Diagnostic accuracy of dynamic CZT-SPECT in coronary artery disease. A systematic review and meta-analysis

Coronary microvascular dysfunction and myocardial area at risk assessed by cadmium zinc telluride single photon emission computed tomography after primary percutaneous coronary intervention in acute myocardial infarction patients

Background

A high proportion of coronary microvascular dysfunction (CMD) has been observed in patients with acute myocardial infarction (AMI) who have received primary percutaneous coronary intervention (PCI), which may affect their prognosis. This study used cadmium zinc telluride (CZT) single photon emission computed tomography (SPECT) to evaluate the prevalence and characteristics of CMD and myocardial area at risk (AAR) in AMI patients who had undergone primary PCI.

Methods

We conducted a single-center cross-sectional retrospective study at TEDA International Cardiovascular Hospital from September 2021 to June 2022. A total of 83 patients received primary PCI for AMI. Subsequently, a rest/stress dynamic and routine gated myocardial perfusion imaging (MPI) were performed 1 week after PCI. The CMD group was defined as having a residual stenosis of infarct-related artery (IRA) <50% and myocardial flow reserve (MFR) <2.0 in this corresponding territory, whereas MFR ≥2.0 of IRA pertained to the normal control group. Rest-AAR of infarction (%) and stress-AAR (%) were expressed by the percentage of measured rest-defect-size and stress-defect-size in the left ventricular area, respectively. Logistic regression analyses were performed to identify significant predictors of CMD.

Results

A total of 53 patients with a mean age of 57.06±11.99 years were recruited, of whom 81.1% were ST-segment elevation myocardial infarction (STEMI). The proportion of patients with CMD was 79.2% (42/53). The time of pain to SPECT imaging was 7.50±1.27 days in the CMD group and 7.45±1.86 days among controls. CMD patients had a higher body mass index (BMI) than controls (26.48±3.26 vs. 24.36±2.73 kg/m2, P=0.053), and a higher proportion of STEMI, thrombolysis in myocardial infarction (TIMI) 0 grade of IRA prior PCI than controls (88.1% vs. 54.5%, P=0.011; 61.9% vs. 18.2%, P=0.004, respectively). No significant difference was identified in the rest-myocardial blood flow (MBF) of IRA between the 2 groups, whereas the stress-MBF and MFR of IRA, rest-AAR, and stress-AAR in the CMD group were remarkably lowered. Higher BMI [odds ratio (OR): 1.332, 95% confidence interval (CI): 1.008-1.760, P=0.044] and stress-AAR (OR: 1.994, 95% CI: 1.122-3.543, P=0.019) were used as independent predictors of CMD occurrence.

Conclusions

The prevalence of CMD is high in AMI patients who received primary PCI. Each 1 kg/m2 increase in BMI was associated with a 1.3-fold increase in CMD risk. A 5% increase in stress-AAR was associated with a nearly 2-fold increase in CMD risk. Increased BMI and stress-AAR predicts decreased coronary reserve function.

Significant Association of Serum Albumin With the Severity of Coronary Microvascular Dysfunction Using Dynamic CZT-SPECT

OBJECTIVE

Both low serum albumin (SA) concentration and coronary microvascular dysfunction (CMD) are risk factors for the development of heart failure (HF). We hypothesized that SA concentration is associated with myocardial flow reserve (MFR) and implicated in pathophysiological mechanism of HF.

METHODS

We retrospectively studied 454 patients undergoing dynamic cardiac cadmium-zinc-telluride myocardial perfusion imaging from April 2018 to February 2020. The population was categorized into three groups according to SA level (g/dL): Group 1: >4, Group 2: 3.5-4, and Group 3: <3.5. Myocardial blood flow (MBF) and myocardial flow reserve (MFR, defined as stress/rest MBF ratio) were compared.

