Evaluación de las alteraciones de la perfusión miocárdica y función ventricular derecha con SPECT y ecocardiografía en la transposición corregida de las grandes arterias / Evaluation of myocardial perfusion and right ventricular function alterations by SPECT and echocardiography after great arteries corrected transposition

Antecedentes: La transposición corregida de grandes arterias (TCGA) es una cardiopatía congénita rara, asociada a disfunción ventricular derecha. El objetivo del presente trabajo fue evaluar por técnicas de medicina nuclear como la ventriculografía en equilibrio y SPECT sincronizado utilizando Tc-99m sestamibi reposo-esfuerzo, la función y perfusión del ventrículo derecho en pacientes adultos con TCGA no operados y comparar los resultados con el ecocardiograma convencional (ETT) y de contraste (EC). Material y métodos: Se estudiaron 13 pacientes a quienes se les realizó ventriculografía con radioisótopos para evaluar la función ventricular derecha y SPECT sincronizado para estudiar la perfusión y función del ventrículo derecho. Los resultados obtenidos se compararon con el ETT y EC. Resultados: La fracción de expulsión ventricular derecha calculada por ventriculografía tuvo correlación de 0.67 (p = 0.059) con la fracción de acortamiento de áreas y de 0.84 (p = 0.01) para el método de descenso del anillo tricuspídeo. Conclusiones: El EC y SPECT sincronizado son métodos de gran utilidad en el estudio de la perfusión miocárdica del ventrículo derecho en pacientes en el que dicho ventrículo se comporta como sistémico. El índice de concordancia diagnóstica entre estas dos técnicas obtenido fue de 0.76 (p = 0.005) para identificar defectos fijos y 0.68 (p = 0.009) para defectos reversibles.

BACKGROUND: Great arteries corrected transposition is a rare congenital heart disease associated with right ventricle dysfunction. The objective of this study was to assess by equilibrium ventriculography (EV) and gated SPECT with Tc-99m sestamibi rest-stress protocol, right ventricle function and perfusion in adult patients with CTGA without previous surgery, and to compare the results with the standard transthoracic cross-sectional (TTE) and color coded Doppler echocardiography (CE) techniques. METHODS: We studied 13 patients, who underwent ventriculography to assess right ventricle function and gated SPECT to evaluate myocardial perfusion and right ventricle function. The data obtained were compared with TTE and CE. RESULTS: Right ventricle ejection fraction was measured using nuclear medicine and showed a Pearson correlation coefficient of 0.67 (p = 0.059) with the shortening area fraction and 0.84 (p = 0.01) with the tricuspid ring descendent method. CONCLUSIONS: Gated SPECT and Echo contrast are extremely valuable methods in the assessment of myocardial perfusion of the right ventricle in this group of patients. The diagnostic agreement index of both studies was 0.76 (p = 0.005) to identify non-reversible defects and 0.68 (p = 0.009) for reversible defects.

Comparison of 18FDG PET with thallium SPECT in the assessment of myocardial viability. A segmental model analysis

BACKGROUND: In patients with myocardial infarction and left ventricular dysfunction, the evidence of myocardial viability is primordial. There are some methods to detect the presence of myocardial viability, 201 thallium reinjection SPECT protocol represents the most common radioisotopic technique to evaluate it. Positron emission tomography (PET) using FDG is considered the gold standard. The aim of this study was to compare globally and by segments the value of both techniques in the detection of viable myocardium. METHODS: Twenty-three consecutive patients with previous myocardial infarction and left ventricular dysfunction were studied. All of them underwent into a SPECT perfusion scan and a FDG PET study to asses myocardial viability. Each study was performed in less than one week between the other. For the analysis, the myocardium was divided into 17 segments. A visual semi-quantitative analysis was carried out according to the following score indicating radiotracer uptake: O = normal to 4 = absent. Myocardial viability was defined as the presence of normal, mildly or moderately reduced radiotracer uptake. The scores obtained by PET were compared to those obtained in SPECT. A statistical analysis was performed using the SPSS v. 10. RESULTS: 391 segments were analyzed. PET detected viability in 130 segments that had been defined as non-viable by SPECT. No differences in the analysis by vascular territories were found. Thirty percent of the segments that were defined as non viable by SPECT were viable by PET, meanwhile only 1% of the segments detected viable by SPECT were considered non viable with PET. CONCLUSIONS: FDG PET study represents a better technique to detect myocardial viability, compared to thallium reinjection SPECT protocol. By this study we have demonstrated that more of 3 of each 10 studies may be diagnosed as non viable where viability is present.