Comparative diagnostic accuracy of Tl-201 and Tc-99m sestamibi SPECT imaging (perfusion and ECG-gated SPECT) in detecting coronary artery disease in women

Stress-First Myocardial Perfusion Imaging

Stress-first approaches to myocardial perfusion imaging provide diagnostically and prognostically accurate perfusion data equivalent to a full rest-stress study while saving time in the imaging laboratory and reducing the radiation exposure to patients and laboratory staff. Unfortunately, implementing a stress-first approach in a nuclear cardiology laboratory involves significant challenges such as the need for attenuation correction, triage of patients to an appropriate protocol, real-time review of stress images, and consideration of differential reimbursement. Despite it being best practice for both the patient and the laboratory, these impediments have kept the proportions of studies performed stress-first relatively unchanged in North America and world-wide in the last 10 years.

Myocardial Viability – An Important Decision Making Factor in the Treatment Protocol for Patients with Ischemic Heart Disease

Ischemic heart disease (IHD) affects > 110 million individuals worldwide and represents an important contributor to the rise in the prevalence of heart failure and the associated mortality and morbidity. Despite modern therapies, up to one-third of patients with acute myocardial infarction would develop heart failure. IHD is a pathologic condition of the myocardium resulting from the imbalance in a given moment between its oxygen demands and the actual perfusion. Acute and chronic forms of the disease may potentially lead to extensive and permanent damage of the cardiac muscle. From a clinical point of view, determination of the still viable extent of myocardium is crucial for the therapeutic protocol – since ischemia is the underlying cause, then revascularization should provide for a better prognosis. Different methods for evaluation of myocardial viability have been described – each one presenting some advantages over the others, being, in the same time, inferior in some respects. The review offers a relatively comprehensive overview of methods available for determining myocardial viability.

Nuclear Cardiology in Women and Underrepresented Minority Populations

PURPOSE OF REVIEW

To outline sex-specific features of coronary artery disease (CAD) that should be considered in the assessment of women, including those from ethnic minority populations with suspected stable ischemic heart disease (IHD). Second, to determine the latest nuclear imaging tools available to assess microvascular CAD.

RECENT FINDINGS

Latest studies indicate that women are more likely to have ischemia with no obstructive coronary arteries (INOCA) and paradoxically have worse outcomes. Therefore, the evaluation of women with suspected IHD should include assessing microvascular and epicardial coronary circulation. The prevalence of CAD is increasing in younger women due to the increased cardiovascular disease (CVD) risk burden. CAD is often underrecognized in these patients. There is increasing recognition that INOCA is not benign and should be accurately diagnosed and managed. Nuclear imaging assesses the full spectrum of CAD from microvascular CAD to multivessel obstructive epicardial CAD. Further research on myocardial blood flow (MBF) assessment with PET MPI is needed.

Myocardial Perfusion and Viability Imaging in Coronary Artery Disease: Clinical Value in Diagnosis, Prognosis, and Therapeutic Guidance

Coronary artery disease is a leading cause of morbidity and mortality worldwide. Noninvasive imaging tests play a significant role in diagnosing coronary artery disease, as well as risk stratification and guidance for revascularization. Myocardial perfusion imaging, including single photon emission computed tomography and positron emission tomography, has been widely employed. In this review, we will review test accuracy and clinical significance of these methods for diagnosing and managing coronary artery disease. We will further discuss the comparative usefulness of other noninvasive tests-stress echocardiography, coronary computed tomography angiography, and cardiac magnetic resonance imaging-in the evaluation of ischemia and myocardial viability.

Head-to-head comparison of diagnostic accuracy of stress-only myocardial perfusion imaging with conventional and cadmium-zinc telluride single-photon emission computed tomography in women with suspected coronary artery disease

BACKGROUND

Breast attenuation may impact the diagnostic accuracy of stress myocardial perfusion imaging (MPI) with single-photon emission computed tomography (SPECT). We compared the performance of conventional (C)-SPECT and cadmium-zinc-telluride (CZT)-SPECT systems in women with low-intermediate likelihood of coronary artery disease (CAD).

METHODS AND RESULTS

A total of 109 consecutive women underwent stress-optional rest MPI by both C-SPECT and CZT-SPECT. In the overall study population, a weak albeit significant correlation between total perfusion defect (TPD) measured by C-SPECT and CZT-SPECT was observed (r = 0.38, P < .001) and at Bland-Altman analysis the mean difference in TPD (C-SPECT minus CZT-SPECT) was 2.40% (P < .001). Overall concordance of semi-quantitative diagnostic performance between C-SPECT and CZT-SPECT was observed in 52 (48%) women with a κ value of 0.09. Normalcy rate was significantly higher using CZT-SPECT compared to C-SPECT (P < .001). Machine learning analysis performed through the implementation of J48 algorithm proved that CZT-SPECT has higher sensitivity, specificity, and accuracy than C-SPECT.

CONCLUSIONS

In women with low-intermediate likelihood of CAD, there is a poor concordance of diagnostic performance between C-SPECT and CZT-SPECT, and CZT-SPECT allows better normalcy rate detection compared to C-SPECT.

Role of DECT in coronary artery disease: a comparative study with ICA and SPECT

PURPOSE

Earlier imaging techniques for coronary artery disease (CAD) focused primarily on either morphological or functional assessment of CAD. However, dual-energy computed tomography (DECT) can be used to assess myocardial blood supply both morphologically and functionally. We aimed to evaluate the diagnostic accuracy of DECT in detecting morphological and functional components of CAD, using invasive coronary angiography (ICA) and single photon emission computed tomography (SPECT) as reference standards.