RESULTS

The mean age of the whole cohort was 66.2 years, and 65.2% were men. As SA decreased, stress MBF (mL min-1 g-1) and MFR decreased (MBF: 3.29 ± 1.03, MFR: 3.46 ± 1.33 in Group 1, MBF: 2.95 ± 1.13, MFR: 2.51 ± 0.93 in Group 2, and MBF: 2.64 ± 1.16, MFR: 1.90 ± 0.50 in Group 3), whereas rest MBF (mL min-1 g-1) increased (MBF: 1.05 ± 0.42 in Group 1, 1.27 ± 0.56 in Group 2, and 1.41 ± 0.61 in Group 3). After adjusting for covariates, compared with Group 1, the odds ratios for impaired MFR (defined as MFR < 2.5) were 3.57 (95% CI: 2.32-5.48) for Group 2 and 34.9 (95% CI: 13.23-92.14) for Group 3. The results would be similar if only regional MFR were assessed. The risk prediction for CMD using SA was acceptable, with an AUC of 0.76.

CONCLUSION

Low SA concentration was associated with the severity of CMD in both global and regional MFR as well as MBF.

Role of 18F-sodium fluoride positron emission tomography in imaging atherosclerosis

Atherosclerosis involving vascular beds across the human body remains the leading cause of death worldwide. Coronary and peripheral artery disease, which are almost universally a result of atherosclerotic plaque, can manifest clinically as myocardial infarctions, ischemic stroke, or acute lower-limb ischemia. Beyond imaging myocardial perfusion and blood-flow, nuclear imaging has the potential to depict the activity of the processes that are directly implicated in the atherosclerotic plaque progression and rupture. Out of several tested tracers to date, the literature is most advanced for 18F-sodium fluoride positron emission tomography. In this review, we present the latest data in the field of atherosclerotic 18F-sodium fluoride positron emission tomography imaging, discuss the advantages and limitation of the techniques, and highlight the aspects that require further research in the future.

Cardiovascular Imaging in Women

Multimodality cardiovascular imaging is a cornerstone diagnostic tool in the diagnosis, risk stratification, and management of cardiovascular diseases, whether those involving the coronary tree, myocardial, or pericardial diseases in general and particularly in women. This manuscript aims to shed some light and summarize the very features of cardiovascular disease in women, explore their unique characteristics and discuss the role of cardiovascular imaging in ischemic heart disease and cardiomyopathies. The role of four imaging modalities will be discussed including nuclear medicine, echocardiography, noninvasive coronary angiography, and cardiac magnetic resonance.

The clinical value of quantitative cardiovascular molecular imaging: a step towards precision medicine

Cardiovascular diseases (CVD) are the leading cause of death worldwide and have an increasing impact on society. Precision medicine, in which optimal care is identified for an individual or a group of individuals rather than for the average population, might provide significant health benefits for this patient group and decrease CVD morbidity and mortality. Molecular imaging provides the opportunity to assess biological processes in individuals in addition to anatomical context provided by other imaging modalities and could prove to be essential in the implementation of precision medicine in CVD. New developments in single-photon emission computed tomography (SPECT) and positron emission tomography (PET) systems, combined with rapid innovations in promising and specific radiopharmaceuticals, provide an impressive improvement of diagnostic accuracy and therapy evaluation. This may result in improved health outcomes in CVD patients, thereby reducing societal impact. Furthermore, recent technical advances have led to new possibilities for accurate image quantification, dynamic imaging, and quantification of radiotracer kinetics. This potentially allows for better evaluation of disease activity over time and treatment response monitoring. However, the clinical implementation of these new methods has been slow. This review describes the recent advances in molecular imaging and the clinical value of quantitative PET and SPECT in various fields in cardiovascular molecular imaging, such as atherosclerosis, myocardial perfusion and ischemia, infiltrative cardiomyopathies, systemic vascular diseases, and infectious cardiovascular diseases. Moreover, the challenges that need to be overcome to achieve clinical translation are addressed, and future directions are provided.

