Worldwide diagnostic reference levels for single-photon emission computed tomography myocardial perfusion imaging: findings from INCAPS.

OBJECTIVES: This study sought to establish worldwide and regional diagnostic reference levels (DRLs) and achievable administered activities (AAAs) for single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI). BACKGROUND: Reference levels serve as radiation dose benchmarks to compare individual laboratories against aggregated data, helping to identify sites in greatest need of dose reduction interventions. DRLs for SPECT MPI have previously been derived from national or regional registries. To date there have been no multiregional reports of DRLs for SPECT MPI from a single standardized dataset. METHODS: Data were submitted voluntarily to the INCAPS (International Atomic Energy Agency Nuclear Cardiology Protocols Study), a cross-sectional, multinational registry of MPI protocols. A total of 7,103 studies were included. DRLs and AAAs were calculated by protocol for each world region and for aggregated worldwide data. RESULTS: The aggregated worldwide DRLs for rest-stress or stress-rest studies employing technetium Tc 99m-labeled radiopharmaceuticals were 11.2 mCi (first dose) and 32.0 mCi (second dose) for 1-day protocols, and 23.0 mCi (first dose) and 24.0 mCi (second dose) for multiday protocols. Corresponding AAAs were 10.1 mCi (first dose) and 28.0 mCi (second dose) for 1-day protocols, and 17.8 mCi (first dose) and 18.7 mCi (second dose) for multiday protocols. For stress-only technetium Tc 99m studies, the worldwide DRL and AAA were 18.0 mCi and 12.5 mCi, respectively. Stress-first imaging was used in 26% to 92% of regional studies except in North America where it was used in just 7% of cases. Significant differences in DRLs and AAAs were observed between regions. CONCLUSIONS: This study reports reference levels for SPECT MPI for each major world region from one of the largest international registries of clinical MPI studies. Regional DRLs may be useful in establishing or revising guidelines or simply comparing individual laboratory protocols to regional trends. Organizations should continue to focus on establishing standardized reporting methods to improve the validity and comparability of regional DRLs

Current worldwide nuclear cardiology practices and radiation exposure : results from the 65 country IAEA Nuclear Cardiology Protocols Cross-Sectional Study (INCAPS)

To characterize patient radiation doses from nuclear myocardial perfusion imaging (MPI) and the use of radiation-optimizing 'best practices' worldwide, and to evaluate the relationship between laboratory use of best practices and patient radiation dose. We conducted an observational cross-sectional study of protocols used for all 7911 MPI studies performed in 308 nuclear cardiology laboratories in 65 countries for a single week in March-April 2013. Eight 'best practices' relating to radiation exposure were identified a priori by an expert committee, and a radiation-related quality index (QI) devised indicating the number of best practices used by a laboratory. Patient radiation effective dose (ED) ranged between 0.8 and 35.6 mSv (median 10.0 mSv). Average laboratory ED ranged from 2.2 to 24.4 mSv (median 10.4 mSv); only 91 (30%) laboratories achieved the median ED ≤ 9 mSv recommended by guidelines. Laboratory QIs ranged from 2 to 8 (median 5). Both ED and QI differed significantly between laboratories, countries, and world regions. The lowest median ED (8.0 mSv), in Europe, coincided with high best-practice adherence (mean laboratory QI 6.2). The highest doses (median 12.1 mSv) and low QI (4.9) occurred in Latin America. In hierarchical regression modelling, patients undergoing MPI at laboratories following more 'best practices' had lower EDs. Marked worldwide variation exists in radiation safety practices pertaining to MPI, with targeted EDs currently achieved in a minority of laboratories. The significant relationship between best-practice implementation and lower doses indicates numerous opportunities to reduce radiation exposure from MPI globally

