Cardiac Pet Power Point


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  • Cardiac Pet Power Point

    1. 1. Cardiac - The Market <ul><li>Heart disease is the number one killer of American men and woman </li></ul><ul><li>Some 650,000 American’s will die this year in the United States </li></ul><ul><li>Early detection and medical therapy can effectively treat the disease </li></ul><ul><ul><li>Lipid control </li></ul></ul><ul><ul><li>Risk factor modification </li></ul></ul>
    2. 2. Tools for risk stratification <ul><li>Treadmill evaluation </li></ul><ul><ul><li>Low sensitivity, moderate specificity </li></ul></ul><ul><li>Stress Echocardiogram </li></ul><ul><li>Perfusion imaging </li></ul><ul><ul><li>Sensitive and specific but still false positives and false negatives </li></ul></ul><ul><ul><li>Rb-82 higher diagnostic accuracy relative to SPECT </li></ul></ul><ul><li>Coronary calcium screening </li></ul><ul><li>Viability </li></ul><ul><li>Coronary angiography </li></ul>
    3. 3. Stress exercise examination <ul><li>Outpatient </li></ul><ul><li>Easy to perform/fast </li></ul><ul><li>No radiation </li></ul><ul><li>Patient must be able to exercise </li></ul><ul><li>Low sensitivity/specificity </li></ul><ul><li>Non localizing </li></ul><ul><li>Resting ECG changes preclude evaluation </li></ul>
    4. 4. Stress testing
    5. 5. Stress testing <ul><li>Meta-analysis-in patients with intermediate probability of disease </li></ul><ul><ul><li>Mean sensitivity/specificity-67%, 72% </li></ul></ul><ul><ul><li>Value is relatively high specificity </li></ul></ul>
    6. 6. Stress echocardiology <ul><li>Performed on an outpatient basis </li></ul><ul><li>No radiation exposure </li></ul><ul><li>Can use with exercise or pharmacological stress (dobutamine) </li></ul><ul><li>Time consuming from a professional component </li></ul><ul><li>Standardized interpretation difficult and therefore high variability of accuracy dependent on experience </li></ul>Marwick, Thomas; Heart Journal 2003 data in the next slides
    7. 7. Stress echocardiology <ul><li>Pathophysiology </li></ul><ul><ul><li>Exercise and or inotropic stress usually evokes an increase in LVEF and wall thickening </li></ul></ul><ul><ul><li>Ischemia is manifested by a drop in LVEF, worsening or new wall motion abnormalities or delayed contraction </li></ul></ul><ul><ul><li>Presence of inducible wall motion abnormalities usually correspond to >50% coronary stenosis </li></ul></ul><ul><ul><li>Interpretation is qualitative and quantitative </li></ul></ul>
    8. 8. Stress echo
    9. 9. Stress Echo
    10. 10. Stress Echo <ul><li>Studies greater than 100 patients-Exercise </li></ul><ul><ul><li>Sensitivity ranges from 74-97% </li></ul></ul><ul><ul><li>Specificity ranges from 64-86% </li></ul></ul><ul><li>One limitation on sensitivity is delay on obtaining the appropriate echo window post stress </li></ul><ul><li>Pharmacologic stress lower overall accuracy </li></ul><ul><ul><li>Dobutamine Sen 61-95%, Spec 51-95% </li></ul></ul><ul><ul><li>Adenosine/persantine Sen 61-81%, Spec 90-94% </li></ul></ul>
    11. 11. Stress Echo
    12. 12. Limitation of Stress Echo <ul><li>In the setting of multivessel disease with normal LVEF sensitivity is only 50% </li></ul><ul><li>Patients with poor echo windows </li></ul><ul><ul><li>Large patients </li></ul></ul><ul><ul><li>Women </li></ul></ul><ul><ul><li>Pulmonary disease </li></ul></ul><ul><li>Interpreter expertise required </li></ul>
    13. 13. Stress Echo
    14. 14. The cardiac imaging market is transitioning SPECT PET Cardiac catheterization CT angiography
    15. 15. SPECT perfusion imaging Low diagnostic accuracy in some patient populations-Balanced ischemia Long Acquisition times Higher radiation exposure Decreasing reimbursement
    16. 16. SPECT perfusion imaging <ul><li>Low energy photons </li></ul><ul><ul><li>Thallium or Tc based </li></ul></ul><ul><li>Usually two imaging sequences (20-30 minutes each) </li></ul><ul><li>Total exam time 3-4 hours </li></ul><ul><li>Study of over 3000 patient with Thallium </li></ul><ul><ul><li>Sensitivity 84% and Specificity 53% </li></ul></ul><ul><li>Attenuation/motion all impact relative accuracy </li></ul><ul><ul><li>Equivocal studies men 10% woman 30-40% </li></ul></ul>
    17. 17. Case study <ul><li>50yo female patient with breast implants </li></ul><ul><li>MPS ordered for evaluation of chest pain syndrome with equivocal GXT </li></ul><ul><li>Patient underwent MPS with Tc-99m Sestamibi </li></ul><ul><li>Patient then underwent Rb-82 PET perfusion </li></ul>