A Comparison of Dynamic SPECT Coronary Flow Reserve with TIMI Frame Count in the Treatment of Non-Obstructive Epicardial Coronary Patients

Background

Microvascular dysfunction in patients with non-obstructive epicardial coronary may aggravate patient's symptoms or lead to various clinical events.

Objective

To investigate the correlation between dynamic single photon emission computed tomography (D-SPECT) derived coronary flow reserve (CFR) and TIMI frame count (TFC) in patients with non-obstructive epicardial coronary patients.

Methods

Patients with suspected or known stable CAD who were recommended to undergo invasive coronary angiography were prospectively enrolled in this study. Those who had non-obstructive coronary received TIMI frame count (TFC) and D-SPECT. A cut-off value of >40 was defined as slow flow referred to TFC.

Results

A total of 47 patients diagnosed with non-obstructive coronary were enrolled. The mean age of patients was 66.09 ± 8.36 years, and 46.8% were male. Dynamic SPECT derived coronary flow reserve (CFR) was significantly correlated with TIMI frame count in 3 epicardial coronary (LAD: r=-0.506, P = 0.0003; LCX: r= -0.532, P = 0.0001; RCA: r= -0.657, P < 0.0001). The sensitivity and specificity of CFR in identifying abnormal TIMI frame count < 40 was 100.0% and 57.6% in LAD, 62.5% and 87.0% in LCX, 83.9% and 75.0% in RCA, respectively. The optimal CFR cut-off values were 2.02, 2.47, and 1.96 among the three vessels.

Conclusion

In patients with non-obstructive coronary, CFR derived from D-SPECT was strongly correlated with TFC. This study demonstrates that that CFR may be an alternative non-invasive method for identifying slow flow in non-obstructive coronary.

Dynamic CZT-SPECT: Characterizing the Lower Values of Myocardial Blood Flow and Reserve

ABSTRACT

CZT-SPECT myocardial perfusion enables quantification of myocardial blood flow (MBF). Normal values and thresholds have been accurately defined in PET but remain unclear in SPECT. The aim of this study was to report normal MBF and myocardial flow reserve values in very low-risk patients referred for coronary artery disease screening with dynamic SPECT, in comparison with patients experiencing coronary artery disease. Eighty-four patients (31 male) were analyzed. The mean 10 years risk of fatal cardiovascular events score was 2.7% ± 1.4%. The mean global stress MBF and myocardial flow reserve were 1.6 ± 0.6 mL/min/g and 2.7 ± 0.7.

Dynamic perfusion SPECT for functional evaluation in symptomatic patients with myocardial bridging

BACKGROUND

The aim of this study was to investigate the feasibility and diagnostic value of myocardial flow reserve (MFR) assessed by rest/stress myocardial perfusion imaging with dynamic single-photon emission computed tomography (SPECT) in the functional evaluation of myocardial bridge (MB).

METHODS

From May 2017 to July 2021, patients with angiographically confirmed isolated MB on the left anterior descending artery (LAD) who underwent dynamic SPECT myocardial perfusion imaging were retrospectively included. The assessment of semiquantitative indices of myocardial perfusion (summed stress scores, SSS) and quantitative parameters (MFR) was performed.

RESULTS

A total of 49 patients were enrolled. The mean age of the subjects was 61.0 ± 9.0 years. All of the patients were symptomatic, and 16 cases (32.7%) presented with typical angina. SPECT-derived MFR showed a borderline significantly negative correlation with SSS (r = 0.261, P = .070). There was a trend of higher prevalence of impaired myocardial perfusion defined as MFR < 2 than as SSS ≥ 4 (42.9% vs 26.5%; P = .090).

CONCLUSION

Our data support that SPECT MFR may be a useful parameter for the functional assessment of MB. In patients with MB, the use of dynamic SPECT could be a potential method for hemodynamic assessment.

