PET/CT and vascular disease: current concepts

Since its introduction in 2001, positron emission tomography associated to computed tomography (PET/CT) has been established as a standard tool in cancer evaluation. Being a multimodality imaging method, it combines in a single session the sensitivity granted by PET for detection of molecular targets within the picomolar range, with an underlying submilimetric resolution inherent to CT, that can precisely localize the PET findings. In this last decade, there have been new insights regarding the pathophysiology of atherosclerosis, particularly about plaque rupture and vascular remodeling. This has increased the interest for research on PET/CT in vascular diseases as a potential new diagnostic tool, since some PET molecular targets could identify diseases before the manifestation of gross anatomic features. In this review, we will describe the current applications of PET/CT in vascular diseases, emphasizing its usefulness in the settings of vasculitis, aneurysms, vascular graft infection, aortic dissection, and atherosclerosis/plaque vulnerability. Although not being properly peripheral vascular conditions, ischemic cardiovascular disease and cerebrovascular disease will be briefly addressed as well, due to their widespread prevalence and importance.

Reduced adverse effects with an accelerated dobutamine stress protocol compared with the conventional protocol: a prospective, randomized myocardial perfusion scintigraphy study

BACKGROUND

Dobutamine (Dob) stress myocardial perfusion scintigraphy (MPS) has been shown to have diagnostic and prognostic value. However, the protocol recommended for Dob-MPS is long and frequently associated with adverse effects. We sought to compare two stress protocols with Dob in patients undergoing MPS.

METHODS AND RESULTS

168 patients undergoing Dob-MPS were consecutively studied. Two protocols were randomly used: progressive doses of Dob (steps of 10 microg/kg/min at 3-min intervals) up to 40 microg/kg/min, aiming at reaching a minimum of 85% of the age-corrected maximal predicted heart rate (HR), possibly adding atropine to maximal Dob dose in case HR was not achieved (conventional protocol) or progressive doses of Dob aiming at the same HR, but adding atropine at the end of the first stage (accelerated protocol). We compared age, gender, coronary risk factors, history of MI or revascularization, Dob infusion and total stress times, maximal HR, percentage of maximal predicted HR, rate-pressure product, ST changes, MPS scores and incidence of adverse effects. In the 84 patients who underwent the accelerated protocol, the incidence of adverse effects was reduced (34.5%) compared to the conventional protocol (54.8%; P < 0.05), as well as Dob infusion duration (508 +/- 130 vs. 715 +/- 142 sec; P < 0.001). We did not observe significant differences between the groups as to age, gender, clinical aspects, maximal HR, percentage of achieved maximal HR, rate-pressure product, ST changes and perfusion scores.

CONCLUSION

Early administration of atropine makes stress faster and reduces incidence of adverse effects, without reducing efficacy towards achieving the proposed goals.

Factors Associated With Coronary Artery Disease Progression Assessed By Serial Coronary Computed Tomography Angiography

Background

Coronary computed tomography angiography (CCTA) allows for noninvasive coronary artery disease (CAD) phenotyping. Factors related to CAD progression are epidemiologically valuable.

Objective

To identify factors associated with CAD progression in patients undergoing sequential CCTA testing.

Methods

We retrospectively analyzed 384 consecutive patients who had at least two CCTA studies between December 2005 and March 2013. Due to limitations in the quantification of CAD progression, we excluded patients who had undergone surgical revascularization previously or percutaneous coronary intervention (PCI) between studies. CAD progression was defined as any increase in the adapted segment stenosis score (calculated using the number of diseased segments and stenosis severity) in all coronary segments without stent (in-stent restenosis was excluded from the analysis). Stepwise logistic regression was used to assess variables associated with CAD progression.

Results

From a final population of 234 patients, a total of 117 (50%) had CAD progression. In a model accounting for major CAD risk factors and other baseline characteristics, only age (odds ratio [OR] 1.04, 95% confidence interval [95%CI] 1.01-1.07), interstudy interval (OR 1.03, 95%CI 1.01-1.04), and past PCI (OR 3.66, 95%CI 1.77-7.55) showed an independent relationship with CAD progression.

Conclusions

A history of PCI with stent placement was independently associated with a 3.7-fold increase in the odds of CAD progression, excluding in-stent restenosis. Age and interstudy interval were also independent predictors of progression.

AS, Zanetti G, Escuissato DL, Gasparetto EL, Araújo Neto CD, Lima RDSL, Xavier SS, Pedrosa RC. A tomografia computadorizada de alta resolução na avaliação da toxicidade pulmonar por amiodarona

OBJETIVO: Avaliar as principais alterações identificadas na tomografia computadorizada de alta resolução do tórax em pacientes com toxicidade pulmonar pela amiodarona. MATERIAIS E MÉTODOS: Foram avaliadas dez tomografias computadorizadas de alta resolução de tórax de pacientes com pneumonite pela amiodarona, seis desses pacientes do sexo masculino e quatro do sexo feminino, com idade média de 73,5 anos. RESULTADOS: Os achados tomográficos mais relevantes foram opacidades lineares ou reticulares em seis casos (60%), pequenos nódulos com densidade elevada em seis casos (60%), consolidações densas em três casos (30%) e aumento da densidade do parênquima hepático em cinco de oito casos em que havia estudo tomográfico do abdome superior (62,5%). CONCLUSÃO: A tomografia computadorizada de alta resolução é um exame importante na avaliação de pacientes com toxicidade pulmonar pela amiodarona, devendo ser realizada sempre que houver suspeita deste diagnóstico. O achado de espessamento de septos interlobulares associado a lesões com aumento de densidade é altamente sugestivo deste diagnóstico.

