Combined assessment of coronary artery calcium and myocardial perfusion by hybrid Rb-82 PET/CT imaging in the identification of obstructive coronary artery disease

Introduction: Myocardial perfusion imaging (MPI) with positron emission tomography (PET)/computed tomography (CT) allows accurate measurements of coronary artery calcium (CAC), myocardial perfusion and coronary flow reserve (CFR). Aim: We sought to determine whether the combined assessment of CAC score, ischemic total perfusion defect (ITPD) and CFR improves the diagnostic accuracy of PET/CT in predicting obstructive CAD. Methods: We analyzed 93 patients with suspected CAD referred to 82Rb PET/CT MPI and available coronary angiography. Obstructive CAD was defined as a ≥75% stenosis. Regional CAC score was categorized into 2 groups: <300 and ≥300. Regional ITPD was categorized into 3 groups 0%, ≥1 to <5% and ≥5%. CFR was defined as the ratio between hyperemic and baseline myocardial blood flow (MBF). ROC curves were used to obtain the best cutoff value for regional CFR in identifying obstructive CAD. Regression analyses were used to identify variables associated with obstructive CAD. The incremental value of CAC score, ITPD and CFR was assessed. The continuous net reclassification improvement (NRI) was used to evaluate whether a reduced regional CFR was additive in the prediction of severe CAD Results: Vessels with obstructive CAD (n=54) had higher ITPD (P<.001) and lower hyperemic MBF (P<.001) and CFR (P<.001) values compared to those without. The prevalence of ITPD 0% was significantly higher in vessels with CAC score <300 (P<.001) compared to vessels with CAC score ≥300; differently, the prevalence of ITPD <5% was higher in vessels with CAC score ≥300 compared to those with CAC score <300. ROC curves showed that a CFR value of 1.64 was the trade-off between sensitivity and specificity in identifying obstructive CAD. In vessels with CAC score <300, both in non-ischemic (P<.001) as well in vessels with ITPD <5% (P<.05) the prevalence of obstructive CAD was higher in the presence of a reduced regional CFR. In vessels with CAC score ≥300 the prevalence of obstructive CAD was comparable among ITPD and CFR groups. At univariable analysis age (P <.001), male gender (P <.01), CAC score ≥300 (P <.01), regional ITPD (P <.001) and CFR <1.64 (P <.001) were significant predictors of severe CAD. At multivariable analysis CAC score ≥300 (P<.05), regional ITPD (P<.001) and CFR <1.64 (P <.001) were independent predictors of severe CAD. The addition of ITPD to a model including clinical data and a CAC score ≥300 increased the global chi-square in predicting obstructive CAD (29.91 to 72.72; P <0.001). The addition of regional CFR<1.64 further increased the global chi-square (72.72 to 91.97; P <0.001). The continuous NRI by adding CFR to clinical data, CAC score and ITPD was 0.682 Conclusions: CFR provides incremental information about the presence of obstructive CAD over established cardiac risk factors, CAC score and MPI parameters. A combined use of CAC score, MPI and CFR can help to predict more accurately the presence of obstructive CAD

Advanced technology in the risk stratification-based strategy: The way forward to keep going

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Quantitative relationship between coronary artery calcium and myocardial blood flow by hybrid rubidium-82 PET/CT imaging in patients with suspected coronary artery disease

BACKGROUND: We assessed the relationship between coronary artery calcium (CAC) score, myocardial blood flow (MBF) and coronary flow reserve (CFR) in patients undergoing hybrid 82Rb positron emission tomography (PET)/computed tomography (CT) imaging for suspected CAD. We also evaluated if CAC score is able to predict a reduced CFR independently from conventional coronary risk factors. METHODS: A total of 637 (mean age 58 ± 13 years) consecutive patients were studied. CAC score was measured according to the Agatston method and patients were categorized into 4 groups (0, 0.01-99.9, 100-399.9, and ≥400). Baseline and hyperemic MBF were automatically quantified. CFR was calculated as the ratio of hyperemic to baseline MBF and it was considered reduced when <2. RESULTS: Global CAC score showed a significant inverse correlation with hyperemic MBF and CFR (both P < .001), while no correlation between CAC score and baseline MBF was found. At multivariable logistic regression analysis age, diabetes and CAC score were independently associated with reduced CFR (all P < .001). The addition of CAC score to clinical data increased the global chi-square value for predicting reduced CFR from 81.01 to 91.13 (P < .01). Continuous net reclassification improvement, obtained by adding CAC score to clinical data, was 0.36. CONCLUSIONS: CAC score provides incremental information about coronary vascular function over established CAD risk factors in patients with suspected CAD and it might be helpful for identifying those with a reduced CFR

The diagnostic role of total-body 18F-FDG PET/CT in patients with multiple tumors: a report of the association of thyroid cancer with lung or renal tumors

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Tracers for Cardiac Imaging: Targeting the Future of Viable Myocardium