Prognostic value of myocardial perfusion imaging by cadmium zinc telluride single-photon emission computed tomography in patients with suspected or known coronary artery disease: a systematic review and meta-analysis

BACKGROUND

Aim of this study was to define the prognostic value of stress myocardial perfusion imaging by cadmium zinc telluride (CZT) single-photon emission computed tomography (SPECT) for prediction of adverse cardiovascular events in patients with known or suspected coronary artery disease (CAD).

METHODS AND RESULTS

Studies published until November 2022 were identified by database search. We included studies using stress myocardial perfusion imaging by CZT-SPECT to evaluate subjects with known or suspected CAD and providing primary data of adverse cardiovascular events. Total of 12 studies were finally included recruiting 36,415 patients. Pooled hazard ratio (HR) for the occurrence of adverse events was 2.17 (95% confidence interval, CI, 1.78-2.65) and heterogeneity was 66.1% (P = 0.001). Five studies reported data on adjusted HR for the occurrence of adverse events. Pooled HR was 1.69 (95% CI, 1.44-1.98) and heterogeneity was 44.9% (P = 0.123). Seven studies reported data on unadjusted HR for the occurrence of adverse events. Pooled HR was 2.72 (95% CI, 2.00-3.70). Nine studies reported data useful to calculate separately the incidence rate of adverse events in patients with abnormal and normal myocardial perfusion. Pooled incidence rate ratio was 2.38 (95% CI, 1.39-4.06) and heterogeneity was 84.6% (P < 0.001). The funnel plot showed no evidence of asymmetry (P = 0.517). At meta-regression analysis, we found an association between HR for adverse events and presence of angina symptoms and family history of CAD.

CONCLUSIONS

Stress myocardial perfusion imaging by CZT-SPECT is a valuable noninvasive prognostic indicator for adverse cardiovascular events in patients with known or suspected CAD.

Multicenter Evaluation of the Feasibility of Clinical Implementation of SPECT Myocardial Blood Flow Measurement: Intersite Variability and Imaging Time

BACKGROUND

Single-center studies have shown that single photon emission computed tomography myocardial blood flow (MBF) measurement is accurate compared with MBF measured with microspheres in a porcine model, positron emission tomography, and angiography. Clinical implementation requires consistency across multiple sites. The study goal is to determine the intersite processing repeatability of single photon emission computed tomography MBF and the additional camera time required.

METHODS

Five sites (Canada, Italy, Japan, Germany, and Singapore) each acquired 25 to 35 MBF studies at rest and with pharmacological stress using technetium-99m-tetrofosmin on a pinhole-collimated cadmium-zinc-telluride-based cardiac single photon emission computed tomography camera with standardized list-mode imaging and processing protocols. Patients had intermediate to high pretest probability of coronary artery disease. MBF was measured locally and at a core laboratory using commercially available software. The time a room was occupied for an MBF study was compared with that for a standard rest/stress myocardial perfusion study.

RESULTS

With motion correction, the overall correlation in MBF between core laboratory and local site was 0.93 (range, 0.87-0.97) at rest, 0.90 (range, 0.84-0.96) at stress, and 0.84 (range, 0.70-0.92) for myocardial flow reserve. The local-to-core difference in global MBF (bias-MBF) was 5.4% (-3.8% to 14.8%; median [interquartile range]) at rest and 5.4% (-6.2% to 19.4%) at stress. Between the 5 sites, bias-MBF ranged from -1.6% to 11.0% at rest and from -1.9% to 16.3% at stress; the interquartile range in bias-MBF was between 9.3% (4.8%-14.0%) and 22.3% (-10.3% to 12.0%) at rest and between 17.0% (-11.3% to 5.6%) and 33.3% (-10.4% to 22.9%) at stress and was not significantly different between most sites. Both bias and interquartile range were like previously reported interobserver variability and less than the SD of the test-retest difference of 30%. The overall difference in myocardial flow reserve was 1.52% (-10.6% to 11.3%). There were no significant differences between with and without motion correction. The average additional acquisition time varied between sites from 44 to 79 minutes.