    18. 18. SPECT PET
    19. 19. Case Study <ul><li>Comparison between SPECT and PET </li></ul><ul><li>Normal scan with Rb-82 PET </li></ul><ul><li>Abnormal with SPECT </li></ul><ul><li>False positive SPECT, patient risk stratified away from invasive evaluation </li></ul><ul><li>No cardiac events in follow up </li></ul>
    20. 20. PET perfusion imaging High diagnostic accuracy regardless of patient status-Gate both stress and rest Shorter acquisition times Lower radiation exposure Increasing reimbursement
    21. 21. 82 Rb <ul><li>+ </li></ul><ul><li>- </li></ul>p  
    22. 22. PET perfusion 2. Nuclear Medicine Self-Study Program III: Nuclear Medicine Cardiology. Botvinik, EH, Ed. 1998: Society of Nuclear Medicine, Reston, VA. Author Sensitivity Specificity # Patients Gould 95% 100% 50 Demer 94% 95% 193 Go 93% 78% 202 Schelbert 97% 100% 45 Yonekura 93% 100% 49 Williams 98% 93% 146 Stewart 84% 88% 319 Weighted Avg. 93% +/- 8 92% +/- 5 766
    23. 23. Economic impact on society <ul><li>Single missed diagnosis of CAD-$90,000 </li></ul><ul><li>Comparison of SPECT and PET </li></ul><ul><ul><li>300 patients </li></ul></ul><ul><ul><li>SPECT over 32% referred for coronary angiography </li></ul></ul><ul><ul><li>PET only 10% referred for coronary angiography </li></ul></ul><ul><ul><li>Additionally 20% of catheterization were normal in the face of a abnormal SPECT study (false positives) </li></ul></ul><ul><ul><li>PET imaging lead to a cost savings of 30-40% </li></ul></ul>Impact of PET on health care cost prepared for General Motors 1996
    24. 24. Economic impact-practice <ul><li>HOPPS reimbursement changing </li></ul><ul><ul><li>SPECT imaging $932.07 </li></ul></ul><ul><ul><li>PET imaging – Iowa $2,467.77 </li></ul></ul><ul><ul><li>Cost of radiopharmaceutical-reimbursed on cost of care rate </li></ul></ul><ul><li>Increased throughput </li></ul><ul><ul><li>Scan times SPECT two imaging sequences (15-25 minutes per scan) </li></ul></ul><ul><ul><li>PET imaging 30 minutes both stress and rest </li></ul></ul><ul><ul><li>Assume 20%-30% increase in throughput </li></ul></ul><ul><li>Rb-82 fixed cost –increased volume=reduced cost per patient (transition point is 7-9 day) </li></ul>
    25. 25. The Myth of Rb-82
    26. 26. 36 inch separation for patient access GEMINI Open PET/CT Advantage Integrated operation (CT/PET Imaging) Separated operation (Independent CT simulation / diagnostic CT or PET) 195 cm PET coverage in closed position 130 cm PET coverage in open
    27. 27. Physics of Rb-82 Positron Emission Tomography (PET) <ul><li>Rb-82 decay via a proton changing into a neutron, a positron and a neutrino (a positron has the same mass as electrons, but a positive charge) </li></ul><ul><li>The positron is emitted into the patient where it comes to a stop (~3mm). The positron then annihilates with a near-by electron. </li></ul><ul><li>Annihilation event – positron and electron collide, then convert into a pair of high energy (511 keV) photons </li></ul><ul><li>Annihilation photons travel in opposite directions, conserving momentum and energy </li></ul>
    28. 28. CardioGen-82 ® (Rubidium Rb 82 Generator) <ul><li>Rubidium-82 (Rb-82) is produced by decay of Strontium-82 (Sr-82) </li></ul><ul><li>75 second T½ </li></ul><ul><li>Kinetics: </li></ul><ul><ul><li>Potassium analog </li></ul></ul><ul><ul><li>High extraction fraction at high flow rates </li></ul></ul><ul><li>Defects visualized 2-7 minutes after injection </li></ul><ul><li>Same sized dose at stress & rest due to short T½ </li></ul><ul><li>New generator every 28 days </li></ul><ul><li>Fixed price, not unit dose </li></ul><ul><li>Dose available 24 hours per day, 7 days per week </li></ul><ul><li>Pharmacologic stress studies </li></ul>
    29. 29. CardioGen-82 ® (Rubidium Rb 82 Generator) <ul><li>Generator replaced every 28 days </li></ul><ul><li>Rb-82 dose is provided within 10 minutes </li></ul><ul><li>Infusion System is automated for the infusion and patient dose </li></ul><ul><li>Permits accurate dosing with minimal operator interface, thus decreasing radiation exposure </li></ul><ul><li>Contains shielding vault for CardioGen-82 ® Generator and waste container </li></ul>
    30. 30. Dose delivery by Infusion System Infusion pump set to deliver 60 mCi or operate for 25 sec, whichever is reached first. Maximizes bolus of Rb-82. As generator decays, amount of dose delivered may drop. Consistent bolus delivery can improve count statistics near the end of generator life.
