1. Radiopharmaceutical In Nuclear Cardiology
RADIATION PROTECTION SEMINAR 2017
UPDATES IN NUCLEAR CARDIOLOGY IMAGING
6TH MAY 2017
AMDI, USM
Mohd Ikhwan Hashim RPh
Nuclear Pharmacy Unit

2. Presentation Outline
Ideal characteristic of cardiac radiopharmaceutical
Radiopharmaceutical in cardiac imaging
Myocardial perfusion
Metabolic Imaging
Myocardial infarct
Cardiac Innervation Imaging
New cardiac radiopharmaceutical

3. Role Of Radiopharmaceutical In Diagnostic Imaging

4. Role Of Cardiac Nuclear Medicine
Cardiac nuclear medicine is useful in diagnosing and assessing coronary artery disease. It is also used to evaluate cardiomyopathy and identify possible damage to the heart from chemotherapy or radiotherapy.
Cardiac nuclear medicine imaging is also performed:
to visualize blood flow patterns to the heart walls, called a myocardial perfusion scan.
to evaluate the presence and extent of suspected or known coronary artery disease.
to determine the extent of injury to the heart following a heart attack, or myocardial infarction.
to evaluate the results of bypass surgery or other revascularization procedures designed to restore blood supply to the heart.
in conjunction with an electrocardiogram (ECG), to evaluate heart-wall movement and overall heart function with a technique called cardiac gating.

5. Role Of Cardiac Nuclear Medicine
Myocardial perfusion imaging using SPECT & PET radiopharmaceuticals successfully identifies the infarcted (necrosis) versus ischemic (reduced blood perfusion) myocardium.
Nonesterified free fatty acid and glucose are two essential metabolic substrates to provide energy to the heart ; 18F-FDG – metabolic agent to determine the myocardial viability

6. Ideal Characteristics For Perfusion Radiopharmaceutical
Distribution in the myocardium in linier proportional to blood flow.
Efficient myocardial extraction from blood on the first passage through the heart
Stable retention within myocardium during data acquisition
Rapid elimination allowing repeat studies under different conditions
Good imaging characteristics (short half life, low radiation burden to the patient)
Ready availability
Competitive pricing
No current tracer possesses all of these properties.

7. Radiopharmaceuticals In Cardiac Imaging
Gopal B Saha ; Fundamentals Of Nuclear Pharmacy

8. 201Tl (Thallous Chloride)
Use for myocardial perfusion imaging
Cyclotron produced & expensive
Low energy photons (69-80keV) degrade the spatial images due to scattering
Long half life ~ 73H ; increases radiation dose to the patient

9. 201Tl (Thallous Chloride)
Protocol (Stress & Rest)
Inject at stress (2-3mCi / 74-11MBq)
First Imaging 5-10 minutes post-injection
Redistribution imaging 3-4 hours post-injection
Thallium ions undergo continuous exchange between extracellular and intracellular compartment – redistribution of thallium
The defect that is seen in mildly perfused area on stress image will disappear on the 3-4 hours redistribution images.

10. 201Tl (Thallous Chloride)
Both stress and redistribution equal = normal
Defect on stress but fills in on redistribution = Ischemia
Defect on both = Infarct

11. 201Tl (Thallous Chloride)
However, in infarct cases there are still defects on 3-4 hours imaging are filled in with 201Tl on delayed distribution images at 8-24 hours
Suggested for second injection of 1 mCi (37 MBq) 201Tl. There methods are employed :
Reinjection after the distribution study and imaging after mins
Reinjection immediately before the redistribution study and imaging after mins
Reinjection immediately after stress imaging and imaging after 3-4 hours later

12. 99mTc-Sestamibi (Cardiolite)
Indicated for myocardial perfusion abnormalities
Imaging with SPECT or SPECT/CT
Predominant liver uptake ; It is suggested to take fatty meals or milk to hasten the clearance of the hepatic activity
Redistribution is minimal / not at all
Require heating in preparation.

