MRI-based differentiation between lymphoma and sarcoidosis in mediastinal lymph nodes.

OBJECTIVE: Evaluation of enlarged mediastinal lymph nodes is crucial for patient management. Malignant lymphoma and sarcoidosis are often difficult to differentiate. Our objective was to determine the diagnostic accuracy of MRI for differentiating between sarcoidosis and malignant lymphoma. METHODS: This was a retrospective study involving 47 patients who underwent chest MRI and were diagnosed with one of the diseases between 2017 and 2019. T1, T2, and diffusion-weighted signal intensity were measured. Apparent diffusion coefficients (ADCs) and T2 ratios were calculated. The diagnostic performance of MRI was determined by ROC analysis. RESULTS: Mean T2 ratio was significantly lower in the sarcoidosis group than in the lymphoma group (p = 0.009). The T2-ratio cutoff value that best differentiated between lymphoma-related and sarcoidosis-related enlarged lymph nodes was 7.1, with a sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of 58.3%, 95.6%, 76.5%, 93.3%, and 68.7%, respectively. The mean ADC was significantly lower in the lymphoma group than in the sarcoidosis group (p = 0.002). The ADC cutoff value that best differentiated between lymphoma-related and sarcoidosis-related enlarged lymph nodes was 1.205, with a sensitivity, specificity, positive predictive value, negative predictive value and accuracy of 87.5%, 82.6%, 85.1%, 84.0% and 86.3%, respectively. No significant differences were found between the two groups regarding T1 signal intensity, T2 signal intensity, and lymph node diameter. CONCLUSIONS: MRI parameters such as ADC, diffusion, and T2 ratio can be useful in the differentiation between sarcoidosis and lymphoma in the evaluation of enlarged lymph nodes.

MRI-based differentiation between lymphoma and sarcoidosis in mediastinal lymph nodes / Diferenciação entre linfoma e sarcoidose em linfonodos mediastinais por RMN

ABSTRACT Objective: Evaluation of enlarged mediastinal lymph nodes is crucial for patient management. Malignant lymphoma and sarcoidosis are often difficult to differentiate. Our objective was to determine the diagnostic accuracy of MRI for differentiating between sarcoidosis and malignant lymphoma. Methods: This was a retrospective study involving 47 patients who underwent chest MRI and were diagnosed with one of the diseases between 2017 and 2019. T1, T2, and diffusion-weighted signal intensity were measured. Apparent diffusion coefficients (ADCs) and T2 ratios were calculated. The diagnostic performance of MRI was determined by ROC analysis. Results: Mean T2 ratio was significantly lower in the sarcoidosis group than in the lymphoma group (p = 0.009). The T2-ratio cutoff value that best differentiated between lymphoma-related and sarcoidosis-related enlarged lymph nodes was 7.1, with a sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of 58.3%, 95.6%, 76.5%, 93.3%, and 68.7%, respectively. The mean ADC was significantly lower in the lymphoma group than in the sarcoidosis group (p = 0.002). The ADC cutoff value that best differentiated between lymphoma-related and sarcoidosis-related enlarged lymph nodes was 1.205, with a sensitivity, specificity, positive predictive value, negative predictive value and accuracy of 87.5%, 82.6%, 85.1%, 84.0% and 86.3%, respectively. No significant differences were found between the two groups regarding T1 signal intensity, T2 signal intensity, and lymph node diameter. Conclusions: MRI parameters such as ADC, diffusion, and T2 ratio can be useful in the differentiation between sarcoidosis and lymphoma in the evaluation of enlarged lymph nodes.