METHODS

Twenty-five patients with known or suspicious CAD and scheduled for ICA were investigated by DECT and SPECT. DECT was performed during the resting state using retrospective electrocardiography (ECG) gating. CT coronary angiography and perfusion images were generated from the same raw data. All patients were evaluated for significant stenosis (≥50%) on both ICA and DECT coronary angiography, and for myocardial perfusion defects on SPECT and DECT perfusion. Comparison was done between ICA and DECT coronary angiography for detection of significant stenosis and between SPECT and DECT perfusion for detecting myocardial perfusion defects.

RESULTS

Using ICA as reference standard, sensitivity, specificity, and accuracy of DECT coronary angiography in detecting ≥50% stenosis of coronary artery lumen were 81.6%, 97.8%, and 95.0%, respectively, by segment-based analysis and 92.1%, 96.1%, and 93.7%, respectively, by vessel-based analysis. Using SPECT as the reference standard, the sensitivity, specificity, and accuracy of DECT perfusion in detecting myocardial perfusion defects were 70.4%, 86.4%, and 80.6%, respectively, on per-segment analysis and 90.7%, 66.6%, and 84.7%, respectively, on per-territorial basis.

CONCLUSION

DECT accurately detected coronary artery stenosis and myocardial ischemia using ICA and SPECT as reference standards. In the same scan, DECT can accurately provide integrative imaging of coronary artery morphology and myocardial perfusion.

Quantitative assessment of consciousness during anesthesia without EEG data

Assessing the depth of anesthesia (DoA) is a daily challenge for anesthesiologists. The best assessment of the depth of anesthesia is commonly thought to be the one made by the doctor in charge of the patient. This evaluation is based on the integration of several parameters including epidemiological, pharmacological and physiological data. By developing a protocol to record synchronously all these parameters we aim at having this evaluation made by an algorithm. Our hypothesis was that the standard parameters recorded during anesthesia (without EEG) could provide a good insight into the consciousness level of the patient. We developed a complete solution for high-resolution longitudinal follow-up of patients during anesthesia. A Hidden Markov Model (HMM) was trained on the database in order to predict and assess states based on four physiological variables that were adjusted to the consciousness level: Heart Rate (HR), Mean Blood Pressure (MeanBP) Respiratory Rate (RR), and AA Inspiratory Concentration (AAFi) all without using EEG recordings. Patients undergoing general anesthesia for hernial inguinal repair were included after informed consent. The algorithm was tested on 30 patients. The percentage of error to identify the actual state among Awake, LOC, Anesthesia, ROC and Emergence was 18%. This protocol constitutes the very first step on the way towards a multimodal approach of anesthesia. The fact that our first classifier already demonstrated a good predictability is very encouraging for the future. Indeed, this first model was merely a proof of concept to encourage research ways in the field of machine learning and anesthesia.

Clinical implication of myocardial FDG uptake pattern in oncologic PET: retrospective comparison study with stress myocardial perfusion imaging as the reference standard

OBJECTIVE

The purpose of this study was to determine the clinical implication of the myocardial FDG uptake patterns by comparing with the results of stress myocardial perfusion imaging (MPI) as the reference standard.

METHODS

By reviewing the medical records, 86 pairs of stress MPI and FDG PET/CT of 84 patients who underwent stress MPI and oncologic FDG PET/CT in 1 month were included in this study. The patterns of the myocardial FDG uptake were classified into five patterns such as 'low', 'diffuse', 'basal ring', 'focal high', and 'focal defect on diffuse high'. MPI was evaluated using a 5-point scoring model ranging from 0 (normal uptake) to 4 (uptake absent) based on the 17-segment model. The summed stress score of 4 or higher was defined as 'abnormal MPI'. Factors predictive of abnormal MPI were analyzed using a log-rank multivariate test and p < 0.05 was set as significant.

RESULTS

Abnormal MPI was observed in only 16 of 36 (44%) patients with 'low' pattern, 10 of 23 (43%) patients with 'diffuse high' pattern, and 1 of 9 (11%) patients with 'basal ring' pattern, but in 8 of 9 (89%) patients with 'focal high' pattern, and 8 of 9 (89%) patients with 'focal defect on diffuse high' pattern. The log-rank multivariate test revealed that 'focal high' and 'focal defect on diffuse high' pattern were correlated with an abnormal MPI.

CONCLUSIONS

These results indicate that further cardiac work-up might be helpful in the patients with 'focal high' pattern or 'focal defect on diffuse high' pattern of myocardial FDG at oncologic PET. A prospective study should be needed to further support this conclusion.

Imaging technology for myocardial perfusion single-photon emission computed tomography 2018 in Japan

AIM

Recently, nuclear cardiology has dramatically advanced by a new technology development such as the device, short-term acquisition system, image reconstruction algorithm and image analysis. Although these innovations have been gradually employed in routine examinations, we did not investigate the current use of image acquisition, image reconstruction, and image analysis with myocardial perfusion single-photon emission computed tomography (MPS). We investigated the current status of MPS imaging technology in Japan.

METHODS

We carried out a survey using a Web-based questionnaire system, the opening of which was announced via e-mail, and it was available on a website for 3 months. We collected data on the current use of MPS with ²⁰¹Tl and/or ^99mTc agents with respect to routine protocols, image acquisition, image reconstruction, and image analysis.

