Diagnosis and quantification of the iron overload through Magnetic resonance. / Diagnóstico y cuantificación de la sobrecarga férrica mediante resonancia magnética.

There are different magnetic resonance techniques and models to quantify liver iron concentration. T2 relaxometry methods evaluate the iron concentration in the myocardium, and they are able to discriminate all the levels of iron overload in the liver. Signal intensity ratio methods saturate with high levels of liver overload and can not assess iron concentration in the myocardium but they are more accessible and are very standardized. This article reviews, in different clinical scenarios, when Magnetic Resonance must be used to assess iron overload in the liver and myocardium and analyzes the current challenges to optimize the aplication of the technique and to be it included in the clinical guidelines.

Medición del T2* hepático y cardíaco en la hemocromatosis secundaria / Liver and heart T2* measurement in secondary haemochromatosis

Objetivo. Valorar la sobrecarga férrica mediante el cálculo del valor T2* en el hígado y el miocardio en los pacientes con hemocromatosis secundaria. Evaluar la correlación de los valores obtenidos con los niveles de ferritina en sangre y la concentración de hierro hepático (CHH) calculada mediante resonancia magnética (RM), y la correlación de los valores T2* entre sí. Material y métodos. Se incluyeron 16 pacientes (13 varones y 3 mujeres), evaluados entre los años 2008 y 2009, con una edad media de 61 años. Quince eran pacientes politransfundidos y uno estaba diagnosticado de anemia sideroblástica hereditaria. Se estudió la ferritina en sangre, la CHH por RM, la función cardíaca mediante RM y el valor T2* mediante secuencias multieco en el hígado (TR/TE1/ΔTE/n°ecos/α: 21/1,18/1.0/20/35°) y el miocardio (26/1,04/0.8/30/60°). Se realizó el análisis de correlación-regresión de los valores T2* cardíaco y hepático con los valores de ferritina y CHH, y entre sí. Resultados. Trece pacientes mostraron valores de ferritina superiores a 1.000 ng/ml (mediana/mínimo/máximo: 1.762/294/3.785 ng/ml). Trece pacientes presentaron CHH elevada, mayor de 80 μmol/g (mediana/mínimo/máximo: 125,4/41,2/241,5 μmol/g). En todos los casos la función cardíaca estaba preservada. En 15 pacientes el valor T2* hepático fue menor de 6,3 ms. Solo en un caso, el valor T2*miocárdico fue menor de 20 ms. Se observó una alta correlación para los valores T2*hepático/CHH (r: -0,912). La correlación fue estadísticamente significativa para T2* hepático/ferritina (r: -0,541). La correlación T2*miocárdico/ferritina, T2*miocárdico/CHH y T2*miocárdico/T2*hepático no fue estadísticamente significativa. Conclusión. Los valores T2* hepático muestran una alta correlación con la CHH y una correlación estadísticamente significativa con la ferritina. No se observó correlación entre los valores T2* miocárdico y la ferritina en sangre, la CHH, ni con el valor T2* hepático (AU)

Objective: To determine whether there is iron overload by calculating the T2* value in the liver and myocardium in patients with secondary haemochromatosis. To analyse the correlation of the values obtained with the iron levels in blood, with the liver iron concentration (LIC) calculated using magnetic resonance (MR) imaging, and the correlation between them. Material and methods: A total of 16 patients (13 males, 3 females), with a mean age of 61 years, were included and evaluated in the years 2008 and 2009. Fifteen of them had received multiple transfusions, and one was diagnosed with hereditary sideroblastic anaemia. The measurements included, blood ferritin, LIC by MRI, cardiac function using MRI and the T2* value by means of multi-echo sequences in the liver (TR/TE1/ TE/No of echos/ : 21/1,18/1.0/20/35◦) and myocardium (26/1.04/0.8/30/60◦). A correlation-regression analysis was performed by comparing the cardiac and liver T2* values with the ferritin, LIC and between each of them. Results: A total of 13 patients had ferritin values greater than 1000 ng/ml (median/minimum/maximum: 1762/294/3785 ng/ml). An increased LIC greater than 80 mol/g (median/minimum/maximum: 125.4/41.2/241.5 mol/g) was observed in 13 patients. In all cases cardiac function was conserved, and in 15 cases the liver T2* value was less than 6.3 ms. The myocardium T2* value was less than 20 ms. in only one case. A high correlation was observed between the liver T2* values and the LIC (r: -0.912). The correlation was statistically significant between the liver T2* value and ferritin (r: -0.541). The correlations between myocardium T2* and ferritin, myocardium T2* and LIC, and myocardium T2* and liver T2* were not statistically significant. Conclusions: The liver T2* showed a high correlation with LIC and a statistically significant correlation with ferritin. No association was observed between the myocardium T2* values and ferritin in blood, the LIC or the liver T2* value (AU)

