Emission Computed Tomography Perfusion Imaging Research Articles

Variations Between Dose-Ventilation and Dose-Perfusion Metrics in Radiation Therapy Planning for Lung Cancer

PurposeCurrently, several active clinical trials of functional lung avoidance radiation therapy using different imaging modalities for ventilation or perfusion are underway. Patients with lung cancer often show ventilation-perfusion mismatch, whereas the significance of dose-function metric remains unclear. The aim of the present study was to compare dose-ventilation metrics with dose-perfusion metrics for radiation therapy plan evaluation. Methods and MaterialsPretreatment 4-dimensional computed tomography and 99mTc-macroaggregated albumin single-photon emission computed tomography perfusion images of 60 patients with lung cancer treated with radiation therapy were analyzed. Ventilation images were created using the deformable image registration of 4-dimensional computed tomography image sets and image analysis for regional volume changes as a surrogate for ventilation. Ventilation and perfusion images were converted into percentile distribution images. Analyses included Pearson’s correlation coefficient and comparison of agreements between the following dose-ventilation and dose-perfusion metrics: functional mean lung dose and functional percent lung function receiving 5, 10, 20, 30, and 40 Gy (fV5, fV10, fV20, fV30, and fV40, respectively). ResultsOverall, the dose-ventilation metrics were greater than the dose-perfusion metrics (ie, fV20, 26.3% ± 9.9% vs 23.9% ± 9.8%). Correlations between the dose-ventilation and dose-perfusion metrics were strong (range, r = 0.94-0.97), whereas the agreements widely varied among patients, with differences as large as 6.6 Gy for functional mean lung dose and 11.1% for fV20. Paired t test indicated that the dose-ventilation and dose-perfusion metrics were significantly different. ConclusionsStrong correlations were present between the dose-ventilation and dose-perfusion metrics. However, the agreement between the dose-ventilation and dose-perfusion metrics widely varied among patients, suggesting that ventilation-based radiation therapy plan evaluation may not be comparable to that based on perfusion. Future studies should elucidate the correlation of dose-function metrics with clinical pulmonary toxicity metrics.

Pseudo–Heart Block and Pseudo-Brugada Morphology From Signal-Averaging Artifact During Exercise Stress Testing

A 57-year-old woman with atypical chest pain presented for exercise stress testing with myocardial single-photon emission computed tomography perfusion imaging. The patient had a history of hypertension and hypothyroidism but no other history of coronary disease or risk factors. The patient's baseline ECG is shown in Figure 1, interpreted as incomplete right bundle-branch morphology. During exercise stress testing, apparent 2:1 A:V conduction occurred, as shown in Figure 2A. Physicians reading the exercise stress test also interpreted ST elevation most prominent in lead V1 as consistent with the type 1 Brugada ECG pattern.1 Intermittent 2:1 A:V block appeared to resolve at high heart rates in Figure 2B. The test was terminated, and the patient appeared to return to normal sinus rhythm conduction with resolution of the ST deviation, as in Figure 2C. She was referred to the electrophysiology service for consideration of pacemaker implantation. Figure 1. ECG tracing of the patient before stress testing. A magnified section of V1 is shown in the window . Although interpreted as incomplete right bundle-branch block by referring physicians, the QRS duration of <100 ms does not meet formal criteria for this diagnosis. The …

Coronary Artery Phenotypes in Subjects With Negative Myocardial Perfusion Imaging and Typical Angina Pectoris

IntroductionLimited data are available on coronary lesion morphology for patients with false-negative radionuclide findings together with typical angina symptoms. MethodsThe study group consisted of 25 subjects with a negative pharmacological thallium (T1)-201 single-photon emission computed tomography perfusion imaging study but typical angina symptoms and coronary artery disease (CAD) confirmed by coronary angiography. The control group included 690 subjects with a positive pharmacological T1-201 single-photon emission computed tomography study and CAD. ResultsThe study group showed a significantly older and higher female ratio than the control group. Significant differences were found between the 2 groups in the presence of current smoking status and hypertension. A noticeably higher percentage of positive metabolic syndrome ratio, number of metabolic syndrome components, high waist-to-hip ratio percentage and high waist circumference percentage in the study group. The study group was noticeably lower in mean numbers of culprit vessel involvement and mean lesion numbers than the control group. There were more individuals with type A classification and a lower proportion of complex stenoses—which contain type B2 and C lesions—in the study group than in the control group. The study group had significantly fewer calcified stenoses and complex morphology stenoses—the latter of which include lesion morphologies with chronic total occlusion, diffuse and calcification—than the control group. ConclusionsFor the high probability of CAD lesions that requires interventional therapy, patients with negative myocardial scintigraphy but typical angina symptoms would be beneficial to intensive medical treatment and coronary study.

