The 14th Annual Scientific Session of the American Society of Nuclear Cardiology (ASNC2009) was held on October 1-5, 2009, in Minneapolis, MN. The meeting, which was entitled “Quality and Patient-Centered Outcomes in Cardiac Imaging”, was chaired by Jeroen Bax, MD, PhD, FASNC, and attracted over 1000 physicians, technologists, nurses, and researchers. The meeting included 81 international attendees from 22 countries. To meet the needs and interests of these various groups, the Scientific Session consisted of Plenary, Core, Technical, Computed Tomography (CT), and Advanced Tracks. Topics ranged from basic clinical concepts of image acquisition and stress protocols to cutting-edge discussions of new camera designs and molecular imaging. These topics were complemented by Read with the Experts sessions, which focused on challenging cases involving single photon emission computed tomography (SPECT), positron emission tomography (PET), and CT imaging. In addition, the meeting included 100 presentations of original research and the Nuclear Cardiology Foundation Young Investigator Competition.
Dr Manuel Cerqueira delivered the 8th annual Mario Verani Memorial lecture, which is presented each year at the annual meeting by a leader in the field of nuclear cardiology. This plenary lecture is given in memory of Dr Mario Verani (1943-2001), a luminary in nuclear cardiology and founder and past president of ASNC. Dr Cerqueira’s presentation entitled “Nuclear Cardiology in the Era of Multimodality Imaging: Can We Survive?” outlined the strengths of nuclear cardiology, including the vast fund of evidence supporting its utility, as well as the focus of nuclear cardiology on quality based on physician certification, laboratory accreditation, the development of guidelines and appropriateness criteria. However, Dr Cerqueira also acknowledged that issues such as inappropriate utilization, radiation exposure, and advances in other imaging modalities including CT and magnetic resonance imaging (MRI) could adversely impact the future of the field. Dr Cerqueira suggested that nuclear cardiology embrace the opportunity to build on its accomplishments and redefine the practice of noninvasive cardiovascular imaging.
The second plenary session entitled “Challenges and Opportunities in Cardiac Imaging for 2009” began with a keynote address by Dr Robert Bonow, “Measuring Quality in Cardiac Imaging”. Dr Bonow discussed the ways in which quality is maintained through adherence to guidelines, certification and accreditation, and through monitoring of performance measures. In addition, he highlighted the need for randomized trials and effectiveness research to better understand whether cardiac imaging leads to improved outcomes. Next, Dr Kim Williams discussed government issues related to imaging, outlining the economic factors affecting the Medicare system and the growth of imaging relative to other procedures making imperative that we continue efforts to demonstrate the effectiveness of cardiac imaging in improving outcomes and reducing mortality. Dr Robert Hendel then reviewed the current practices of radiology benefits managers to reduce overutilization with preauthorization, noting that these measures only serve to reduce volume and costs but do not address quality. Dr Hendel put forth that the emphasis must be on quality as well as preserving the patient-provider relationship, adding that physician certification, laboratory accreditation, clinical guidelines, performance measures, and quality metrics should serve as the foundation to select the appropriate test in the right patient, and thereby reduce inappropriate utilization. Finally, Dr Timothy Bateman discussed the need to justify the benefits of an imaging procedure given the potential risks, including radiation exposure, and highlighted how newer technologies for SPECT imaging, such as attenuation correction and new camera and processing technology that allow shorter acquisition times, can reduce risk. Dr Bateman also recommended a strategy of employing newer technologies selectively, such as using SPECT in low-risk patients and reserving technology such as PET with quantitative myocardial blood flow, to address more complex questions and patient populations in which added value is anticipated (e.g., obese women, diabetic individuals, and patients with known coronary artery disease (CAD) and prior myocardial infarction or revascularization).
