Evaluación de la intensidad de señal en núcleo dentado, puente, globus pallidus y tálamo en pacientes con esclerosis múltiple: valoración de la retención de gadolinio / Evaluation of signal intensity in dentate nucleus, pons, globus pallidus and thalamus in patients with multiple sclerosis: assessment of gadolinium retention

Introduction: Recently, some studies have reported accumulation of gadolinium in the brain of patients with multiple administrations of gadolinium-based contrast. Patients with multiple sclerosis are subjected to multiple contrasting resonances and could become a population at risk. Objective: To determine whether repeated intravenous exposure to gadolinium is associated with more intensity in the thalamus, dentate nucleus, pons and the globus pallidus. Methods: A retrospective study of 60 patients with MS who had undergone two or more contrasted MRs between 2007 and 2015, was performed. The ratios calculated were: dentate nuclei-to-pons (DNP), thalamus-to-pons (TP), caudate nuclei-to-pons (CNP), globus pallidus-to-thalamus (GPT), globus pallidus-to-pons (GPP), by reviewing simple T1 axial sequences. Relative changes were calculated and compared with the number of contrasted MRs. The concordance between observers and the intraclass correlation coefficient was evaluated. Results: There was no evidence of increased signal intensity in T1 sequences (DNP 0.524, GPT 0.466, GPP 0.684, TP 0.771, CNP 0.352). As there were no differences, the Spearman coefficient showed no correlation between relative changes and the number of resonances performed. Inter-observer agreement was almost perfect (0.982) for all structures. Conclusion: Our study did not find a statistically significant increase in the T1 signal intensity in patients with multiple sclerosis. However, there are factors to consider, such as the type of gadolinium and the time lapse between administrations.

Introducción: Recientemente, algunos estudios han informado acumulación de gadolinio en el cerebro de los pacientes con múltiples administraciones de contraste basado en gadolinio. Los pacientes con esclerosis múltiple son sometidos a múltiples resonancias contrastadas y podrían convertirse en una población de riesgo. Objetivo: Determinar si la exposición repetida por vía intravenosa a gadolino se asocia con mayor intensidad en el tálamo, el dentado, el puente y el globo pálido. Métodos: Se realizó un estudio retrospectivo núcleo de 60 pacientes con EM que habían sido sometidos a dos o más RM contrastadas entre 2007 - 2015. Se calcularon las razones núcleo dentado - puente (DNP), tálamo-puente (TP), núcleo caudado- puente (CNP), globus pallidus - tálamo (GPT), globus pallidos - puente (GPP), revisando secuencias T1 axiales simples. Se calcularon los cambios relativos y se compararon con el número de RM contrastadas. Se evaluó la concordancia entre observadores con el coeficiente de correlación intraclase. Resultados: No hubo evidencia de aumento de la intensidad de la señal en secuencias T1 (DNP 0,524, 0,446 GPT, GPP 0,684, 0,771 PT, CNP 0.352). Al no existir diferencias, el coeficiente de Spearman no mostró correlación entre los cambios relativos y el número de resonancias realizadas. La concordancia interobservador fue casi perfecta (0.982) para todas las estructuras. Conclusión: Nuestro estudio no encontró un aumento estadísticamente significativo en la intensidad de la señal T1 en pacientes con esclerosis múltiple. Sin embargo, hay factores a considerar, tales como el tipo de gadolinio y el lapso de tiempo entre las administraciones.

Hepatic Arterial Phase on Gadoxetic Acid-Enhanced Liver MR Imaging: A Randomized Comparison of 0.5 mL/s and 1 mL/s Injection Rates

OBJECTIVE: To compare gadoxetic acid injection rates of 0.5 mL/s and 1 mL/s for hepatic arterial-phase magnetic resonance (MR) imaging. MATERIALS AND METHODS: In this prospective study, 101 consecutive patients with suspected focal liver lesions were included and randomly divided into two groups. Each group underwent dynamic liver MR imaging using a 3.0-T scanner after an intravenous injection of gadoxetic acid at rates of either 0.5 mL/s (n = 50) or 1 mL/s (n = 51). Arterial phase images were analyzed after blinding the injection rates. The signal-to-noise ratios (SNRs) of the liver, aorta, portal vein, hepatic vein, spleen, and pancreas were measured. The contrast-to-noise ratios (CNRs) of the hepatocellular carcinomas (HCC) were calculated. Finally, two experienced radiologists were independently asked to identify, if any, HCCs in the liver on the images and score the image quality in terms of the presence of artifacts and the proper enhancement of the liver, aorta, portal vein, hepatic vein, hepatic artery, spleen, pancreas, and kidney. RESULTS: The SNRs were not significantly different between the groups (p = 0.233-0.965). The CNRs of the HCCs were not significantly different (p = 0.597). The sensitivity for HCC detection and the image quality scores were not significantly different between the two injection rates (p = 0.082-1.000). CONCLUSION: Image quality and sensitivity for hepatic HCCs of arterial-phase gadoxetic acid-enhanced MR were not significantly improved by reducing the contrast injection rate to 0.5 mL/s compared with 1 mL/s.

