardium

  • Traditionally the gold standard

  • Two sets of resting images to detect viable and hibernating myocardium:

    • Perfusion image (usually with N-13 ammonia or rubidium-82)

    • Glucose metabolic image (with F-18 fluorodeoxyglucose = FDG)

Cellular membrance integrity

Glucose metabolism


* PET mismatch pattern indicative of viable myocardium


Pet viability scan patterns
PET Viability PET mismatch pattern indicative of viable myocardiumScan Patterns

Contractility PerfusionMetabolism

Normal N NN

Stunning - NN -

Hibernation

Scar


Guidelines
Guidelines PET mismatch pattern indicative of viable myocardium

  • Acute syndromes

    • Assessment of patients presenting to ED with chest pain

    • Diagnosis of AMI when other measures non diagnostic-Tc99m

    • Risk assessment,prognosis in AMI

    • Risk assessment,prognosis in NSTEMI/UA


Chronic syndromes recommendations
Chronic syndromes-recommendations PET mismatch pattern indicative of viable myocardium

Class1-

  • Exercise SPECT for identifying location ,severity of ischemia in pts without baseline ECG abnormalities that interfere with ST seg.analysis

  • Adenosine SPECT for LBBB,paced rhythem,unable to exercise

  • To assess functional significance of an intermediate coronary lesion(25-75%)

  • Intermediate duke TMT score

  • Rpt.MPI for recent change of symptoms


  • Class 2a- PET mismatch pattern indicative of viable myocardium

    • 3-5 yrs after revascularisation in asymptomatic patients

    • As initial test in high risk patients(>20% 10yr risk)

  • Class 2 b-

    • Pts with cor.calcium score more than 75 percentile

    • Asymptomatic pts.high risk occupation


Indications for pet for risk stratification of patients with intermediate likelihood of cad
Indications for PET for risk stratification of patients with intermediate likelihood of CAD

CLASS1-

  • SPECT study equivocal

  • Class 2a-

    • As initial test in patients unable to exercise

    • As initial test in pts. With baseline ECG abnormalities


  • Risk stratification
    Risk Stratification with intermediate likelihood of CAD

    • Normal perfusion imaging after adequate stress: very low cardiac event rate < 1%

    • Small fixed defect with normal global LV function: good prognosis

    • High risk: (reversible defects) more than one territory, LAD (most important coronaryartery), post-stress LV (left ventricular) dysfunction (LV dilatation, abnormal wall motion, decreased LVEF, lung uptake)


    ad