In the final plenary session, “Great Debates in Cardiac Imaging”, Drs Gary Heller and Kim Williams compared and contrasted how newer hardware and software solutions for SPECT imaging, such as attenuation correction, shorter acquisition times, and stress only imaging protocols, can both limit radiation exposure and improve laboratory efficiency. Next, Drs Jamshid Maddahi and Randolph Patterson debated whether viability assessment with magnetic resonance imaging is superior to [F-18]fluorodeoxyglucose (FDG)-PET, and reviewed data outlining the strengths and weakness of each modality. Finally, Drs Robert Beanlands and Manuel Cerqueira participated in a lively debate as to whether PET is superior to SPECT for diagnosis and prognostic assessment of CAD.
The core track covered a diverse set of topics focused on the importance of high-quality nuclear cardiac imaging in daily practice. The first session, “Imaging the Spectrum of Ischemic Heart Disease”, centered on evaluation of the patient with established CAD or at risk for CAD. The session was introduced by Dr Todd Miller who reviewed the diagnostic performance of myocardial perfusion imaging (MPI) and the effects that referral bias can have on those parameters. Through a discussion of the pivotal trials that affect clinical decision making, Dr Leslee Shaw emphasized the importance of determining test effectiveness, particularly in specific subgroups of patients, including women, diabetic patients, and individuals with acute chest pain. In the final presentation, Dr Kevin Allman discussed the critical role that SPECT and PET imaging play in determining the etiology of heart failure and the presence of viable myocardium as well as the impact of this information on treatment decisions.
The second Core Track session evaluated the use of guidelines in clinical practice. The session started with a discussion by Drs Raymond Gibbons and Robert Hendel of the resources available through ASNC, AHA, and ACC, including guidelines for performing SPECT MPI, gated blood pool imaging, and reporting of nuclear cardiac imaging studies. In particular, the changes in the appropriateness criteria were discussed, as well as the need to incorporate them into our daily practice as an important quality metric. Dr Scott Jerome reviewed practical approaches to improve quality, giving attendees an opportunity to explore a large number of methods to improve daily practice.
The third session complemented the program on appropriateness and quality improvement by addressing optimization of stress protocols and the selection of the appropriate stress testing modality. Dr Milena Henzlova reviewed treadmill, bicycle, and vasodilator stress protocols, and the choice of protocols in light of the current isotope shortages and the growing concern for radiation dosimetry. The mechanisms of action for pharmacologic stress agents, including the new A2A receptor agonists, were discussed. The safety and effectiveness of incorporating exercise with vasodilator stress testing in patients without comorbidity and in patients with reactive airways diseases, COPD and asthma were reviewed by Drs Thomas Holly and Gregory Thomas.
New technologies and their impact on image quality, imaging time, and reduction in radiation exposure were the focus of a session entitled “The Need for Speed in Nuclear Cardiology”. Hardware solutions based on new advances in camera design and collimation, which decrease acquisition time and/or radiation dose, were discussed by Dr Ernest Garcia. This review was complemented by a presentation by Dr Gordon DePuey of software solutions that decrease image time or radiation dose by approximately 50% for Tc-99m-based studies. Opportunities to improve laboratory efficiency and minimize radiation exposure through the use of stress-only testing in appropriate patients were discussed by Dr Donna Polk. The session closed with a discussion of automated reporting systems by Dr Elizabeth Klodas in which she emphasized the importance of compliance with existing standards and guidelines to insure high-quality reports.
Of long-standing importance to the nuclear cardiac imaging community and ASNC is the provision of quality studies that provide added value with minimal risk to a patient’s care. An in-depth discussion of factors that are important in optimizing quality was presented in the fifth Core Track session. The importance of minimizing radiation exposure to staff and patients was emphasized by Dr Kenneth Nicholls as an important cornerstone of quality outcomes. Dr Kevin Kett discussed the Intersocietal Commission for the Accreditation of Nuclear Medicine Laboratories process of accreditation and the outcomes from this process. In the final presentation of the session, Dr Peter Tilkemeier emphasized the importance of the imaging report reviewing the use of structured reporting to generate the report and its use in quality assurance and research.