CONCLUSIONS

The average bias-MBF and bias-MFR values were small with standard deviations substantially less than the test-retest variability. This demonstrates that MBF can be measured consistently across multiple sites and further supports that this technique can be reliably implemented.

REGISTRATION

URL: https://www.

CLINICALTRIALS

gov; Unique identifier: NCT03427749.

Role of nuclear cardiology in diagnosis and risk stratification of coronary microvascular disease

Coronary flow reserve (CFR) with positron emission tomography/computed tomography (PET/CT) has an important role in the diagnosis of coronary microvascular disease (CMD), aids risk stratification and may be useful in monitoring therapy. CMD contributes to symptoms and a worse prognosis in patients with coronary artery disease (CAD), nonischemic cardiomyopathies, and heart failure. CFR measurements may improve our understanding of the role of CMD in symptoms and prognosis in CAD and other cardiovascular diseases. The clinical presentation of CAD has changed. The prevalence of nonobstructive CAD has increased to about 50% of patients with angina undergoing angiography. Ischemia with nonobstructive arteries (INOCA) is recognized as an important cause of symptoms and has an adverse prognosis. Patients with INOCA may have ischemia due to CMD, epicardial vasospasm or diffuse nonobstructive CAD. Reduced CFR in patients with INOCA identifies a high-risk group that may benefit from management strategies specific for CMD. Although measurement of CFR by PET/CT has excellent accuracy and repeatability, use is limited by cost and availability. CFR measurement with single-photon emission tomography (SPECT) is feasible, validated, and would increase availability and use of CFR. Patients with CMD can be identified by reduced CFR and selected for specific therapies.

Quantitative SPECT/CT Parameters in the Assessment of Transthyretin Cardiac Amyloidosis-A New Dimension of Molecular Imaging

AIMS

Cardiac transthyretin amyloidosis (ATTR) represents the accumulation of misfolded transthyretin in the heart interstitium. Planar scintigraphy with bone-seeking tracers has long been established as one of the three main steps in the non-invasive diagnosis of ATTR, but lately, single-photon emission computed tomography (SPECT) has gained wide recognition for its abilities to exclude false positive results and offer a possibility for amyloid burden quantitation. We performed a systematic review of the existing literature to provide an overview of the available SPECT-based parameters and their diagnostic performances in the assessment of cardiac ATTR. Methods and Methods: Among the 43 papers initially identified, 27 articles were screened for eligibility and 10 met the inclusion criteria. We summarised the available literature based on radiotracer, SPECT acquisition protocol, analysed parameters and their correlation to planar semi-quantitative indices.

RESULTS

Ten articles provided accurate details about SPECT-derived parameters in cardiac ATTR and their diagnostic potential. Five studies performed phantom studies for accurate calibration of the gamma cameras. All papers described good correlation of quantitative parameters to the Perugini grading system.

CONCLUSIONS

Despite little published literature on quantitative SPECT in the assessment of cardiac ATTR, this method offers good prospects in the appraisal of cardiac amyloid burden and treatment monitoring.

Review of cardiovascular imaging in the Journal of Nuclear Cardiology 2022: single photon emission computed tomography

In this review, we will summarize a selection of articles on single-photon emission computed tomography published in the Journal of Nuclear Cardiology in 2022. The aim of this review is to concisely recap major advancements in the field to provide the reader a glimpse of the research published in the journal over the last year. This review will place emphasis on myocardial perfusion imaging using single-photon emission computed tomography summarizing advances in the field including in prognosis, non-perfusion variables, attenuation compensation, machine learning and camera design. It will also review nuclear imaging advances in amyloidosis, left ventricular mechanical dyssynchrony, cardiac innervation, and lung perfusion. We encourage interested readers to go back to the original articles, and editorials, for a comprehensive read as necessary but hope that this yearly review will be helpful in reminding readers of articles they have seen and attracting their attentions to ones they have missed.