El patrón discordante, representación visual de viabilidad miocárdica con PET

El estudio no invasivo de la perfusión y el metabolismo cardíaco mediante la tomografía por emisión de positrones (PET) es una técnica considerada como el estándar de oro para la detección de la viabilidad miocárdica. El radionúclido empleado para esta tarea es el 18 FDG (flúor-18-desoxiglucosa), el cual permite valorar la utilización de glucosa por el miocardio. La comparación del estudio de viabilidad con el de perfusión, para el cual se utilizan otros radiotrazadores como el 13N-amonio, permite establecer tres diferentes patrones para la evaluación de la viabilidad miocárdica: concordante transmural, concordante no transmural y el discordante. Este último está asociado al miocardio hibernante y demuestra la existencia de viabilidad miocárdica. La importancia de su detección es elemental para el estudio del paciente isquémico, pues permite establecer el diagnóstico preciso, el pronóstico y la decisión terapéutica más adecuada. Además, logra predecir tanto la recuperación de la función regional como la fracción de expulsión posterior a la revascularización en caso de haber sido determinada como necesaria. Todas estas consideraciones en torno a la viabilidad son determinantes para reducir el número de eventos adversos y mejorar el pronóstico del paciente

Endothelial dysfunction in systemic lupus erythematosus: evaluation with 13N-ammonia PET.

Systemic lupus erythematosus (SLE) affects multiple organs and systems, severely involving the cardiovascular system. The aim of this study was to evaluate the presence of endothelial dysfunction with N-13-ammonia PET in asymptomatic SLE patients. Methods: We enrolled 16 women with SLE and 16 healthy women. Myocardial blood flow (MBF) was quantified in a 64-slice PET/CT scanner at rest, during a cold pressor test (CPT), and during stress. Endothelium-dependent vasodilation index, %Delta MBF, and myocardial flow reserve (MFR) were calculated. Results: There were 16 women in the SLE group (mean age +/- SD, 31.4 +/- 8.3 y) and 16 women in the healthy control group (31.5 +/- 11.1 y). Mean endothelium-dependent vasodilatation index and %Delta MBF were significantly lower in SLE patients (1.18 +/- 0.55 vs. 1.63 +/- 0.65, P = 0.04, and 18 +/- 55 vs. 63 +/- 65, P = 0.04, respectively). MFR was also lower in the SLE group (2.41 +/- 0.59 vs. 2.73 +/- 0.77, P = 0.20). Conclusion: SLE patients who are free of active disease present abnormal coronary flow and endothelial dysfunction. It is necessary to develop and intensify treatment strategies directed to CAD in SLE patients

Diagnóstico de las cardiopatías congénitas complejas por resonancia magnética

Objetivo: Analizar la utilidad de la resonancia magnética para el diagnóstico morfológico en las cardiopatías congénitas complejas comparada con el ecocardiograma transtorácico. Método: Se incluyeron 45 pacientes con sospecha clínica de cardiopatía congénita grave, se les realizó una resonancia magnética y ecocardiograma transtorácico y se comparó anatomía y tamaño de cavidades cardíacas. Para el análisis se empleó estadística descriptiva y análisis de Bland-AItman para la concordancia entre ambos métodos. Resultados: No hubo diferencias significativas en mediciones obtenidas por ambos métodos, excepto en la fracción de expulsión del ventrículo izquierdo (66.56 ± 9.47 por ECO vs 52.32 ± 13.85 por RM, p = 0.0001) y la medición del diámetro de la rama izquierda de la arteria pulmonar (9.77 ± 6.80 por ECO vs 13.83 ± 8.46 por RM, p = 0.05). La sensibilidad, especificidad y los valores predictivos de la RM fueron elevados para analizar la conexión AV y VA, no así para el situs atrial y los drenajes venosos (pulmonar y sistémico) donde el ECO tiene baja resolución. La concordancia de las mediciones de la FE, índice de McGoon y tamaño del VD mostró pocos valores extremos. Conclusiones: La RM y el ECO son similares para el diagnóstico morfológico de las cardiopatías congénitas graves, pero la RM puede superar al ECO en la visualización de estructuras extracardíacas

Advanced Imaging in Chagas Heart Disease: From Diagnosis to Sudden Death Risk Stratification.

Chagas disease constitutes a relatively prevalent condition in Latin America and is increasing worldwide, with a wide spectrum of clinical subsets. Imaging modalities are critical for adequate diagnosis, staging and prognosis of this entity. Currently Echocardiography and Cardiac Magnetic Resonance are the most valuable techniques for this purpose. Evidence for both modalities has increased in the last years, as the role of advanced techniques such as Speckle Tracking Echocardiography has been explored. We aim to review the evidence of advanced imaging in the spectrum of patients with Chagas Heart Disease