RESUMO
BACKGROUND: Prolonged breath holding results in hypoxemia and hypercapnia. Compensatory mechanisms help maintain adequate oxygen supply to hypoxia sensitive organs, but burden the cardiovascular system. The aim was to investigate human compensatory mechanisms and their effects on the cardiovascular system with regard to cardiac function and morphology, blood flow redistribution, serum biomarkers of the adrenergic system and myocardial injury markers following prolonged apnoea. METHODS: Seventeen elite apnoea divers performed maximal breath-hold during cardiovascular magnetic resonance imaging (CMR). Two breath-hold sessions were performed to assess (1) cardiac function, myocardial tissue properties and (2) blood flow. In between CMR sessions, a head MRI was performed for the assessment of signs of silent brain ischemia. Urine and blood samples were analysed prior to and up to 4 h after the first breath-hold. RESULTS: Mean breath-hold time was 297 ± 52 s. Left ventricular (LV) end-systolic, end-diastolic, and stroke volume increased significantly (p < 0.05). Peripheral oxygen saturation, LV ejection fraction, LV fractional shortening, and heart rate decreased significantly (p < 0.05). Blood distribution was diverted to cerebral regions with no significant changes in the descending aorta. Catecholamine levels, high-sensitivity cardiac troponin, and NT-pro-BNP levels increased significantly, but did not reach pathological levels. CONCLUSION: Compensatory effects of prolonged apnoea substantially burden the cardiovascular system. CMR tissue characterisation did not reveal acute myocardial injury, indicating that the resulting cardiovascular stress does not exceed compensatory physiological limits in healthy subjects. However, these compensatory mechanisms could overly tax those limits in subjects with pre-existing cardiac disease. For divers interested in competetive apnoea diving, a comprehensive medical exam with a special focus on the cardiovascular system may be warranted. TRIAL REGISTRATION: This prospective single-centre study was approved by the institutional ethics committee review board. It was retrospectively registered under ClinicalTrials.gov (Trial registration: NCT02280226 . Registered 29 October 2014).
Assuntos
Apneia/diagnóstico por imagem , Suspensão da Respiração , Sistema Cardiovascular/diagnóstico por imagem , Mergulho , Imagem Cinética por Ressonância Magnética , Adaptação Fisiológica , Adulto , Apneia/sangue , Apneia/fisiopatologia , Biomarcadores/sangue , Sistema Cardiovascular/metabolismo , Sistema Cardiovascular/fisiopatologia , Mergulho/efeitos adversos , Epinefrina/sangue , Feminino , Hemodinâmica , Humanos , Masculino , Pessoa de Meia-Idade , Peptídeo Natriurético Encefálico/sangue , Norepinefrina/sangue , Fragmentos de Peptídeos/sangue , Valor Preditivo dos Testes , Fluxo Sanguíneo Regional , Fatores de Risco , Fatores de Tempo , Troponina/sangue , Função Ventricular Esquerda , Adulto JovemRESUMO
Cystic renal lesions are most often simple or complicated cysts, which can be seen solitary or as part of cystic renal disease. The minority of these lesions are benign or malignant cystic tumors. The classification of cystic renal masses by Bosniak (category l - IV) based on specific ultrasound and CT features is very useful for the characterization of the lesion and for the therapeutic decision. The main objective of this classification is to differentiate nonsurgical (category II) from surgical cystic masses (category III/IV). Ultrasound is the first modality of choice in the diagnostic work-up of cystic renal masses, because an accurate and economically reasonable diagnosis of the frequent simple cyst can be made by maintaining rigid ultrasound criteria of the Bosniak classification. If a complicated cyst or a cystic tumor is suspected a three phasic contrast-enhanced CT of the kidneys should be performed. MRI is superior to CT in the characterization of complex cystic masses.