Advances in Single-Photon Emission Computed Tomography

The clinical presentation of coronary artery disease (CAD) has changed during the last 20 years with less ischemia on stress testing and more nonobstructive CAD on coronary angiography. Single-photon emission computed tomography (SPECT) myocardial perfusion imaging should include the measurement of myocardial flow reserve and assessment of coronary calcium for the diagnosis of nonobstructive CAD and coronary microvascular disease. SPECT/CT systems provide reliable attenuation correction for better specificity and low-dose CT for coronary calcium evaluation. SPECT MFR measurement is accurate, well validated, and repeatable.

2023 Guidelines of the Taiwan Society of Cardiology on the Diagnosis and Management of Chronic Coronary Syndrome

Coronary artery disease (CAD) covers a wide spectrum from persons who are asymptomatic to those presenting with acute coronary syndromes (ACS) and sudden cardiac death. Coronary atherosclerotic disease is a chronic, progressive process that leads to atherosclerotic plaque development and progression within the epicardial coronary arteries. Being a dynamic process, CAD generally presents with a prolonged stable phase, which may then suddenly become unstable and lead to an acute coronary event. Thus, the concept of "stable CAD" may be misleading, as the risk for acute events continues to exist, despite the use of pharmacological therapies and revascularization. Many advances in coronary care have been made, and guidelines from other international societies have been updated. The 2023 guidelines of the Taiwan Society of Cardiology for CAD introduce a new concept that categorizes the disease entity according to its clinical presentation into acute or chronic coronary syndromes (ACS and CCS, respectively). Previously defined as stable CAD, CCS include a heterogeneous population with or without chest pain, with or without prior ACS, and with or without previous coronary revascularization procedures. As cardiologists, we now face the complexity of CAD, which involves not only the epicardial but also the microcirculatory domains of the coronary circulation and the myocardium. New findings about the development and progression of coronary atherosclerosis have changed the clinical landscape. After a nearly 50-year ischemia-centric paradigm of coronary stenosis, growing evidence indicates that coronary atherosclerosis and its features are both diagnostic and therapeutic targets beyond obstructive CAD. Taken together, these factors have shifted the clinicians' focus from the functional evaluation of coronary ischemia to the anatomic burden of disease. Research over the past decades has strengthened the case for prevention and optimal medical therapy as central interventions in patients with CCS. Even though functional capacity has clear prognostic implications, it does not include the evaluation of non-obstructive lesions, plaque burden or additional risk-modifying factors beyond epicardial coronary stenosis-driven ischemia. The recommended first-line diagnostic tests for CCS now include coronary computed tomographic angiography, an increasingly used anatomic imaging modality capable of detecting not only obstructive but also non-obstructive coronary plaques that may be missed with stress testing. This non-invasive anatomical modality improves risk assessment and potentially allows for the appropriate allocation of preventive therapies. Initial invasive strategies cannot improve mortality or the risk of myocardial infarction. Emphasis should be placed on optimizing the control of risk factors through preventive measures, and invasive strategies should be reserved for highly selected patients with refractory symptoms, high ischemic burden, high-risk anatomies, and hemodynamically significant lesions. These guidelines provide current evidence-based diagnosis and treatment recommendations. However, the guidelines are not mandatory, and members of the Task Force fully realize that the treatment of CCS should be individualized to address each patient's circumstances. Ultimately, the decision of healthcare professionals is most important in clinical practice.