RESULTS

We received responses to the Web-based questionnaire from 178 and 174 people for ^99mTc and ²⁰¹Tl MPS, respectively. The routine protocols of MPS of stress-rest and rest-stress MPS on 1-day protocols with ^99mTc were 41.2% and 14.5%, respectively, and the rest-only scan response rate was 23.7%, whereas that of ²⁰¹Tl MPS was 65.9% with stress-rest MPS, 19.0% with rest-only MPS, and 10.9% with stress-rest MPS adding a rest scan 24 h after injection. The filtered back projection (FBP) method is most commonly used image reconstruction method, yielding 70.5% for ^99mTc MPS and 76.8% for ²⁰¹Tl MPS, including combined FBP and ordered subset expectation maximization method. The results for no-correction (NC) images were 49.2% with ^99mTc MPS and 55.2% with ²⁰¹Tl MPS including the response of NC and combined attenuation correction (AC) and scatter correction (SC) (i.e., ACSC) images. The AC or ACSC images of ^99mTc and ²⁰¹Tl were provided by 30-40% of the institutions surveyed.

CONCLUSIONS

We investigated the current status of MPS imaging technology in Japan, and found that although the use of various technical developments has been reported, some of these technologies have not been utilized effectively. Hence, we expect that nuclear medicine technology will be used more effectively to improve diagnosis.

Evaluating the effectiveness of a single CT method for attenuation correction in stress-rest myocardial perfusion imaging with thallium-201 chloride SPECT

This study aimed to evaluate the effectiveness of a single computed tomography (CT) based attenuation correction method using thallium-201 chloride (²⁰¹TlCl) in stress-rest myocardial perfusion imaging (MPI). The data of 106 patients who underwent MPI with single photon emission computed tomography (SPECT) using ²⁰¹TlCl were retrospectively reviewed. MPI SPECT images were reconstructed using stress SPECT and stress CT (SI_O), rest SPECT and rest CT (RI_O), and rest SPECT and stress CT (RI_A). The accuracy of alignment between the SPECT and CT images was evaluated with normalized cross-correlation (NCC) and visual examination. The summed rest score (SRS) was used to evaluate hypoperfusion at rest; washout rate (WO) was used to assess ischemia; and left ventricular ejection fraction (LVEF) was used to evaluate the left ventricle (LV) function. There was no significant difference in NCC and visual evaluation in all three dimensions. The SRS of both RI_O and RI_A (7.5 ± 7.7 and 7.7 ± 7.6, respectively) did not differ significantly. However, SRSs of RI_O and RI_A showed a strong correlation (r = 0.98). The WO was 39.0 ± 0.98% for both RI_O and RI_A, with a strong correlation between the two values (r = 1.00). LVEF was 61.1 ± 17.4% for RI_O and 61.3 ± 17.4% for RI_A, and a strong correlation was observed between the two values (r = 1.00). In conclusion, the single CT-based attenuation correction method with ²⁰¹TlCl SPECT has an accuracy equivalent to that of the conventional two CT-based attenuation correction method.

Cardiac motion correction for improving perfusion defect detection in cardiac SPECT at standard and reduced doses of activity

In cardiac SPECT perfusion imaging, cardiac motion can lead to motion blurring of anatomical detail and perfusion defects in the reconstructed myocardium. In this study, we investigated the potential benefit of cardiac motion correction for improving the detectability of perfusion defects. We considered a post-reconstruction motion correction (PMC) approach in which the image motion between two cardiac gates is obtained with optical flow estimation. In the experiments, we demonstrated the proposed post-reconstruction motion correction with optical flow estimation (PMC-OFE) approach on a set of clinical acquisitions from 194 subjects. We quantified the detectability of perfusion defects in the reconstructed images by using the total perfusion deficit scores, calculated by the clinical software tool QPS, and conducted a receiver-operating-characteristic (ROC) study to obtain the detection performance. Besides imaging with conventional standard dose, we also evaluated the approach for reduced dose SPECT imaging where the imaging dose was retrospectively reduced to 50%, 25%, and 12.5% of the standard dose. The proposed PMC-OFE approach achieved at each dose level higher area-under-the-ROC-curve (AUC) for perfusion defect detection than the traditional approach of using ungated data (Non-MC) (p -value  <  0.05); in particular, with half dose, PMC-OFE achieved AUC  =  0.813, which is comparable to Non-MC with standard dose (AUC  =  0.795). Moreover, the proposed PMC-OFE approach also outperformed the 'Motion Frozen' (MF) method implemented in the clinical quantitative gated SPECT (QGS) software. In particular, at 25% and 12.5% of standard dose, the AUC values obtained by PMC-OFE are 0.788 and 0.779, respectively, compared to 0.758 and 0.731 for MF (p -value  <  0.05).

