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John D Friedman

Publications and source records attributed to John D Friedman.

At least 19 recordsLinked to original sources
PubMed2007

Comparative use of radionuclide stress testing, coronary artery calcium scanning, and noninvasive coronary angiography for diagnostic and prognostic cardiac assessment.

Noninvasive cardiac imaging has undergone a recent resurgence with the development of new approaches for imaging coronary atherosclerosis. Non-contrast computed tomography (CT) for imaging the extent of coronary artery calcification (CAC) and contrast CT for noninvasive coronary angiography (CTA) are developments with a growing evidence base regarding risk assessment and the diagnosis of obstructive coronary disease. This review discusses the role of CAC for risk assessment of asymptomatic individuals and for the use of coronary CTA in symptomatic patients. By comparison, gated myocardial perfusion scintigraphy (MPS) is a well-established noninvasive imaging modality that is a core element in evaluation of patients with stable chest pain syndromes. Stress MPS is the most commonly used stress imaging technique for patients with suspected or known coronary disease. In contrast to the nascent evidence noted with coronary CTA, MPS has a robust evidence base, including the support of numerous clinical guidelines. We highlight the current evidence supporting the diagnostic accuracy and risk stratification data for MPS for symptomatic patients with known or suspected coronary artery disease. It is likely that assessing the extent of atherosclerosis using CAC or coronary CTA will become an increasing part of mainstream cardiovascular imaging practices. In some patients, further ischemia testing with MPS will be required. Similarly, in some patients referred for MPS, anatomic definition of atherosclerosis using CAC by CT may be appropriate. Thus, this review also provides a synopsis of the available literature on imaging that integrates both CT and MPS in combined strategies for the assessment of atherosclerotic and obstructive coronary disease burden. We also propose possible risk-based strategies through which imaging might be used to identifying candidates for more intensive prevention and risk factor modification strategies as well as those who would benefit from referral to coronary angiography and revascularization.

Calcinosis↗
PubMed2006

Impact of body mass index on cardiac mortality in patients with known or suspected coronary artery disease undergoing myocardial perfusion single-photon emission computed tomography.

OBJECTIVES: The purpose of this study was to assess the relationship between body mass index (BMI) and the prognostic value of myocardial perfusion single-photon emission computed tomography (MPS). BACKGROUND: The prognostic value of MPS in the obese has not been evaluated. METHODS: We studied 4,720 patients with and 10,019 patients without known coronary artery disease (CAD) who underwent rest Tl-201/stress Tc-99m sestamibi MPS, including 5,233 gated MPS studies and followed up (mean 2.7 to 3.2 years). Patients were categorized as normal weight (BMI 18.5 to 24.9 kg/m2), overweight (BMI 25.0 to 29.9 kg/m2), or obese (BMI > or =30.0 kg/m2). RESULTS: Unadjusted annual rates of cardiac death (CD) rose versus stress MPS abnormalities in all weight groups (p < 0.001). Obese or overweight patients with or without known CAD who had normal MPS were at low CD risk (<1%/year), similar to normal weight patients. In CAD, obese and overweight patients with abnormal MPS had lower rates of CD compared with normal weight patients (p < 0.01). In patients with low ejection fraction (EF) by gated MPS, those with normal weight had highest CD rate (p = 0.001). Multivariable models revealed that BMI was not a predictor of CD in suspected CAD patients (hazard ratio [HR] 0.99; 95% confidence interval [CI] 0.95 to 1.02) but was an independent inverse predictor of CD in known CAD patients (HR 0.95; 95% CI 0.92 to 0.98), especially in women, adenosine stress, low EF, or abnormal perfusion. CONCLUSIONS: Normal MPS was associated with low risk of CD in patients of all weight categories. In patients with known CAD undergoing MPS, obese and overweight patients were at lower risk of CD over three years than normal weight patients.

Aged↗
PubMed2006

Direct quantitative in vivo comparison of calcified atherosclerotic plaque on vascular MRI and CT by multimodality image registration.