Single-Photon Emission Computed Tomography Perfusion Imaging

In business and legal transactions, a warranty is an assurance by one party to the other party that certain facts or conditions are true or will happen; the other party is permitted to rely on that assurance and seek some type of remedy if it is not true or followed. http://en.wikipedia.org/wiki/Warranty As single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) has reached scientific and clinical maturity, we have grown to expect that the results of this test when negative, reliably predicts an excellent patient outcome. Typically, less than 1% of patients with a normal study will have a “hard” cardiac event, defined as myocardial infarction or cardiac death, but that 1% can be shortened or lengthened based on the presence of coronary artery disease (CAD), cardiac symptoms, age, sex, the need for pharmacological stress, and coronary risk factors such as diabetes mellitus. The time variability was assessed by Hachamovitch et al,1 and termed the “warranty period” for a normal SPECT MPI, defined the time to 1% risk of a cardiac event per year. The study published in this issue of Circulation: Cardiovascular Imaging by Carryer et al2 sought to explore the timing of follow-up SPECT study after a normal initial study and its prediction of cardiac events during a 5-year follow-up. They identified 3010 patients with a normal SPECT …

A Novel 18 F-Labeled Tracer for the Quantification of Myocardial Blood Flow and Infarct Size With Positron-Emission Tomography

Currently, nuclear imaging techniques can be used to diagnose coronary macrovascular and microvascular disease and to measure infarct size and left ventricular ejection fraction. Semiquantitative assessment of regional myocardial perfusion with single-photon emission computed tomography is a noninvasive, robust, and widely available method of assessing myocardial ischemia and has an established role in the clinical setting.1 A great number of studies have assessed the sensitivity and specificity of this technique for the detection of coronary artery disease (CAD), with coronary arteriography usually being used as the standard by which the accuracy of scintigraphy is judged.1 The main limitation of single-photon emission computed tomography perfusion imaging is that it provides only semiquantitative information on the regional distribution of myocardial blood flow (MBF). This is particularly relevant in conditions in which MBF and coronary flow reserve (CFR) are diffusely abnormal, (eg, in patients with hypertrophic and dilated cardiomyopathies).2 Article p 77 The ability to make quantitative measurements of MBF with positron-emission tomography (PET) allows determination of the functional significance of epicardial coronary lesions. In patients with single-vessel CAD, chronic stable angina, and no previous history of myocardial infarction (MI), CFR in response to a standard dose of dipyridamole was found to be markedly reduced in the myocardial regions subtended by the stenosed coronary artery compared with regions subtended by angiographically normal vessels.3 Using H215O or 13NH3 with PET, the relationship between stenosis severity, measured by quantitative coronary angiography, and its consequences on regional MBF and CFR has been …

Renal abnormalities as incidental findings on myocardial single photon emission computed tomography perfusion imaging

Incidental noncardiac abnormalities are frequent in myocardial perfusion imaging studies. It is important for interpreting physicians to be aware of the spectrum of abnormalities that can be detected from these studies. This report describes four cases with polycystic kidney disease with or without liver involvement and one case with polycystic liver disease with corroborative radiological studies.

Repeatability and reproducibility of phase analysis of gated single-photon emission computed tomography myocardial perfusion imaging used to quantify cardiac dyssynchrony

