Transesophageal and intracardiac ultrasound in arrhythmogenic right ventricular dysplasia/cardiomyopathy: Two case reports.

RATIONALE: Two-dimensional echocardiography (2D echo) is a major tool for the diagnosis of Arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C). However 2D echo can skip regional localized anomalies of the right ventricular wall. We aimed to determine whether transesophageal and intracardiac ultrasound can provide additional information, on the right ventricular abnormalities compared to 2D echo. PATIENT CONCERNS: Case 1 is a 30-year-old patient that presented in the Emergency Department with multiple episodes of fast monomorphic ventricular tachycardia (VT) manifested by palpitations and diziness. Case 2 is a 65-year-old patient that also presented with episodes of ventircular tachycardia associated with low blood pressure. DIAGNOSIS: Both patients had a clear diagnosis of arrhythmogenic right ventricular dysplasia/cardiomyopathy confirmed by cardiac magnetic resonance imaging. INTERVENTION: In both patients transesophageal and intracardiac ultrasound was performed, which brought more information on the diagnosis of ARVD/C compared to transthoracic echocardiograpy. OUTCOMES: The first patient was implanted with an internal cardiac defibrillator and treated with Sotalol for VT recurrences. He presented episodes of VT during follow-up, treated with antitachycardia pacing. The second patient was implanted with an internal cardiac defibrillator and treated with Sotalol without any VT recurrence at 18 month-follow-up. LESSONS: Transesophageal echocardiography and intracardiac echocardiography can provide additional information on small, focal structural abnormalities in patients with ARVD/C: bulges, saculations, aneurysms with or without associated thrombus, partial or complete loss of trabeculations and hypertrophy of the moderator band. These changes are particularly important in cases with "concealed" form of the disease in which no morphological abnormalities are evident in transthoracic echocardiograpy.

Utilização de radiofármacos marcados com tecnécio 99m como potenciais marcadores na obtenção de imagens de perfusão miocárdica / Using technetium-99m-marked radiopharmaceuticals as potential markers in obtaining myocardial perfusion images

A Organização Mundial de Saúde (OMS) aponta as doenças cardiovasculares como a principal causa de morte no mundo, caracterizando um grave problema na saúde pública. Os três tipos de doenças que mais acarretam em óbito são: acidente vascular cerebral, seguido de infarto agudo do miocárdio e outras doenças isquêmicas do coração.Apesar dos avanços terapêuticos das últimas décadas, o infarto ainda apresenta altas taxas de mortalidade. Para as pessoas com doenças cardiovasculares ou com alto risco cardiovascular é fundamental o diagnóstico precoce da doença. A cintilografia de perfusão miocárdica é um método de investigação diagnóstica e prognóstico não invasivo de várias doenças cardiovasculares. Esse exame consiste na administração de um radiofármaco para obtenção de imagens de perfusão cardíaca. Dois traçadores marcados com Tecnécio-99m são amplamente utilizados na clínica, porém, esses dois radiofármacos não atendem aos requisitos de um agente de perfusão ideal, por sofrerem significativa excreção biliar, produzindo artefatos na imagem, o que pode inteferir um diagnóstico preciso, já que a qualidade é comprometida, e prolongando o tempo de obtenção da imagem após a administração do radiotraçador. Para superar essa lacuna, pesquisadores vêm estudando novos complexos catiônicos marcados com o Tecnécio. O objetivo desse artigo é fazer uma revisão, abordando a literatura sobre os radiofármacos que estão sendo estudados, suas vantagens e desvantagens sobre os traçadores já utilizados, e sobre sua potencial utilização na obtenção de imagem de perfusão cardíaca.

The World Health Organization (WHO) acknowledges cardiovascular diseases as the leading cause of death in the world, being regarded as a serious public health issue. The three types of diseases with the greatest mortality are: stroke, followed by acute myocardial infarction (AMI) and other ischemic heart diseases. Despite the therapeutic advances of the last decades, AMI still presents high mortality rates. Early diagnosis is essential for people with cardiovascular diseases or with a high cardiovascular risk. Myocardial perfusion scintigraphy is a method of diagnostic investigation and noninvasive prognosis of various cardiovascular diseases. This examination consists in the administration of a radiopharmaceutical drug to obtain images of cardiac perfusion. Two tracers labeled with Technetium-99m are widely used, however, these two radiopharmaceuticals do not meet the requirements of an ideal perfusion agent, because they have a high liver absorption, producing artifacts in the image, which can disrupt a precise diagnosis, since the quality is compromised, and prolonging the imaging time after administration of the radioisotope. To overcome this gap, researchers have been studying new cationic complexes marked with technetium. The objective of this article is to review the literature on the radiopharmaceuticals being studied, their advantages and disadvantages on the tracers already used, and their potential use in obtaining a cardiac perfusion image.