PURPOSE: To investigate direct volumetric in vivo correspondence of calcified atherosclerotic plaque lesions in MRI and CT images of the thoracic aorta by multimodality image registration and fusion. MATERIALS AND METHODS: Twelve CT (11 noncontrast and one contrast) and MRI (TruFISP, contrast T1-weighted volumetric interpolated breath-hold examination (VIBE)) data sets were co-registered by approximate segmentation of the aorta and subsequent automatic co-registration by maximization of mutual information (MI). We quantitatively assessed 22 co-registered calcified plaque lesions on CT and MRI. RESULTS: The three-dimensional registration consistency and accuracy were 1.74 +/- 1.3 mm, and 2.42 +/- 1.65 mm, respectively. The ratio of CT/MRI calcified plaque volume decreased asymptotically with MRI volume, and correlated with average CT lesion density (r = 0.72) for small lesions (<25 mm(3)). The average calcified plaque volume, circumferential extent, and maximal radial width by MRI were significantly smaller compared to CT (35%, 68%, and 53%, respectively; P < 0.05). CONCLUSION: Software co-registration allowed precise, direct, and voxel-based comparison of calcified atherosclerotic plaque lesions imaged by MRI and CT. In comparison with co-registered MRI, overestimation of calcified plaque in aortic CT due to "blooming" correlates with the average lesion density for small plaques, and is greater for small plaques.

Aged↗
PubMed2006

Prognostic value of poststress left ventricular volume and ejection fraction by gated myocardial perfusion SPECT in women and men: gender-related differences in normal limits and outcomes.

BACKGROUND: Whether there are gender differences in the prognostic application of gated myocardial perfusion single photon emission computed tomography (SPECT) has not been assessed. METHODS AND RESULTS: Gender-specific normal limits of poststress volume and ejection fraction (EF) were obtained in 597 women and 824 men with a low likelihood of coronary artery disease and normal perfusion and were applied in a prognostic evaluation of 6713 patients (2735 women and 3978 men). Patients underwent rest thallium-201/stress technetium-99m sestamibi gated myocardial perfusion SPECT and were followed up for 35 +/- 14 months. The upper limit of the end-systolic volume (ESV) index was 27 mL/m2 in women and 39 mL/m2 in men, and the upper limit of the end-diastolic volume index was 60 mL/m2 in women and 75 mL/m2 in men. The lower limit of the EF was 51% in women and 43% in men. Gated SPECT variables provided incremental prognostic information in both genders. Women with severe ischemia and an EF lower than 51% or an ESV index greater than 27 mL/m2 were at very high risk of cardiac death or myocardial infarction (3-year event rates of 39.8% and 35.1%, respectively), whereas women with severe ischemia but an EF of 51% or greater or an ESV index of 27 mL/m2 or less were at intermediate or high risk (3-year event rates of 10.8% and 15.2%, respectively). CONCLUSION: Poststress EF and ESV index by gated myocardial perfusion SPECT provide comparable incremental prognostic information over perfusion in women and men. After separate criteria for abnormal EF and ESV index in women are used, the combination of severe ischemia and abnormal EF or ESV index identifies women at very high risk of cardiac events.

Aged↗
PubMed2006

Left ventricular shape index assessed by gated stress myocardial perfusion SPECT: initial description of a new variable.