The final session in the core track focused on PET imaging and its impact on the future of cardiac imaging. Dr Gary Heller reviewed the different types of cameras, PET/CT, dedicated PET and mobile PET, comparing each with respect to cost, space requirements, and functional differences. Dr Sharmila Dorbala demonstrated the clinical utility of PET/CT in the evaluation of CAD and emphasized the unique ability of PET to provide information concerning coronary flow reserve (CFR) and coronary artery calcium (CAC). Selection of the appropriate patient for PET scanning was the focus of the presentation by Dr Nisha D’Mello, identifying appropriate patients as those patients whose SPECT scans are discrepant with their clinical presentation and those in whom viability needs to be assessed. Dr Timothy Bateman closed the session by discussing the practical aspects of integrating PET into clinical practice, concerning the topics of pre-test screening, identification of appropriate patients, design of a room for PET imaging, and managing the realities of preauthorization and reimbursement.
The CT track consisted of 8 sessions ranging from basic aspects of CT, such as how to perform CT angiography (CTA) and post-processing techniques, to advanced sessions describing techniques for plaque characterization and MPI. Throughout many of these sessions, an emphasis was placed on appropriate patient selection and how to use cardiac CT effectively with other existing modalities.
There were several presentations reviewing the various techniques employed to reduce radiation dose by cardiac CT. Dr John Lesser provided a comprehensive overview of the radiation saving techniques available to date, with a focus on the use of dual source CT scanners. Dr Randall Thompson outlined the substantial radiation reduction that can be achieved with prospective EKG triggering techniques. Other techniques that were discussed include the use of lower tube voltage (i.e., 100 kV) and high-pitch algorithms to minimize radiation exposure.
The utility of CAC scoring was outlined in several sessions. Dr Leslee Shaw provided an up-to-date summary of the strong prognostic value of CAC scoring and reviewed the many emerging studies of the prognostic value of CTA, but cautioned that the current data is insufficient to demonstrate that CTA improves health outcomes. An emerging application of cardiac CT that received significant attention at this meeting was the use of stress MPI. Dr Ron Blankstein presented the findings of recently published work showing that stress MPI with a dual source CT is able to detect hemodynamically significant stenosis with similar diagnostic accuracy as SPECT MPI. The presentations by Drs Rich George and Karl Schuleri complemented this talk by presenting data on stress CT MPI obtained using a 320-detector system.
The role of cardiac CT in the evaluation of patients with acute chest pain was another topic of great interest. Dr Tracy Callister presented an overview regarding the logistics and typical clinical scenarios encountered when performing cardiac CT in the emergency department while Dr Jack Ziffer discussed how to use both SPECT and CT angiography effectively in the emergency department. Dr Blankstein presented an overview of recently published studies in this field and addressed the challenges and need to further risk stratify patients with plaques that cause mild to moderate stenosis. Dr Allen Taylor summarized our current knowledge regarding different types of plaque, including identifying potential CT characteristics of “vulnerable plaques”, and Dr Shaw outlined a construct of how we may be able to integrate features such as plaque morphology, extent, and location in order to refine our risk assessment. In a stimulating debate on the use of CT for acute chest pain, Dr Callister stated that CT is the best modality to determine which patients have CAD and to identify other causes of chest pain. In the opposing position, Dr Robert Hendel pointed out that recent studies such as ROMICAT excluded many patients who had contraindications to CT angiography and also remarked that despite excellent negative predictive value, CT has a lower positive predictive value and specificity than SPECT MPI.
In another debate, Dr James Min argued that CT is the test of choice for the patient with intermediate likelihood of CAD based on recent data showing that CT has improved diagnostic and prognostic accuracy compared to SPECT MPI in selected populations. Furthermore, CT could lead to better outcomes because of the recognition of subclinical disease. Dr George Beller agreed that CT has an excellent ability to identify subclinical disease but described how newer tracers and quantitative techniques can also permit nuclear perfusion imaging to identify subclinical disease for full risk quantification. Dr Beller concluded by recognizing the potential advantages that may be realized by combining CT angiography and MPI with SPECT or PET.
