***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: The coronary artery calcium ( CAC ) score is a readily and widely available tool for the noninvasive diagnosis of atherosclerotic coronary artery disease ( CAD ) . The aim of this study was to investigate the added value of the CAC score as an adjunct to gated SPECT for the assessment of CAD in an intermediate-risk population . Methods : Seventy-seven prospect ively recruited patients with intermediate risk ( as determined by the Framingham Heart Study 10-y CAD risk score ) and referred for coronary angiography because of suspected CAD underwent stress 99mTc-tetrofosmin SPECT myocardial perfusion imaging ( MPI ) and CT CAC scoring within 2 wk before coronary angiography . The sensitivity and specificity of SPECT alone and of the combination of the 2 methods ( SPECT plus CAC score ) in demonstrating significant CAD ( ≥50 % stenosis on coronary angiography ) were compared . Results : Forty-two ( 55 % ) of the 77 patients had CAD on coronary angiography , and 35 ( 45 % ) had abnormal SPECT results . The CAC score was significantly higher in subjects with perfusion abnormalities than in those who had normal SPECT results ( 889 ± 836 [ mean ± SD ] vs. 286 ± 335 ; P < 0.0001 ) . Similarly , with rising CAC scores , a larger percentage of patients had CAD . Receiver-operating-characteristic analysis showed that a CAC score of greater than or equal to 709 was the optimal cutoff for detecting CAD missed by SPECT . SPECT alone had a sensitivity and a specificity for the detection of significant CAD of 76 % and 91 % , respectively . Combining SPECT with the CAC score ( at a cutoff of 709 ) improved the sensitivity  of SPECT ( from 76 % to 86 % ) for the detection of CAD , in association with a nonsignificant decrease in specificity ( from 91 % to 86 % ) . Conclusion : The CAC score may offer incremental diagnostic information over SPECT data for identifying patients with significant CAD and negative MPI results UNLABELLED In July 2009 , the Medical Advisory Secretariat ( MAS ) began work on Non-Invasive Cardiac Imaging Technologies for the Diagnosis of Coronary Artery Disease ( CAD ) , an evidence -based review of the literature surrounding different cardiac imaging modalities to ensure that appropriate technologies are accessed by patients suspected of having CAD . This project came about when the Health Services Branch at the Ministry of Health and Long-Term Care asked MAS to provide an evidentiary platform on effectiveness and cost-effectiveness of non-invasive cardiac imaging modalities . After an initial review of the strategy and consultation with experts , MAS identified five key non-invasive cardiac imaging technologies for the diagnosis of CAD . Evidence -based analyses have been prepared for each of these five imaging modalities : cardiac magnetic resonance imaging , single photon emission computed tomography , 64-slice computed tomographic angiography , stress echocardiography , and stress echocardiography with contrast . For each technology , an economic analysis was also completed ( where appropriate ) . A summary decision analytic model was then developed to encapsulate the data from each of these reports ( available on the OHTAC and MAS website).The Non-Invasive Cardiac Imaging Technologies for the Diagnosis of Coronary Artery Disease series is made up of the following reports , which can be publicly accessed at the MAS website at : www.health.gov.on.ca/mas or at www.health.gov.on.ca/english/providers/program/mas/mas_about.htmlSINGLE PHOTON EMISSION COMPUTED TOMOGRAPHY FOR THE DIAGNOSIS OF CORONARY ARTERY DISEASE : An Evidence -Based Analysis STRESS ECHOCARDIOGRAPHY FOR THE DIAGNOSIS OF CORONARY ARTERY DISEASE : An Evidence -Based Analysis STRESS ECHOCARDIOGRAPHY WITH CONTRAST FOR THE DIAGNOSIS OF CORONARY ARTERY DISEASE : An Evidence -Based Analysis 64-Slice Computed Tomographic Angiography for the Diagnosis of Coronary Artery Disease : An Evidence -Based Analysis CARDIAC MAGNETIC RESONANCE IMAGING FOR THE DIAGNOSIS OF CORONARY ARTERY DISEASE : An Evidence -Based Analysis Pease note that two related evidence -based analyses of non-invasive cardiac imaging technologies for the assessment of myocardial viability are also available on the MAS website : POSITRON EMISSION TOMOGRAPHY FOR THE ASSESSMENT OF MYOCARDIAL VIABILITY : An Evidence -Based Analysis MAGNETIC RESONANCE IMAGING FOR THE ASSESSMENT OF MYOCARDIAL VIABILITY : an Evidence -Based Analysis The Toronto Health Economics and Technology Assessment Collaborative has also produced an