Assessment of Myocardial CZT SPECT Recording in a Forward-Leaning Bikerlike Position

This prospective randomized study assessed myocardial perfusion imaging with the high-sensitivity D.SPECT cadmium-zinc-telluride camera in a forward-leaning bikerlike position, which may potentially lower diaphragmatic attenuation and reduce breathing-related cardiac motion, in a manner comparable to the prone position proposed with other SPECT cameras. Methods: Patients referred for a stress-rest ^99mTc-sestamibi protocol and positioned in the biker position, with the chest leaning forward on the D.SPECT camera-head at 35° from vertical, had an additional resting D.SPECT recording in the supine position (n = 40) or in the sitting position with the back rearward at 30° from vertical (n = 40). Segments with attenuation artifacts were defined as those with less than 65% uptake but with strictly normal contractility at gated SPECT and no defect reversibility from stress images. Results: The biker position was associated with lower heart-to-detector distances than the supine or sitting positions (both P < 0.001); lower cardiac motion amplitudes, assessed on panograms, than the supine position (P < 0.001); and fewer segments with attenuation artifacts than the supine position (on average, 1.10 ± 1.01 vs. 1.90 ± 1.74, P = 0.010) or the sitting position (0.75 ± 0.93 vs. 1.38 ± 1.60, P = 0.011). Conclusion: Myocardial perfusion images from D.SPECT are enhanced for patients positioned in a forward-leaning bikerlike position comparatively to sitting or supine positions, with a notably lower rate of attenuation artifacts.

Ultrasensitive quantification of cardiac troponin I by a Single Molecule Counting method: analytical validation and biological features

AIM

To evaluate analytical and biological characteristics of the Singulex Clarity® cTnI assay, based upon Single Molecule Counting technology.

METHODS

Assay's analytical sensitivity, precision, linearity, hook effect, cross-reactivity or interference by endogenous and exogenous substances, stability, 99th reference percentile [p99th] in EDTA plasma were evaluated in single or multi-site studies.

RESULTS

Detection limit was 0.12 ng/L. Sensitivity was 0.14 ng/L at 20% CV (functional sensitivity) and 0.53 ng/L at 10% CV. Imprecision was 3.16%-10.0% in a multi-lot, single-site study, and 5.5%-12.0% in a single-lot, multi-site study; assay was linear from 0.08 to 25,000 ng/L. No hook effect was observed; any cross-reactivity/interference exceeded the 10%. Healthy subjects were recruited using clinical history, normal NT-proBNP and eGFR (n = 560) or plasma creatinine (n = 535) as inclusion criteria. cTnI was detectable in 96.8% of healthy subjects. The p99th were 8.01 (eGFR used) and 8.15 ng/L (plasma creatinine); both were measured with ≤5.7% CV. Median cTnI were significantly higher in older and male than in young and female subjects.

CONCLUSIONS

The Singulex Clarity cTnI assay show analytical features and % detection in healthy subjects that improve the corresponding values of most of the existing high-sensitivity cTnI assays.

Myokard-Perfusions-SPECT

Die S1-Leitlinie Myokard-Perfusions-SPECT wurde überarbeitet und bei der Arbeitsgemeinschaft der wissenschaftlichen Fachgesellschaften (AWMF) online publiziert. Sie ist in ihrer aktuellen Fassung bis 2/2022 gültig. Dieser Beitrag gibt in gekürzter Form und mit Kommentaren versehen die Kapitel und Unterkapitel wieder, in denen Änderungen und Ergänzungen vorgenommen wurden.

Degradable Vanadium Disulfide Nanostructures with Unique Optical and Magnetic Functions for Cancer Theranostics

Multifunctional biodegradable inorganic theranostic nano-agents are of great interest to the field of nanomedicine. Upon lipid modification, VS₂ nanosheets could be converted into ultra-small VS₂ nanodots encapsulated inside polyethylene glycol (PEG) modified lipid micelles. Owing to paramagnetism, high near-infrared (NIR) absorbance, and chelator-free ^99m Tc⁴⁺ labeling of VS₂ , such VS₂ @lipid-PEG nanoparticles could be used for T1-weighted magnetic resonance (MR), photoacoustic (PA),and single photon emission computed tomography (SPECT) tri-modal imaging guided photothermal ablation of tumors. Importantly, along with the gradual degradation of VS₂ , our VS₂ @lipid-PEG nanoparticles exhibit effective body excretion without appreciable toxicity. The unique advantages of VS₂ nanostructures with highly integrated functionalities and biodegradable behaviors mean they are promising for applications in cancer theranostics.

Myocardial perfusion imaging in women for the evaluation of stable ischemic heart disease-state-of-the-evidence and clinical recommendations

This document from the American Society of Nuclear Cardiology represents an updated consensus statement on the evidence base of stress myocardial perfusion imaging (MPI), emphasizing new developments in single-photon emission tomography (SPECT) and positron emission tomography (PET) in the clinical evaluation of women presenting with symptoms of stable ischemic heart disease (SIHD). The clinical evaluation of symptomatic women is challenging due to their varying clinical presentation, clinical risk factor burden, high degree of comorbidity, and increased risk of major ischemic heart disease events. Evidence is substantial that both SPECT and PET MPI effectively risk stratify women with SIHD. The addition of coronary flow reserve (CFR) with PET improves risk detection, including for women with nonobstructive coronary artery disease and coronary microvascular dysfunction. With the advent of PET with computed tomography (CT), multiparametric imaging approaches may enable integration of MPI and CFR with CT visualization of anatomical atherosclerotic plaque to uniquely identify at-risk women. Radiation dose-reduction strategies, including the use of ultra-low-dose protocols involving stress-only imaging, solid-state detector SPECT, and PET, should be uniformly applied whenever possible to all women undergoing MPI. Appropriate candidate selection for stress MPI and for post-MPI indications for guideline-directed medical therapy and/or invasive coronary angiography are discussed in this statement. The critical need for randomized and comparative trial data in female patients is also emphasized.