In a third debate, Dr John Mahmarian explained why selective screening with CAC scoring is a reasonable strategy. He explained that while the use of traditional risk factors such as the Framingham risk score may apply to a large population, CAC provides direct evidence of CAD. Dr Gibbons outlined the disadvantages of screening CAC, including cost, anxiety resulting from a positive test, and the notion that screening is generally less effective than assumed. He concluded that there is no evidence demonstrating that CAC screening will improve outcome or is cost effective.
The Advanced Track covered a wide range of cutting-edge topics in nuclear cardiology including imaging in acute coronary syndrome (ACS), assessment of coronary blood flow and CFR, addressing the challenges of evaluating heart failure with cardiac imaging, molecular imaging focused on left ventricular (LV) remodeling, and advances in hardware and software. In addition, ASNC2009 included two joint sessions, one with the Society of Cardiovascular CT (SCCT) and one with the American Society of Echocardiography (ASE).
A major challenge in combating cardiovascular disease is the identification of patients at risk for coronary plaque rupture, leading to ACS. To provide the background for imaging, Dr Rajiv Gulati gave a comprehensive review of the processes of initiation, progression and composition, and disruption of vulnerable atherosclerotic plaques. Dr Ahmed Tawakol followed with a discussion of the clinical potential for PET imaging of unstable coronary atherosclerotic plaques based on FDG uptake by activated macrophages. Dr Ziffer reviewed the challenges of SPECT and CT angiographic imaging for patients presenting to the emergency room with chest pain, and Dr Robert Gropler discussed the diagnostic potential of metabolic imaging to diagnose ACS. Dr Raymond Gibbons concluded this session by summarizing the current ACC/AHA guidelines for imaging of ACS, providing perspective on how nuclear imaging can be used in conjunction with clinical assessment and other testing techniques to best diagnose and manage these patients.
In order to better manage patients with, or at risk for, atherosclerotic coronary disease, the ability to assess coronary myocardial blood flow (MBF) and coronary flow reserve (CFR) quantitatively is crucial. Dr Heinrich Schelbert began this session by reviewing the anatomy and complex physiology of MBF. Dr Robert deKemp then provided a comprehensive description of the technique and challenges of accurately measuring MBF and CFR. The promising clinical utility of quantitatively assessing MBF and its potential use in the detection of microvascular disease was discussed by Dr Rob Beanlands. Finally, Dr Karl Schuleri reviewed the potential of CT and cardiac MRI to assess coronary blood flow.
Congestive heart failure remains the most prevalent and most expensive form of heart disease. The somewhat underappreciated present ability and future promise of radionuclide imaging to evaluate heart failure was explored in detail in two sessions. The first session began with detailed reviews of the pathophysiology of heart failure and of current device therapies by Drs Wayne Miller and Dr David Hayes, respectively. Dr Mark Travin then discussed the extensive evidence supporting the ability of cardiac neuronal imaging with 123I-meta-iodobenzylguanidine and PET agents to risk stratify and guide therapy in patients with heart failure. Dr Katherine Wu described the potential use of cardiac MRI to predict sudden cardiac death. The second session began with a review of neurohormonal and cellular aspects of heart failure by Dr Jay Cohn, who challenged the nuclear cardiology community to develop novel imaging techniques that will aid in improving the outcome of patients with heart failure. Dr Myron Gerson addressed the challenging problem of differentiating ischemic from nonischemic cardiomyopathy noninvasively. Dr Ji Chen discussed recent developments using nuclear imaging to assess systolic dyssynchrony to identify patients who would benefit from cardiac resynchronization therapy, and Dr Heinrich Schelbert closed the session by describing radionuclide methods to assess cardiac metabolism in heart failure.
Many of the clinical manifestation of heart failure derive from ventricular remodeling and a session focusing on the molecular imaging aspects of this process was introduced by Dr Raymond Russell who reviewed the cellular basis of remodeling. Dr Albert Sinusas followed by describing studies on radionuclide imaging of integrins and matrix metalloproteinases that play integral roles in chamber remodeling. Dr James Caldwell then explored the challenge of radionuclide imaging to study the physiologically important adrenergic post-synaptic receptor system.