BACKGROUND: Ventricular remodeling is predictive of congestive heart failure (CHF). We aimed to automatically quantify a new myocardial shape variable on gated myocardial perfusion single photon emission computed tomography (SPECT) (MPS) and to evaluate the association of this new SPECT parameter with the risk of hospitalization for CHF. METHODS AND RESULTS: A computer algorithm was used to measure the 3-dimensional (3D) left ventricular (LV) shape index (LVSI), derived as the ratio of maximum 3D short- and long-axis LV dimensions, for end systole and end diastole. LVSI normal limits were obtained from stress technetium 99m sestamibi MPS images of 186 patients (60% of whom were men) (control subjects) with a low likelihood of CAD (< 5%). These limits were tested in a consecutive series of 93 inpatients (85% of whom were men) having MPS less than 1 week after hospitalization, of whom 25 were hospitalized for CHF exacerbation. Variables associated with CHF hospitalization were tested by receiver operating characteristic curve and multivariate logistic regression analyses. LVSI repeatability was assessed in 52 patients with ischemic cardiomyopathy who had sequential stress MPS within 60 days after the initial MPS without clinical events in the interval between MPS studies. Control subjects had lower end-systolic and end-diastolic LVSIs compared with patients with CHF and those without CHF (P < .001). Receiver operating characteristic curve areas for the prediction of hospitalization as a result of CHF were similar for LV ejection fraction and end-systolic LVSI. End-systolic and end-diastolic LVSIs were independent predictors of CHF hospitalization by multivariate analysis; however, end-systolic LVSI had the greatest added value among all tested variables. Repeatability was excellent for both end-systolic LVSI (R2 = 0.85, P < .0001) and end-diastolic LVSI (R2 = 0.82, P < .001). CONCLUSION: LVSI is a promising new 3D variable derived automatically from gated MPS providing highly repeatable ventricular shape assessment. Preliminary findings suggest that LVSI might have clinical implications in patients with CHF.

Adult↗
PubMed2006

Predicting therapeutic benefit from myocardial revascularization procedures: are measurements of both resting left ventricular ejection fraction and stress-induced myocardial ischemia necessary?

BACKGROUND: We hypothesized that ejection fraction (EF) best predicts cardiovascular death but only measures of ischemia predict relative survival benefit from revascularization compared with medical therapy. METHODS AND RESULTS: We followed up 5366 consecutive patients without prior revascularization who underwent stress electrocardiography-gated myocardial perfusion single photon emission computed tomography (MPS) for 2.8 +/- 1.2 years, during which 146 cardiac deaths occurred (2.7%, 1.0%/y). The treatment received within 60 days after MPS was used to define the subgroups (revascularization in 402 patients, with cardiac death occurring in 6.2%, vs medical therapy in 4964 patients, with cardiac death occurring in 2.4%; P < .0001, chi2 = 18.7). Adjustment for nonrandomized treatment assignment used a propensity score based on logistic regression modeling of referral to revascularization. The percent of myocardium that was ischemic was the most important predictor of revascularization. The overall model (multivariate chi2 = 728, c index = 0.89, P < 10(-5)) was used as a propensity score. Cox proportional hazards analysis, assessing the relationship between MPS results, non-MPS covariates, and cardiac death, revealed that EF was superior to percent ischemic myocardium in the prediction of cardiac death after adjustment for pre-MPS data and the propensity score. However, an interaction between percent ischemic myocardium and revascularization was present such that, irrespective of EF, patients with little or no ischemia had an improved survival rate with medical therapy, whereas with increasing ischemia, progressive improvements in survival rate were noted with revascularization. CONCLUSIONS: Although EF predicts cardiac death, only inducible ischemia identifies which patients have a short-term benefit from revascularization.

Coronary Artery Disease↗
PubMed2006

Rapid assessment of left ventricular segmental wall motion, ejection fraction, and volumes with single breath-hold, multi-slice TrueFISP MR imaging.