RESUMO Objetivo: A avaliação de linfonodomegalias mediastinais é crucial para o manejo dos pacientes. O linfoma maligno e a sarcoidose costumam ser difíceis de diferenciar. Nosso objetivo foi determinar a precisão diagnóstica da RMN para diferenciar sarcoidose de linfoma maligno. Métodos: Estudo retrospectivo com 47 pacientes submetidos a RMN de tórax e diagnosticados com uma das doenças entre 2017 e 2019. Foi medida a intensidade do sinal em T1, T2 e difusão. Foram calculados o coeficiente de difusão aparente (ADC, do inglês apparent diffusion coefficient) e a razão T2. O desempenho diagnóstico da RMN foi determinado pela análise da curva ROC. Resultados: A média da razão T2 foi significativamente menor no grupo sarcoidose que no grupo linfoma (p = 0,009). A razão T2 = 7,1 foi o melhor valor de corte para diferenciar linfonodomegalias relacionadas com linfoma daquelas relacionadas com sarcoidose, com sensibilidade, especificidade, valor preditivo positivo, valor preditivo negativo e precisão de 58,3%, 95,6%, 76,5%, 93,3% e 68,7%, respectivamente. A média do ADC foi significativamente menor no grupo linfoma que no grupo sarcoidose (p = 0,002). O ADC = 1,205 foi o melhor valor de corte para diferenciar linfonodomegalias relacionadas com linfoma daquelas relacionadas com sarcoidose, com sensibilidade, especificidade, valor preditivo positivo, valor preditivo negativo e precisão de 87,5%, 82,6%, 85,1%, 84,0% e 86,3%, respectivamente. Não houve diferença significativa entre os grupos quanto à intensidade do sinal em T1, intensidade do sinal em T2 e diâmetro dos linfonodos. Conclusões: Parâmetros de RMN como ADC, difusão e razão T2 podem ser úteis na diferenciação entre sarcoidose e linfoma na avaliação de linfonodomegalias.

Mild Therapeutic Hypothermia Increases Glutathione Levels in Postcardiac Arrest Patients.

Ischemia-reperfusion (I/R)-induced oxidative stress is one of the main mechanisms of tissue injury after cardiac arrest (CA). A decrease in antioxidant defenses may contribute to I/R injury. The present study aims to investigate the influence of mild therapeutic hypothermia (MTH) on levels of nonenzymatic antioxidants after CA. We investigated antioxidant levels at 6, 12, 36, and 72 hours after CA in central venous blood samples of patients admitted to intensive care. The sample consisted of 31 patients under controlled normothermia (36°C) and 11 patients treated with 24 hours of MTH (33°C). Erythrocyte glutathione (GSH) levels were elevated by MTH, increasing at 6, 12, 36, and 72 hours after CA in hypothermic patients (mean GSH levels in normothermic patients: 6 hours = 73.89, 12 hours = 56.45, 36 hours = 56.46, 72 hours = 61.80 vs. hypothermic patients: 6 hours = 176.89, 12 hours = 198.78, 36 hours = 186.96, and 72 hours = 173.68 µmol/g of protein). Vitamin C levels decreased significantly at 6 and 12 hours after CA in hypothermic patients (median vitamin C levels in normothermic patients: 6 hours = 7.53, 12 hours = 9.40, 36 hours = 8.56, and 72 hours = 8.51 vs. hypothermic patients: 6 hours = 5.46, 12 hours = 5.44, 36 hours = 6.10, and 72 hours = 5.89 mmol/L), coinciding with the period of therapeutic hypothermia. Vitamin E and nitric oxide levels were not altered by hypothermic treatment. These findings suggest that MTH alters nonenzymatic antioxidants differently, decreasing circulating vitamin C levels during treatment; however, MTH elevates GSH levels, possibly protecting tissues from I/R injury after CA.

Therapeutic Hypothermia Reduces Oxidative Damage and Alters Antioxidant Defenses after Cardiac Arrest.

After cardiac arrest, organ damage consequent to ischemia-reperfusion has been attributed to oxidative stress. Mild therapeutic hypothermia has been applied to reduce this damage, and it may reduce oxidative damage as well. This study aimed to compare oxidative damage and antioxidant defenses in patients treated with controlled normothermia versus mild therapeutic hypothermia during postcardiac arrest syndrome. The sample consisted of 31 patients under controlled normothermia (36°C) and 11 patients treated with 24 h mild therapeutic hypothermia (33°C), victims of in- or out-of-hospital cardiac arrest. Parameters were assessed at 6, 12, 36, and 72 h after cardiac arrest in the central venous blood samples. Hypothermic and normothermic patients had similar S100B levels, a biomarker of brain injury. Xanthine oxidase activity is similar between hypothermic and normothermic patients; however, it decreases posthypothermia treatment. Xanthine oxidase activity is positively correlated with lactate and S100B and inversely correlated with pH, calcium, and sodium levels. Hypothermia reduces malondialdehyde and protein carbonyl levels, markers of oxidative damage. Concomitantly, hypothermia increases the activity of erythrocyte antioxidant enzymes superoxide dismutase, glutathione peroxidase, and glutathione S-transferase while decreasing the activity of serum paraoxonase-1. These findings suggest that mild therapeutic hypothermia reduces oxidative damage and alters antioxidant defenses in postcardiac arrest patients.