Performance of cardiac cadmium-zinc-telluride gamma camera imaging in coronary artery disease: a review from the cardiovascular committee of the European Association of Nuclear Medicine (EANM).

The trade-off between resolution and count sensitivity dominates the performance of standard gamma cameras and dictates the need for relatively high doses of radioactivity of the used radiopharmaceuticals in order to limit image acquisition duration. The introduction of cadmium-zinc-telluride (CZT)-based cameras may overcome some of the limitations against conventional gamma cameras. CZT cameras used for the evaluation of myocardial perfusion have been shown to have a higher count sensitivity compared to conventional single photon emission computed tomography (SPECT) techniques. CZT image quality is further improved by the development of a dedicated three-dimensional iterative reconstruction algorithm, based on maximum likelihood expectation maximization (MLEM), which corrects for the loss in spatial resolution due to line response function of the collimator. All these innovations significantly reduce imaging time and result in a lower patient's radiation exposure compared with standard SPECT. To guide current and possible future users of the CZT technique for myocardial perfusion imaging, the Cardiovascular Committee of the European Association of Nuclear Medicine, starting from the experience of its members, has decided to examine the current literature regarding procedures and clinical data on CZT cameras. The committee hereby aims 1) to identify the main acquisitions protocols; 2) to evaluate the diagnostic and prognostic value of CZT derived myocardial perfusion, and finally 3) to determine the impact of CZT on radiation exposure.

Traditional gamma cameras are preferred.

Although the new solid-state dedicated cardiac cameras provide excellent spatial and energy resolution and allow for markedly reduced SPECT acquisition times and/or injected radiopharmaceutical activity, they have some distinct disadvantages compared to traditional sodium iodide SPECT cameras. They are expensive. Attenuation correction is not available. Cardio-focused collimation, advantageous to increase depth-dependent resolution and myocardial count density, accentuates diaphragmatic attenuation and scatter from subdiaphragmatic structures. Although supplemental prone imaging is therefore routinely advised, many patients cannot tolerate it. Moreover, very large patients cannot be accommodated in the solid-state camera gantries. Since data are acquired simultaneously with an arc of solid-state detectors around the chest, no temporally dependent "rotating" projection images are obtained. Therefore, patient motion can be neither detected nor corrected. In contrast, traditional sodium iodide SPECT cameras provide rotating projection images to allow technologists and physicians to detect and correct patient motion and to accurately detect the position of soft tissue attenuators and to anticipate associated artifacts. Very large patients are easily accommodated. Low-dose x-ray attenuation correction is widely available. Also, relatively inexpensive low-count density software is provided by many vendors, allowing shorter SPECT acquisition times and reduced injected activity approaching that achievable with solid-state cameras.

Nuclear cardiology practice and associated radiation doses in Europe: results of the IAEA Nuclear Cardiology Protocols Study (INCAPS) for the 27 European countries.