A novel method to quantify dyssynchrony has been developed using phase analysis of gated single-photon emission computed tomography perfusion imaging. We report on the effect of variability in image reconstruction on the phase analysis results (repeatability) and on the interobserver and intraobserver reproducibility of the technique. Phase standard deviation (SD) and bandwidth are phase indices that quantify dyssynchrony. To evaluate repeatability, raw data sets were processed twice in 50 patients with left ventricular dysfunction and 50 normal controls. To determine the optimal processing method, two replicated phase analysis results were obtained using automated and manual base parameter placement. Reproducibility of the phase analysis was determined using the data from 20 patients. In normal controls, manual base parameter placement improves repeatability of the phase analysis as measured by the mean absolute difference between two reads for phase SD (12.0 degrees vs. 1.2 degrees , P<0.0001) and bandwidth (33.7 degrees vs. 3.6 degrees , P<0.0001). Repeatability is better for normal controls than for patients with left ventricular dysfunction for phase SD (1.2 degrees vs. 6.0 degrees , P<0.0001) and bandwidth (3.6 degrees vs. 26.5 degrees , P<0.0001). Reproducibility of the phase analysis is high as measured by the intraclass correlation coefficients for phase SD and bandwidth of 0.99 and 0.99 for the interobserver comparisons and 1.00 and 1.00 for the intraobserver comparisons. A novel method to quantify dyssynchrony has been developed using gated single-photon emission computed tomography perfusion imaging. Manual base parameter placement reduces the effect that variability in image reconstruction has on phase analysis. A high degree of reproducibility of phase analysis is observed.

Angina in a 41-year-old man with a congenital coronary abnormality and cardiac surgery 27 years earlier

Patient presentation. A 41-year-old man with unknown heart surgery at 14 years of age was admitted with exertional chest heaviness, radiating to the left arm, associated with dyspnea and nausea. The findings of the physical examination were unremarkable, with no murmur. Serial creatine phosphokinase and troponin levels and the electrocardiogram were all normal. The patient’s medical history is significant for an asymptomatic heart murmur noted at 14 years of age. Cardiac catheterization and heart surgery were performed. However, his clinicians were unable to locate any information about the diagnosis or procedure that had been performed. During the current admission, the patient underwent repeat cardiac catheterization. Single photon emission computed tomography perfusion imaging was considered but was not performed, given the classical cardiac symptoms and risk factors of smoking, hypertension, and hyperlipidemia, as well as a family history of premature coronary disease. Left ventricular function was normal, and selective angiography of the left coronary artery (LCA) revealed ectatic left main, left anterior descending, and left circumflex arteries, all of which were nonobstructive (Figure 1). Collaterals filled the posterior descending artery (PDA) and posterior left ventricular (PLV) branches of the distal right coronary artery (RCA), as well as the acute right ventricular marginal (RVM) branch (Figure 2). The orifice of the RCA could not be located. Additional collaterals originating near the proximal RCA remnant supplied blood flow to the upper right and left ventricles. A coronary computed tomography angiogram (CTA) was ordered after invasive coronary angiography in an attempt to locate the origin of the RCA, to better explain the patient’s symptoms and to define his previous heart surgery. A GE 64-slice multidetector computed tomography scanner (GE Healthcare, Buckinghamshire, England) with reconstruction at the 70% to 80% phase provided the most optimal images. The coronary CTA revealed similar findings of an ectatic, nonobstructive left coronary system (Figure 3). The CTA of the RCA revealed a remnant originating from the pulmonary artery (PA) (Figure 4). Collateral filling to the RVM, PDA, and PLV branches was noted coming from the LCA system. We observed minimal antegrade flow from a collateral near the mediastinum feeding the proximal remnant of the RCA with blood flow to the upper region of the right ventricle and to a vessel that extended around

Effect of Caffeine on Ischemia Detection by Adenosine Single-Photon Emission Computed Tomography Perfusion Imaging

The purpose of this research was to study the effect of one cup of coffee taken 1 h before adenosine stress on the results of myocardial perfusion imaging. Caffeine is believed to attenuate the coronary hyperemic response to adenosine by competitive blockade of the A2a receptor. Caffeine is commonly withheld before adenosine single-photon emission computed tomography (SPECT) perfusion imaging so as not to mask ischemia detection. We studied the effect of one 8-oz cup of coffee taken 1 h before adenosine stress in patients who had demonstrable reversible defects on adenosine SPECT perfusion imaging performed while off caffeine. There were 22 men and 8 women, age 64 +/- 9 years. The blood level of caffeine 1 h after intake was 3.1 +/- 1.6 mg/l. There were two patients with ST-segment depression before and one after caffeine intake (p = NS). The summed stress score (SSS) based on 17 segments (scale of 0 to 3, 3 being normal) was 44 +/- 5 before and 45 +/- 5 after caffeine (p = NS). The summed difference score was 3.8 +/- 1.9 before and. 3.9 +/- 2.3 after caffeine (p = NS), reflecting that around 50% of the perfusion abnormality was reversible before and after caffeine. Using polar maps, the perfusion abnormality was 12 +/- 10% at baseline and 12 +/- 10% after caffeine (p = NS) in agreement with SSS. The left ventricular ejection fraction by gated SPECT was 50 +/- 13% at baseline and 51 +/- 13 % after caffeine (p = NS). A cup of coffee does not mask the presence or severity of reversible defects induced by adenosine SPECT imaging.