Blood markers of oxidative stress predict weaning failure from mechanical ventilation.

Patients undergoing mechanical ventilation (MV) often experience respiratory muscle dysfunction, which complicates the weaning process. There is no simple means to predict or diagnose respiratory muscle dysfunction because diagnosis depends on measurements in muscle diaphragmatic fibre. As oxidative stress is a key mechanism contributing to MV-induced respiratory muscle dysfunction, the aim of this study was to determine if differences in blood measures of oxidative stress in patients who had success and failure in a spontaneous breathing trial (SBT) could be used to predict the outcome of MV. This was a prospective analysis of MV-dependent patients (≥72 hrs; n = 34) undergoing a standard weaning protocol. Clinical, laboratory and oxidative stress analyses were performed. Measurements were made on blood samples taken at three time-points: immediately before the trial, 30 min. into the trial in weaning success (WS) patients, or immediately before return to MV in weaning failure (WF) patients, and 6 hrs after the trial. We found that blood measures of oxidative stress distinguished patients who would experience WF from patients who would experience WS. Before SBT, WF patients presented higher oxidative damage in lipids and higher antioxidant levels and decreased nitric oxide concentrations. The observed differences in measures between WF and WS patients persisted throughout and after the weaning trial. In conclusion, WF may be predicted based on higher malondialdehyde, higher vitamin C and lower nitric oxide concentration in plasma.

Oxidative stress in the kidney of reproductive male rats during aging.

Reproduction alters the male physiology. We performed a comprehensive examination of oxidative stress in the kidneys of male rats with (experienced) or without (naïve) reproductive activity during aging. Oxidative stress was assessed by measuring the activity of catalase, glutathione peroxidase, glutathione S-transferase, and superoxide dismutase, and by measuring protein carbonylation, lipid peroxidation, nitrite and nitrate levels, vitamin C levels, and glutathione (total, reduced, and oxidized forms) levels, and metabolism was accessed by aconitase activity in kidney tissue, as well as testosterone and estradiol levels in serum. Reproductively active animals exhibited increased testosterone levels and altered metabolism. Aging affects tissues and organs and contributes to their functional decline. Elderly naïve rats showed high nitrite and nitrate levels. The experienced rats had less damage in elderly ages, probably because they had higher antioxidant amount and antioxidant enzyme activities at earlier ages, which would have avoided oxidative damage seen in naïve group, and because of the metabolism decline. Glutathione increase in naïve elder rats probably was induced for direct protection against oxidative damage and indirect protection by higher glutathione peroxidase and glutathione S-transferase activities. Linear regression shows that lipid peroxidation levels explained vitamin C levels (B standardized value of 0.42), indicating that vitamin C was properly produced or recruited into kidneys to combat lipid peroxidation. Catalase activity reflected the protein carbonylation and lipid peroxidation levels (B standardized values of 0.28 and 0.48). These results add comprehensive data regarding changes in oxidative stress during aging, and suggest an explanation for the costs of reproduction.

Carbonyl groups: Bridging the gap between sleep disordered breathing and coronary artery disease.

Sleep disordered breathing (SDB) is related to coronary artery disease (CAD), but the mechanisms are uncertain. SDB is characterized by periods of intermittent hypoxia and free radical formation. This study tested the hypothesis that carbonylation can be the link between SDB and CAD. It included 14 cases with CAD and 33 controls with <50% coronary narrowing. CAD cases have higher erythrocyte carbonyl levels than controls (p = 0.012). Positive correlation was observed between apnea-hypopnea index (AHI) and erythrocyte carbonyl concentration (rho = 0.310; p = 0.027). To predict CAD, including as regressors: AHI, erythrocyte carbonyl, gender, age and body mass index, the significant variables in the Poisson multiple regression model were AHI and erythrocytes carbonyl. An increase of 1 pmol/gHb in erythrocyte carbonyl levels increases by 1.8% the risk of CAD and one unit of AHI increases by 3.8% the risk of CAD. The present findings represent the first evidence in humans that SDB may cause CAD through protein carbonylation.