NUCLEAR CARDIOLOGY UPDATE

Transcription

1 Nuclear Cardiology David K. Shelton, Jr., MD NUCLEAR CARDIOLOGY UPDATE No Conflicts. No Disclosures. No Smoking. David K. Shelton UCDMC Nuclear Cardiology Nuclear Cardiology Radionuclide Ventriculography (RNV) or MUGA 1 st Pass Study Shunt evaluation Neurocardiology (I-123 MIBG) Fatty Acid Metabolism (BMIPP) Myocardial Perfusion Imaging (MPI) Myocardial Viability Radionuclide Ventriculography (RNV) or MUGA 1 st Pass Study Shunt evaluation Neurocardiology (I-123 MIBG) Fatty Acid Metabolism (BMIPP) Myocardial Perfusion Imaging (MPI) Myocardial Viability Reasons To Do MPI Diagnose CAD Atypical chest pain Screening, Exec PE, high risk surgery Risk stratification Ischemic cardiomyopathy Viable myocardium Treatment planning and follow-up Before Rx After Rx Reversible defect: stress 115

2 Reversible defect: stress with Reversible defect: stress MPI Techniques Reversible defect: stress Hypokinetic Planar Gated Planar SPECT Gated SPECT and prone imaging Gated SPECT-CT PET-MPI PET viability MPI Radiotracers MPI Tracer Protocols Thallium-201 Tc-teboroxime Cardiotec Tc-sestamibi (MIBI) Cardiolite Tc-tetrofosmin Myoview NH-3 Rubidium Tl-201 Stress/redistribution or with reinjection Tc two day Tc one day Dual isotope PET NH-3 PET Rb

3 Thallium-201 Protocol Tc Two Day Protocol Tl-201: 72hr ½ life, kev, 3 mci poss 1 mci booster Tc: 6 hr ½ life, 140 kev, mci, Stress then Rest 1 mci booster? Tc One Day Protocol Dual Isotope Technique Tc: 6 hr ½ life, 140 kev, 10mCi Rest then 30 mci Stress Tl Rest followed immediately by Tc Stress, high energy 2nd PET-CT Rubidium-82 Protocol Stress Agents Position Rb-82 Pharm Rb-82 CT Inject Rest Scan Stress Inject Stress Scan Time (min) ETT Dipyridamole Adenosine Regadenoson Dobutamine 117

4 Stress Agents: Mechanism of Action Dipyridamole Protocol ETT: Inc cardiac demand Dipyridamole: cor vasodilator Adenosine: cor vasodilator Regadenoson: cor vasodilator Dobutamine: Inc cardiac demand Persantine infusion Possible aminophylline reversal Adenosine Protocol Regadenoson Protocol Adenoscan infusion Lexiscan, flush not infusion Possible aminophylline reversal Protocol Comparison Lexiscan, flush not infusion Regadenoson» The first and only selective A2a adenosine receptor agonist» Standard-dose, dose rapid IV injection from a prefilled syringe» No weight-based dosing calculations» Pump-free administration» Hx of asthma or COPD is not a contraindication 118

5 MP Imaging Adjuncts Scoring Ischemia Wall motion analysis Ejection fraction Post stress dilatation Circumferential profile Bulls-eye Summed stress score Normative database, male and female Segments: 20 Scale 0 4 Summed stress score, rest score and difference score PET MPI Tracers PET Myocardial Perfusion Imaging Agent Half-life Positron Range (mm) Production Extraction 13N-NH3 NH min Cyclotron 80% 82-Rb 78 s 2.6 Generator 50-60% 15O-H2O 2.0 min 1.1 Cyclotron Diffusible 18F-FDG 110 min 0.2 Cyclotron 3% N-13 Ammonium, NH3 half life = 10 min, near cyclotron Rubidium, Rb-82 half life = 76 sec therefore higher dose (40-60 mci) and photon flux Rest, stress in < 1 hour Generator PET Myocardial Perfusion Imaging Rubidium, Rb-82 half life = 76 sec therefore higher dose (40-60 mci) and photon flux Rest, stress in < 1 hour Generator (cart) Can milk recurrently up to two weeks Can bill separately for isotope Tl-201 SPECT Sensitivity/Specificity 119

6 Diagnostic Accuracy of PET MPI Viable Myocardium Sensitivity (%) Specificity (%) No. Patients Agent Author NH3, Rb Gould et al Rb Demer et al Rb Go et al NH3 Schelbert et al NH3 Yonekura et al Rb Williams et al Rb Stewart et al NH3 Tamaki et al Average Normal, usually not questioned Hibernating Stunning Post-injury stunning (near infarction) Prolonged ischemia (post stress) Hibernating Myocardium Hibernating myocardium, further evaluation Critical stenosis (>85%) Akinetic or hypokinetic Looks and acts like infarct Resting and stress defects = fixed defect Suspect it if no history of MI and no EKG changes of MI Delayed thallium Db Dobutamine Echo Eh Dobutamine or NTG Tc SPECT PET FDG Delayed Gd contrast MRI Diagnosing Hibernating Myocardium Summary: What s New Delayed Tl-201: fills in MRI: no contrast enhancement on delayed images, enhancement implies scar PET FDG: fills in the suspected area or even is paradoxically hotter than other myocardium Gated MPI with SPECT-CT PET FDG for viable myocardium, hibernating myocardium PET MPI: Rb generator, rest/stress, heavy weights, accuracy, speed, efficiency Regadenoson: new, more receptor specific, coronary vasodilator 120

7 The Future Questions? Faster scans Coronary CTA with MPI fusion PET/MRI: simultaneous scan Hypoxia tracers Apoptosis tracers 121