CAD – leading cause of death Cardiac SPECT – steady growth in last two decades & played an important role in clinical mangement Radionuclide ventriculography (MUGA) First pass studies PET/CT

1. Role of Nuclear medicine in
Cardiology
Lokendra Yadav

2. Radionuclide studies in
cardiology
 CAD – leading cause of death
 Cardiac SPECT – steady growth in last two
decades & played an important role in clinical
mangement
 Radionuclide ventriculography (MUGA)
 First pass studies
 PET/CT

3. Detection of Ischemia
Noninvasive Testing: Critical Concepts
• Differences between testing options
• Diagnostic accuracy and pretest likelihood
of disease
• Posttest risk assessment

7. Radionuclide ventriculography
 99m Tc- RBC blood pool study (ERNA)
 Acqusition protocol : Gated
 Processing
- Automatic
- Semiautomatic
-Manual
 Indications :
Monitoring LVEF
low LVEF
Doxorubicin toxicity
Stem cell therapy

9. Indications for Stress Testing
 Objective confirmation of ischaemia
 Assessing extent of ischaemia
 Documenting exercise capacity
 Functional assessment of known CAD
 Determining risk and prognosis
 Determining need for angiography
 High risk cut points
 Assessing response to treatment

10. Contraindications for stress
testing
 Acute myocardial infarction (within two days)
 Unstable angina pectoris
 Uncontrolled arrhythmias causing symptoms of
hemodynamic compromise
 Symptomatic severe aortic stenosis
 Uncontrolled symptomatic heart failure
 Active endocarditis or acute myocarditis or
pericarditis
 Acute aortic dissection
 Acute pulmonary or systemic embolism
 Acute noncardiac disorders that may affect exercise
performance or may be aggravated by exercise

11. Stress Testing Options
 Exercise stress alone (usually Bruce protocol)
 Exercise stress with nuclear myocardial perfusion imaging
(MPI)
 Pharmacologic stress nuclear myocardial perfusion
imaging (MPI)
 Exercise stress echo
 Pharmacologic stress echo

12. Sensitivity and Specificity of Non-
invasive Tests for the Diagnosis of
CAD*
Diagnostic
Test
Sensitivity
% (range)
Specificity
% (range)
# Studies # Patients
TMT 68 77 132 24,027
Planar MPI 79
(70-94)
73
(43-97)
6 510
SPECT 88
(73-98)
77
(53-96)
8 628
Stress echo 76
(40-100)
88
(80-95)
10 1174
* NEJM Vol. 344, No. 24 June 14, 2001

13. Exercise stress testing
 Treadmill or bicycle
ergometer
 Protocols vary -
symptom limited
 Bruce most popular
 8 stages
 Incline and speed
increment every 3
minutes
 Target 85-100%
maximum age
predicted HR
 Achieve at least 6 METS
for diagnostic accuracy

14. ECG Patterns Indicative of Myocardial Ischaemia
ECG Patterns Not Indicative of Myocardial Ischaemia

15. Indications for Myocardial
Perfusion Imaging (Exercise or
Pharmacologic Stress) 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
 Assessing myocardial
viability
 Risk evaluation in non-
cardiac surgery patients
 Assessment functional
significance of
documented coronary
stenosis

16. Myocardial Perfusion
Imaging
Exercise Stress
 Treadmill
 Bicycle ergometer
Pharmacologic
Stress
 dipyridamole
 Adenosine
 Dobutamine
 Isotopes
 Thallium 201
 Technesium 99m
 Sestamibi MIBI
(Cardiolyte)
 Tetrofosmin
(Myoview)
 PET
 Rubidium 82 (flow
agent)
 FDG (viability)

17. Scanning

18. Myocardial Perfusion
Gated SPECT Scan

19. Computer-rendered, 3-D Image
of Left Ventricular Surfaces

20. Coronary Territories

22. High Risk Indicators
Myocardial Perfusion
Imaging Increased pulmonary thallium uptake indicating low CO
or elevated LVEDP
 Ischaemic LV dilatation (TID)
 Multiple perfusion defects
 Large perfusion defects

25. NR - 14-7-2011 - Stress-Rest MPS
Stress- Rest Myocardial perfusion imaging
Stress- Adenosine 140 mcg/kg/min for 4
minutes. Injection of 10 mCi of Tc99m
labelled MIBI at 2 minutes.
ECG Gated SPECT-CT after approx 45
minutes.
Nitrate augmented Rest myocardial
perfusion - 5 mg sublingual nitrate -
followed by 30 mCi of Tc99m MIBI, 2 hours
after stress
ECG Gated SPECT-CT after 1 hour

26. NR - 14-7-2011 - Stress - Rest MPS - Slices

27. NR - 14-7-2011 - Stress - Rest MPS - Polar Plot

28. NR - 14-7-2011 - Stress - Rest MPS - Scores

29. NR - 14-7-2011 - Stress - Rest MPS -
Viability

30. NR - 14-7-2011 - Stress - Rest MPS - Summary

33. PD - 27-7-2011 - Rest MPS
Rest Myocardial perfusion imaging was
done 1 hour following iv injection of 24
mCi of Tc-99m MIBI

34. PD - 27-7-2011 - Rest MPS - Slices

35. PD - 27-7-2011 - Rest MPS - Polar Plot

36. PD - 27-7-2011 - Rest MPS - Viability

37. PD - 27-7-2011 - Rest MPS - LVEF

38. PD - 27-7-2011 - Rest MPS - Myocardial mass

39. Limitations of cardiac SPECT
 Decreased sensitivity and specificity in single
vessel CAD ( 60 – 76% )
 Diffuse disease in all three vessels (Balanced
ischemia)
 Diffuse disease without segmental
stenosis(Vulnerable for plaque rupture and
coronary events)
 Early disease identification
 Artifacts – Non uniform attenuation
 Relative low efficiency of Gamma camera
 Longer acquisition protocols