The Advanced Track included two sessions that focused on the important complementary roles of radionuclide imaging and other noninvasive imaging techniques. A session jointly sponsored by ASNC and the SCCT reviewed important aspects of the cardiac application of CT, including patient selection, CT MPI and radiation exposure. The joint session with the ASE compared and contrasted the abilities of echocardiography and radionuclide imaging to assess patients with hypertrophic cardiomyopathy.
Two late-breaking clinical trials were presented at ASNC2009. Dr Fabio Esteves presented preliminary data comparing the diagnostic performance of a dedicated cardiac camera equipped with cadmium zinc telluride crystals with standard dual detector SPECT cameras in dual-isotope myocardial perfusion imaging. Preliminary results from 55 patients suggest that the dedicated cardiac nuclear medicine camera provides diagnostic performance comparable to standard SPECT in dual-isotope myocardial perfusion with a significant reduction in acquisition time because of improved count sensitivity and image contrast. Dr James Udelson presented preliminary data from a multicenter study of [I-123] iodofiltic acid (BMIPP) imaging to evaluate patients in the emergency department with suspected ACS. The addition of data derived from BMIPP imaging was found to add incremental value toward the early diagnosis of an ACS, which might facilitate the earlier identification of ACS.
Dedicated cardiac cameras that have been introduced in the last two years continue to generate a great amount of excitement and interest, as clinical trials showing their efficacy are being reported. These cameras are available from a variety of vendors and share the common feature of a small footprint. In these new camera designs, specially designed collimators (multiple pinhole or slit hole collimators) are used to focus specifically on the heart. These cameras utilize solid-state cadmium zinc telluride or cesium iodide detectors to improve sensitivity because these detectors rely on direct light conversion instead of photomultiplier tubes to turn the scintillation into an electrical signal. This improves spatial resolution for more accurate evaluation of small defects. In addition, these detectors provide better energy resolution, which may allow simultaneous dual isotope acquisitions. These new detectors use more of the detector area to image the heart and allow detection of photons that are out-of-plane, effectively acting as 3D detectors. These features act to increase the sensitivity of the detector 5-10-fold, translating clinically into drastic reductions in either scanning time or radiation dose.
Other hardware advances available on some of these cameras include the use of tungsten collimators, which are more radio-opaque to I-123 than standard lead collimators. This promises to improve energy resolution for new I-123-based imaging agents. In addition, the list mode acquisition capabilities of these cameras coupled with simultaneous acquisition of all data can provide true dynamic imaging for kinetic modeling of SPECT radiotracers.
Software advances have primarily focused on improving quantitative characteristics of iterative reconstruction algorithms. All equipment manufacturers now provide programs that include detector and collimator-specific models within the projection and backprojection pair of ordered subset expectation maximization (OSEM) or maximum a posteriori principle (MAP) iterative reconstruction algorithms to reduce image blur. The use of resolution recovery algorithms has been shown to improve image quality compared to filtered backprojection. The enhanced accuracy provided by iterative reconstruction algorithms is imperative for achieving true absolute quantitation. These new programs have the potential to reduce scan time or reduce radiation dose.
Finally, a very important advance in quantitative imaging is the ability to perform true kinetic modeling for PET Rb-82 dynamic imaging. Absolute MBF and CFR can be computed using time-activity curves from myocardial regions of interest and the time-activity curves of the LV blood pool, which is used to determine the input function. The quantification of absolute MBF and CFR by PET offers the potential for improved evaluation of patients with triple vessel and microvascular CAD.
A total of 100 abstracts were selected from a group of competitive submissions following peer review. All selected abstracts were presented in one of five moderated poster sessions and published in the July/August issue of the Journal of Nuclear Cardiology. Additionally, 7 abstracts were presented in the Young Investigator Award Competition.