Ischemic heart disease is the leading cause of mortality worldwide. In this context, myocar- dial viability is defined as the amount of myocardium that, despite contractile dysfunction, maintains metabolic and electrical function, having the potential for functional enhancement upon revascular- ization. Recent advances have improved methods to detect myocardial viability. The current paper summarizes the pathophysiological basis of the current methods used to detect myocardial viability in light of the advancements in the development of new radiotracers for cardiac imaging

Diagnosis, Management and Theragnostic Approach of Gastro-Entero-Pancreatic Neuroendocrine Neoplasms

Abstract: Gastro-entero-pancreatic neuroendocrine neoplasms (GEP-NENs) constitute an ideal target for radiolabeled somatostatin analogs. The theragnostic approach is able to combine diagnosis and therapy by the identification of a molecular target that can be diagnosed and treated with the same radiolabeled compound. During the last years, advances in functional imaging with the introduction of somatostatin analogs and peptide receptor radionuclide therapy, have improved the diagnosis and treatment of GEP-NENs. Moreover, PET/CT imaging with 18F-FDG represents a complementary tool for prognostic evaluation of patients with GEP-NENs. In the field of personalized medicine, the theragnostic approach has emerged as a promising tool in diagnosis and management of patients with GEP-NENs. The aim of this review is to summarize the current evidence on diagnosis and management of patients with GEP-NENs, focusing on the theragnostic approach

Relation between myocardial blood flow and cardiac events in diabetic patients with suspected coronary artery disease and normal myocardial perfusion imaging

Background: We assessed the prognostic value of structural abnormalities and coronary vasodilator function in diabetic patients referred to a PET/CT for suspected coronary artery disease (CAD). Methods: We studied 451 diabetics and 451 nondiabetics without overt CAD and normal myocardial perfusion. Myocardial blood flow (MBF) was computed from the dynamic rest and stress imaging. Myocardial flow reserve (MFR) was defined as ratio of hyperemic to baseline MBF and was considered reduced when < 2. Results: During a mean follow-up of 44 months 33 events occurred. Annualized event rate (AER) was higher in diabetic than nondiabetic patients (1.4% vs 0.3%, P < .001). Diabetic patients with reduced MFR had higher AER compared to those with preserved MFR (3.3% vs 0.4%, P < .001). At Cox analysis, age, BMI and reduced MFR were independent predictors of events in diabetic patients. Patients with diabetes and reduced MFR had lower event-free survival compared to nondiabetic patients and MFR < 2 (P < .001). Event-free survival was similar in patients with diabetes and normal MFR and those without diabetes and reduced MFR. Conclusions: Diabetic patients with reduced MFR had higher AER and lower event-free survival compared to those with preserved MFR and to nondiabetic patients

Advances in functional imaging of differentiated thyroid cancer

Abstract: The present review provides a description of recent advances in the field of functional imaging that takes advantage of the functional characteristics of thyroid neoplastic cells (such as radioiodine uptake and FDG uptake) and theragnostic approach of differentiated thyroid cancer (DTC). Physical and biological characteristics of available radiopharmaceuticals and their use with state-of-the-art technologies for diagnosis, treatment, and follow-up of DTC patients are depicted. Radioactive iodine is used mostly with a therapeutic intent, while PET/CT with 18F-FDG emerges as a useful tool in the diagnostic management and complements the use of radioactive iodine. Beyond 18F-FDG PET/CT, other tracers including 124I, 18F-TFB and 68Ga-PSMA, and new methods such as PET/MR, might offer new opportunities in selecting patients with DTC for specific imaging modalities or treatments

Prognostic value of coronary vascular dysfunction assessed by rubidium-82 PET/CT imaging in patients with resistant hypertension without overt coronary artery disease

Purpose: The identification of coronary vascular dysfunction may enhance risk stratification in patients with resistant hypertension (RH). We evaluated if impaired coronary vascular function, assessed by rubidium-82 (82Rb) positron emission tomography/computed tomography (PET/CT) imaging, is associated with increased cardiovascular risk in patients with hypertension without overt coronary artery disease (CAD). Methods: We studied 517 hypertensive subjects, 26% with RH, without overt CAD, and with normal stress-rest myocardial perfusion imaging at 82Rb PET/CT. The outcome end points were cardiac death, nonfatal myocardial infarction, coronary revascularization, and admission for heart failure. Results: Over a median of 38 months (interquartile range 26 to 50), 21 cardiac events (4.1% cumulative event rate) occurred. Patients with RH were older (p < 0.05) and had a higher prevalence of left ventricular hypertrophy (p < 0.001), a lower hyperemic myocardial blood flow (MBF), and myocardial perfusion reserve (MPR) (both p < 0.001) compared to those without. Conversely, coronary artery calcium content and baseline MBF were not different between patients with and without RH. At univariable Cox regression analysis, age, RH, left ventricular ejection fraction, coronary artery calcium score, and reduced MPR were significant predictors of events. At multivariable analysis, age, RH, and reduced MPR (all p < 0.05) were independent predictors of events. Patients with RH and reduced MPR had the highest risk of events and the major risk acceleration over time. Conclusion: The findings suggest that the assessment of coronary vascular function may enhance risk stratification in patients with hypertension