The T2-Shortening Effect of Gadolinium and the Optimal Conditions for Maximizing the CNR for Evaluating the Biliary System: a Phantom Study

OBJECTIVE: Clear depiction of the common bile duct is important when evaluating neonatal cholestasis in order to differentiate biliary atresia from other diseases. During MR cholangiopancreatography, the T2-shortening effect of gadolinium can increase the contrast-to-noise ratio (CNR) of the bile duct and enhance its depiction. The purpose of this study was to confirm, by performing a phantom study, the T2-shortening effect of gadolinium, to evaluate the effect of different gadolinium chelates with different gadolinium concentrations and different magnetic field strengths for investigating the optimal combination of these conditions, and for identifying the maximum CNR for the evaluation of the biliary system. MATERIALS AND METHODS: MR imaging using a T2-weighted single-shot fast spin echo sequence and T2 relaxometry was performed with a sponge phantom in a syringe tube. Two kinds of contrast agents (Gd-DTPA and Gd-EOB-DTPA) with different gadolinium concentrations were evaluated with 1.5T and 3T scanners. The signal intensities, the CNRs and the T2 relaxation time were analyzed. RESULTS: The signal intensities significantly decreased as the gadolinium concentrations increased (p < 0.001) with both contrast agents. These signal intensities were higher on a 3T (p < 0.001) scanner. The CNRs were higher on a 1.5T (p < 0.001) scanner and they showed no significant change with different gadolinium concentrations. The T2 relaxation time also showed a negative correlation with the gadolinium concentrations (p < 0.001) and the CNRs showed decrease more with Gd-EOB-DTPA (versus Gd-DTPA; p < 0.001) on a 3T scanner (versus 1.5T; p < 0.001). CONCLUSION: A T2-shortening effect of gadolinium exhibits a negative correlation with the gadolinium concentration for both the signal intensities and the T2 relaxation time. A higher CNR can be obtained with Gd-DTPA on a 1.5T MRI scanner.

Neurotoxic Manifestations of an Overdose Intrathecal Injection of Gadopentetate Dimeglumine

The intravenous administration of gadopentetate dimeglumine (GD) is relatively safe and rarely causes systemic toxicity in the course of routine imaging studies. However, the general safety of intrathecal GD has not been established. We report a very rare case of an overdose intrathecal GD injection presenting with neurotoxic manifestations, including a decreased level of consciousness, global aphasia, rigidity, and visual disturbance.

Caracterización del infarto agudo del miocardio en la clínica popular "Simón Bolívar" / Characterization of myocardial acute infarction in "Simón Bolívar" popular clinic

Introducción: en Venezuela las enfermedades del corazón son la primera causa de defunción, y es frecuente la hospitalización por infarto en la clínica popular «Simón Bolívar¼. Hasta la fecha no existen estudios sobre el comportamiento de esta enfermedad en la misión Barrio Adentro. Objetivo: caracterizar a los pacientes con diagnóstico de infarto agudo del miocardio tratados en la clínica popular «Simón Bolívar¼. Métodos: se realizó un estudio descriptivo, retrospectivo y transversal, desde enero hasta septiembre de 2006, en la clínica popular «Simón Bolívar¼, del municipio Diego Ibarra, Carabobo, Venezuela, con los 52 pacientes con infarto agudo del miocardio, atendidos en ella. Resultados: el 63,5 % de los pacientes que sufrieron infarto pertenecían al sexo masculino, los intervalos de 60-69 años representaron el 40,4 %, el 71,2 % de los pacientes tenían hipertensión arterial, el infarto Killip I se presentó en 80,8 % de los casos, y el 13,5 % de los pacientes se complicaron con insuficiencia del ventrículo izquierdo. Conclusiones: predominó el sexo masculino con edades entre 60 y 69 años, los principales factores de riesgo fueron: hipertensión arterial, obesidad, diabetes mellitus y tabaquismo. La mayoría presentó infarto del miocardio Killip I, y las complicaciones intrahospitalarias fueron la insuficiencia del ventrículo izquierdo, las arritmias y el infarto recurrente.