[Liver and heart T2* measurement in secondary haemochromatosis]. / Medición del T2* hepático y cardíaco en la hemocromatosis secundaria.

OBJECTIVE: To determine whether there is iron overload by calculating the T2* value in the liver and myocardium in patients with secondary haemochromatosis. To analyse the correlation of the values obtained with the iron levels in blood, with the liver iron concentration (LIC) calculated using magnetic resonance (MR) imaging, and the correlation between them. MATERIAL AND METHODS: A total of 16 patients (13 males, 3 females), with a mean age of 61 years, were included and evaluated in the years 2008 and 2009. Fifteen of them had received multiple transfusions, and one was diagnosed with hereditary sideroblastic anaemia. The measurements included, blood ferritin, LIC by MRI, cardiac function using MRI and the T2* value by means of multi-echo sequences in the liver (TR/TE1/ΔTE/No of echos/α: 21/1,18/1.0/20/35°) and myocardium (26/1.04/0.8/30/60°). A correlation-regression analysis was performed by comparing the cardiac and liver T2* values with the ferritin, LIC and between each of them. RESULTS: A total of 13 patients had ferritin values greater than 1000ng/ml (median/minimum/maximum: 1762/294/3785ng/ml). An increased LIC greater than 80µmol/g (median/minimum/maximum: 125.4/41.2/241.5µmol/g) was observed in 13 patients. In all cases cardiac function was conserved, and in 15 cases the liver T2* value was less than 6.3ms. The myocardium T2* value was less than 20ms. in only one case. A high correlation was observed between the liver T2* values and the LIC (r:-0.912). The correlation was statistically significant between the liver T2* value and ferritin (r:-0.541). The correlations between myocardium T2* and ferritin, myocardium T2* and LIC, and myocardium T2* and liver T2* were not statistically significant. CONCLUSIONS: The liver T2* showed a high correlation with LIC and a statistically significant correlation with ferritin. No association was observed between the myocardium T2* values and ferritin in blood, the LIC or the liver T2* value.

[How are the hypothesis and the objectives established in a Radiology research project?]. / ¿Cómo establecer la hipótesis y los objetivos de un proyecto de investigación en Radiología?

Research is a systematic process designed to answer a question. This is the starting point of the whole project and specifically formulates a problem observed in the analysis of the reality. The answer to this attempts to clarify an uncertainty in our knowledge. The conceptual hypothesis is the theoretical answer to the question set out. The operational hypothesis is the particular form that which sets out to demonstrate the conceptual hypothesis. The objectives are the justification for conducting the research. They help to define what it attempts to obtain, and what answers it will give to the formulated questions. It must show a clear and consistent relationship with the description of the problem and, specifically, with the questions and/or hypothesis that are to be resolved.

[Quantification of liver iron concentration using 1-Tesla MRI]. / Cuantificación de la concentración de hierro en hígado mediante RM de 1 Tesla.