Gated SPECT perfusion imaging for the simultaneous assessment of myocardial perfusion and ventricular function in the BARI 2D trial: An initial report from the Nuclear Core Laboratory

The BARI 2D (Bypass Angioplasty Revascularization Investigation 2 Diabetes) trial, a National Heart, Lung, and Blood Institute-sponsored study in type 2 diabetic patients with coronary artery disease, completed patient recruitment in March 2005. This trial had a nuclear substudy in addition to many other substudies. After patient enrollment, adenosine gated single photon emission computed tomography perfusion imaging is performed at years 1 and 3. The images are interpreted at the core laboratory. Among the objectives of the nuclear substudy are (1) to determine the impact of the mode of therapy on left ventricular function, extent of ischemia, and scar; (2) to determine the impact of therapy on the progression/regression of ischemia/scar and changes in left ventricular function between years 1 and 3; and (3) to determine the independent and incremental prognostic value of ischemia, scar, and left ventricular function on the primary and secondary endpoints of the trial in the entire patient population and specified subgroups such as women, elderly patients, and minorities. This article describes the methodology and the initial experience of the nuclear core laboratory in this large multicenter trial and provides a summary of variables that are available for future analysis by the working group.

Single-photon emission computed tomography perfusion imaging in the differential diagnosis of dementia: a retrospective regional audit

A retrospective audit of (99m)Tc-HMPAO SPECT scans was undertaken to assess the utility of brain perfusion imaging in a cohort of young cognitively impaired patients in whom diagnostic uncertainty remained after standard clinical and neuropsychological assessment and structural brain imaging. SPECT scans were assessed by five raters (two neurologists and three nuclear medicine specialists) on two occasions 6 months apart, first without any clinical data and second with brief pertinent clinical information. SPECT diagnoses were compared with criterion diagnoses subsequently established by the two neurologists with access to all clinical, neuropsychological and neuroimaging data. Despite reasonable intra- and interrater reliability, diagnostic accuracy ranged from 32 to 58%. SPECT scan normality or abnormality in blind and informed viewings gave respective sensitivities of 77 and 71%, specificities of 44 and 38%, positive predictive values of 88 and 87% and negative predictive values of 27 and 18%. Calculating pairwise disease group comparisons, likelihood ratios suggested some diagnostic gain in differentiating AD from 'not AD' and from FTD/focal syndromes. SPECT scanning was of little help in establishing diagnoses in this cohort of patients, a finding which supports the conclusion of the American Academy of Neurology evidence-based review that SPECT imaging cannot be recommended for either the initial or the differential diagnosis of suspected dementia because it has not demonstrated superiority to clinical criteria.

Magnetic resonance imaging in the assessment of coronary artery disease

Magnetic resonance imaging (MRI) is gaining importance in cardiology as the noninvasive test of choice for patients with a multitude of cardiovascular problems. Recently, cardiovascular MRI has emerged as an important noninvasive diagnostic modality in the assessment of coronary artery disease. Because of its superior spatial resolution, integration of qualitative and quantitative methodology, and excellent reproducibility, MRI has advantages over conventional noninvasive modalities currently used in the evaluation of coronary artery disease. This article reviews the rapidly expanding recent literature that has now established cardiovascular MRI as an ideal choice in the evaluation of myocardial ischemia (including dobutamine cine MRI and vasodilator perfusion MRI techniques). We further discuss the role of delayed contrast-enhanced MRI and low-dose dobutamine cine MRI for evaluation of myocardial viability. Comparisons with more established techniques, such as dobutamine stress echocardiography, single-photon emission computed tomography perfusion imaging, and positron emission tomography, are reviewed.