First Validation of Myocardial Flow Reserve Derived from Dynamic 99mTc-Sestamibi CZT-SPECT Camera Compared with 13N-Ammonia PET

¹³N-ammonia positron emission tomography (NH₃-PET) can evaluate myocardial blood flow (MBF) at rest, stress, and myocardial flow reserve (MFR) as well as the ratio of MBF at stress to that at rest. MFR is useful in predicting the prognoses of patients with various heart diseases. Cadmium-zinc-telluride single photon emission computed tomography (CZT-SPECT) enables us to acquire dynamic images of radiotracer kinetics and measure original MBF and MFR using ^99mTc-sestamibi. This study aimed to investigate the utility of CZT-SPECT for quantitative assessment of MBF compared to NH₃-PET. We validated the correlation of MBF and MFR between CZT-SPECT and NH₃-PET. Fourteen patients using one-day rest/stress CZT-SPECT, D-SPECT followed by NH₃-PET within 1 month were enrolled and analyzed prospectively. The reproducibility of the MBF and MFR obtained with these two methods was examined using Spearman's correlation coefficient and Bland-Altman plot analysis. The diagnostic value of D-SPECT for abnormal MFR defined using NH₃-PET results as MFR < 2.0 was assessed using receiver-operating characteristic (ROC) analysis. The median duration between D-SPECT and NH₃-PET was 20 days. Although MBF was overestimated by D-SPECT compared to NH₃-PET at high value (mean difference, 0.43 [0.34-0.53]), MBF and MFR were correlated with the two modalities (MBF: r = 0.71, P < 0.0001, MFR: r = 0.60, P < 0.0001). The ROC curve analysis demonstrated a cutoff of 1.6 for detecting abnormal MFR with D-SPECT (sensitivity, 68%; specificity, 91%; AUC, 0.75). MBF and MFR obtained using D-SPECT and NH₃-PET had a good correlation, suggesting that the quantitative MFR evaluation by CZT-SPECT may help understand the trend of NH₃-PET MFR.

Changing Paradigms in the Diagnosis of Ischemic Heart Disease by Multimodality Imaging

Coronary artery disease (CAD) represents the most common cardiovascular disease, with high morbidity and mortality. Historically patients with chest pain of suspected coronary origin have been assessed with functional tests, capable to detect haemodynamic consequences of coronary obstructions through depiction of electrocardiographic changes, myocardial perfusion defects or regional wall motion abnormalities under stress condition. Stress echocardiography (SE), single-photon emission computed tomography (SPECT), positron emission tomography (PET) and cardiovascular magnetic resonance (CMR) represent the functional techniques currently available, and technical developments contributed to increased diagnostic performance of these techniques. More recently, cardiac computed tomography angiography (cCTA) has been developed as a non-invasive anatomical test for a direct visualisation of coronary vessels and detailed description of atherosclerotic burden. Cardiovascular imaging techniques have dramatically enhanced our knowledge regarding physiological aspects and myocardial implications of CAD. Recently, after the publication of important trials, international guidelines recognised these changes, updating indications and level of recommendations. This review aims to summarise current standards with main novelties and specific limitations, and a diagnostic algorithm for up-to-date clinical management is also proposed.

Molecular Imaging of Vulnerable Coronary Plaque with Radiolabeled Somatostatin Receptors (SSTR)

Atherosclerosis is responsible for the majority of heart attacks and is characterized by several modifications of the arterial wall including an inflammatory reaction. The silent course of atherosclerosis has made it necessary to develop predictors of disease complications before symptomatic lesions occur. Vulnerable to rupture atherosclerotic plaques are the target for molecular imaging. To this aim, different radiopharmaceuticals for PET/CT have emerged for the identification of high-risk plaques, with high specificity for the identification of the cellular components and pathophysiological status of plaques. By targeting specific receptors on activated macrophages in high-risk plaques, radiolabelled somatostatin analogues such as ⁶⁸Ga-DOTA-TOC, TATE,0 or NOC have shown high relevance to detect vulnerable, atherosclerotic plaques. This PET radiopharmaceutical has been tested in several pre-clinical and clinical studies, as reviewed here, showing an important correlation with other risk factors.