associated economic report entitled : The Relative Cost-effectiveness of Five Non-invasive Cardiac Imaging Technologies for Diagnosing Coronary Artery Disease in Ontario [ Internet ] . Available from : http://theta.utoronto.ca/reports/?id=7 OBJECTIVE The objective of the analysis is to determine the diagnostic accuracy of single photon emission tomography ( SPECT ) in the diagnosis of coronary artery disease ( CAD ) compared to the reference st and ard of coronary angiography ( CA ) . The analysis is primarily meant to allow for indirect comparisons between non-invasive strategies for the diagnosis of CAD , using CA as a reference st and ard . SPECT : Cardiac SPECT , or myocardial perfusion scintigraphy ( MPS ) , is a widely used nuclear , non-invasive image acquisition technique for investigating ischemic heart disease . SPECT is currently appropriate for all aspects of detecting and managing ischemic heart disease including diagnosis , risk assessment /stratification , assessment of myocardial viability , and the evaluation of left ventricular function . Myocardial perfusion scintigraphy was originally developed as a two-dimensional planar imaging technique , but SPECT acquisition has since become the clinical st and ard in current practice . Cardiac SPECT for the diagnosis of CAD uses an intravenously administered radiopharmaceutical tracer to evaluate regional coronary blood flow usually at rest and after stress . The radioactive tracers thallium ( 201Tl ) or technetium-99 m ( 99mTc ) , or both , may be used to visualize the SPECT acquisition . Exercise or a pharmacologic agent is used to achieve stress . After the administration of the tracer , its distribution within the myocardium ( which is dependent on myocardial blood flow ) is imaged using a gamma camera . In SPECT imaging , the gamma camera rotates around the patients for 10 to 20 minutes so that multiple two-dimensional projections are acquired from various angles . The raw data are then processed using computational algorithms to obtain three-dimensional tomographic images . Since its inception , SPECT has evolved and its techniques/applications have become increasingly more complex and numerous . Accordingly , new techniques such as attenuation correction and ECG gating have been developed to correct for attenuation due to motion or soft-tissue artifact and to improve overall image clarity . RESEARCH QUESTIONS What is the diagnostic accuracy of SPECT for the diagnosis of CAD compared to the reference st and ard of CA?Is  SPECT cost-effective compared to other non-invasive cardiac imaging modalities for the diagnosis of CAD?What are the major safety concerns with SPECT when used for the diagnosis of CAD ? METHODS A preliminary literature search was performed across OVID MEDLINE , MEDLINE In-Process and Other Non-Indexed Citations , EMBASE , the Cochrane Library , and the International Agency for Health Technology Assessment ( INAHTA ) for all systematic review s/meta- analysis published between January 1 , 2004 and August 22 , 2009 . A comprehensive systematic review was identified from this search and used as a basis for an up date d search . A second comprehensive literature search was then performed on October 30 , 2009 across the same data bases for studies published between January 1 , 2002 and October 30 , 2009 . Abstract s were review ed by a single review er and , for those studies meeting the eligibility criteria , full-text articles were obtained . Reference lists were also h and - search ed for any additional studies . Inclusion Criteria Exclusion Criteria Systematic review s , meta-analyses , controlled clinical trials , and observational studies Minimum sample size of 20 patients who completed coronary angiographyUse of CA as a reference st and ard for the diagnosis of CAD Data available to calculate true positives ( TP ) , false positives ( FP ) , false negatives ( FN ) and true negatives (TN)Accuracy data reported by patient not by segmentEnglish language Non- systematic review s , case reportsGrey literature and abstract sTrials using planar imaging onlyTrials conducted in patients with non-ischemic heart disease Studies done exclusively in special population s ( e.g. , patients with left branch bundle block , diabetics , minority population s ) unless insufficient data available SUMMARY OF FINDINGS Eighty-four observational studies , one non-r and omized , single arm controlled clinical trial , and one poorly reported trial that appeared to be a r and omized controlled trial ( RCT ) met the inclusion criteria for