Functional significance of stenoses in coronary artery bypass graftsEvaluation by single-photon emission computed tomography perfusion imaging, cardiovascular magnetic resonance, and angiography

This study was designed to perform a head-to-head comparison between single-photon emission computed tomography (SPECT) and cardiovascular magnetic resonance (CMR) to evaluate hemodynamic significance of angiographic findings in bypass grafts. The hemodynamic significance of a bypass graft stenosis may not always accurately be determined from the coronary angiogram. A variety of diagnostic tests (invasive or noninvasive) can further characterize the hemodynamic consequence of a lesion. Fifty-seven arterial and vein grafts in 25 patients were evaluated by angiography, SPECT perfusion imaging, and coronary flow velocity reserve determination by CMR. Based on angiography and SPECT, four different groups could be identified: 1) no significant stenosis (&lt;50%), normal perfusion; 2) significant stenosis (≥50%), abnormal perfusion; 3) significant stenosis, normal perfusion (no hemodynamic significance); and 4) no significant stenosis, abnormal perfusion (suggesting microvascular disease). A complete evaluation was obtained in 46 grafts. Single-photon emission computed tomography and CMR provided similar information in 37 of 46 grafts (80%), illustrating good agreement (kappa = 0.61, p &lt; 0.001). Eight grafts perfused a territory with scar tissue. When agreement between SPECT and CMR was restricted to grafts without scar tissue, it improved to 84% (kappa = 0.68). Integration of angiography with SPECT categorized 14 lesions in group 1, 23 in group 2, 6 in group 3, and 3 in group 4. Single-photon emission computed tomography and CMR agreement per group was 86%, 78%, 100%, and 33%, respectively. Head-to-head comparison showed good agreement between SPECT and CMR for functional evaluation of bypass grafts. Cardiovascular magnetic resonance may offer an alternative method to SPECT for functional characterization of angiographic lesions.

Functional significance of stenoses in coronary artery bypass grafts: Evaluation by single-photon emission computed tomography perfusion imaging, cardiovascular magnetic resonance, and angiography

This study was designed to perform a head-to-head comparison between single-photon emission computed tomography (SPECT) and cardiovascular magnetic resonance (CMR) to evaluate hemodynamic significance of angiographic findings in bypass grafts. The hemodynamic significance of a bypass graft stenosis may not always accurately be determined from the coronary angiogram. A variety of diagnostic tests (invasive or noninvasive) can further characterize the hemodynamic consequence of a lesion. Fifty-seven arterial and vein grafts in 25 patients were evaluated by angiography, SPECT perfusion imaging, and coronary flow velocity reserve determination by CMR. Based on angiography and SPECT, four different groups could be identified: 1) no significant stenosis (<50%), normal perfusion; 2) significant stenosis (>/=50%), abnormal perfusion; 3) significant stenosis, normal perfusion (no hemodynamic significance); and 4) no significant stenosis, abnormal perfusion (suggesting microvascular disease). A complete evaluation was obtained in 46 grafts. Single-photon emission computed tomography and CMR provided similar information in 37 of 46 grafts (80%), illustrating good agreement (kappa = 0.61, p < 0.001). Eight grafts perfused a territory with scar tissue. When agreement between SPECT and CMR was restricted to grafts without scar tissue, it improved to 84% (kappa = 0.68). Integration of angiography with SPECT categorized 14 lesions in group 1, 23 in group 2, 6 in group 3, and 3 in group 4. Single-photon emission computed tomography and CMR agreement per group was 86%, 78%, 100%, and 33%, respectively. Head-to-head comparison showed good agreement between SPECT and CMR for functional evaluation of bypass grafts. Cardiovascular magnetic resonance may offer an alternative method to SPECT for functional characterization of angiographic lesions.

MRI for the diagnosis of myocardial ischemia and viability.

Assessment of myocardial ischemia and viability plays a crucial role in the clinical management of patients with coronary artery disease. Recently, cardiovascular MRI has emerged as an important noninvasive diagnostic modality in the assessment of coronary artery disease. MRI is able to evaluate both myocardial perfusion as well as myocardial contractile reserve. Because of its superior spatial resolution, integration of qualitative and quantitative methodology, and excellent reproducibility, MRI has advantages over conventional noninvasive modalities currently used in the evaluation of myocardial ischemia and viability, and may well emerge as the premier noninvasive technique in the assessment of patients with coronary artery disease. The authors review the rapidly expanding recent literature that has now established cardiovascular MRI (including dobutamine cine MRI and vasodilator perfusion MRI techniques) as an ideal choice in the evaluation of myocardial ischemia and delayed contrast-enhanced MRI and low-dose dobutamine cine MRI for evaluation of viability. Comparisons with more established techniques such as dobutamine stress echocardiography, single photon emission computed tomography perfusion imaging, and positron emission tomography are reviewed.