BACKGROUND AND OBJECTIVE: To reduce imaging time and complexity, we sought to determine whether single breath-hold, multi-slice TrueFISP (SB-MST) magnetic resonance imaging (MRI) method is comparable to standard multi-breath-hold, multi-slice TrueFISP (MB-MST) for assessment of left ventricular (LV) wall motion abnormality (WMA), volumes, and ejection fraction (EF). METHODS AND RESULTS: We studied 62 patients having cardiac MRI at 1.5-Tesla. After acquiring standard MB-MST (one slice per breath-hold), SB-MST was performed, acquiring 3 short- and 2 long-axis views over only 20 heartbeats. Using both techniques, wall motion was scored using a 6-point, 17-segment LV model for all scans (62 patients x 2 techniques/patient = 124 scans) on two separate occasions. Separately, EF and ventricular volumes were evaluated using both MB-MST and SB-MST. For all analyses, MB-MST was considered the standard against which SB-MST was compared. Twenty-six of 62 patients exhibited at least one segmental WMA by MB-MST. Exact agreement for wall motion was found in 965/1054 segments (92%, kappa = 0.74, p < 0.001), and agreement was within 1 score point in 1010/1054 segments (96%). Considering a score >1 abnormal, exact agreement for presence of WMA was found in 131/193 segments (68%) abnormal by MB-MST and for absence of WMA in 838/861 segments (97%) normal by MB-MST. Agreement within 1 score point occurred in 167/193 abnormal (87%) and in 843/861 normal segments (98%). There were no significant differences in agreement between first and second read of the data. Variability of SB-MST on read one versus read two was small (5%, 996/1054 segments read identically, p = ns) and statistically identical to variability of MB-MST on read one versus read two (4%, 1007/1054 segments read identically, p = ns). For end-diastolic volumes, end-systolic volumes, and EF using SB-MST compared to MB-MST, mean differences were 9 +/- 15 ml, 6 +/- 12 ml, and 2 +/- 5%, and correlations were r = 0.97, 0.98 and 0.95, respectively. CONCLUSION: SB-MST accurately assesses wall motion, volumes and EF. This approach may serve as a screening exam for assessment of WMA and, under select circumstances, may substitute for standard multi-breath-hold method in situations requiring rapid accurate assessments of LV function.

Aged↗
PubMed2006

Cardiovascular magnetic resonance of primary tumors of the heart: A review.

Overall, the prevalence of primary cardiac neoplasms is approximately 0.3% and these masses should be distinguished from the myriad of other primary and secondary processes that can occur in the heart. Tumors within, attached to, or near the heart can cause direct cardiac damage, can result in thrombus formation, can compromise blood flow and can embolize distally. Hence, proper diagnosis is clinically important. It has been suggested that cardiovascular magnetic resonance (CMR) imaging is a useful tool for diagnosing and characterizing cardiac tumors. In this report, we present a case example of a patient with a large, mobile right atrial myxoma imaged by CMR with results of histopathologic analysis after excision. We also demonstrate the utilization of CMR for characterization of cardiac lesions, review the basic characteristics of primary cardiac neoplasms, provide an overview of published cases describing use of CMR, and give suggested guidelines for imaging of cardiac masses with emphasis on diagnosis of cardiac tumors. CMR is an important technique for diagnosing and characterizing cardiac tumors.

Aged↗
PubMed2006

Computer-aided detection and evaluation of lipid-rich plaque on noncontrast cardiac CT.

OBJECTIVE: Noncontrast electron beam CT (EBCT) and MDCT are established for the assessment of calcified plaque, but not lipid-rich plaque. We developed software to identify lipid-rich plaque with noncontrast electron beam tomography (EBT) and MDCT. MATERIALS AND METHODS: A computer algorithm was developed to automatically find contiguous lipid-rich lesions with voxel intensities below a calculated patient-specific lipid threshold. Lipid density and lipid inhomogeneity in Hounsfield units were calculated in the proximal left coronaries of three populations: 34 low-risk patients (low-risk group < 6% Framingham risk score, no calcium), 31 high-risk patients (high-risk group > 20% Framingham risk score, no calcium), and 37 patients with calcified plaque (calcium group). RESULTS: The mean lipid density was -19.6 +/- 3.0 (SD) H in the low-risk group, -25.3 +/- 8.2 H in the high-risk group, and -34.3 +/- 13.0 H in the calcium group (p < 0.05). The mean lipid inhomogeneity was 17.7 +/- 3.6 H in the low-risk group, 21.5 +/- 5.5 H in the high-risk group, and 29.0 +/- 7.6 H in the calcium group (p < 0.05). The mean interscan variability in lipid density and lipid inhomogeneity were 2.0 +/- 3.3 H and 2.1 +/- 3.6 H, respectively. In five patients, the locations of lipid-rich plaque correlated well with available intravascular sonography findings. CONCLUSION: Our method may be able to identify lipid-rich plaque on noncontrast cardiac CT.