this review . All studies assessed the diagnostic accuracy of myocardial perfusion SPECT  for the diagnosis of CAD using CA as a reference st and ard . Based on the results of these studies the following conclusions were made : According to very low quality evidence , the addition of attenuation correction to traditional or ECG-gated SPECT greatly improves the specificity of SPECT  for the diagnosis of CAD although this improvement is not statistically significant . A trend towards improvement of specificity was also observed with the addition of ECG gating to traditional SPECT.According to very low quality evidence , neither the choice of stress agent ( exercise or pharmacologic ) nor the choice of radioactive tracer ( technetium vs. thallium ) significantly affect the diagnostic accuracy of SPECT  for the diagnosis of CAD although a trend towards accuracy improvement was observed with the use of pharmacologic stress over exercise stress and technetium over thallium . Considerably heterogeneity was observed both within and between trials . This heterogeneity may explain why some of the differences observed between accuracy estimates for various subgroups were not statistically significant . More complex analytic techniques such as meta-regression may help to better underst and which study characteristics significantly influence the diagnostic accuracy of SPECT Background Although single photon emission computed tomography ( SPECT ) and positron emission tomography ( PET ) myocardial perfusion imaging ( MPI ) have evolved considerably over the last decade , there is no recent comparison of diagnostic performance . This study was design ed to assess relative image quality , interpretive confidence , and diagnostic accuracy by use of contemporary technology and protocol s. Methods and Results By consensus and without clinical information , 4 experienced nuclear cardiologists interpreted  112 SPECT technetium-99 m sestamibi and 112 PET rubidium-82 MPI electrocardiography (ECG)-gated rest/pharmacologic stress studies in patient population s matched by gender , body mass index , and presence and extent of coronary disease . The patients were categorized as having a low likelihood for coronary artery disease ( 27 in each group ) or had coronary angiography within 60 days .  SPECT scans were acquired on a Cardio-60 system and PET scans on an ECAT ACCEL scanner . Image quality was excellent for 78 % and 79 % of rest and stress PET scans , respectively , versus 62 % and 62 % of respective SPECT scans ( both p < .05 ) . An equal percent of PET and SPECT gated images were rated excellent in quality . Interpretations were definitely normal or abnormal for 96 % of PET scans versus 81 % of SPECT scans ( p = .001 ) . Diagnostic accuracy was higher for PET for both stenosis severity thresholds of 70 % ( 89 % vs 79%,p = .03 ) and 50 % ( 87 % vs 71%,p = .003 ) and was higher in men and women , in obese and nonobese patients , and for correct identification of multivessel coronary artery disease . Conclusion In a large population of matched pharmacologic stress patients , myocardial perfusion PET was superior to SPECT in image quality , interpretive certainty , and diagnostic accuracy BACKGROUND The present study compared computed tomographic coronary angiography ( CTA ) and positron emission tomography ( PET ) for the detection of significant anatomical coronary artery stenosis as defined by conventional invasive coronary angiography ( CICA ) . METHODS The study protocol was approved by the local ethics board , and informed consent was obtained from all patients . Of the 26 patients ( mean age 57+/-9 years , 18 men ) who prospect ively underwent CTA and rubidium-82 PET before CICA , 24 patients had a history of chest pain . Images were interpreted by expert readers and assessed for the presence of anatomically significant coronary stenosis ( 50 % luminal diameter stenosis or greater ) or myocardial perfusion defects . Diagnostic test characteristics were analyzed using patient-based , territory-based , vessel-based and segment-based analyses . RESULTS In the 24 patients referred for chest pain , CTA had similar sensitivity to PET , but was more specific ( sensitivity 95 % [ 95 % CI 72 % to 100 % ] versus 95 % [ 95 % CI 72 % to 100 % ] , respectively ; specificity 100 % [ 95 % CI 46 % to 100 % ] versus 6 
    Output:
    
Rb-82 PET is accurate for the detection of obstructive CAD and , despite advances in SPECT technology , remains superior .
More widespread use of Rb-82 PET may be beneficial to improve CAD detection