Cardiac Imaging in the Diagnosis of Coronary Artery Disease

Coronary artery disease (CAD) continues to be a leading cause of morbidity and mortality worldwide. Although invasive coronary angiography has previously been the gold standard in establishing the diagnosis of CAD, there is a growing shift to more appropriately use the cardiac catheterization laboratory to perform interventional procedures once a diagnosis of CAD has been established by noninvasive imaging modalities rather than using it primarily as a diagnostic facility to confirm or refute CAD. With ongoing technological advancements, noninvasive imaging plays a pre-eminent role in not only diagnosing CAD but also informing the choice of appropriate therapies, establishing prognosis, all while containing costs and providing value-based care. Multiple imaging modalities are available to evaluate patients suspected of having coronary ischemia, such as stress electrocardiography, stress echocardiography, single-photon emission computed tomography myocardial perfusion imaging, positron emission tomography, coronary computed tomography (CT) angiography, and magnetic resonance imaging. These imaging modalities can variably provide functional and anatomical delineation of coronary stenoses and help guide appropriate therapy. This review will discuss their advantages and limitations and their usage in the diagnostic pathway for patients with CAD. We also discuss newer technologies such as CT fractional flow reserve, CT angiography with perfusion, whole-heart coronary magnetic resonance angiography with perfusion, which can provide both anatomical as well as functional information in the same test, thus obviating the need for multiple diagnostic tests to obtain a comprehensive assessment of both, plaque burden and downstream ischemia. Recognizing that clinicians have a multitude of tests to choose from, we provide an underpinning of the principles of ischemia detection by these various modalities, focusing on anatomy vs physiology, the database justifying their use, their prognostic capabilities and lastly, their appropriate and judicious use in this era of patient-centered, cost-effective imaging.

[Myocardial ischaemia detection in women]

Screening of myocardial ischemia refers to the use of one or more diagnostic tests for coronary heart disease with a dual objective of appropriateness and promptness. In women, as compared to men, the accuracy of the different tests is worse. Thus, to overcome this sex-related penalty, we must define a diagnosis strategy based on risk stratification, enabling the identification of patients requiring invasive investigations. This review discusses various non-invasive diagnostic tests focusing on a female-specific approach and defines the use of numerous diagnostic tests with respect to both risk stratification and symptoms.

The role of pharmacological stress testing in women

Pharmacological stress is an alternative method to dynamic exercise that combined with noninvasive imaging allows the detection of flow-limiting coronary artery disease (CAD). It represents the stress procedure of choice in patients who cannot exercise appropriately. In women, pharmacological stress combined with myocardial perfusion scintigraphy (MPS) has demonstrated to be highly accurate for the detection of obstructive CAD and a valuable tool that helps separate patients at low cardiac risk from those with an adverse prognosis. Pharmacological stress with positron emission tomographic (PET) imaging is increasingly used in the investigation of suspected obstructive CAD; available evidence shows that the diagnostic profile and prognostic value of stress PET imaging is similar to that of stress MPS in women.

The role of treadmill exercise testing in women

Treadmill exercise electrocardiogram (ECG) is one of the most commonly used noninvasive tests for the assessment of ischemic heart disease (IHD). Sex-specific challenges in diagnostic and prognostic tests methods for IHD outlined the importance of pretest probability evaluation and referral bias using risk-prediction charts available for both asymptomatic and symptomatic women. Accordingly, exercise ECG has been indicated as the initial test for the symptomatic women at intermediate risk of IHD who has a normal resting ECG and is capable of maximal exercise. However, the difficulties of using exercise testing for diagnosing IHD in women have led to an initial speculation that stress imaging may be preferred to standard stress testing. This editorial analyzed a large body of evidence on the diagnostic and prognostic powers of treadmill ECG and exercise myocardial perfusion imaging (MPI) according to new advanced imaging technologies.

Facile rhenium-peptide conjugate synthesis using a one-pot derived Re(CO)3 reagent

We have synthesized two Re(CO)3-modified lysine complexes (1 and 2), where the metal is attached to the amino acid at the Nε position, via a one-pot Schiff base formation reaction. These compounds can be used in the solid phase synthesis of peptides, and to date we have produced four conjugate systems incorporating neurotensin, bombesin, leutenizing hormone releasing hormone, and a nuclear localization sequence. We observed uptake into human umbilical vascular endothelial cells as well as differential uptake depending on peptide sequence identity, as characterized by fluorescence and rhenium elemental analysis.

Thallium-201 is comparable to technetium-99m-sestamibi for estimating cardiac function in patients with abnormal myocardial perfusion imaging

We analyzed the left-ventricular functional data obtained by cardiac-gated single-photon emission computed tomography myocardial perfusion imaging (MPI) with thallium-201 (Tl-201) and technetium-99m-sestamibi (MIBI) protocols in different groups of patients, and compared the data between Tl-201 and MIBI. Two hundred and seventy-two patients undergoing dipyridamole stress/redistribution Tl-201 MPI and 563 patients undergoing 1-day rest/dipyridamole stress MIBI MPI were included. Higher mean stress ejection fraction (EF), rest EF, and change in EF (ΔEF) were noticed in the normal MPI groups by both Tl-201 and MIBI protocols. Higher mean EF was observed in the females with normal MPI results despite their higher mean age. Comparisons between the Tl-201 and MIBI groups suggested a significant difference in all functional parameters, except for the rest end diastolic volume/end systolic volume and ΔEF between groups with negative MPI results. For the positive MPI groups, there was no significant difference in all parameters, except for the change in end diastolic volume and change in end systolic volume after stress between both protocols. The Tl-201 provides comparable left-ventricular functional data to MIBI cardiac-gated single-photon emission computed tomography in patients with positive MPI results, and may therefore be undertaken routinely for incremental functional information that is especially valuable to this patient group.