Adult↗
PubMed2006

Combined supine and prone quantitative myocardial perfusion SPECT: method development and clinical validation in patients with no known coronary artery disease.

UNLABELLED: Acquisition in the prone position has been demonstrated to improve the specificity of visually analyzed myocardial perfusion SPECT (MPS) for detecting coronary artery disease (CAD). However, the diagnostic value of prone imaging alone or combined acquisition has not been previously described using quantitative analysis. METHODS: A total of 649 patients referred for MPS comprised the study population. Separate supine and prone normal limits were derived from 40 males and 40 females with a low likelihood (LLk) of CAD using a 3 average-deviation cutoff for all pixels on the polar map. These limits were applied to the test population of 369 consecutive patients (65% males; age, 65 +/- 13 y; 49% exercise stress) without known CAD who had diagnostic coronary angiography within 3 mo of MPS. Total perfusion deficit (TPD), defined as a product of defect extent and severity scores, was obtained for supine (S-TPD), prone (P-TPD), and combined supine-prone datasets (C-TPD). The angiographic group was randomly divided into 2 groups for deriving and validating optimal diagnostic cutoffs. Normalcy rates were validated in 2 additional groups of consecutive LLk patients: unselected patients (n = 100) and patients with body mass index >30 (n = 100). RESULTS: C-TPD had a larger area under the receiver-operating-characteristic (ROC) curve than S-TPD or P-TPD for identification of stenosis >or=70% (0.86, 0.88, and 0.90 for S-TPD, P-TPD, and C-TPD, respectively; P < 0.05). In the validation group, sensitivity for P-TPD was lower than for S- or C-TPD (P < 0.05). C-TPD yielded higher specificity than S-TPD and a trend toward higher specificity than P-TPD (65%, 83%, and 86% for S-, P-, and C-TPD, respectively, P < 0.001; vs. S-TPD and P = 0.06 vs. P-TPD). Normalcy rates for C-TPD were higher than for S-TPD in obese LLk patients (78% vs. 95%, P < 0.001). CONCLUSION: Combined supine-prone quantification significantly improves the area under the ROC curve and specificity of MPS in the identification of obstructive CAD compared with quantification of supine MPS alone.

Coronary Artery Disease↗
PubMed2006

Roles of nuclear cardiology, cardiac computed tomography, and cardiac magnetic resonance: assessment of patients with suspected coronary artery disease.

Noninvasive cardiac imaging is now central to the diagnosis and management of patients with known or suspected chronic coronary artery disease (CAD). Although rest echocardiography has become the most common of the techniques, nuclear cardiology and more recently cardiac computed tomography (CCT) and cardiac magnetic resonance (CMR) play important roles in this regard. This review examines the current applications and interactions of noninvasive cardiac imaging approaches for the assessment of patients with suspected CAD. In addition to considering the strengths and weaknesses of each technique, this review attempts to provide a guide to the selection of a test (or tests) that is based on the question being asked and the ability of each test to answer this question. In patients with suspected CAD, the pretest likelihood of disease, a clinical assessment, becomes the most important determinant of the initial test. If the likelihood is very low, no testing is needed. However, if the likelihood is low, recent data suggest that assessment of early atherosclerosis is likely to be the most useful and cost-effective test. In patients who have an intermediate likelihood of CAD, nuclear cardiology with myocardial perfusion SPECT (MPS) becomes highly valuable; however, coronary CT angiography (CTA), with fast 16-slice or greater scanners, may emerge as the initial test of choice. MPS would then be used if the CTA is inconclusive or if there is a need to assess the functional significance of a stenosis defined by CTA. Coronary CTA, however, is not yet widely available and is limited in patients with dense coronary calcification. In older patients with a high likelihood of CAD, MPS may be the initial test of choice, since a high proportion of these patients have too much coronary calcium to allow accurate assessment of the presence of coronary stenoses. PET/CT or SPECT/CT could emerge as important modalities combining the advantages of each modality. While CMR has great promise as a radiation-free and contrast-free "one-stop" shop, it currently lags behind CTA for noninvasive coronary angiography. Nonetheless, CMR clearly has the potential for this application and has already emerged as a highly effective method for assessing ventricular function, myocardial mass, and myocardial viability, and there is increasing use of this approach for clinical rest and stress perfusion measurements. CMR is particularly valuable in distinguishing ischemic from nonischemic cardiomyopathy. While CT and CMR are likely to grow considerably in diagnostic evaluation over the next several years, MPS and PET will continue to be very valuable techniques for this purpose.