    31. 31. Sample PET/CT Protocol Protocol courtesy of Marcelo DiCarli, MD Approximately 30 minutes scout CT-trans Rb-82 50-60 mCi 70-90 sec 90-120 sec gated rest pt out Dipy 0.56 mg/kg scout CT-trans 70-90 sec 90-120 sec Rb-82 50-60 mCi gated stress Approx 1 min Approx 7 min Approx 6 min Approx 1 min Approx 7 min
    32. 32. Transitioning the perfusion market <ul><li>Why Rb-82 now? </li></ul><ul><ul><li>Improved patient outcomes/lower false positives </li></ul></ul><ul><ul><li>Appointment times reduced to 30-45 minutes </li></ul></ul><ul><ul><li>Improved accuracy irrespective of body mass index, sex ect. </li></ul></ul><ul><ul><li>Lower radiation exposure </li></ul></ul><ul><ul><li>Improve throughput and reimbursement-favorable economic drivers </li></ul></ul><ul><ul><li>Equipment </li></ul></ul>
    33. 33. Diagnostic accuracy comparison <ul><li>Bateman etal, Diagnostic accuracy of rest/stress ECG gated Rb-82 myocardial perfusion PET: comparison with ECG-gated Tc-99m sestamibi SPECT. J Nucl Cardiology 2006 Jan-Feb </li></ul><ul><li>112 SPECT/PET studies matched for gender, BMI, presence and extent of ASCAD </li></ul>
    34. 34. Diagnostic Accuracy <ul><li>PET image quality excellent 78% and 79% for rest and stress </li></ul><ul><li>SPECT image quality excellent 62% and 62% for rest and stress </li></ul><ul><li>Intepretations </li></ul><ul><ul><li>Definitely normal/abnormal </li></ul></ul><ul><ul><li>PET 96% </li></ul></ul><ul><ul><li>SPECT 81% </li></ul></ul>
    35. 35. Diagnostic Accuracy <ul><li>Diagnostic accuracy </li></ul>PET SPECT Stenosis (70%) 89% 79% Stenosis (50%) 87% 71% Men vs Women + - Obese vs. nonobese + -
    36. 38. Patient Radiation Dosimetry Copyright Dr. Mark Nathan Isotope Effective Dose Equivalent Per study Total Rb-82 1.6 mrem/mCi 50 mCi 80 mrem Tc-99m mibi 51 mrem/mCi 30 mCi 1500 mrem Th-201 850 mrem/mCi 4 mCi 3200 mrem CT mu-map 440 mR 1 scan 440 mrem
    37. 39. Acquisition Times <ul><li>Acquisition times need to recognize the fast decay time of Rb-82 </li></ul><ul><li>95% theoretical maximum of all counts will be acquired in the first five minutes </li></ul><ul><li>Acquiring an additional 60 seconds only adds 2.4% more counts! </li></ul>
    38. 40. Transmission Quality Control <ul><ul><li>Counts, Truncation and Registration </li></ul></ul>Good transmission counts, no truncation, but stress misregistration MISREGISTRATION OF TRANSMISSION AND EMISSION DATA IS THE #1 SOURCE OF DIAGNOSTIC ARTIFACTS Must always correct this artifact Misregistration appear as LCx or left main disease
    39. 41. Mismatch artifact <ul><li>Slow CT designed to match transmission and emission data sets </li></ul><ul><li>Minimize artifacts </li></ul>CONVENTIONAL SLOW CT
    40. 43. Patient 1 <ul><li>65yo male 280 lbs </li></ul><ul><li>Chest pain syndrome </li></ul><ul><li>Cannot exercise due to knee arthritis </li></ul>
    41. 45. The Power of PET <ul><li>Perfusion images reveal reversible perfusion defects involving the anterior/ anterior septal and septal walls consistent with LAD obstruction </li></ul><ul><li>Coronary catherization revealed 85% proximal stenosis of the LAD </li></ul>
    42. 46. Patient 2 <ul><li>45 yo female with abnormal non diagnostic GXT </li></ul><ul><li>Perfusion study ordered </li></ul>
    43. 48. The Power of PET <ul><li>Normal perfusion pattern </li></ul><ul><li>Prognosis good </li></ul>
    44. 49. Patient 3 <ul><li>75yo female with history of PTCA of left circumflex artery </li></ul><ul><li>Now presents with recurrent atypical chest pain syndrome and fatigue </li></ul>
    45. 52. The Power of PET <ul><li>Rb-82 PET revealed a reversible perfusion pattern in the distribution of the left circumflex artery consistent with re stenosis of the artery </li></ul>
    46. 53. Advantages of PET <ul><li>Faster study </li></ul><ul><li>More accurate </li></ul><ul><li>Attenuation correction </li></ul><ul><li>Health care cost savings </li></ul>
    47. 54. PET perfusion imaging High diagnostic accuracy regardless of patient status Shorter acquisition times Higher insurance reimbursement Lower radiation exposure Value for the patient Value for the practice