Stress-first Myocardial Perfusion Imaging

Stress-first approaches to myocardial perfusion imaging provide diagnostically and prognostically accurate perfusion data equivalent to a full rest-stress study, save time in the imaging laboratory, and reduce the radiation exposure to patients and laboratory staff. Converting a nuclear cardiology laboratory from a conventional rest-stress strategy to a stress-first approach involves challenges such as the need for attenuation correction, triage of patients to an appropriate protocol, real-time review of stress images, and consideration of differential reimbursement.

Feasibility of SPECT myocardial perfusion imaging in the super-obese using a multi-head semiconductor camera with attenuation correction

BACKGROUND

Obesity is not only associated with an increased risk of coronary artery disease, but also decreases the accuracy of many diagnostic modalities pertinent to this disease. Advances in myocardial perfusion imaging (MPI) have mitigated somewhat the effects of obesity, although the feasibility of MPI in the super-obese (defined as a BMI > 50) is currently untested. We undertook this study to assess the practicality of MPI in the super-obese using a multi-headed solid-state gamma camera with attenuation correction.

METHODS

We retrospectively identified consecutive super-obese patients referred for MPI at our institution. The images were interpreted by 3 blinded, experienced readers and graded for quality and diagnosis, and subjectively evaluated the contribution of attenuation correction. Clinical follow-up was obtained from review of medical records.

RESULTS

72 consecutive super-obese patients were included. Their BMI ranged from 50 to 67 (55.7 ± 5.1). Stress image quality was considered good or excellent in 45 (63%), satisfactory in 24 (33%), poor in 3 (4%), and uninterpretable in 0 patients. Rest images were considered good or excellent in 34 (49%), satisfactory in 23 (33%), poor in 13 (19%), and uninterpretable in 0 patients. Attenuation correction changed the interpretation in 34 (47%) of studies.

CONCLUSIONS

MPI is feasible and provides acceptable image quality for super-obese patients, although it may be camera and protocol dependent.

Clinical value of supine and upright myocardial perfusion imaging in obese patients using the D-SPECT camera

PURPOSE

We have assessed whether additional upright imaging increases the confidence of interpretation of stress only supine myocardial perfusion imaging (MPI) in obese patients.

METHODS AND RESULTS

Tc-MIBI stress MPI of 101 consecutive patients (M = 49, 62 ± 12 years) with BMI ≥30 scanned on the D-SPECT cardiac camera were assessed. Images were interpreted as diagnostic or equivocal and the need for a rest study was recorded. Stress supine MPI was interpreted first, then gated and finally upright data were added. Defects on supine but not on upright were defined as artefacts and defects seen on both as abnormal. The total perfusion deficit (TPD) was also quantified. There were 27 normal, 22 abnormal, and 52 equivocal supine scans. The median EF was 52%, unaffecting the need for rest imaging. Upright imaging reclassified 32/52 (62%) equivocal studies as normal and 6/52 (11%) as abnormal (P < 0.001). Rest scan was deemed needed in 74/101 patients on supine vs 42/101 on supine/upright (P < 0.001). Supine TPD was normal in 53 and supine/upright TPD was normal in 70 patients (P < 0.001).

CONCLUSION

Supine stress MPI is inadequate in obese patients. The addition of upright imaging significantly increases the ability to interpret scans as diagnostic and may reduce considerably the need for rest imaging.

Gated SPECT in assessment of regional and global left ventricular function: an update

Gated myocardial perfusion SPECT (GSPECT) is a major clinical tool, widely used for performing myocardial perfusion imaging procedures. In this review, we have presented the fundamentals of GSPECT and the ways in which the functional measurements it provides have contributed to the emergence of myocardial perfusion SPECT in its important role as a major tool of modern cardiac imaging. GSPECT imaging has shown unique capability to provide accurate, reproducible and operator-independent quantitative data regarding myocardial perfusion, global and regional systolic and diastolic function, stress-induced regional wall-motion abnormalities, ancillary markers of severe and extensive disease, left ventricular geometry and mass, as well as the presence and extent of myocardial scar and viability. Adding functional data to perfusion provides an effective means of increasing both diagnostic accuracy and reader's confidence in the interpretation of the results of perfusion scans. Assessment of global and regional LV function has improved the prognostic power of myocardial perfusion SPECT and has been shown in a large registry to add to the perfusion assessment in predicting benefit from revascularization.

Taking the perfect nuclear image: quality control, acquisition, and processing techniques for cardiac SPECT, PET, and hybrid imaging

Nuclear Cardiology for the past 40 years has distinguished itself in its ability to non-invasively assess regional myocardial blood flow and identify obstructive coronary disease. This has led to advances in managing the diagnosis, risk stratification, and prognostic assessment of cardiac patients. These advances have all been predicated on the collection of high quality nuclear image data. National and international professional societies have established guidelines for nuclear laboratories to maintain high quality nuclear cardiology services. In addition, laboratory accreditation has further advanced the goal of the establishing high quality standards for the provision of nuclear cardiology services. This article summarizes the principles of nuclear cardiology single photon emission computed tomography (SPECT) and positron emission tomography (PET) imaging and techniques for maintaining quality: from the calibration of imaging equipment to post processing techniques. It also will explore the quality considerations of newer technologies such as cadmium zinc telleride (CZT)-based SPECT systems and absolute blood flow measurement techniques using PET.