Cardiology↗
PubMed2006

Roles of nuclear cardiology, cardiac computed tomography, and cardiac magnetic resonance: Noninvasive risk stratification and a conceptual framework for the selection of noninvasive imaging tests in patients with known or suspected coronary artery disease.

This review deals with noninvasive imaging for risk stratification and with a conceptual approach to the selection of noninvasive tests in patients with suspected or known chronic coronary artery disease (CAD). Already widely acknowledged with SPECT, there is an increasing body of literature data demonstrating that CT coronary calcium assessment is also of prognostic value. The amount of coronary atherosclerosis, as can be extrapolated from CT coronary calcium score, has been shown to be highly predictive of cardiac events. The principal difference between myocardial perfusion SPECT (MPS) and CT coronary calcium for prognostic application appears to be that the former is an excellent tool for assessing short-term risk, thus effectively guiding decisions regarding revascularization. In contrast, the atherosclerosis imaging methods are likely to provide greater long-term risk assessment and, thus, are more useful in determination of the need for aggressive medical prevention measures. Although the more recent development of CT coronary angiography is promising for diagnosis, there has been no information to date regarding the prognostic value of the CT angiographic data. Similarly, cardiac MRI has not yet been adequately studied for its prognostic content. The selection of the most appropriate test for a given patient depends on the specific question being asked. In patients with a very low likelihood of CAD, no imaging test may be required. In screening the remaining asymptomatic patients, atherosclerosis imaging may be beneficial. In symptomatic patients, MPS, CT coronary angiography, and cardiac MRI play important roles. We consider it likely that, with an increased emphasis on prevention and a concomitant aging of the population, many forms of noninvasive cardiac imaging will continue to grow, with nuclear cardiology continuing to grow.

Atherosclerosis↗
PubMed2005

Prognostic significance of dyspnea in patients referred for cardiac stress testing.

BACKGROUND: Although dyspnea is a common symptom, there has been only limited investigation of its prognostic significance among patients referred for cardiac evaluation. METHODS: We studied 17,991 patients undergoing myocardial-perfusion single-photon-emission computed tomography during stress and at rest. Patients were divided into five categories on the basis of symptoms at presentation (none, nonanginal chest pain, atypical angina, typical angina, and dyspnea). Multivariable analysis was used to assess the incremental prognostic value of symptom categories in predicting the risk of death from cardiac causes and from any cause. In addition, the prognosis associated with various symptoms at presentation was compared in subgroups selected on the basis of propensity analysis. RESULTS: After a mean (+/-SD) follow-up of 2.7+/-1.7 years, the rate of death from cardiac causes and from any cause was significantly higher among patients with dyspnea (both those previously known to have coronary artery disease and those with no known history of coronary artery disease) than among patients with other or no symptoms at presentation. Among patients with no known history of coronary artery disease, those with dyspnea had four times the risk of sudden death from cardiac causes of asymptomatic patients and more than twice the risk of patients with typical angina. Dyspnea was associated with a significant increase in the risk of death among each clinically relevant subgroup and remained an independent predictor of the risk of death from cardiac causes (P<0.001) and from any cause (P<0.001) after adjustment for other significant factors by multivariable and propensity analysis. CONCLUSIONS: In a large series of patients, self-reported dyspnea identified a subgroup of otherwise asymptomatic patients at increased risk for death from cardiac causes and from any cause. Our results suggest that an assessment of dyspnea should be incorporated into the clinical evaluation of patients referred for cardiac stress testing.

Aged↗
PubMed2005

A prognostic score for prediction of cardiac mortality risk after adenosine stress myocardial perfusion scintigraphy.