The use of SPECT in specific patient groups was examined in several of the poster presentations. In a meta-analysis of stress testing in the elderly, stress SPECT was superior to exercise testing alone or stress echocardiography for risk stratification.1 A study of 237 elderly patients demonstrated that an ischemic defect ≥5% of the left ventricle predicted worse outcome.2 Another study found that abnormal SPECT was predictive of similar adverse outcome across different ethnic groups.3 A study from Japan reported that patients with chronic kidney disease and normal SPECT images had a higher cardiac event rate than healthy individuals with normal SPECT.4 In a study of 371 patients with reduced LVEF, the extent of ischemic myocardium was a significant predictor of outcome.5 Several studies demonstrated that the yield for SPECT was relatively low in certain clinical settings. Ischemic defects on SPECT were present in only 8.2% of 1379 patients without cardiac symptoms and were related to the presence of risk factors.6 Furthermore, in a group of 134 patients referred for SPECT before bariatric surgery, only 9.7% of patients had an abnormal study, and there were no perioperative cardiac events in those patients.7
The ACCF/ASNC appropriateness criteria were examined in several studies. A study from Canada reported that 79% of SPECT studies were appropriate and there was no difference in appropriateness scores between an academic and a community practice.8 Another study reported a significant increase in the percentage of appropriate studies (from 66.5% to 82.8%) over a 3-year period and attributed this increase to incorporation of the ACCF/ASNC criteria into clinical practice and a carry-over effect of preauthorization from a radiology benefits manager.9 The same group also found that most inappropriate studies were ordered by female primary care physicians.10
In 27 patients with acute ST-elevation myocardial infarction, LV end systolic volume and LVEF measured by gated SPECT were predicted by the left anterior descending coronary artery as being the infarct-related artery rather than multi-vessel involvement or TIMI flow grade.11 Interestingly, a study of 778 patients who underwent equilibrium radionuclide angiography and were followed for 20 years demonstrated that LV end-systolic volume index and LVEF, but not peak rapid early filling rate, had independent prognostic value in the subset of patients with LVEF <50%.12
Several studies evaluated the application of nuclear techniques to help clarify mechanisms of disease. A study examining biomarkers and exercise-induced ischemia on SPECT found that changes in serum vascular endothelial growth factor concentration were more predictive than changes in NT-pro-BNP.13 The duration of ST-segment depression after exercise was associated with more abnormal and high-risk SPECT results.14 Gated SPECT phase analysis was used to demonstrate that post-operative paradoxical septal motion is not associated with LV dyssynchrony.15 Another study that used tomographic radionuclide angiography found that patients who underwent an upgrade from chronic right ventricular to biventricular pacing and experienced an improvement in symptom status had a decrease in LV end diastolic and end systolic volumes with no change in right ventricular volumes.16
Improvement in image quality was a topic of great interest to many of the contributors of original research. Both CT and line source attenuation correction were found to result in a similar improvement in accuracy for diagnosing CAD compared to uncorrected SPECT in men while CT-based attenuation correction was slightly better in women.17 In a study of new reconstruction techniques, SPECT image acquisition with wide-beam reconstruction was similar in accuracy to imaging with filtered back projection.18 Non-filtered high-resolution image “morphing” in which systolic frames are expanded to conform to the end-diastolic LV configuration was shown to result in superior overall image quality and more noticeable defects in patients with small LV volumes.19 A study examining interobserver reproducibility of parameters derived from the LV volume curve reported highest reproducibility for end-systolic and end-diastolic volumes and LVEF while there was lower reproducibility for the rate-dependent parameters of peak filling rate and peak ejection rate.20 A study from Japan found that “motion frozen” myocardial images can improve diagnostic performance by eliminating wall thinning in the apical region.21