The Prognostic Value and Clinical Use of Myocardial Perfusion Scintigraphy in Asymptomatic Patients after Percutaneous Coronary Intervention

Background

The role of myocardial perfusion scintigraphy (MPS) in the follow-up of asymptomatic patients after percutaneous coronary intervention (PCI) is not established.

Objectives

To evaluate the prognostic value and clinical use of MPS in asymptomatic patients after PCI.

Methods

Patients who underwent MPS consecutively between 2008 and 2012 after PCI were selected. The MPS were classified as normal and abnormal, the perfusion scores, summed stress score (SSS), and summed difference score (SDS) were calculated and converted into percentage of total perfusion defect and ischemic defect. The follow-up was undertaken through telephone interviews and consultation with the Mortality Information System. Primary endpoints were death, cardiovascular death, and nonfatal acute myocardial infarction (AMI), and secondary endpoint was revascularization. Logistic regression and COX method were used to identify the predictors of events, and the value of p < 0.05 was considered statistically significant.

Results

A total of 647 patients were followed for 5.2 ± 1.6 years. 47% of MPS were normal, 30% were abnormal with ischemia, and 23% were abnormal without ischemia. There were 61 deaths, 27 being cardiovascular, 19 non-fatal AMI, and 139 revascularizations. The annual death rate was higher in those with abnormal perfusion without ischemia compared to the groups with ischemia and normal perfusion (3.3% × 2% × 1.2%, p = 0.021). The annual revascularization rate was 10.3% in the ischemia group, 3.7% in those with normal MPS, and 3% in those with abnormal MPS without ischemia. The independent predictors of mortality and revascularization were, respectively, total perfusion defect greater than 6%, and ischemic defect greater than 3%. Forty-two percent of the patients underwent MPS less than 2 years after PCI, and no significant differences were observed in relation to those who underwent it after that period.

Conclusion

Although this information is not contemplated in guidelines, in this study MPS was able to predict events in asymptomatic after PCI patients, regardless of when they were performed.

Changes in Medical Management after Coronary CT Angiography

Introduction

Coronary computed tomography angiography (CCTA) allows for non-invasive coronary artery disease (CAD) phenotyping. There are still some uncertainties regarding the impact this knowledge has on the clinical care of patients.

Objective

To determine whether CAD phenotyping by CCTA influences clinical decision making by the prescription of cardiovascular drugs and their impact on non-LDL cholesterol (NLDLC) levels.

Methods

We analysed consecutive patients from 2008 to 2011 submitted to CCTA without previous diagnosis of CAD that had two serial measures of NLDLC, one up to 3 months before CCTA and the second from 3 to 6 months after.

Results

A total of 97 patients were included, of which 69% were men, mean age 64 ± 12 years. CCTA revealed that 18 (18%) patients had no CAD, 38 (39%) had non-obstructive (< 50%) lesions and 41 (42%) had at least one obstructive ≥ 50% lesion. NLDLC was similar at baseline between the grups (138 ± 52 mg/dL vs. 135 ± 42 mg/dL vs. 131 ± 44 mg/dL, respectively, p = 0.32). We found significative reduction in NLDLC among patients with obstrctive lesions (-18%, p = 0.001). We also found a positive relationship between clinical treatment intensification with aspirin and cholesterol reducing drugs and the severity of CAD.

Conclusion

Our data suggest that CCTA results were used for cardiovascular clinical treatment titration, with especial intensification seen in patients with obstructive ≥50% CAD.

Mapping COVID-19 functional sequelae: the perspective of nuclear medicine

Severe acute respiratory syndrome coronavirus 2 infection is capable of affecting several organs. Direct viral toxicity, pro-inflammatory and pro-thrombotic induction, endothelial damage, immune imbalance, and dysregulation of the renin-angiotensin-aldosterone system are the mechanisms underlying the viral potential of multiple organ damage. The impairment of four organs stands out among severe patients: lung, heart, kidney, and endothelium. The nuclear medicine field holds accurate and safe exam techniques, such as positron emission tomography-computed tomography and scintigraphy, that allow the anatomophysiological study of the majority of human organ systems. By choosing the most appropriate method and radiopharmaceutical, analyzing the presence of inflammation, fibrosis, changes in perfusion, and function of desired organs is possible. Therefore, its use in the monitoring of patients with coronavirus disease 2019 becomes relevant, especially for monitoring sequelae. In this review, we discuss the use of Nuclear Medicine in the detection, monitoring, and therapeutic evaluation of pulmonary and extrapulmonary sequelae by coronavirus disease 2019.