Diagnosing and characterizing coronary artery disease in women: developments in noninvasive and invasive imaging techniques

Cardiovascular disease is the leading cause of death in men and women in the USA; yet, coronary artery disease (CAD) continues to be underrecognized and underdiagnosed in women. Noninvasive and invasive imaging techniques are constantly being developed in order to more accurately assess CAD. At the same time, the impact of gender on the interpretation and accuracy of these studies is still being elucidated. Furthermore, new imaging techniques have improved our understanding of CAD pathophysiology and progression and have begun to reveal gender differences in the development of CAD. This article will review current imaging techniques and their application to diagnosing and understanding CAD in women.

Gender differences in the evaluation of coronary artery disease with a cadmium-zinc telluride camera

PURPOSE

Coronary artery disease remains one of the most significant causes of morbidity and mortality among women. The published literature shows the importance of standard single photon emission computed tomography in the evaluation of women with known or suspected ischaemic heart disease, in terms of target intervention and clinical treatment. The purpose of the present study was to ascertain the diagnostic accuracy of cadmium-zinc-telluride (CZT) myocardial perfusion imaging according to gender, within a prospective database of patients with known or suspected coronary artery disease, using coronary angiography as the reference standard.

METHODS

Included in the study were 309 consecutive patients, of whom 248 were men (80 %), with known or suspected coronary artery disease and who had been referred to our laboratory for stress-rest myocardial perfusion imaging. All patients underwent coronary angiography within 30 days. All patients underwent a single-day stress-rest low-dose ultrafast protocol. Fifteen minutes after the end of the stress (dose range 185 to 222 MBq of (99m)Tc-tetrofosmin), all patients underwent the first scan with an acquisition time of 7 min. The rest scan (dose range 370 to 444 MBq of (99m)Tc-tetrofosmin) was acquired from 30 min to 45 min after injection, with an acquisition time of 6 min. Images were visually inspected, and summed stress scores (SSS) and summed rest scores (SRS) were obtained.

RESULTS

Image quality was graded "good" or better in more than 90 % of patients. On coronary angiography, left main trunk stenosis, left anterior descending artery stenosis, left circumflex artery stenosis and right coronary artery stenosis were seen in 3, 155 , 142 and 131 patients, respectively. In women, the mean SSS and SRS were 8 ± 5 and 3 ± 1, respectively. Semiquantitative regional and global SSS were good discriminants of coronary artery disease, and the overall area under the receiver operator characteristic (ROC) curve was 0.822 (95 % CI 0.685 - 0.959). The value was comparable to that obtained in men (overall ROC area 0.884, 95 % CI 0.836 - 0.933).

CONCLUSION

A low-dose protocol with a CZT camera can be routinely used in women with known or suspected coronary artery disease without loss of accuracy and with lower radiation exposure of the patients.

Journey in evolution of nuclear cardiology: will there be another quantum leap with the F-18-labeled myocardial perfusion tracers?

The field of nuclear cardiac imaging has evolved from being rather subjective, more "art than a science," to a more objective, digital-based quantitative technique, providing insight into the physiological processes of cardiovascular disorders and predicting patient outcome. In a mere 4 decades of its clinical use, the technology used to image myocardial perfusion has made quantum leaps from planar to single-photon emission computed tomography (SPECT) and now to a more contemporary rapid SPECT, positron emission tomography (PET), and hybrid SPECT-computed tomography (CT) and PET-CT techniques. Meanwhile, radiotracers have flourished from potassium-43 and red blood cell-tagged blood pool imaging to thallium-201 and technetium-99m-labeled SPECT perfusion tracers along with rubidium-82, ammonia N-13, and more recently F-18 fluorine-labeled PET perfusion tracers. Concurrent with this expansion is the introduction of new quantitative methods and software for image processing, evaluation, and data interpretation. Technical advances, particularly in obtaining quantitative data, have led to a better understanding of the physiological mechanisms underlying cardiovascular diseases beyond discrete epicardial coronary artery disease to coronary vasomotor function in the early stages of the development of coronary atherosclerosis, hypertrophic cardiomyopathy, and dilated nonischemic cardiomyopathy. Progress in the areas of molecular and hybrid imaging are equally important areas of growth in nuclear cardiology. However, this paper focuses on the past and future of nuclear myocardial perfusion imaging and particularly perfusion tracers.

Coronary artery disease in women: a 2013 update

Coronary artery disease (CAD) is a leading cause of death of women and men worldwide. CAD's impact on women traditionally has been underappreciated due to higher rates at younger ages in men. Microvascular coronary disease disproportionately affects women. Women have unique risk factors for CAD, including those related to pregnancy and autoimmune disease. Trial data indicate that CAD should be managed differently in women. In this review, we will examine risk assessment for CAD in women, CAD's impact on women, as well as CAD's female-specific presentation and management strategies.

The Role of Myocardial Perfusion Gated SPECT Study in Women with Coronary Artery Disease: A Correlative Study

Objective: We aimed to evaluate the role of gated myocardial perfusion SPECT (MPS) and to investigate whether only the invasive coronary angiography (CAG) is sufficient in the diagnosis of the coronary artery disease (CAD) in women.