Several studies focused on the role of CTA and CAC scoring in detecting CAD. In one study, increasing severity of thoracic aortic calcium on multislice CT was found to be associated with higher CAC scores and the presence of obstructive CAD by CTA.22 Elevated C-reactive protein was associated with an increase in the prevalence but not the severity of CAC.23 A CT angiographic study demonstrated that the vascular supply of the inferior wall is highly variable, with a vessel other than the RCA supplying the apical segments 91% of the time and the mid segments 31% of the time.24
Several studies examined the association between CT calcium scoring or CTA with SPECT evidence of ischemia. One study reported that the combination of CTA and SPECT was more accurate than either technique alone for identifying CAD.25 Another study reported the surprising finding that the distribution of CAC scores were the same whether ischemia was present or absent on SPECT imaging.26 The same group also found that lesions characterized by longer length and negative remodeling by CTA were associated with evidence of ischemia on SPECT images.27 Another group reported that the calcified plaque score predicted SPECT defects.28 Both CTA and gated SPECT were found to provide reproducible measurements of LV mass, although there were significant discrepancies between the two techniques.29
With the growing interest in cardiac PET, several studies focused on the diagnostic performance of this imaging modality. In one study, PET was shown to be superior to SPECT for image quality and assessment of regional perfusion in 49 patients who underwent both techniques.30 Another study reported that patients referred for PET rather than SPECT are more likely to weigh more, be female, have more cardiac risk factors and have typical symptoms concerning for CAD.31
Several studies were performed to validate technical advances in PET imaging to improve image quality, including applying a technique that performs “dead-time” correction during high-dose Rb-82 infusion.32 Two studies evaluating a software program to estimate MBF and CFR demonstrated high intra- and inter-observer reproducibility and accuracy.33,34 One study utilized quantitative PET to demonstrate differences in CFR between calcineurin and non-calcineurin inhibitor-based immunosuppressive regimens in cardiac transplant recipients.35
The Young Investigator Award session featured the 7 best abstracts submitted by young investigators. First place was awarded to Dr Shishir Mathur from Hartford Hospital. Dr Mathur examined the prognostic value of a blunted heart rate response in 3891 patients undergoing dipyridamole gated SPECT and found that a blunted heart rate response was an independent predictor of poorer outcome in patients regardless of whether they were on beta blocker therapy.36 Dr Malolan Rajagopalan from the University of Pittsburgh reported that SPECT attenuation correction with CT acquired in a separate gantry produced very similar results to Gd-153 line-source attenuation correction if the CT images were acquired at the end of shallow expiration; however, discordant results were obtained if CT images were acquired during deep inspiration.37 Dr Angela Koh from the National Heart Centre in Singapore applied the ACC/ASNC appropriateness criteria to a population of 413 patients from Singapore undergoing SPECT MPI and found that 80.6% of studies were appropriate, with pre-operative evaluation for noncardiac surgery accounting for the majority of inappropriate studies.38 Dr Sadia Qadir from Massachusetts General Hospital reported that a novel catheter-mounted beta-probe could accurately distinguish between varying degrees of inflammation based on FDG uptake in atherosclerotic plaques in the hypercholesterolemic rabbit aorta.39 Dr Reza Mazrashahi from the University of Cincinnati reported that the ratio of right-to-left ventricular radiotracer uptake on SPECT images correlated with right ventricular wall thickness and estimated pulmonary artery pressure on uncorrected but not attenuation corrected images.40 Dr Mati Friehling from the University of Pittsburgh reported the feasibility of assessing the acute effects of cardiac resynchronization therapy using serial gated SPECT following a single tracer injection.41 This study was complemented by Dr Prashant Atri’s presentation showing that LV dyssynchrony is influenced to a greater degree by mechanical than electrical abnormality in patients with ischemic cardiomyopathy.42
In summary, the ASNC2009 Scientific Session provided a rich program to meet the needs of a wide variety of attendees. In addition to sessions designed to help office-based cardiologists and technologists perform outpatient stress testing, sessions provided important reviews of other noninvasive imaging modalities, cutting-edge advances in technology and glimpses into the future of nuclear cardiac imaging. ASNC2010 will be held September 23-26, 2010, in Philadelphia, PA.