OBJECTIVES: We sought to derive and validate a score to estimate risk after adenosine stress. BACKGROUND: Maximizing the prognostic information extracted from adenosine stress myocardial perfusion scintigraphy, a commonly performed test, is often challenging for referring physicians. METHODS: A split-set validation of a score predicting cardiovascular mortality was performed in 5,873 consecutive patients studied by adenosine stress, dual-isotope single-photon emission computed tomography (SPECT; follow-up 94% complete, mean 2.2 +/- 1.1 years). RESULTS: On follow-up, 387 cardiac deaths occurred (6.6%). The Cox proportional hazards model most predictive of cardiac death included age, % myocardium ischemic, % myocardium fixed, early revascularization, dyspnea, diabetes mellitus, rest and peak stress heart rates, abnormal rest electrocardiogram (ECG), and an interaction between % myocardium ischemic and early revascularization (chi-square = 376). The final prognostic score was calculated as follows: (age [decades] x 5.19) + (% myocardium ischemic [per 10%] x 4.66) + (% myocardium fixed [per 10%] x 4.81) + (diabetes mellitus x 3.88) + (if patient treated with early revascularization, 4.51) + (if dyspnea was a presenting symptom, 5.47) + (resting heart rate [per 10 beats] x 2.88) - (peak heart rate [per 10 beats] x 1.42) + (ECG score x 1.95) - (if patient treated with early revascularization, % myocardium ischemic [per 10%] x 4.47). Scores of <49, 49 to 57, and >57 identified low, intermediate, and high risk (0.9%, 3.3%, and 9.5% cardiac death/year, respectively). Score results further risk stratified patients with respect to cardiac death in all categories of SPECT abnormality. CONCLUSIONS: We derived and validated a score incorporating data available after adenosine stress perfusion SPECT. This score maximizes the prognostic information extracted from this test and may enhance the application of this test as part of an overall strategy.

Adenosine↗
PubMed2005

Concordance of coronary artery calcium estimates between MDCT and electron beam tomography.

OBJECTIVE: The objective of our study was to compare MDCT with electron beam tomography (EBT) for the quantification of coronary artery calcification (CAC). MATERIALS AND METHODS: Sixty-eight patients underwent both MDCT and EBT within 2 months for the quantification of CAC. The images were scored in a blinded fashion and independently by two observers with a minimum of 7 days between the interpretations of images obtained from one scanner type to the other. RESULTS: Presence versus absence of CAC was discordant by EBT versus MDCT in 6% (n = 4) of the cases by observer 1, with one of these cases also discordant by observer 2. All cases except one (aortic calcium misidentified as CAC) were among those with a mean Agatston score of less than 5 present on EBT but absent on MDCT. EBT and MDCT scores correlated well (r = 0.98-0.99). The relative median variability between EBT and MDCT for the Agatston score was 24% for observer 1 and 27% for observer 2 and was 18% and 14%, respectively, for volume score (average for both observers: 27% for Agatston score and 16% for volume score). Scores were higher for EBT than MDCT in approximately half of the cases, with little systematic difference between the two (median EBT-MDCT difference: Agatston score, -0.55; volume score, 3.4 mm3). The absolute median difference averaged for the two observers was 28.75 for the Agatston score and 15.4 mm3 for the volume score. CONCLUSION: Differences in CAC measurements using EBT and MDCT are similar to interscan differences in CAC measurements previously reported for EBT or for other MDCT scanners individually.

Aged↗
PubMed2005

Automatic detection and size quantification of infarcts by myocardial perfusion SPECT: clinical validation by delayed-enhancement MRI.