13. 99mTc-Sestamibi (Cardiolite)
1 day protocol
First dose 8-10 mCi (296 – 370 MBq), imaging after 1 hour
Second dose mCi ( MBq) after 3-4 hours, imaging after 1 hour
Rest or Stress First?
2 days protocol
Stress and rest are performed on separate days with 20-25mCi ( MBq), imaging after 1 hour

14. 99mTc-Sestamibi (Cardiolite)
Dual isotope technique
Rest ; Injection of 201Tl mCi ( MBq), imaging after 15 mins
Stress ; Injection of 25 mCi (925 MBq) of 99mTc-sestamibi at peak stress and imaging after mins
Short time needed but very much difference in physical imaging characteristics ; 201Tl images show smaller left ventricular cavity than 99mTc-sestamibi

15. 99mTc-Tetrofosmin (Myoview)
Indicated for myocardial perfusion abnormalities
Imaging with SPECT or SPECT/CT
Rapidly cleared by the blood
By 48H, urinary excretion is approximately 40%
Fast clearance of the hepatic, lung & gallbladder activity
Redistribution is minimal / not at all

16. 99mTc-Tetrofosmin (Myoview)
1 day protocol
First dose 8-10 mCi (296 – 370 MBq), imaging after 1 hour
Second dose mCi ( MBq) after 3-4 hours, imaging after 1 hour
Rest or Stress First?
2 days protocol
Stress and rest are performed on separate days with 20-25mCi ( MBq), imaging after 1 hour

17. 82Rb-Rubidium Chloride
Indicated for myocardial perfusion abnormalities
Imaging with PET
Very short t1/2 = 75s ; administer via infusion system
1 Day protocol
Rest ; Administer 60mCi (2.22GBq) 82Rb via transfusion with subject lying supine (4-6 minutes)
Stress ; induce with dypiridamole, administer another 60mCi (2.22GBq) 82Rb

18. 13N-Ammonia PET radiopharmaceutical & cyclotron produced
Indicated for myocardial perfusion abnormalities
T1/2 = minutes
1 Day protocol
Rest ; Administer 15-20mCi ( MBq) 13N-Ammonia via transfusion with subject lying supine (4-6 minutes)
Stress ; induce with dypiridamole, administer another 15-20mCi ( MBq) 13N-Ammonia

19. 15O-H2O Indicated for myocardial perfusion abnormalities
T1/2 = 2 minutes
Cyclotron produced and limited in availability
Imaging with PET
Study is performed by administering on-line from the cyclotron with an intermediate conversion of 15O2 to 15H-H2O in a reaction vessel

20. Comparison

21. 18F-Fluorodeoxyglucose
Indicated for myocardial metabolic imaging
The suggested guideline will be American College of Nuclear Cardiology
Glucose monitoring need to be done
Following glucose monitoring, mCi ( MBq) injected IV
Imaging via PET
Other metabolic imaging radiopharmaceutical are 123I-labelled fatty acid, 11C-palmitic acid, 13N-labeled amino acid and 11C-acetate

22. 99mTc-Pyrophosphate Indicated for myocardial infarcts
Dose mCi ( MBq) via IV and imaging 1-2 hours post injection
Minimum of hours after the onset of infarction for accumulation. Maximum uptake will be seen after hours after the onset of infarction
Infarct sites remain detectable for 6-10 days

23. 123I-MIBG Indicated for cardiac innervation imaging
MIBG behaves like norepinephrine
5-10 mCi ( MBq) injected IV
SPECT images obtained at 3, 24 & 48 hours post injection

24. Future Cardiac Radiopharmaceutical
99mTc-N-DBODC5 ; a new myocardial perfusion imaging agent with rapid liver clearance
99mTc N-MPO demonstrates a highly favorable biodistribution in humans
99mTc-TMEOP
123I-CMICE-013 is a promising new radiotracer for SPECT MPI with high myocardial uptake, very good target to background ratios and favorable biodistribution characteristics.
18F-Flurpiridaz
“The emerging and expansion of nuclear medicine modalities has contributed for the needs of new research and findings for new radiopharmaceuticals”

25. Cardiac Stress Test Physical Exercise Treadmill or ergocycle
Pharmacological
Important option if patient unable to exercise
Remove the need for patient cooperation and motivation, and enable a confident assessment of cardiac function in virtually all cases
Dipyridamole
Dobutamine
Adenosine

26. Reference

27. Presented by Mohd Ikhwan bin Hashim RPh
Presented by
Mohd Ikhwan bin Hashim RPh