Material and Methods: Sixty-four women (62±10 years) with known CAD were included in this study. They had echocardiography (ECHO), stress/rest gated MPS and invasive CAG. Coronary stenosis as of > 50 % in invasive CAG was accepted as significant. Gated MPS data were compared with invasive CAG and ECHO.

Results: Invasive CAG results were abnormal in 34 patients, and normal in 30 cases. Myocardial ischemia was detected by gated MPS in 22/ 30 cases with normal invasive CAG, 6 had mild coronary stenosis in major coronary arteries ranging from 30% to 50% in invasive CAG. 16/ 22 women were diagnosed as metabolic syndrome according to MetSend Diagnostic Criteria and only 8 of 30 patients with normal invasive CAG had false positive MPS data on the reevaluation by a nuclear cardiologist.

Conclusion: We think that invasive coronary angiography method is not sufficient alone in the diagnosis of CAD in women. Gated MPS study is recommended to achieve the final decision for myocardial ischemia in the cases with CAD and raw data must always be evaluated to avoid attenuation artifacts.

Conflict of interest:None declared.

Incremental value of objective cardiac testing in addition to physician impression and serial contemporary troponin measurements in women

OBJECTIVES

Guidelines recommend that patients presenting to the emergency department (ED) with chest pain who are at low risk for acute coronary syndrome (ACS) receive an objective cardiac evaluation with a stress test or coronary imaging. It is uncertain whether all women derive benefit from this process. The study aim was to determine the incremental value of objective cardiac testing after serial cardiac markers and physician risk assessment.

METHODS

Women enrolled in the 18-site Myeloperoxidase in the Diagnosis of Acute Coronary Syndrome (MIDAS) study had serial troponin I measured at time 0 and 90 minutes and physician risk assessment for the presence of ACS. Risk estimates obtained at the time of ED evaluation were dichotomized as high or non-high risk. The primary outcome was the composite of acute myocardial infarction (AMI) or revascularization at 30 days. Logistic regression with receiver operator characteristic (ROC) curves and net reclassification index were used to determine the diagnostic accuracy for the composite outcome of 30-day MI or revascularization for two models: 1) troponin I results and physician risk assessment alone and 2) troponin I results, physician risk assessment, and objective cardiac testing.

RESULTS

A total of 460 women with a median age 58 years (interquartile range [IQR] = 48.5 to 68 years) were included, and 32 (6.9%) experienced AMI or revascularization by 30 days. Comparison of the area under the ROC curves (AUC) showed that the addition of objective cardiac testing to the combination of troponin I results and physician risk assessment did not significantly improve prediction of 30-day AMI or revascularization (AUC = 0.85 vs. 0.89; p = .053). Using a threshold of 1%, net reclassification index showed that the addition of objective cardiac testing to troponin I results and physician risk assessment worsened the prediction for 30-day AMI and revascularization. All of the reclassified patients were false positives, with nine (2.1%) patients incorrectly reclassified from <1% risk to ≥ 1% risk of 30-day AMI or revascularization.

CONCLUSIONS

In the era of contemporary troponin assays, objective cardiac testing after an ED clinician risk assessment of non-high risk and negative troponin I results at 0 and 90 minutes does not improve the prediction of 30-day AMI or revascularization in women presenting with chest pain or other symptoms of cardiac ischemia.

[Myocardial perfusion scintigraphy - short form of the German guideline]

This guideline is a short summary of the guideline for myocardial perfusion scintigraphy published by the Association of the Scientific Medical Societies in Ger-many (AWMF). The purpose of this guideline is to provide practical assistance for indication and examination procedures as well as image analysis and to present the state-of-the-art of myocardial-perfusion-scintigraphy. After a short introduction on the fundamentals of imaging, precise and detailed information is given on the indications, patient preparation, stress testing, radiopharmaceuticals, examination protocols and techniques, radiation exposure, data reconstruction as well as information on visual and quantitative image analysis and interpretation. In addition possible pitfalls, artefacts and key elements of reporting are described.

Gender differences in the diagnostic accuracy of SPECT myocardial perfusion imaging: a bivariate meta-analysis

BACKGROUND

It remains controversial whether the diagnostic accuracy of single-photon emission computed tomography myocardial perfusion imaging (SPECT MPI) is different in men as compared to women. We performed a meta-analysis to investigate gender differences of SPECT MPI for the diagnosis of CAD (≥50% stenosis).

METHOD

Two investigators independently performed a systematic review of the MEDLINE and EMBASE databases from inception through January 2012 for English-language studies determining the diagnostic accuracy of SPECT MPI. We included prospective studies that compared SPECT MPI with conventional coronary angiography which provided sufficient data to calculate gender-specific true and false positives and negatives. Data from studies evaluating <20 patients of one gender were excluded. Bivariate meta-analysis was used to create summary receiver operating curves.

RESULTS

Twenty-six studies met inclusion criteria, representing 1,148 women and 1,142 men. Bivariate meta-analysis yielded a mean sensitivity and specificity of 84.2% (95% confidence interval [CI] 78.7%-88.6%) and 78.7% (CI 70.0%-85.3%) for SPECT MPI in women and 89.1% (CI 84.0%-92.7%) and 71.2% (CI 60.8%-79.8%) for SPECT MPI in men. There was no significant difference in the sensitivity (P = .15) or specificity (P = .23) between male and female subjects.

CONCLUSION

In a bivariate meta-analysis of the available literature, the diagnostic accuracy of SPECT MPI is similar for both men and women.