40. Characteristics of SPECT vs. PET.
SPECT PET
 Availability Wide Limited
 Atten. correction Less accurate
Accurate
 Spatial resolution 12-15 mm 5-7 mm
 Protocol 2 days <1 hour
 Radiation >10 mSv <10 mSv
 Images Qualitative Quantitative
 Hybrid with CT Yes Yes

41. Rationale for PET/CT MPS
 To decrease invasive coronary
angiography unless necessary i.e if
therapeutic
 Highly sensitive and specific
 Absolute Quantification of myocardial
blood flow
 Assesment of coronary flow reserve
 Blood flow,myocardial cell integrity,Wall
motion and LVEF
 Calcium score & Luminal narrowing

42. Imaging Protocol
 Patient preparation and stress testing
- Dypiridamole & adenosine
 Imaging 82 Rb varies with PET scanner crystal
 Reconstruction of images
Perfusion: filtered back
projection
Gated wall motion : iterative
 2 D Vs 3 D & 4 D PET
 LVEF
PET Vs planar gated blood pool ( r = 0.81)
PET Vs MIBI SPECT ( r = 0.91)

43. Current status of Cardiac PET
 Extensive infrastructure
 Improved PET scanners with LSO
crystal
 Availability of PET-CT
 Rubidium –82 PET perfusion tracer
-Generator produced
- Reimbursible since 1995 in USA
- Already clinically useful in tertiary
care and community hospitals

44. Present Status
 CMS Reimbursment Fee Schedule Changes State a
20% Increase in Cardiac PET and a 36% Decrease in
SPECT
 Clinical Indications :
Low risk CAD
Intermediate risk CAD
LBBB
Women
Obese
Diabetes
 Research : Endothelial function and Plaque bilology

45. Cardiac PET Perfusion Tracers
Agent Physical
half life
Extraction Production
13N NH3 10 min 80 % Cyclotron
82 Rb 75 sec 50-60% Generator
15 O H2O 2 min Diffusible Cyclotron

46. Rb – 82 Production
 Cation like Tl-201 and Potassium analogue
 Uptake reflects function of blood flow and
myocardial cell integrity
 Generator produced from Sr-82
 Replaced every 4 weeks
 Decays by positron emission with short half
life (75 sec)
 Eluted with 25-50 ml normal saline by
controlled elution pump and connected with
IV tubing to patient
 Fully replenished every 10 min and 90% of
max. activity can be available after 5 min.

47. Imaging Protocol for Rb 82 PET
imaging With a LSO PET-CT Scanner
Procedure Time
Positioning (Scout) 1 min
CT transmission scan 1 min
Rest gated imaging 8 min
Rest perfusion imaging 8 min
Pharmacological stress 7 min
CT transmission scan 1 min
Stress imaging 8 min
Total duration 34 min

53. Diagnostic Accuracy of PET MPI for CAD
Author Year Agent No.of
Patient
Sensitivit
y
Specificit
y
Gould et
al
1986 NH3,Rb
82
50 95 100
Demer 1989 Rb 82 193 94 95
Go et al 1990 Rb 82 202 93 78
Schelbert 1982 NH 3 45 97 100
Yonekura 1987 NH 3 49 93 100
Williams 1989 Rb 82 146 98 93
Stewart 1991 Rb 82 81 84 88
Tamaki 1988 NH 3 25 95 95
Average 791 93 92

54. Comparison of PET and SPECT MPI for
detection of CAD in same patient
Author
et al
Year Tracer Accurac
y (% )
Sensitivi
ty
Specifici
ty
Go
n=132
1990 Rb 82
Tl-201
92
78
95
79
82
76
Stewart
n = 81
1991 Rb 82
Tl 201
85
78
87
87
82
52
Tamaki
n=51
1988 NH 3
Tl 201
98
98
98
96
100
100
Total
n=264
PET
SPECT
91
81
93
85
82
67

55. Coronary calcium score

57. Clinical applications of PET/CT MPS
 Diagnosis of coronary artery disease
 Assesment of blood flow : Prognosis
(Yosinaga K et al JACC 2006 :48;Sept.1029-30)
 Noninvasive coronary angiography (CTA)
High false positivity- 25 %
Poor assesment of lumen – 18-24%
 Early detection of CAD in asymptomatic
patients
 Identifying plaques by molecular markers
 Assesment of heart failure

58. Calcium score,Perfusion and
Viabilty

59. Radiation dose from PET/CT
Study Effective radiation dose (mSv)
PET
 F-18 FDG (370 MBq) 7.0
 N-13 NH3 rest/stress (2×550 MBq) 2.2
 Rb-82 rest/stress (2×740 MBq) 3.6
 H2O-15 rest/stress (2×740 MBq) 1.4
 Transmission Ge-68 rod sources 0.08–0.13
MSCT
 Calcium scoring 0.7–6.2
 CT angiography 3.7–13.0
 CT based PET attenuation correction 0.23–5.66

60. Utility of PET/CT in CAD
 Excellent noninvasive imaging procedure
 Extent & severity of perfusion abnormality
 Extent of tissue viability
 Risk stratify each patient prior to clinical
decision making
 Attractive translational research tool in
combination with molecular probes i.e
Cell therapy or Gene therapy

61. Thank you