Introduction: In Venezuela, the heart diseases are the leading cause of decease and it is frequent admission from infarction in the "Simón Bolivar" popular clinic. To date there are not studies on the course of this entity in the "Barrio Adentro" mission. Objective: To characterize the patients diagnosed with myocardial acute infarction treated in the above mentioned clinic. Methods: A descriptive, retrospective and cross-sectional study was conducted from January to September, 2006 in "Simón Bolivar" popular clinic from Diego Ibarra municipality, Carabobo, Venezuela in 52 patients presenting with myocardial acute infarction seen there. Results: The 63,5% of patients with infarction were men, intervals of 60-69 years old represented the 40,4%, the 71,1% of patients suffered arterial hypertension, Killip infarction was present in the 80,8% of cases, and the 13,5% becomes complicated with a left ventricle failure. Conclusions: There was predominance of male sex aged between 60 and 69, major risk factors were: arterial hypertension, obesity, diabetes mellitus and smoking. Most had a Killip I myocardial infarction and the intrahospital complications included a left ventricle failure, arrhythmias and the recurrent infarction.

Quantitative Evaluation of Liver Function with MRI Using Gd-EOB-DTPA

OBJECTIVE: Gadolinium ethoxybenzyl diethylenetriaminepentaacetic acid (Gd-EOB-DTPA) is a newly developed MR contrast agent. After intravenous injection, Gd-EOB-DTPA is gradually taken up by the hepatocytes and eventually excreted via the biliary pathway without any change to its chemical structure. Because of these characteristics, it can be used as a tracer for quantitative liver function testing. The purpose of this study is to develop a noninvasive method of quantitation of the hepatic function using Gd-EOB-DTPA through the deconvolution analysis. MATERIALS AND METHODS: Adult New Zealand white rabbits (n = 10, average body weight = 3.5 kg) were used in the present study. Hepatic injury was induced to by the intragastric administration of carbon tetrachloride (CCl4) three times a week for three weeks. Liver enzyme (aspartate aminotransferase, AST; alanine aminotransferase, ALT) levels and the plasma indocyanine green (ICG) retention rate 15 minutes after an intravenous injection of ICG (ICG R15), was checked before and after the three-week administration of CCl4. At the end of experimental period, an observer "blinded" to the treatment given the rabbits performed the histological examination. MRI studies were performed before and after the three-week administration of CCl4 on a 1.5 T scanner using a human extremity coil. After intravenous bolus injection of Gd-EOB-DTPA (0.3 mL of Gd-EOB-DTPA freshly prepared in 2.7 mL of normal saline) through the ear vein, the 250 axial single level dynamic MR images were obtained using a fast low angle shot (FLASH, TR/TE = 11/4.2 msec, flip angle = 15, acquisition time 1 second, slice thickness = 5 mm, matrix = 128x128, field of view = 120 mm) sequence with 1.5 sec time intervals. The time-intensity curves were obtained at the abdominal aorta and the liver parenchyma that was devoid of blood vessels. Deconvolution analysis of the aortic (input function) and hepatic parenchymal (output function) time-intensity curves was performed with a modified Fourier transform technique to calculate the hepatic extraction fraction (HEF). The presence and type of hepatic injury were determined by the histopathologic examination and statistical analysis of the changes of the hepatic enzyme levels, the ICG R15 and Gd-EOB-DTPA HEF values between the time before and after CCl4 administration with Wicoxon signed rank test. Correlation between the Gd-EOB-DTPA HEF and the change of the ICG R15 were analyzed with Pearson's correlation coefficient. RESULTS: Histopathologic examination showed findings that were compatible with hepatic fibrosis caused by chronic liver injury. The initial blood biochemical studies before the administration of carbon tetrachloride showed that the mean AST and ALT levels were 39.8+/-5.2 IU/L and 59.1+/-11.7 IU/L, respectively. The AST and ALT levels increased to 138.4+/-50.5 IU and 172.0+/-71.6 IU/L, respectively, after the three week administration of CCl4. The ALT and AST levels were significantly increased after the three weeks of CCl4 administration (p=0.018). The ICG R15 values were 4.47+/-2.08% and 19.43+/-3.98% before and after three-week administration of CCl4, respectively. The ICG R15 values were significantly increased after hepatic injury (p=0.018). After normalizing the HEF as 100% in each rabbit before CCl4 administration, the deconvoluted curve after CCl4 administration revealed less hepatocyte extraction efficiency with a mean value of 77.7+/-3.6. There was a significant correlation between the HEF and changes of the ICG R15 by the Pearson correlation coefficient assessment (correlation coefficient = -0.965, p=0.000). CONCLUSION: The Gd-EOB-DTPA HEF could be calculated from deconvolution analysis of aortic and hepatic parenchymal time-intensity curves obtained by dynamic MRI. The Gd-EOB-DTPA HEF was well correlated with changes of the ICG R15, which is the most common parameter used in the quantitative estimation of the hepatic function. The Gd-EOB-DTPA HEF is a direct, noninvasive technique for the quantitative evaluation of liver function. It could be a promising alternative for the determination of noninvasive hepatic function in those patients with liver disease.