Assuntos
Doenças Renais Císticas/diagnóstico , Neoplasias Renais/diagnóstico , Imageamento por Ressonância Magnética , Tomografia Computadorizada por Raios X , Ultrassonografia , Análise Custo-Benefício , Alemanha , Humanos , Doenças Renais Císticas/classificação , Doenças Renais Císticas/economia , Doenças Renais Císticas/patologia , Neoplasias Renais/classificação , Neoplasias Renais/economia , Neoplasias Renais/patologia , Imageamento por Ressonância Magnética/economia , Tomografia Computadorizada por Raios X/economia , Ultrassonografia/economiaRESUMO
The combined use of perfusion imaging (PI) and diffusion-weighted imaging (DWI) is opening a new window into the processes that occur during the first hours of ischemia. DWI detects changes in molecular diffusion associated with cytotoxic edema. PI characterizes the degree of regional hypoperfusion. Regions showing mismatches between DWI and PI, i.e. hypoperfused areas with normal diffusion behavior are considered potentially salvageable. We present results of 11 patients with an occlusion of the middle cerebral artery stem and spontaneous stroke evolution. Whereas the infarct was clearly visible on initial DWI and PI, surrounding tissue at risk of infarction was marked in all patients by an increased blood volume and transit time, but only in a subgroup (n = 3) where alteration were more pronounced this tissue at risk was progressively infarcted. These human DWI and PI data show alterations in the area of tissue at risk which correlates with infarct progression.
Assuntos
Isquemia Encefálica/patologia , Encéfalo/anatomia & histologia , Encéfalo/patologia , Imagem de Difusão por Ressonância Magnética , Angiografia por Ressonância Magnética , Adolescente , Adulto , Idoso , Isquemia Encefálica/fisiopatologia , Circulação Cerebrovascular/fisiologia , Feminino , Humanos , Infarto da Artéria Cerebral Média , Masculino , Pessoa de Meia-IdadeRESUMO
We sought to evaluate a three-dimensional (3D) whole-brain perfusion technique based on echo-shifting (PRESTO) for its performance in evaluation of acute stroke. Twenty-six patients were scanned within 6 hours after onset of hemispheric symptoms, and the results were compared with results of diffusion-weighted imaging (DWI) and digital subtraction angiography (DSA). The signal-to-noise ratio of the images was 61 +/- 3 pre-contrast and 47 +/- 3 at the bolus peak. Brain coverage on perfusion parameter maps was 95% +/- 2% compared with that displayed on T2-weighted images, with only minor artifacts related to susceptibility at the skull base. Measured regional cerebral blood volume (rCBV) reduction closely correlated to lesion size on initial DWI and to final clinical outcome (P = 0.006), consistent with results previously reported for 2D perfusion methods. Mismatches between DWI and perfusion imaging characterized the total extent of tissue at risk, and the contrast timing correlated with the amount of collateral circulation as shown on DSA. In conclusion, 3D imaging using the PRESTO technique permits high-quality perfusion imaging of the entire brain.
Assuntos
Infarto Cerebral/diagnóstico , Imagem Ecoplanar , Aumento da Imagem , Processamento de Imagem Assistida por Computador , Imageamento por Ressonância Magnética , Adolescente , Adulto , Idoso , Angiografia Digital , Artefatos , Encéfalo/irrigação sanguínea , Angiografia Cerebral , Meios de Contraste , Feminino , Gadolínio DTPA , Humanos , Masculino , Pessoa de Meia-Idade , Fluxo Sanguíneo Regional/fisiologia , Sensibilidade e EspecificidadeRESUMO
PURPOSE: Evaluation of the diagnostic value of the imaging modalities computed tomography (CT), magnetic resonance imaging (MRI), and thoracic sonography in the preoperative staging of malignant pleural mesothelioma. MATERIALS AND METHODS: The diagnostic accuracy of CT (n = 41), MRI (n = 24), and thoracic sonography (n = 37) were evaluated in 51 patients with histologically proven diffuse malignant pleural mesothelioma. Values of sensitivity, specificity, positive and negative predictive values, and accuracy were calculated for the assessment of the diaphragm, lung, thoracic wall, pericardial wall, myocardium, and (retro)peritoneal space. RESULTS: The accuracy rates for CT were 85%, 98%, 83%, 73%, 71%, and 83%. MRI had an accuracy of 71%, 92%, 71%, 83%, 71%, and 96%, the thoracic ultrasound examinations of 76%, 63%, 51%, 60%, 71%, and 89%. CONCLUSIONS: According to these results CT remains the method of choice in the preoperative assessment of T-stage of malignant pleural mesothelioma. MRI is of nearly the same value, but is not a must. Sonography may be supplementary method for operation planning.