OBJECTIVE: To evaluate the quantification of liver iron concentration using 1-Tesla magnetic resonance imaging (MRI) and its ability to diagnose or rule out hemochromatosis. To evaluate the role of 1.5-Tesla MRI in inconclusive cases. MATERIAL AND METHOD: Between 2002 and 2006, we used 1-Tesla MRI (Gandon method) and liver biopsy to quantify the liver iron concentration in 31 patients. Moreover, we used 1.5-Tesla MRI (according to Alústiza's model) and liver biopsy to determine the liver iron concentration in 10 additional patients and to check the results of 10 patients in whom 1-Tesla MRI detected iron overload. RESULTS: In the first group of 31 patients, liver biopsy classified the liver iron concentration as normal (<36 micromol.Fe/g) in 11 patients, as hemosiderosis (36-80 micromol.Fe/g) in 15, and as hemochromatosis (>80 micromol.Fe/g) in 5. The correlation with the values calculated at MRI was 100% in the 5 cases with hemochromatosis; in the 15 patients with hemosiderosis, 5 were correctly classified and the liver iron concentration was overestimated in 10; of the 11 patients with normal liver iron concentration, 6 were correctly classified and 5 were overestimated. Quantification >80 at MRI has a sensitivity and negative predictive value of 100% and specificity of 50% for the diagnosis of hemochromatosis. Quantification <36 at MRI has a positive predictive value and specificity of 100% to identify the absence of iron overload. In the 10 patients with liver biopsy that underwent 1.5-Tesla MRI, there was a high correlation between the two techniques. CONCLUSION: The reliability of the evaluation of liver iron concentration using 1-Tesla MRI is useful for ruling out hemochromatosis and identifying patients without iron overload. We observed a tendency to overestimate liver iron concentration in both patients with overload and in those without, and this limits the reliability of the technique. 1.5-Tesla MRI is a good alternative for quantifying liver iron concentration more precisely.

[Diagnosis and quantification of iron overload in the liver using MRI]. / Diagnóstico y cuantificación de la sobrecarga férrica en el hígado mediante resonancia magnética.

Hereditary hemochromatosis is the most common cause of iron overload. The diagnosis of hereditary hemochromatosis has improved since Feder et al. isolated the HFE gene in 1996 and discovered the mutations related with this disease. Nevertheless, in many cases genetic tests for hereditary hemochromatosis are negative. These cases require diagnostic confirmation by quantifying the concentration of iron in the liver (LIC); this has traditionally been accomplished by liver biopsy. Many studies have shown that it is possible to quantify LIC using MRI. However, a consensus has yet to be reached about the most appropriate technique or whether it is possible to reproduce the same methods of calculation on different MRI units. This article reviews the current state of these questions and points to possible lines to standardize this noninvasive method of quantifying LIC in the future.

Diagnóstico y cuantificación de la sobrecarga férrica en el hígado mediante resonancia magnética / Diagnosis and quantification of iron overload in the liver using MRI

La hemocromatosis hereditaria es la modalidad más frecuente de sobrecarga férrica. El diagnóstico de la misma ha mejorado desde que en 1996 Feder et al aislaron el gen HFE descubriendo las mutaciones relacionadas con la enfermedad. Sin embargo, son muchos los pacientes con estudios genéticos negativos, y que por tanto requieren una confirmación diagnóstica mediante la cuantificación de la concentración de hierro en hígado (CHH) que tradicionalmente se ha realizado mediante biopsia hepática. Muchos estudios han demostrado la posibilidad de cuantificar la CHH mediante resonancia magnética. Sin embargo, todavía no existe un consenso en cuanto a la técnica más idónea ni en cuanto a la posibilidad o no de reproducir el mismo método de cálculo en diferentes máquinas. Este artículo revisa la realidad de estas cuestiones y señala posibles líneas de futuro para estandarizar este método no invasivo de cuantificación de la CHH

Hereditary hemochromatosis is the most common cause of iron overload. The diagnosis of hereditary hemochromatosis has improved since Feder et al. isolated the HFE gene in 1996 and discovered the mutations related with this disease. Nevertheless, in many cases genetic tests for hereditary hemochromatosis are negative. These cases require diagnostic confirmation by quantifying the concentration of iron in the liver (LIC); this has traditionally been accomplished by liver biopsy. Many studies have shown that it is possible to quantify LIC using MRI. However, a consensus has yet to be reached about the most appropriate technique or whether it is possible to reproduce the same methods of calculation on different MRI units. This article reviews the current state of these questions and points to possible lines to standardize this noninvasive method of quantifying LIC in the future