Catheter-based autologous bone marrow myocardial injection in no-option patients with advanced coronary artery disease: A feasibility study

ObjectivesWe conducted a pilot study to evaluate the feasibility of transendocardial delivery of autologous bone marrow (ABM) strategy in patients with severe symptomatic chronic myocardial ischemia not amenable to conventional revascularization. BackgroundTransendocardial injection of ABM cells appears to enhance perfusion of ischemic porcine myocardium. MethodsTen patients underwent transendocardial injection of freshly aspirated and filtered unfractionated ABM using left ventricular electromechanical guidance. Twelve injections of 0.2 ml each were successfully delivered into ischemic noninfarcted myocardium pre-identified by single-photon emission computed tomography perfusion imaging. ResultsAutologous bone marrow injection was successful in all patients and was associated with no serious adverse effects; in particular, there was no arrhythmia, evidence of infection, myocardial inflammation, or increased scar formation. Two patients were readmitted for recurrent chest pain. At three months, Canadian Cardiovascular Society angina score significantly improved (3.1 ± 0.3 vs. 2.0 ± 0.94, p = 0.001), as well as stress-induced ischemia occurring within the injected territories (2.1 ± 0.8 vs. 1.6 ± 0.8, p < 0.001). Treadmill exercise duration, available in nine patients, increased, but the change was not significant (391 ± 155 vs. 485 ± 198, p = 0.11). ConclusionsThis study provides preliminary clinical data indicating feasibility of catheter-based transendocardial delivery of ABM to ischemic myocardium.

Fractional flow reserve of the infarct-related artery early after myocardial infarction identifies reversibility on dipyridamole sestamibi single-photon emission computed tomography perfusion imaging

Fractional flow reserve of the infarct-related artery early after myocardial infarction identifies reversibility on dipyridamole sestamibi single-photon emission computed tomography perfusion imaging

Single photon emission computed tomography perfusion imaging for assessment of myocardial viability and management of heart failure.

In the setting of coronary artery disease, some areas of dysfunctional myocardium may realize significant improvement in function as a consequence of revascularization. These areas represent viable myocardium, encompassing a spectrum of pathophysiology ranging from chronic stunning, in which resting blood flow is preserved, to hibernating myocardium, in which resting blood flow is decreased. The accurate preoperative evaluation of viable myocardium helps identify those patients with left ventricular dysfunction who will most benefit from coronary revascularization. Of the various modalities available for viability assessment, the nuclear medicine techniques (201)Thallium and (18)Fluorodeoxyglucose positron emission tomography have emerged as the most sensitive. It has been consistently shown that in patients with a significant amount of viable myocardium, there is a substantial survival benefit in revascularization versus medical therapy. The likelihood of affecting a significant improvement decreases with time to revascularization, however, particularly in the setting of an enlarged left ventricle secondary to ventricular remodeling.

Major advances in single-photon emission computed tomography perfusion imaging.

Major advances in single-photon emission computed tomography (SPECT) myocardial perfusion imaging have been realized with the introduction of state-of-the-art imaging equipment and radiopharmaceuticals. Gated tomographic myocardial perfusion imaging with technetium-99m (Tc-99m)-labeled radiopharmaceuticals provides a combined evaluation of both myocardial perfusion and function. Left ventricular ejection fraction can be measured accurately from the gated SPECT images. Recently, hardware and software have been introduced, which minimize the effect of soft tissue attenuation, thereby improving test specificity in the diagnosis of coronary artery disease. Myocardial viability may be assessed with the use of rest/delayed thallium-201 SPECT or F-18 fluorodeoxyglucose SPECT with modified scintillation camera collimation and electronics, or coincidence detection. Imaging patients to assess myocardial infarction or resting ischemia in the emergency department has expedited patient care and improved cost effectiveness. Teleradiography has also facilitated the interpretation of studies performed in the emergency department and at remote facilities, likewise improving cost-effectiveness.

Impact of stress single-photon emission computed tomography perfusion imaging on downstream resource utilization

This study shows that in patients with intermediate pretest probability of coronary artery disease stress single-photon emission computed tomography perfusion imaging decreases the rate of coronary angiography and coronary revascularization and is economically a superior strategy to routine coronary angiography.