PURPOSE: Nuclear cardiology is widely used to diagnose coronary artery disease and to guide patient management, but data on current practices, radiation dose-related best practices, and radiation doses are scarce. To address these issues, the IAEA conducted a worldwide study of nuclear cardiology practice. We present the European subanalysis. METHODS: In March 2013, the IAEA invited laboratories across the world to document all SPECT and PET studies performed in one week. The data included age, gender, weight, radiopharmaceuticals, injected activities, camera type, positioning, hardware and software. Radiation effective dose was calculated for each patient. A quality score was defined for each laboratory as the number followed of eight predefined best practices with a bearing on radiation exposure (range of quality score 0 - 8). The participating European countries were assigned to regions (North, East, South, and West). Comparisons were performed between the four European regions and between Europe and the rest-of-the-world (RoW). RESULTS: Data on 2,381 European patients undergoing nuclear cardiology procedures in 102 laboratories in 27 countries were collected. A cardiac SPECT study was performed in 97.9 % of the patients, and a PET study in 2.1 %. The average effective dose of SPECT was 8.0 ± 3.4 mSv (RoW 11.4 ± 4.3 mSv; P < 0.001) and of PET was 2.6 ± 1.5 mSv (RoW 3.8 ± 2.5 mSv; P < 0.001). The mean effective doses of SPECT and PET differed between European regions (P < 0.001 and P = 0.002, respectively). The mean quality score was 6.2 ± 1.2, which was higher than the RoW score (5.0 ± 1.1; P < 0.001). Adherence to best practices did not differ significantly among the European regions (range 6 to 6.4; P = 0.73). Of the best practices, stress-only imaging and weight-adjusted dosing were the least commonly used. CONCLUSION: In Europe, the mean effective dose from nuclear cardiology is lower and the average quality score is higher than in the RoW. There is regional variation in effective dose in relation to the best practice quality score. A possible reason for the differences between Europe and the RoW could be the safety culture fostered by actions under the Euratom directives and the implementation of diagnostic reference levels. Stress-only imaging and weight-adjusted activity might be targets for optimization of European nuclear cardiology practice.

W(h)ither human cardiac and body magnetic resonance at ultrahigh fields? technical advances, practical considerations, applications, and clinical opportunities.

The objective of this study was to document and review advances and groundbreaking progress in cardiac and body MR at ultrahigh fields (UHF, B0 ≥ 7.0 T) with the goal to attract talent, clinical adopters, collaborations and resources to the biomedical and diagnostic imaging communities. This review surveys traits, advantages and challenges of cardiac and body MR at 7.0 T. The considerations run the gamut from technical advances to clinical opportunities. Key concepts, emerging technologies, practical considerations, frontier applications and future directions of UHF body and cardiac MR are provided. Examples of UHF cardiac and body imaging strategies are demonstrated. Their added value over the kindred counterparts at lower fields is explored along with an outline of research promises. The achievements of cardiac and body UHF-MR are powerful motivators and enablers, since extra speed, signal and imaging capabilities may be invested to overcome the fundamental constraints that continue to hamper traditional cardiac and body MR applications. If practical obstacles, concomitant physics effects and technical impediments can be overcome in equal measure, sophisticated cardiac and body UHF-MR will help to open the door to new MRI and MRS approaches for basic research and clinical science, with the lessons learned at 7.0 T being transferred into broad clinical use including diagnostics and therapy guiding at lower fields. Copyright © 2015 John Wiley & Sons, Ltd.

MR-based attenuation correction for cardiac FDG PET on a hybrid PET/MRI scanner: comparison with standard CT attenuation correction.

PURPOSE: The aim of this study was to evaluate the feasibility of attenuation correction (AC) for cardiac (18)F-labelled fluorodeoxyglucose (FDG) positron emission tomography (PET) using MR-based attenuation maps. METHODS: We included 23 patients with no known cardiac history undergoing whole-body FDG PET/CT imaging for oncological indications on a PET/CT scanner using time-of-flight (TOF) and subsequent whole-body PET/MR imaging on an investigational hybrid PET/MRI scanner. Data sets from PET/MRI (with and without TOF) were reconstructed using MR AC and semi-quantitative segmental (20-segment model) myocardial tracer uptake (per cent of maximum) and compared to PET/CT which was reconstructed using CT AC and served as standard of reference. RESULTS: Excellent correlations were found for regional uptake values between PET/CT and PET/MRI with TOF (n = 460 segments in 23 patients; r = 0.913; p < 0.0001) with narrow Bland-Altman limits of agreement (-8.5 to +12.6 %). Correlation coefficients were slightly lower between PET/CT and PET/MRI without TOF (n = 460 segments in 23 patients; r = 0.851; p < 0.0001) with broader Bland-Altman limits of agreement (-12.5 to +15.0 %). PET/MRI with and without TOF showed minimal underestimation of tracer uptake (-2.08 and -1.29 %, respectively), compared to PET/CT. CONCLUSION: Relative myocardial FDG uptake obtained from MR-based attenuation corrected FDG PET is highly comparable to standard CT-based attenuation corrected FDG PET, suggesting interchangeability of both AC techniques.

A new ex vivo beating heart model to investigate the application of heart valve performance tools with a high-speed camera.

