Nuclear imaging techniques like SPECT and PET scans use radioactive tracers to evaluate myocardial perfusion and function. SPECT involves injecting radioactive materials like thallium or technetium intravenously, which accumulate in heart muscle cells and are detected by a gamma camera. Images are obtained at rest and after stress to identify any reduced radiotracer uptake indicating ischemia. PET scans use tracers like rubidium or ammonia to assess perfusion, or FDG to evaluate glucose metabolism in the heart muscle. These nuclear imaging modalities can detect coronary artery disease, evaluate viability after interventions, and predict future cardiac risks.

1. Nuclear imaging
Dr vasanthi
Dnb ctvs
Madras medical Mission

2. SPECT (single photon emission
computed tomography)
• Radioactive material used :
• Myocardial perfusion study : Th 201,Te99m
• Radionuclide ventriculography : I 123 MIBG
Dual isotope
• Thalium for resting image
• Technitium for stress images
Principle :
• i.v – radiactive material injected
• Accumulated in myocardial cells
• Radioactive material decayed after short period of time
• Emitted photons are captured by gamma camera

5. Preparation
• Npo – 4 hrs
• No caffeine for 12 hrs
• Hold beta blockers ,CCB for24hrs
• Avoid insulin

6. • Stress images acquired after exercise or drugs which is compared
with images acquired during rest.
• Image display :
• Short axis
• Vertical long axis (VLA)
• Horizontal long axis (HLA)

7. septum
anterior
inferior
Lateral
ant
Base
apex
inferior
sep Lateral
apex
Base

8. Polar map

14. RWMA
End diastole End systole

16. Indications :
• Suspected false +ve or-ve TMT
• Resting ST changes
• LBBB,RBBB,LVH, digitalis,pre-excitation or pacemaker
• Women with +ve TMT and low or intermediate probability CAD
• Inability to exercise
• Prognosis of known CAD
• Detecting post PTCA or CABG ischaemia ( positive predictive value of 90%)
• Assessing myocardial viability
• Risk evaluation in non- cardiac surgery patients
• Assessment functional significance of documented coronary stenosis

17. Uses of SPECT
• As screening method to detect CAD (sensitivity-68%)
• Medical therapy vs revascularisation : mild defect + no high risk =
medical , high risk + multivessel disease ,large territory =
revascularisation
• Dipyramidol vasodilator stress-predicts future cardiac events

18. PET SCAN(positron emission tomography)
• Radioactive material emit positron which are detected by positron
camera
• Perfusion tracer – Rb82,N13 ammonia (cellular membrane integrity)
• Metabolic tracer – FDG 18 (glucose metabolism)