Contrast-Enhanced Magnetic Resonance Angiography: Dose the Test Dose Bolus Represent the Main Dose Bolus Accurately?

OBJECTIVE: To determine whether the time-intensity curves acquired by test and main dose contrast injections for MR angiography are similar. MATERIALS AND METHODS: In 11 patients, repeated contrast-enhanced 2D-turbo-FLASH scans with 1-sec interval were obtained. Both test and main dose time-intensity curves were acquired from the abdominal aorta, and the parameters of time-intensity curves for the test and main boluses were compared. The parame-ters used were arterial and venous enhancement times, arterial peak enhance-ment time, arteriovenous circulation time, enhancement duration and enhance-ment expansion ratio. RESULTS: Between the main and test boluses, arterial and venous enhance-ment times and arteriovenous circulation time showed statistically significant correlation (p < 0.01), with correlation coefficients of 0.95, 0.92 and 0.98 respectively. Although the enhancement duration was definitely greater than infusion time, reasonable measurement of the end enhancement point in the main bolus was impossible. CONCLUSION: Only arterial and venous enhancement times and arteriovenous circulation time of the main bolus could be predicted from the test-bolus results. The use of these reliable parameters would lead to improvements in the scan timing method for MR angiography.

Contrast-Enhanced Magnetic Resonance Angiography: Dose the Test Dose Bolus Represent the Main Dose Bolus Accurately?

OBJECTIVE: To determine whether the time-intensity curves acquired by test and main dose contrast injections for MR angiography are similar. MATERIALS AND METHODS: In 11 patients, repeated contrast-enhanced 2D-turbo-FLASH scans with 1-sec interval were obtained. Both test and main dose time-intensity curves were acquired from the abdominal aorta, and the parameters of time-intensity curves for the test and main boluses were compared. The parame-ters used were arterial and venous enhancement times, arterial peak enhance-ment time, arteriovenous circulation time, enhancement duration and enhance-ment expansion ratio. RESULTS: Between the main and test boluses, arterial and venous enhance-ment times and arteriovenous circulation time showed statistically significant correlation (p < 0.01), with correlation coefficients of 0.95, 0.92 and 0.98 respectively. Although the enhancement duration was definitely greater than infusion time, reasonable measurement of the end enhancement point in the main bolus was impossible. CONCLUSION: Only arterial and venous enhancement times and arteriovenous circulation time of the main bolus could be predicted from the test-bolus results. The use of these reliable parameters would lead to improvements in the scan timing method for MR angiography.

Artrorresonancia magnética del hombro / MR arthrography of the shoulder

La Artrorresonancia Magnética Nuclera (ARM) del hombro es una modalidad diagnóstica que combina las ventajas de la Artrografía convencional y la Resonancia Magnética Nuclear (MN). La inyección intraarticular de Gadolinio distiende y contrasta la articulación, destacándose estructuras intraarticulares que normalmente no se ven adecuadamente en un estudio de RM convencional, entre ellas el lábrum, la cápsula y los ligamentos glenohumerales, el complejo lábrum-biceps y la superficie articular de los tendones del manguito rotador. Las principales indicaciones de la ARM son los estados de inestabilidad glenohumeral, ciertos casos de afectación del manguito rotador y del tendón bicipital y el dolor de hombro de causa no probada con RM previa. El objetivo de este trabajo es el de evaluar la ARM aplicada al estudio de la anatomía y la patología de la articulación del hombro