UNLABELLED: We aimed to validate the accuracy of a new automated myocardial perfusion SPECT quantification based on normal limits for detection and sizing of infarcts, using delayed-enhancement MRI (DE-MRI) as a gold standard. METHODS: Eighty-two immediate (201)Tl rest scans and 26 (201)Tl delayed redistribution scans were compared with resting DE-MRI scans acquired within 24 h of SPECT acquisition. The immediate (201)Tl scans were considered for validation of infarct detection and the delayed (201)Tl scans were considered for infarct sizing. A simplified quantification scheme was used in which defect extent (EXT) and total perfusion deficit (TPD) parameters were derived automatically from SPECT images by comparison with sex-matched normal limits and applying a 3.0 average deviation criterion. The total extent of hyperenhancement expressed as the percentage of the left ventricle was derived from DE-MRI images by visual definition of myocardial contours and defects. DE-MRI and SPECT images were fused in 3 dimensions for visual comparison. Phantom data were also quantified using the same EXT and TPD measures for defects ranging from 5% to 70% of the myocardium. RESULTS: The area under the receiver-operator-characteristic curve for the detection of infarct on immediate rest scans was 0.91 +/- 0.03 for EXT and 0.90 +/- 0.03 for TPD (P = not significant). The sensitivity and specificity for the detection of infarct by EXT on immediate (201)Tl rest scan were 87% and 91%, respectively, with the optimal defect size threshold of 4%. Six of 7 cases with DE-MRI defects < 5% were detected by SPECT. Infarct sizes obtained from DE-MRI correlated well with EXT (slope = 0.94, offset = 3.8%; r = 0.84) and TPD (slope = 0.75, offset = 4.2%; r = 0.85) obtained from delayed SPECT (201)Tl scans. Excellent correlation was observed between the SPECT quantification and the physical defect size for the phantom data. The actual size of the defect was better estimated by EXT (slope = 1.00, offset 1.33%; r = 0.99) than by TPD (slope = 0.79, offset = 1.9%; r = 0.99). CONCLUSION: Automated quantification of the EXT on myocardial perfusion SPECT images can reliably detect infarcts and measure infarct sizes.

Aged↗
PubMed2005

Assessment of diastolic function using 16-frame 99mTc-sestamibi gated myocardial perfusion SPECT: normal values.

UNLABELLED: The purposes of this study were (a) to assess the feasibility of diastolic function (DFx) evaluation using standard 16-frame postexercise gated (99m)Tc-sestamibi myocardial perfusion SPECT (MPS), (b) to determine the relationship of the 2 common DFx parameters, peak filling rate (PFR) and time to peak filling (TTPF), to clinical and systolic function (SFx) variables in patients with normal myocardial perfusion and SFx, and (c) to derive and validate normal limits. METHODS: Ninety patients (71 men; age, 30-79 y) with normal exercise gated MPS were studied. None had hypertension, diabetes, rest electrocardiogram abnormality, or known cardiac disease. All patients reached > or = 85% of maximum predicted heart rate (HR). The population was randomized into derivation (n = 50) and validation (n = 40) groups. Univariable and multivariable approaches were deployed to assess the influence of clinical and functional variables on DFx parameters. RESULTS: PFR and TTPF were assessed in all patients. Mean values of PFR and TTPF in the whole study population were 2.62 +/- 0.46 end-diastolic volumes per second (EDV/s) and 164.6 +/- 21.7 ms, respectively. By applying a 2-SD cutoff to the mean values in the derivation group, the threshold for abnormal PFR and the threshold for abnormal TTPF were < 1.71 EDV/s and > 216.7 ms, respectively. The normalcy rates in the validation group for PFR and TTPF were both 100%. The PFR showed weak but significant correlations with age, EDV, end-systolic volume, left ventricular ejection fraction (LVEF), and poststress HR. However, TTPF did not correlate with these parameters. Final normal thresholds determined from the combined populations were PFR = 1.70 EDV/s and TTPF = 208 ms. Multivariable analysis showed that age, sex, LVEF, and HR are strong predictors for PFR, whereas TTPF was not influenced by any clinical or SFx variable. CONCLUSION: With a new algorithm in QGS, assessment of LV DFx is feasible using 16-frame gated MPS even without bad-beat rejection, resulting in normal limits similar to those reported with gated blood-pool studies. However, due to the dependency of PFR on SFx parameters, sex, HR, and age, TTPF appears to be a stable and more useful parameter with this approach. The clinical usefulness of these findings requires further study.

Adult↗