High-speed camera examination of heart valves is an established technique to examine heart valve prosthesis. The aim of this study was to examine the possibility to transmit new tools for high-speed camera examination of heart valve behavior under near-physiological conditions in a porcine ex vivo beating heart model. After explantation of the piglet heart, main coronary arteries were cannulated and the heart was reperfused with the previously collected donor blood. When the heart started beating in sinus rhythm again, the motion of the aortic and mitral valve was recorded using a digital high-speed camera system (recording rate 2,000 frames/sec). The image sequences of the mitral valve were analyzed, and digital kymograms were calculated at different angles for the exact analysis of the different closure phases. The image sequence of the aortic valve was analyzed, and several snakes were performed to analyze the effective orifice area over the time. Both processing tools were successfully applied to examine heart valves in this ex vivo beating heart model. We were able to investigate the exact open and closure time of the mitral valve, as well as the projected effective orifice area of the aortic valve over the time. The high-speed camera investigation in an ex vivo beating heart model of heart valve behavior is feasible and also reasonable because of using processing feature such as kymography for exact analysis. These analytical techniques might help to optimize reconstructive surgery of the mitral valve and the development of heart valve prostheses in future.

[Intracardiac echography in interventional cardiology]. / L'ecografia intracardiaca in cardiologia interventistica.

Since its early development, interventional cardiology relies on radiological imaging to show and describe vascular structures involved in percutaneous treatment. However, the development of the transcatheter approach to structural heart disease has highlighted the limits of X-rays in guiding interventions targeting soft heart tissues because of their low radiological resolution. Transesophageal echocardiography has thus gained an important role in many catheterization laboratories that perform percutaneous structural heart disease interventions. The endorsement of this technique necessarily requires expertise of echocardiographers and anesthesiologists for endotracheal intubation, thus increasing the logistic complexity of the procedure. Hence, the idea to apply ultrasonography directly into the heart, thus the introduction of intracardiac echography. At present, there are two different technological implementations of intracardiac echography related to the use of an electronic or mechanical ultrasonic transducer placed at the tip of a catheter inserted into the cardiac chambers, most frequently via femoral venous vascular access. In this review, we describe the potentials, advantages and limits of intracardiac echography, as well as its operative function, current use, and future developments.

In vivo intracardiac optical coherence tomography imaging through percutaneous access: toward image-guided radio-frequency ablation.

Complete catheter-tissue contact and permanent tissue destruction are essential for efficient radio-frequency ablation (RFA) during cardiac arrhythmia treatment. Current methods of monitoring lesion formation are indirect and unreliable. The purpose of this study is to evaluate the feasibility of using optical coherence tomography (OCT) catheter to image endocardial wall in actively beating hearts through percutaneous access. We reported the first in vivo intracardiac OCT imaging through percutaneous access with a thin and flexible OCT catheter. This is a critical step toward image-guided RFA in a clinical setting. A cone-scanning forward-viewing OCT catheter was advanced into beating hearts through percutaneous access in four swine. The OCT catheter was steered by an introducer to touch the endocardial wall. We are able to acquire high quality OCT images in beating hearts, observe the polarization-related artifacts induced by the birefringence of myocardium, and readily evaluate catheter-tissue contact. The observations indicate that OCT could be a promising technique for in vivo guidance of RFA.

Noninvasive diagnosis of chemotherapy related cardiotoxicity.

Chemotherapeutic agents reduce mortality and can prevent morbidity in a wide range of malignancies. These agents are, however, associated with toxicities of their own, and the treating physician must remain ever vigilant against the risk outgrowing the benefit of therapy. Thus, pre-treatment evaluation and monitoring for toxicity during and following administration is a fundamental tenet of oncologic practice. Among the most insidious and deadly toxicities of antitumor agents is cardiac toxicity, which in some cases may be irreversible. Early detection of cardiotoxicity allows the treating oncologist to redirect therapy or dose modify, taking into account the cost of a reduction in therapy against the potential of further injury to the patient. In these instances, the role of the cardiologist is to assist and advise the oncologist by providing diagnostic and prognostic information regarding developing cardiotoxicity. This review discusses noninvasive diagnostic options to identify and characterize cardiotoxicity and their use in prognosis and guiding therapy. We also review established protocols for cardiac safety monitoring in the treatment of malignancy.